ABSTRACT. Improving the temporal and spatial distribution of the archaeomagnetic reference data is necessary to increase the reliability and accuracy of current geomagnetic field models and to provide information on the past evolution of the Earth’s magnetic field. Even though Europe is characterized by the highest density of archaeomagnetic data compared to other continents, there are still some geographical areas that are poorly covered by reliable and high-quality geomagnetic field records, such as the Eastern Mediterranean. Actually, apart from Greece and Bulgaria that have a long history of archaeomagnetic investigations, and Israel that has recently published a catalogue with archaeomagnetic directions, the available directional data from Turkey, Cyprus, Syria and Lebanon are still scarce. In this study we present new directional archaeomagnetic results from four archaeological sites in Cyprus, and also explore the feasibility of archaeomagnetic dating in the island.

ABSTRACT. Sphakia is a diverse and moutainous region in SW Crete, Greece. The present study deals with the archaeometric characterization of the Roman-Late Roman ceramic assemblage collected during the archaeological surface survey undertaken in the 1980s and 1990s.by Drs J. Moody and L. Nixon. The ceramic shapes recognized include fine drinking and serving vessels such as kantharoi, skyphoi, hydriae, bowls, cups, dishes, plates, transport vessels mainly amphorae, and some domestic vessels (mainly beehives). Our main aim was to identify the Cretan production against potential imports from off-Cretan centers and local imitations of foreign prototypes. For this reason a total of 101 ceramic sherds were analyzed through mineralogical (X-ray powder Diffraction - XRPD; Optical microscopy – OM), petrographic (OM), and microstructural (Scanning Electron Microscopy – SEM) techniques. In spite of their qualitative similarities in terms of their content in aplastic inclusions, the textural differences observed through OM helped us identify five petrographic groups and two loners. Moreover, the compositional analysis of the clay pastes helped us distinguish between calcareous and non calcareous groups, and investigate further the technological parameters of this assemblage, namely the clay recipes and firing temperatures. The study and analysis of the material offers an in-depth investigation of the pottery that was produced in or reached this remote part of Crete in an era of intense circulation and sea trade in the Mediterranean. Moreover, it shows the potential of the interdisciplinary approach in a challenging pottery assemblage like the one from Sphakia deriving from surface survey.

ABSTRACT. In the present study petrographic and mineralogical techniques are employed for the compositional characterization of a ceramic assemblage from the site of Kephala Vasilikis, situated on the northern part of the Ierapetra Isthmus in east Crete. The aim is to investigate the provenance of the raw materials and the technology of manufacture of the ceramics.

ABSTRACT. Mt Olympus (2919 m.a.s.l.) and Mt Ossa (1978 m.a.s.l.) form the northeastern boundaries of the Thessalian Plain in Central Greece, separating the plain from the Aegean Sea. At the lower slopes of Mt Olympus and Mt Ossa, a series of intra-mountain basins develop between the lower eastern Thessalian Plain and the main mountain blocks. The most prominent of these basins is Sikourio basin, separated from the Larisa plain by the Chassambali chain of hills. Sikourio basin is nowadays connected to another complex of smaller basins forming the Elateia basin. These intra-mountain basins probably were formed during the post-orogenic extension of Middle Tertiary (Caputo & Pavlides, 1993; Kilias, 1995). Today, Sikourio and Elateia basins are hydrologically connected to the Pinios river basin through the Kalamitsa drainage that flows towards northwest into the main Pinios river body. The river Xerias drains a large part of Mt Ossa and flows to the south towards the remnants of the lake Bara Toibasi in the southern part of Sikourio basin (Fig.1). Kalamitsa river and its smaller tributaries drain the largest part of Sikourio and Elateia basins, forming a steep gorge at Magoula Bounarbasi, near Kispelochori. Through small sinkholes around Bara Toibasi lake, a result of karstification, lake water infiltrates and feeds the karstic aquifer developed inside the limestone formations. This karstic aquifer connects hydraulically both the surficial and the ground water of Sykourio basin with the springs that are found at the border of the bedrock formations of Chassambali hills and the East Thessalianalluvial aquifer, to the south of Sykourio basin.

The hydrological conditions affected greatly the behaviour of human groups since prehistoric times. Permanent settlements were founded here already during the Neolithic Age – some of them forming in the course of many centuries (ca. 6000 calBC to ca. 4500 calBC) several meter high mounds (e.g. Nessonis II or Magoula Bounarbasi ). Additionally, thanks to systematic surveys, a number of flat sites were detected, mainly in the area of the former lake Bara Toibasi (Fig. 1). Our working hypothesis is that these sites relate to the lake and were founded close to its former shores. We interpret Bara Toibasi lake as a remnant of an older larger lake inside Sikourio basin. This lake is different from the ancient Lake Nessonis that extended in the Larisa plain south of Girtoni and from the Lake Karla south of Eleftherio (Gallis, 1992; Caputo et al. 1994, Reingruber et al. in print). Lacustrine (lake) sediments are exposed in large abandoned clay quarries around Bara Toibasi lake, while in this study we document more outcrops to the northern part of Sikourio basin, with additional indications of probable extensive lacustrine sedimentation also in Elateia basin (Fig.1). These extensive lacustrine sediments are indicators of a wider lake system that existed inside Sikourio and Elateia basins from Pliocene (?) up to Late Pleistocene-Holocene and are covered by recent alluvial sediments from the Xerias fan and secondary fans around the basin borders.

Bara Toibasi lake was previously considered as a product of hanging-wall subsidence of a proposed eastwards segment of Girtoni fault (Caputo 1990; Caputo et al., 1994). Using geological, geomorphological and archaeological observations, we propose the existence of a proto-Sikourio lake that covered Sikourio basin during Late Neogene - Quaternary. The draining of the lake was facilitated by a) the expansion of the Xerias fan that covered the central part of the basin and b) the lake outflow towards Elateia basin through Bounarbasi gorge and probably along Kipselochori area. Xerias fan expansion and lake draining led to the creation of Bara Toibasi lake at the southern part of Sikourio, that remains disconnected hydrologically with the northern part (Fig. 2). Sediment and water supply towards the northern part of proto-Sikourio lake/basin was probably affected by changes in the mountain catchments at Mt Ossa and identified large paleo-landslides that temporarily blocked drainage towards the lake/basin. Bounarbasi gorge opening and lake outflow is estimated to have taken place before the Mesolithic period and the beginning of the Holocene, probably around or shortly after the Last Glacial Maximum (LGM, ~24-16ka BP). Neolithic sites at the southern Sikourio basin are found around the estimated paleo-shoreline of Bara Toibasi. Draining through the karstic aquifers of Chassambali hills and a probable lower water supply through Xerias river led to the shrinkage of Bara Toibasi from the Neolithic era up to today. Conditions in Elateia basin are more complex; the Elateia basin complex includes a series of small closed connected intra-mountain basins that were cut through by Pinios river during Late Quaternary, as the Pinios river eroded through Olympus-Ossa mountain range and exited towards the Aegean Sea. While lacustrine sedimentation is present in Elateia basin, its previous connection with the Sikourio basin is under investigation.

ABSTRACT. Introduction Many researchers have presented that ground penetrating radar (GPR) is a subsurface survey method indicated to acquire important preliminary information in various geological subsurface investigations, but also in archaeological and cultural heritage studies (Conyers, 2016). GPR stands out among the geophysical methods applied in archaeology, given the fact that it is a non-destructive practical field technique. GPR results can be presented as bi-dimensional profiles (2D) and three-dimension images (3D), in the form of block diagrams, fence-diagrams and volume/depth-slices. Especially the amplitude maps (e.g., depth-slices maps) allow the identification of areas with high or low amplitude of specific deep reflectors. Therefore, they can be used to identify buried targets and their dimensions, allowing the reconstruction of the subsurface in 3D (Porsani et al., 2010). Geophysical survey A combined GPR and ERT survey was performed during the summer of 2018, in the excavation of the Department of History and Archaeology of the NKUA at Plasi Marathon (Attica). On the basis of the walls of the Classical period already revealed in 2017 and the geoenvironmental conditions of the study area, the main objective of this study is to assess the existence of possible architectural remains in unexcavated parts of the site, particularly in an indicated area of 655 m^2. The existence of architectural remains would be of particular importance for the archaeologists in order to plan the next steps of the project but also to understand the density of habitation in the area. The revealed architectural remains in the adjacent excavation trenches were found in a mean depth of 0.5 m and the walls have a mean width of 0.5m. A MALA 250 MHz shielded antenna was used for the field measurements. Single-fold exploratory GPR profiles were initially carried out at the site with a horizontal spacing between the parallel profiles equal to 2 m, in order to create a 2x2 m grid. Therefore, thirty-four (34) GPR profiles were carried out (Fig.1), with a total length of 610 m, using the following specifications: i) Time sampling rate Δt=512, ii) Time window Wt=196 ns and iii) spatial sampling rate Δxs=0.02 m. The GPR data were processed with REFLEXW software, using the following package of filters: Subtract-mean (Dewow), Time-Zero Correction, Background Removal, Bandpass Filter, Deconvolution, Migration and final Hilbert Transformation-Envelope (Goodman and Piro, 2013; Porsani et al., 2010). The obtained radargrams are presented in the form of fence-diagrams in Figure 1. This simultaneous view of multiple radargrams allows us to identify the presence of the reflectors and their distribution within each radar section (Imposa et al, 2018). At this fence-diagram (Fig.1), we can observe numerous reflections, sometimes fairly pronounced, located at depths between 0.25 m and 0.85 m. Many detectable reflections appear isolated, observed with a fairly small extension within each single scan, probably generated by objects with rather small dimensions. However, in the context of the fence diagram analysis, it was observed that these isolated reflectors often show a lateral continuity. Beyond this, twenty (20) electrical resistivity tomography (ERT) sections were carried out, with a total length 413 m, in a 3x3 m grid and electrode spacing 0.25 m. An ABEM Terrameter system was used for the field measurements. The processing of the ERT data was performed with Res2DInv software. The robust inversion method is indicated for the ERT processing (Alexopoulos et al., 2014), since it provides results with sharper edges, similar to the shape of ancient domestic structures. For all the acquired ERT and GPR profiles, the coordinates were determined with dGPS (TOPCON Hiper-Pro). Discussion and Results The volume/depth-slices illustrated in Figure 2 were obtained through the interpolation of the radar scans, derived from the processed data. These slices show the variation of the reflected signal amplitude distribution at different depths/volumes (Zhao et al., 2013; 2015). The most reflective zones are illustrated in green and red colors. After a careful analysis of each radargram, we obtained three slices for depths between 0.35 and 0.65 meters (Fig. 2), where the areas characterized by high amplitude values (reflection strength) are illustrated. In many cases, these areas do not show a lateral continuity probably due to the existence of targets with limited extension. These outcomes seem to enhance the results obtained from the previous analysis (Fig.1). In the SW area of these slices (Fig.2-red dotted zone) and in a smaller part at the SE area (Fig.2-orange dotted zone), additional areas that are characterized by high amplitude values but are not identified by the previous analysis, are now observed. These areas display continuity in depth, suggesting the possible presence of significant targets that may correspond to buried archaeological remains. The validity of the results will be tested during the excavations of 2019-2020, but they suggest a rather dense pattern of habitation, implying that Plasi could have been the location of the ancient demos of Marathon. The inversion results (Fig.3) of the acquired ERT profiles, have also adumbrated areas of higher resistivity (Fig.3-reddish and purplish colors, ERT 25-04 positioned in Fig.2) that probably correspond to buried architectural remains.

ABSTRACT. The strain energy accumulated in the Earth's crust is released by a continuum of slip processes ranging from completely aseismic (i.e., slow and continuous) to fully seismic (i.e. instant rupture with km/s propagation resulting in corresponding ground motions) through several types of intermediate signals such as episodic tremor or slow earthquakes (e.g. Shelly et al., 2006, 2007; Ide et al., 2007; Rubinstein et al., 2007; 2009; Peng and Gomberg, 2010). While it is generally accepted that the occurrence of aseismic vs. seismic deformation is controlled by the fault structure (i.e. frictional properties, existence and size of asperities) (Scholz, 2002; Rubin and Ampuero, 2005; Rubin, 2008), our current process understanding on which of these deformation types dominates under which conditions is still incomplete (Harris, 2017). Furthermore, the aseismic energy release or fault creep has been usually considered in seismic hazard models as a factor reducing the amount of energy available to produce large earthquakes (Field et al., 2014). Whether aseismic slip really leads to a decreased seismic hazard also depends on many factors, such as the fraction of the fault on which creep occurs and the effect of aseismic deformation on potentially loading nearby faults. Furthermore, recent studies have shown that large earthquakes may be preceded by an acceleration of the slow slip on the interface (Bouchon et al. 2011, 2013, Kato et al. 2012, Ruiz et al. 2014), and that moderate to large earthquakes can be triggered by the propagation of a slow deformation (Durand et al. 2014). In consequent, it is important to understand how slow and fast slip interact, and what is controlling the type of slip on a fault.

The ICDP-GONAF geophysical observatory started operating in 2015 with the main goal of characterizing the deformation in the eastern Sea of Marmara region in direct vicinity of Istanbul metropolitan region and its > 15 Million inhabitants. GONAF includes seven borehole seismic arrays at different locations of the eastern Sea of Marmara as well as four boreholes equipped with strainmeters operated by UNAVCO. Recently, a large strain signal lasting for 50 days has been found in the strainmeter data recorded at the GONAF-Esenkoy station in 2016 (Martinez-Garzon et al., 2019), suggesting that the slow slip source could be located within the nearby Cinarcik segment, an intermediate branch of the North Anatolian Fault. The offset observed in the strain signal is concomitant with the occurrence of a MW4.4 earthquake located 30km away in the Cinarcik basin. This signal also corresponds to an increase of the seismic moment released in the region, including eight earthquakes of magnitude greater than 3.5. On another hand, the strain signal does not correlate with known environmental parameters such as changes of sea level, rainfall or temperature. By consequence, we infer that this signal could indicate local slow slip on the Cinarcik fault. Before the same MW4.4 earthquake, a sequence of foreshocks has been observed (Malin et al. 2018). These foreshocks exhibit waveforms strikingly similar to the one of the mainshock. This similarity may mean that the source area of the mainshock is failing in a repetitive way before the occurrence of the main earthquake, maybe under the action of a transient forcing, like slow slip. Furthermore, identifying clusters of seismicity based on the rescaled nearest neighbor distance between events, we show that the Cinarcik region is particularly prone to the presence of foreshocks. All these observations are in favor of the existence of interplay between slow and fast deformation in the Cinarcik fault region. It is of particular interest to understand the processes controlling the deformation in this region because the Cinarcik fault could have hosted the M6.3 earthquake which occurred in 1963, and so is contributing to increase the seismic hazard to which Istanbul is exposed. In January 2019, in order to intensify the seismic coverage of the Armutlu Peninsula in the eastern Sea of Marmara, we deployed a temporal seismic network (Figure 1) directly on top of the Cinarcik fault, located roughly -50 km away from the Istanbul metropolitan region. We installed at total of 20 short-period stations (1Hz and 4.5Hz) and 5 broadband stations to capture a broader frequency range and reach a good azimuthal coverage for locating microseismicity and creep processes along the onshore portion of the Cinarcik fault. The main objective of this experiment is to characterize the seismic and aseismic deformation of this eventually creeping fault which is in direct vicinity to the recent 2016 MW 4.4 earthquake (Malin et al., 2018) and the slow-slip episode recorded in the strainmeter in relation to the MW 4.4 event (Martinez-Garzon et al., 2019)

ABSTRACT. The North Aegean Trough (NAT) is considered as an expression of the prolongation of the North Anatolian Fault (NAF) into the Aegean Sea (McKenzie, 1970; Lyberis, 1984; Armijo et al., 1999; Papanikolaou et al., 2002, 2006; Brun et al., 2016). The NAF is divided into eastern and western branch, with mean strike N70°E and N40°E respectively, and the turning point is been located NW of Lemnos Island (Sakellariou and Tsampouraki-Kraounaki, 2018). These two branches of the fault are responsible for the formation of the eastern and the western North Aegean basins, respectively. The present study is specialized in the western termination of the NAT, in order to analyze the tectonic structures that consist the North Anatolian Fault. The database utilized in this analysis, i.e. swath bathymetry data and seismic profiles, was acquired in the framework of the nationally funded "YPOTHER/Aegean Explorations" project, implemented by the Institute of Geology & Mining Exploration (IGME) and the Hellenic Centre for Marine Research (HCMR). Swath bathymetry data were acquired with a 20 kHz SeaBeam 2120 (L3 ELAC Nautic), hull-mounted, multibeam system and were complemented with data obtained by HCMR in 2000, reprocessed at 25m grid. The fault network across the western branch of NAF was analyzed using 53 seismic profiles, of which 38 are airgun 10 in3 seismic profiles and 15 are airgun 40 in3 seismic profiles. The analysis of the submarine morphology and the structural analysis along the western termination of the NAF, revealed that it consists a fault – controlled area. The western NAF is not a major, linear brittle structure, but rather a zone of numerous, parallel to sub – parallel, undulating fault segments, overlapping with others with soft – linkage, forming the western NAF zone. The fault segments are arranged in a mean strike N40°E, they are very steep or nearly vertical, their direction of dip is towards NW or SE and they accommodate a combination of shear and dip slip component, with the latter being greater towards the southwestern segments. The results of the seismic profiles analysis of the area, implied that the fault segments consist the upper parts of negative and positive flower structures, that are created due to the oblique slip along the main strike – slip faults. Furthermore, the pure dextral strike – slip motion with a dip – slip component is verified by the determined focal mechanisms for all the earthquakes with magnitude Mw > 3.5 that occurred in the vicinity of the study area from 2006 until present (Figure 1B). The submarine morphology of the NE – SW oriented marginal zone is rather complex and disparate. In particular, subsided areas with relatively greater water depth and uplifted areas with relatively smaller water depth can be observed. In other words, the southern marginal zone of NAT consists of a series of spatially alternating structural highs and lows. Specifically, three morphological depressions and two ridges can be distinguished from SW to NE: Alonissos Deep, Psathoura Ridge, Psathoura Deep and Myrina Ridge and Lemnos Deep. Alonissos Deep is the last structure before the SW end of the NAF zone and corresponds to a tectonic half – graben. The master marginal fault is located along the southern margin of the deep. This marginal fault accommodates significant normal component, with dip direction towards NW. The uplifted footwall is composed of the alpine basement and the basin is formed on the subsided hanging wall block. The direction of the extension of the basin is almost N44°W. The depression is characterized by enhanced subsidence, due to the contemporary activity of the NE – SW trending strike – slip fault segments of the NAF zone with the normal component, dipping towards NW and the normal Pelion – Skiathos Fault with direction NW – SE, dipping NE (Papanikolaou et al., 2006; Sakellariou et al., 2016). The area between Alonissos Deep and Psathoura Ridge is a submarine hill with the SE area being uplifted. The hill is formed by parallel, NE – SW trending faults segments with normal component, dipping NW. Psathoura Ridge is located east of the islet Psathoura, and represents a structural high that is formed by two parallel fault segments that accommodate normal dip – slip component and have opposite direction of dip, i.e. the major northern marginal fault has dip direction towards NW and the southern one has dip direction towards SE. Between the two aforementioned faults, a tectonic horst is pushed upwards. Psathoura Deep consists a tectonic graben by arranged strike – slip NAF segments with normal component that dip towards the center of the depression. The northern NE – SW margin is composed of two overlapping marginal fault segments that have a dip direction towards SE. The direction of the extension of the basin is almost N42°W. The area between Psathoura Deep and Myrina Ridge is quite complex and only few insufficient data were available, thus detailed structural analysis and therefore, submarine mapping, could not be possible. However, on Myrina Ridge, two major, parallel fault segments were mapped. These faults dip NW and accommodate normal component that uplifts the footwall block of both of them (SE block) and subsides the hanging wall block (NW block). There were not data available further NE, to investigate the possibility of the existence of an antithetic NE – SW trending fault that dips SE and might be the marginal fault of a horst structure, like the one on Psathoura Ridge. A major landslide affected Lesvos Deep, creating a characteristic submarine morphology and thus, the original structure of the deep cannot be determined. Further analysis of the submarine morphology was made by constructing a slope map of the study area. The abrupt change of slope usually reflects the location of active tectonic structures, thus corresponds to their location and the negligible change of slope corresponds to the location of flat-lying areas between the tectonic features (Papanikolaou et al., 2002; Sakellariou et al., 2018) Consequently, the slope map of Figure 2 confirms the results of the structural analysis through the seismic reflection profiles, that is the area along the western NAT consist of many active tectonic elements.

ABSTRACT. GPS data describe well deformation of the crust in tectonicaly active regions, but they cover a period of up to few decades only, and this interval is very short compared to geological processes and the repeat intervals of earthquakes. A possibility to expand this geodetic record is to exploit historical geodetic data. In this article we analyze triangulation data covering the west edge of the North Aegean Trough (NAT), an area of complicated tectonics, and document an instability in the kinematics of the study area in time scale of a few tens of years. This result is consistent with the distribution of earthquakes and may provide some clues on the termination of major strike slip faults.

ABSTRACT. North Aegean is in the broader Eastern Mediterranean region. The general geodynamic evolution of the area is related to the westward tectonic escape of the Anatolia plate, which is interacting with the Arabian plate, as well as with the ogoing subduction of the African plate beneath the Eurasian one. This coupled interaction is causing the southwestern movement of the Aegean region (McKenzie, 1978; Le Pichon and Angelier, 1979). The recorded, by permanently installed GPS/GNSS stations, geodetic data confirm this movement (McClusky et al., 2000; Hollenstein et al., 2008). The surficial deformation of the area can also be estimated by using the recorded GPS/GNSS velocities. Regarding the tectonic setting of the study area, numerous onshore and offshore active tectonic structures have been documented (Sboras, 2011 and references therein). The dominant one is the ENE – WSW trending North Aegean Trough (NAT) fault zone, while fault zones of different strikes (Thrace, Drama, Belles, Mygdonia, Aliakmonas, Tyrnavos, etc.) associated to the Oligocene – Miocene extensional regime are deforming parts of the northern Greek mainland (e.g. Mountrakis et al., 2006; Sboras et al., 2017). Several of these fault zones are associated with modern or historical seismic events. Palaeomagnetic research in the broader Aegean area (including continental Greece and western Anatolia) has provided a considerable amount of data, a part of which covers the presently studied area (Kondopoulou, 2000 and references therein; van Hinsbergen et al., 2005; Kaymakci et al., 2007; Zananiri et al., 2013). The pattern arising from these studies for the last 5 to 20Myr clearly defines a fast, clockwise rotating block at the north-western part of the studied area. The pattern is less precise at its eastern and northern parts with a mixture of counter-clockwise and no rotations. The northern Greece deformation appearing from palaeomagnetic data has also been documented by independent models (Brun and Sokoutis, 2018). The use of Satellite Geodesy is a reliable way for estimating the current activity pattern, as well as the crustal deformation of a study area. To this end, a dense network of permanently installed GPS/GNSS is necessary to collect the geodetic data. The study area is covered by 77 different GPS/GNSS stations collecting primary geodetic data. A subset covering a seven-year period (2008 – 2014) was used in this study, using data recorded during 30-sec daily GPS observations. The European Terrestrial Reference Frame 2000 (ETRF2000), which considers Eurasia plate as stable, is the geodetic data reference frame. Based on the primary geodetic data, including the East and North velocity components and their uncertainties, derived from the permanently installed GPS/GNSS stations, both the rotation rate and the orientation were calculated, implementing the triangulation method. The combination of 77 stations resulted in the construction of 1,610 different triangles and therefore the extraction of 1,610 different rotation rate vectors. Based on this process, the annual rotation rate and type (clockwise rotation, counter-clockwise rotation, zero rotation) were calculated for the triangular centroids. The rate of annual rotation is minimal, therefore it cannot be visualized properly, nor it can lead to the construction of rotation models. By assuming that the rotation rate of the study area is constant, the annual rotation rate values were extrapolated, resulting in the extraction of the rotation models of -5, -10, -15 and -20 Myr (Lazos et al., 2018). The results were then geostatistically processed, using interpolation methods, in order for the entirety of the study area to be covered (Figure 1). The extrapolated rotation model has then been compared to the one suggested from palaeomagnetic data, so that it can be validated and checked for each of the time periods under consideration, to provide information about the geodynamic evolution of the study area. Based on the combination of palaeomagnetic and geodetic rotational models, the North Aegean region can been divided into five distinct blocks (Figure 2). Blocks 1 and 3 are characterized by clockwise rotation, while Blocks 2 and 4 show counter-clockwise rotation. Although Blocks 1 and 3 both show clockwise rotational behavior, they are considered separate based on their different rotation rate. Block 5 delimits an area, where the rotational regime is not clear; this block however is subjected to the general clockwise rotation of the broader area.

ABSTRACT. Objectives Several studies (e.g., Jolivet et al., 2010) suggest that the Cyclades in central Aegean region have been affected by back-arc extension triggered by the retreat of the Hellenic subduction slab. However, the initiation time of the Aegean back-arc extension remains controversial. Specifically, post-orogenic back-arc extension in Cyclades is considered to have begun either in late Eocene/early Oligocene (Jolivet et al., 2010; Laurent et al., 2017) or late Oligocene/early Miocene (Avigad et al., 1997) or late Miocene (Chatzaras et al., 2011) or potentially in lower Pliocene (Boronkay and Doutsos, 1994). In order to shed light on this controversy, we focus on the Oligocene deformation history of the Cycladic Blueschist Unit.

Tectonic framework The Cycladic Blueschist Unit suffered blueschist to eclogite facies metamorphism at early Eocene (Bröcker et al., 2013 and references therein). Subsequent ductile-stage exhumation of the unit initiated at blueschist facies conditions and progressively continued and completed at greenschist facies conditions until early Miocene (Bröcker et al., 2013). The Oligocene exhumation-related ductile deformation is mainly expressed by a penetrative foliation and an associated NE-trending stretching lineation. It is broadly accepted that top-to-the-NE shearing was dominant in west Cyclades during this deformation phase (Fig. 1: inset map) (e.g., Jolivet et al., 2010).

Figure 1. Cross-sections from (a) south Evia (after Xypolias et al., 2012), (b) north Andros (after Gerogiannis et al., 2019) and (c) north Sifnos (after Aravadinou et al., 2016) illustrating the internal structural architecture of the Cycladic Blueschist Unit. Inset shows a simplified geological map of Cyclades indicating the sense of shear in the Cycladic Blueschist Unit during Oligocene-Miocene as well as the position of the cross sections (a-c). Bu, Basal unit; Pe, Pelagonian; Upu, Uppermost unit; NCDS and WCDS, North and West Cycladic Detachment System, respectively.

However, the tectonic context in which this shearing occurred remains controversial. Specifically, it has been suggested that the Oligocene NE-directed shearing has: (a) a normal-sense and reflects the motion of the upper NE-dipping detachment formed during SW-wards Oligocene extrusion/exhumation of the Cycladic Blueschist Unit under overall orogenic compression (Ring et al., 2007); (b) a normal-sense and genetically linked with the formation of the North Cycladic Detachment System due to overall, back-arc related extension (Laurent et al., 2017); and (c) a thrust-sense and reflects the direction of extrusion/exhumation of the Cycladic Blueschist Unit under overall orogenic compression (Xypolias et al., 2012).

Key structural observations Outcrop-scale kinematic indicators indicating top-down-to-NE and top-up-to-NE sense of shear cannot be used to discriminate between large-scale normal- and thrust-sense of shearing during exhumation. Post-orogenic doming in Cyclades has probably masked the original orientation of the foliation formed during exhumation. Therefore, other criteria should be used to discriminate between the above assumptions. The absence of Oligocene extensional sedimentary basins and magmatism, as well as the absence of downward increase in the metamorphic pressure, do not support the interpretation that NE-directed shearing was linked with normal-sense movements under an overall extension. Moreover, in many Cycladic islands, the NE-directed shearing is associated with the restacking of the early nappe pile of the Cycladic Blueschist Unit, which formed during the burial stage. In south Evia and north Andros, for example, we have mapped a series of NE-directed shear zones that cut up-section in their transport direction and have brought the lower North Cyclades nappe (also known as Styra nappe in Evia) over the upper Ochi-Makrotantalo nappe (Fig. 1a, b). Such a deformation pattern is to be expected in contractional belts, and therefore, it seems that the NE-directed shear zones have operated as ductile thrusts. Chemical analysis of amphiboles defining the mylonitic foliation in these shear zones has shown that thrust-sense movements started at blueschist facies conditions and progressively continued until the completion of the greenschist facies metamorphism at early Miocene. A similar situation has also been observed in northern Sifnos. There, a lower marble sequence was thrust over an upper meta-volcano-sedimentary sequence via a series of NE-directed shear zones that operated under blueschist facies to greenschist facies conditions (Fig. 1c).

Conclusions Our structural observations show that NE-directed shearing in the Cycladic Blueschist Unit had a thrust-sense until the early Miocene when the greenschist facies metamorphism was completed. Therefore, the Oligocene NE-directed shearing within the Cycladic Blueschist Unit was associated with thrust-sense movements that occurred under overall orogenic contraction. This finding implies that the Cyclades area was affected by back-arc extension not earlier than early Miocene times.

References Aravadinou, E., Xypolias, P., Chatzaras, V., Iliopoulos, I., Gerogiannis, N., 2016. Ductile nappe stacking and refolding in the Cycladic Blueschist Unit: insights from Sifnos Island (south Aegean Sea). Int J Earth Sci 105, 2075-2096. Avigad, D., Garfunkel, Z., Jolivet, L., Azañon, J.M., 1997. Back arc extension and denudation of Mediterranean eclogites. Tectonics 16, 924-941. Boronkay, K., Doutsos, T., 1994. Transpression and transtension within different structural levels in the central Aegean region. J Struct Geol 16, 1555-1573. Bröcker, M., Baldwin, S., Arkudas, R., 2013. The geological significance of 40Ar/39Ar and Rb-Sr white mica ages from Syros and Sifnos, Greece: a record of continuous (re)crystallization during exhumation? J Metamorph Geol 31, 629-646. Chatzaras, V., Xypolias, P., Kokkalas, S., Koukouvelas, I., 2011. Oligocene-Miocene thrusting in central Aegean: insights from the Cycladic island of Amorgos. Geol J 46, 619-636. Gerogiannis, N., Xypolias, P., Chatzaras, V., Aravadinou, E., Papapavlou, K., 2019. Deformation within the Cycladic subduction–exhumation channel: new insights from the enigmatic Makrotantalo nappe (Andros, Aegean). Int J Earth Sci, doi.org/10.1007/s00531-019-01680-3 Jolivet, L., Lecomte, E., Huet, B., Denèle, Y., Lacombe, O., Labrousse, L., Le Pourhiet, L., Mehl, C., 2010. The North Cycladic Detachment System. Earth Planet Sci Lett 289, 87-104. Laurent, V., Huet, B., Labrousse, L., Jolivet, L., Monié, P., Augier, R., 2017. Extraneous argon in high-pressure metamorphic rocks: Distribution, origin and transport in the Cycladic Blueschist Unit (Greece). Lithos 272-273, 315-335. Ring, U., Glodny, J., Will, T., Thomson, S.N., 2007. An Oligocene extrusion wedge of blueschist-facies nappes on Evia, Aegean Sea, Greece: implications for the early exhumation of high-pressure rocks. J Geol Soc Lond 164, 637-652. Xypolias, P., Iliopoulos, I., Chatzaras, V., Kokkalas, S., 2012. Subduction- and exhumation-related structures in the Cycladic Blueschists: insights from south Evia Island (Aegean region, Greece). Tectonics 31, TC2001. doi.org/10.1029/2011TC002946.

ABSTRACT. Back-arc extension in the Greek Cyclades has been widely studied and its extensional style seems to have evolved through time. The earliest stages started with high-pressure, low-temperature rock exhumation, and metamorphic core complex exhumation in the Late Oligocene – Early Miocene (Jolivet et al., 2013, Brun et al., 2016). It has since progressed to low angle normal faulting, and through to high angle normal faulting estimated since the Late Miocene (Jolivet et al, 2013, Philippon et al., 2012). Recent studies suggest that the latest brittle stage is more complex, as strike slip faulting may have been active in the Cyclades since the Mid-Late Miocene (Kokkalas and Aydin, 2013). This study aims to constrain the relationship between strike slip and normal faulting in the Cyclades.

We combine offshore data in the Cyclades with field data from the island of Syros to better understand the tectonic pattern and how it has evolved since the Miocene. Our data from Syros consists of structural measurements of high angle faults. These are used in combination with other published data, such as lithological and geochronological data (compilation in Philippon et al., 2012), to understand fault kinematics. We find two dominant directions of high angle (apparently normal) faults at the scale of the island: NNW-SSE (with some oblique component) and NW-SE (mostly pure normal component).

Offshore in the Cyclades, we interpret legacy shallow seismic reflection data provided by the Hellenic Centre for Marine Research. We use this in combination with bathymetry to constrain the present day tectonics in the Cyclades. Similar to Syros, we find two directions of normal faults: NNW-SSE and NW-SE (Fig. 1). However, syn-kinematic sediments within the faulted grabens show broad folding and local inversion. We suggest that this indicates oblique slip along these high angle normal faults. From the offshore data, we also interpret two strike slip faults trending NE-SW, and locally trending NNE-SSW. The northern strike slip is a negative flower structure creating a major strike slip trough across the northern Cyclades. The southern strike slip fault is smaller and only locally affects the surrounding geology.

We suggest that the two directions of normal faulting are a result of progressive rotation within the strike slip zones. The first set opens in the direction of maximum stretching (NW-SE) due to slab rollback. As the block is bound by dextral strike slip faults, it rotates clockwise, rotating the faults to their current NNW-SSE position, while a new set of NW-SE faults starts to open. Since the rotated faults are no longer aligned with the direction of maximum stretching, they experience oblique slip and hence create local inversion in former graben systems.

This scenario is compatible with palaeomagnetic data that show that north of the Mid-Cycladic lineament, the Cyclades have rotated 22-23 degrees clockwise since the Miocene (Avigad et al., 1998; Morris and Andersen, 1996). The data from Syros also shows activity around the mid-Miocene (Philippon et al., 2012) which can be explained by our tectonic interpretation.

Our results support the idea that strike slip faulting has been active in the Cyclades since the Miocene (Kokkalas and Aydin, 2013), making it much younger than the NAF, which has only been active since the Pliocene (Armijo et al., 1999). We also conclude that coeval with this strike slip faulting, the Cyclades are affected by distributed, high angle faults, which create tilted blocks and sedimentary basins. Our interpretation suggests that these faults are still presently active in the Cyclades and experience dominantly oblique slip, accommodating strike slip components from Anatolian extrusion and normal components from the retreating Hellenic subduction zone.

References: Avigad, D., Baer, G. & Heimann, A., 1998. Block rotations and continental extension in the central Aegean Sea: palaeomagnetic and structural evidence from Tinos and Mykonos (Cyclades, Greece). Earth and Planetary Science Letters, 157(1), pp.23–40. Morris, A. & Anderson, M., 1996. First palaeomagnetic results from the Cycladic Massif, Greece, and their implications for Miocene extension directions and tectonic models in the Aegean. Earth and Planetary Science Letters, 142(3–4), pp.397–408. Armijo, R., Meyer, B., Hubert, A., & Barka, A. (1999). Westward propagation of the North Anatolian fault inoto the northern Aegean: Timing and kinematics. Geology, 27(3), 267–270. Brun, J.-P., Faccenna, C., Gueydan, F., Sokoutis, D., Philippon, M., Kydonakis, K., & Gorini, C. (2016). The two-stage Aegean extension, from localized to distributed, a result of slab rollback acceleration. Canadian Journal of Earth Sciences, 53(11). https://doi.org/10.1139/cjes-2015-0203 Jolivet, L., Faccenna, C., Huet, B., Labrousse, L., Le Pourhiet, L., Lacombe, O., … Driussi, O. (2013). Aegean tectonics: Strain localisation, slab tearing and trench retreat. Tectonophysics, 597–598. https://doi.org/10.1016/j.tecto.2012.06.011 Kokkalas, S., & Aydin, A. (2013). Is there a link between faulting and magmatism in the south-central Aegean Sea ? Geological Magazine, 150, 193–224. https://doi.org/10.1017/S0016756812000453 Philippon, M., Brun, J. P., & Gueydan, F. (2012). Deciphering subduction from exhumation in the segmented Cycladic Blueschist Unit (Central Aegean, Greece). Tectonophysics, 524–525, 116–134. https://doi.org/10.1016/j.tecto.2011.12.025 Philippon, M., Brun, J.-P., Gueydan, F., & Sokoutis, D. (2014). The interaction between Aegean back-arc extension and Anatolia escape since Middle Miocene. Tectonophysics, 631(C). https://doi.org/10.1016/j.tecto.2014.04.039

ABSTRACT. Recent compilation of the bathymetry along with processing and interpretation of seismic profiling provide insights into the deformation and kinematics in the South Aegean during Plio-Quaternary. The mapped fault network, the spatial distribution of the basins and ridges, along with seismological data indicate a dual kinematic pattern. The southeastern part undergoes transtension and sinistral shearing along NE-SW to ENE-WSW faults. The rest of the South Aegean experiences transtenion along NE-SW dextral strike slip to oblique faulting. A major unconformity in Late Pliocene / Early Quaternary marks the onset of this kinematic pattern. The establishment of the kinematic regime has been triggered by the gradual propagation of the North Anatolian Fault into the Aegean and accommodates the SSW-ward movement and general NNE-SSW extension in the South Aegean.

ABSTRACT. The recent technological development has sharply increased the number of instruments that can be adopted for slope instabilities monitoring. Nowadays, a multiscale approach that considers satellites, aerial or UAVs systems and in place monitoring solutions can be considered state of the art for landslides monitoring. Satellites and aerial systems are good solutions for the first identification and characterization of active slides, and in situ monitoring networks are the best solution for a near real-time acquisition of a series of parameters that could support an early warning procedure. The use of early warning systems is essential in particular where the activation of large landslides can have a critical impact on infrastructure or population. In these cases, monitoring systems are usually a part of a more complex civil protection procedure that should also consider possible scenarios and risk reduction solutions. Even if the technological evolution offers complex and advanced monitoring instruments, the validation of monitoring results can always be done considering the geological model of the slope instability. When a validated result has been obtained, the last step for the effective use of these systems is a correct and dedicated communication strategy.

ABSTRACT. A variety of remote sensing tools have been extensively used in the past years for landslide detection and mapping purposes. In addition, detection and mapping of landslide and rockfall events using remote sensing products has been proved to be an effective approach to provide landslide inventories (Scaioni et al., 2014). However, most of the studies are lacking valuable semantic information about landslide elements and how they react with the surrounding environment; natural and man-made primitives. In addition, post classification object-based approaches have been proved to result in better accuracies compared with the pixel-based (Martha et al., 2011). Lately, innovative close-range remote sensing technology such as Unmanned Aerial Vehicle (UAV) photogrammetry and Terrestrial Laser Scanning (TLS) are widely applied in the field of geoscience due to their efficiency in collecting data about terrain morphology rapidly. Their main advantage stands on the fact that conventional methods are mainly collecting point measurements such as compass measurements of bedding and fracture orientation only from areas that were accessible. Aerial platforms are capable to overcome technical issues such as potential occlusions and unfavorable incidence angles due to their ability to capture imagery from multiple positions and with different angles. Nowadays, UAVs tend to be more flexible and powerful tools for landslide and rockfall investigations compared to TLS, due to their low-cost and ease of transportability in harsh environments but also with technology advances such as maintaining of Real Time Kinematic (RTK) positioning. An important factor of their usefulness is their capability to offer unprecedented spatial resolution over wide inaccessible areas, maintain a variability of different sensors (optical, laser, thermal, multispectral) and great ability to reach remote areas and acquire data as close as the user defines. UAVs applications are widely used in post-disaster situations for emergency support, in infrastructure monitoring, in natural resources management, in geohazard monitoring etc. (Corominas et al., 2016; Vassilakis et al., 2019). The latter proves that UAV market has been rapidly growing over the last decade and in future more applications will be introduced in the public. Thus, rapidness and efficiency of Structure-from-Motion (SfM) technology in landslide management provides numerous advantages such as creating landslide inventory maps providing 3D information of large areas. This research aims to demonstrate the applicability of UAV technology for automated semantic labeling in managing landslide and rockfall hazard in mountainous environments during emergency situations. SfM photogrammetry in addition to high accuracy RTK-GNSS ground control point establishment, is used to provide detailed 3D point clouds describing the surface morphology of the landslide and rockfall elements. Specifically, two test sites were exploited, a detailed UAV survey took place in a landslide case site, on Santorini island and specifically in Red Beach which constitutes one of the most touristic places on the island. In addition, a rockfall test site namely as «Proussos», near one of the most visited and famous Monasteries in the territory of Evritania prefecture, in Greece, was investigated via detailed UAV flight plans. The latter site is formed as an unstable steep slope across the main road network, on which continuous failures and road cuts appear after heavy rainfall events (Figure 1). The Red Beach test site is located on Santorini island, which in turn represents one of the most unique geological structures as it is formed around the caldera of an active volcano. Moreover, rockfalls and landslides are widespread phenomena due to the orientation and steepness of the cliffs (Karantanellis et al., 2019) which are mainly formed as high elevated lava domes (>50 m) with loose material inside, extruded by sticky, slow-flowing dacite lava due to continuous coastal erosion. The proposed methodology was divided in five main working phases. The first phase includes designing and execution of an optimal UAV flight planning in order to collect accurate 3D data. The current step is crucial in order to provide complete and precise model at the later processing stages. During the second phase, the pre-processing and raw data preparation such as point cloud filtering and elimination of ambiguities is taking place, while at the next phase an image segmentation using the 3D point cloud RGB information is created. The main task was focused on identifying the specific landslide elements by using an object-based approach. Object-Based Image Analysis (OBIA) is an image analysis technique, remarkably developed during the last decade, since recent advances in computer vision and machine learning with the main task to automatically replicate human interpretation to identify objects in remote sensing images brought impressive results (Blaschke, 2010). It is only during the last decade, that OBIA methods have proved to outperform the pixel ones such as elimination of false positives which are missed by pixel-based approaches (Keyport et al., 2018). A sequence of image-based processes was applied, including multi-scale object segmentation, spectral, morphometric and contextual information extraction aiming to detect the landslide among other features. The latter is mainly developed as a knowledge-driven ruleset to serve for identifying individual landslide objects based on their morphometric and spectral parameters. The next phase was set up for object classification in meaningful and homogeneous landslide classes (e.g. scarp, depletion zone, accumulation zone) which are spatially connected by introducing contextual information in the ruleset. The validation of the results represents the final phase, which is based on accuracy assessment against a digitized landslide map and field observations. The resulted models were used as reference to detect and characterize 3D landslide features and provide detailed identification of hazardous regions. The proposed methodology presents the effectiveness and efficiency of UAV platforms to acquire accurate photogrammetric datasets from intense relief environments and complex surface topographies by providing a holistic assessment and characterization of the failure site based on semantic classification of the landslide and rockfall objects. Results have demonstrated the capabilities of combining UAV platforms with computer-based methods for rapid and accurate identification of valuable semantic information subjectively and even from inaccessible areas of the landslide and rockfall body.

ABSTRACT. Documentation of earthquake environmental effects (surface ruptures, landslides etc.) is a very critical issue, since based on the accuracy of the provided information, protection and mitigation measures can be designed. However, it is well known that mapping these features is not always feasible due to several adverse factors e.g. near-vertical slopes, coastal cliffs, imposing high risk to human surveys. In order to overcome this issue and to quantitatively describe the earthquake-induced geological failures e.g. landslides and liquefaction-induced lateral spreading, remote sensing techniques were applied during the last two decades such as Interferometric Synthetic Aperture Radar (InSAR), Light Detection and Ranging (LiDAR) and photogrammetric surveys. The latter one, a photogrammetric survey, is frequently conducted by use of Unmanned Aerial Vehicles (UAV), such as multicopters equipped with webcams, digital cameras and other sensors (Colomina and Molina, 2014; Lindner et al., 2016; Rossi et al., 2017, Yu et al., 2017). UAVs provide a convenient remote sensing platform for post-earthquake surveys given their ability to collect ultra-high-resolution imagery in short time over terrain that is often difficult to access. Using the Structure from Motion (SfM) image processing technique, a 3D point cloud can be created by intersecting the matched features between the overlapping, offset images. Point clouds from optical images enable the detailed representation of complex 3D surfaces, better editing and classification of the dataset and creation of further products like orthophotos, DSMs, DTMs, textured models etc. Comparison between different point cloud sets enables highly accurate change detection analysis, using recently developed matching algorithms. This work presents the mapping of earthquake-induced failures from two strong and shallow earthquakes occurred on November 17, 2015 onshore Lefkada (Mw 6.5; Ganas et al. 2016; Papathanassiou et al. 2017) and July 20, 2017 offshore Kos (Mw 6.6; Papathanassiou et al. 2019) , Greece. In the latter case, the SfM-based technique was applied using a ground-based digital camera, while in the former one a UAV DJI Phantom 3 was used. The Lefkada case study focuses on a deep-seated landslide triggered at the coastal area of Athani village (Okeanos site), SW Lefkada that induced severe damages to a recently constructed luxury hotel, while the Kos case study deals with the lateral spreading reported in the old harbor of the city.

The outcomes arisen by this study are that i) in the case of Okeanos landslide, the extraction of a detailed point cloud enabled the high-resolution modeling of the landslide at a site with challenging conditions such as limited accessibility and complex relief. It was demonstrated that both change analysis and volumetric calculation for co-seismic landslides demand a pre-event detailed point cloud set that can be co-registered and compared with the post-event set. Coastal areas are usually covered by multi-temporal aerial imagery in working scales (1:5K – 1:30K) that can be used to extract point clouds suitable as a reference (Valkaniotis et al., 2018). Regarding the effects mapped on Kos, it was found that the SfM-based technique provides reliable data (on horizontal axis) for documenting and modeling lateral displacement features and accordingly, could be used for the purposes of a rapid post-earthquake field survey (Papathanassiou et al., 2019). Furthermore, this technique can be applied even with a low-cost ground-based technique e.g. a simple hand-held digital camera. However, it cannot be characterized as satisfactory on vertical axis since a 12% deviation exists between the measurements obtained by these two techniques (SfM and traditional one), and some caution should be applied when using SfM-based technique . Acknowledgements We thank Nikos Grendas and Elisavet Kollia for field support. We acknowledge support of this research by the project “HELPOS - Hellenic Plate Observing System” (MIS 5002697) which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund). References

Colomina, I., and Molina, P., 2014. Unmanned Aerial Systems for Photogrammetry and Remote Sensing: A Review. ISPRS Journal of Photogrammetry and Remote Sensing, 92, 79-97 Ganas, Athanassios, Panagiotis Elias, George Bozionelos, George Papathanassiou, Antonio Avallone, Asterios Papastergios, Sotirios Valkaniotis, Issaak Parcharidis, Pierre Briole, 2016. Coseismic deformation, field observations and seismic fault of the 17 November 2015 M = 6.5, Lefkada Island, Greece earthquake, Tectonophysics, 687, 210-222, ISSN 0040-1951, http://dx.doi.org/10.1016/j.tecto.2016.08.012 Lindner, G., Schraml, K., Mansberg, R., Hübl, J., 2016. UAV monitoring and documentation of a large landslide. Applied Geomatics, 8, 1-11. Papathanassiou George, Sotiris Valkaniotis, Athanassios Ganas, Nikos Grendas, Elisavet Kollia, 2017. The November 17th, 2015 Lefkada (Greece) strike-slip earthquake: Field mapping of generated failures and assessment of macroseismic intensity ESI-07, Engineering Geology, 220, 13-30, http://dx.doi.org/10.1016/j.enggeo.2017.01.019. Papathanassiou G., Valkaniotis S., Pavlides S. 2019. The July 20, 2017 Bodrum-Kos, Aegean Sea Mw=6.6 earthquake; preliminary field observations and image-based survey on a lateral spreading site, Soil Dynamics and Earthquake Engineering, Volume 116, January 2019, Pages 668-680, https://doi.org/10.1016/j.soildyn.2018.10.038 Rossi G., Tanteri L., Tofani V., Vannoci P., Moretti S., Casagli N., 2017. Use of multicopter drone optical images for landslide mapping and characterization. Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2017-46. Valkaniotis S., Papathanassiou G., Ganas Ath. 2018. Mapping an earthquake-induced landslide based on UAV imagery; case study of the 2015 Okeanos landslide, Lefkada, Greece, Engineering Geology, vol. 245, pp. 141-152 Yu, M., Huang, Yu., Zhou, J., Mao, L., 2017. Modeling of landslide topography based on micro-unmanned aerial vehicle photography and structure-from-motion. Environ Earth Sci., 76, 520 doi:10.1007/s12665-017-6860-x

ABSTRACT. Introduction Fault specific approaches are of decisive value for seismic hazard assessment by providing quantitative assessments through measurement of geologically recorded slip on active faults (Wesnousky, 1986). The geometry and kinematics of active faults are important for locating and characterizing the seismic sources. In addition, the long-term prediction of future earthquakes can be achieved through the study of the cumulative patterns of slip on active faults. Fault slip-rates that govern earthquake recurrence can be extracted from dated geologic and/or geomorphic indicators offset by faults, covering a time span that generally encompasses a large number of earthquake cycles. Terrestrial Light Detection and Ranging (T-LIDAR) is nowadays a major tool for earthquake geology and seismic hazard assessment by providing high spatial resolution (Papanikolaou et al. 2015). Resolution usually ranges from several cm to a few mm, depending on the distance to the target. T-LIDAR has been early used for studying the fault geometry and quantifying the fault plane characteristics. The Arkitsa fault Plane in Central Greece plane was one of the first worldwide applications and the first one in Greece by Jones et al., 2009. Methodology Over the last few years we have implemented a large number of T-LIDAR studies for several active faults in Greece, introducing also some pioneer methodologies. These include: a) the extraction of kinematic data for the Spili fault in Crete (Wiatr et al., 2013), b) the extraction of fault slip-rates based on the height of postglacial fault scarps in the Lastros Fault (Mason et al., 2016), c) tracing of paleoevents based on the reflectivity and roughness changes along the scarp, (Wiatr et al., 2015), d) tracing of paleoevents from fault plane weathering features, combined with Cosmogenic isotope dating offering info regarding both the slip and date of past events (Mechernich et al., 2018), e) the combined use of LiDAR multispectral analysis with GPR (Ground Penetrating Radar) in paleoseismic trenching, (Schneiderwind et al., 2016) using as an example the Kapareli trench site (Kokkalas et al., 2007,) f) the identification of undiscovered paleoshoreline notches in the Perachora Peninsula adding more info regarding local tectonic movements (Schneiderwind et al., 2017). Results & Discussion Kinematic indicators were accurately calculated on the Spili fault scarp in Crete (Figure 1), where the percentage threshold error of the individual vector angle is lower than 3% for the dip direction and dip for planes. Vertical displacements along a 1.3km long scanned segment of the Lastros fault in Crete were accurately determined using a T-LIDAR induced 3D model of the fault scarp, yielding a slip rate of 0.69±0.15mm/y (Figure 2, left). T-LIDAR backscatter analyses at the Pisia fault scarp, along with Cosmogenic 36Cl isotope dating, provided evidence for at least 6 paleoearthquakes (Figure 2, right). The combination of laser scanning with GPR provided a 3D visualisation of a paleoseismic trench site in Kapareli, showing that trench stratigraphy and logging can be made using both techniques. Moreover, data from terrestrial laser scanning of coastal cliffs enhanced the recognition of tidal notches and supported palaeoseismic studies by providing spatial information and exact measurements of horizontal movements (Figure 3). All the above applications in Greece strongly imply that Τ-LIDAR is a major tool for earthquake geology and tectonic geomorphology, by offering quantitative data on the fault geometry, fault kinematics and deformation rates. References Jones, R.R., Kokkalas, S., McCaffrey, K.J.W., 2009. Quantitative analysis and visualization of nonplanar fault surfaces using terrestrial laser scanning (LIDAR)-the Arkitsa fault, central Greece, as a case study. Geosphere 5, 465–482. Kokkalas, S., Pavlides, S., Koukouvelas, I., Ganas, A., Stamatopoulos, L, 2007. Paleoseismicity of the Kaparelli fault (eastern Corinth Gulf): evidence for earthquake recurrence and fault behavior. Italian Journal of Geosciences 126, 387-395. Mason, J., Schneiderwind S., Pallikarakis, A., Wiatr T., Mechernich, S., Papanikolaou, I., Reicherter, K., 2016. Fault structure and deformation rates at the Lastros-Sfaka Graben, Crete. Tectonophysics 683, 216–232. Mechernich, S., Schneiderwind, S., Mason, J., Papanikolaou, I.D., Deligiannakis, G., Pallikarakis, A., Binnie, S.A., Dunai, T.J., Reicherter, K., 2018. The Seismic History of the Pisia Fault (Eastern Corinth Rift, Greece) From Fault Plane Weathering Features and Cosmogenic 36Cl Dating. Journal of Geophysical Research: Solid Earth 123, 4266-4284. Papanikolaοu, I.D., Van Balen, R., Silva, P.G., Reicherter, K., 2015. Geomorphology of Active Faulting and seismic hazard assessment: New tools and future challenges. Geomorphology 237, 1-13. Schneiderwind, S., Boulton, S.J., Papanikolaou, I., Reicherter, K., 2017. Innovative tidal notch detection using TLS and fuzzy logic: Implications for palaeo-shorelines from compressional (Crete) and extensional (Gulf of Corinth) tectonic settings. Geomorphology 283, 189-200. Schneiderwind, S., Mason, J., Wiatr, T., Papanikolaou, I., and Reicherter, K., 2016. 3-D visualisation of palaeoseismic trench stratigraphy and trench logging using terrestrial remote sensing and GPR – a multiparametric interpretation. S. Earth 7, 323–340. Wesnousky, S.G., 1986. Earthquakes, quaternary faults and seismic hazard in California. J. Geophys. Res. 91, 12587–12631. Wiatr Τ., Reicherter Κ., Papanikolaou Ι., Fernández-Steeger Τ., Mason J., 2013. Slip vector analysis with high resolution t-LiDAR scanning. Tectonophysics 608, 947-957. Wiatr, T., Papanikolaou, I., Fernández-Steeger, T., Reicherter K., 2015. Bedrock fault scarp history: Insight from t-LiDAR backscatter behavior and analysis of structure changes. Geomorphology 228, 421–431.

ABSTRACT. Abstract Rockfalls constitute an abrupt type of landslide process with manifold impact at local level, on economy and mostly on a human modified environment. Over the past few decades, urban expansion in hazardous areas and development of modern transportation and energy infrastructure, combined with a global demand for higher safety standards, have rendered the assessment of rockfall hazard most urgent than ever. In this context, up to date, rapid automated and accurate mapping of rockfall characteristics is key to identifying hazardous areas and proposing mitigation measures in an efficient manner. The current study proposes a novel, semi-automated approach to detect rockfall hazard from detailed 3D point clouds and highlights the significance of UAV application in the landslides domain. A case study of a recent rockfall event, triggered by heavy rainfall in Plomari, Lesvos island is presented. The event occurred within the boundaries of the settlement and induced damage on several houses, forcing 37 people to evacuate the proximal area. Data was collected shortly post-failure with a commercial UAV platform and implemented in producing a high-resolution 3D point cloud from which block geometry measurements of sliding slope have been provided in relation with the geometrical characteristics of the main discontinuity surfaces and the slope morphology. Field measurements and laboratory tests of the rock joint strength were contributed for the analysis of the slope stability of the rock blocks. A practical, qualitative hazard assessment system is proposed, based on parameterization of corresponding rock discontinuity factors detected in terms of point cloud analysis. Results have demonstrated the capabilities of combining UAV platforms with computer-based methods for rapid and accurate identification of discontinuity parameters, objectively, and even in inaccessible areas of the rockfall body. These capabilities

Introduction Rockfalls present a substantial increase in their spatial and temporal distribution over the last decade especially in developed societies with severe impact on infrastructure and livehood. The latter has a direct link with the tremendous increase of population in urban areas where built-up zones extended in landslide and rockfall prone areas (Glade et al., 2005). Geo-information techniques and remote sensing have played a vital role in the interpretation and understanding of landslide and rockfall kinematics. A variety of sensors and techniques have been implemented in the field, demonstrating a relationship between the desired application and the method of choice. Lately, Unmanned Aerial Vehicles (UAVs) are widely applied in harsh environments for utra-high resolution data acquisition and accurate 3D surface reconstruction (Nex et al., 2015). Their ability to collect data subjectively from different orientation angles and inaccessible steep rock faces, with very low operational cost and reduced risk for the surveyor make UAVs an integral tool for landslide assessment and rockmass characterization. The collected imagery is taking full advantage of Structure from Motion (SfM) technique with Multi-View Stereo (MVS) to build a 3D point cloud as well as a Digital Surface Model (DSM) and an orthophoto of the area. This work aims to point out the applicability of UAVs in detecting and characterizing rockfall hazard on mountainous environment based on photogrammetric 3D point clouds derived from low-cost UAVs. The acquisition survey aims to produce topographic-grade accurate 3D data from which reliable, valuable geotechnical information can be extracted in an effective manner. The focus of this study was mainly on geometric discontinuity information retrieval, specifically, orientation and and spacing of the main joint sets, through block volume measurements in 3D space. Field measurements were also exploited to assess the mechanical characteristics of the discontinuities as well as to cross-correlate the data derived from the UAV. The acquired discontinuity properties were parameterized and included in a formulated Hazard Index to provide concrete and accurate rockfall hazard analysis.

Methodology The approach discussed involved the quantification of rock discontinuity characteristics; five major joint set properties were implemented in the hazard assessment system, namely: Joint Set Spacing, Orientation (dip/dip direction), Roughness, Joint Wall Compressive Strength and Persistence. A morphology factor was also introduced. All the data used in this study were collected shortly after the rockfall event of November 24, 2018. A commercial UAV platform with a built-in optical sensor was used to collect imagery. A total of 200 images were used to construct a dense point cloud of 20 million points (2100 points/m2). Manual measurements were also made on the accessible foot of the slope using conventional equipment (compass clinometer, profilometer, Schmidt hammer, measure tape). For the hazard assessment process, Orientation and Spacing and Morphology have been derived from block volume measurements made on the obtained point cloud, while Roughness, Wall Strength and Persistence have been imported as-is from the manual survey. The data derived from the point cloud has been post-validated via the respective manual measurements. The hazard zonation has been categorized in three main qualitative fields, namely: i) High, where areas have a greater possibility to fail, ii) Moderate and iii) Low, where areas have a lesser possibility to fail. A novel qualitative hazard matrix has been developed, taking consideration on the aforementioned properties: each joint set property, except for the orientation, has been parameterized accordingly, to a Low-Moderate-High order. A multi-criteria process has been implemented to calculate a formulated Hazard Index (H.I.) in a GIS environment. The slope is sectioned in parts(planes), for each of which a separate H.I. is calculated, based on its discrete parameter values. The final product of the hazard assessment process is a hazard map, which includes an outline of the slope divided in polygons, each assigned a color according to its calculated H.I.

Conclusions Rapid rockfall mapping is important in post-disaster situations. UAVs, in combination with field investigations, have limitless advantages for emergency situations, in specific rockfall management, due to their clear benefits over conventional methods of collecting surface measurements, in harsh environments. Their main contribution in such cases, is the combined ability to provide holistic 3D topographic data in a time efficient manner and with minimized human exposure. The five selected parameters (Roughness, Wall Compressive Strength, Spacing and Persistence) tuned in the proposed Hazard Index revealed good results in comparison with the in-situ investigations and raised expectations for the discussed approach. At a subsequent time, the proposed method will be implemented in different case studies to validate its transferability in different rockfall scenarios. In addition, machine learning algorithms will be tested for exporting discontinuity properties in an automated and subjective way without user interaction.

Acknowledgements This research is co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Strengthening Human Resources Research Potential via Doctorate Research” (MIS-5000432), implemented by the State Scholarships Foundation (ΙΚΥ).

References Glade, T., Anderson, M., & Crozier, M. J., 2005. Landslide Hazard and Risk. (T. Glade, M. Anderson, & M. J. Crozier, Eds.). Chichester, West Sussex, England: John Wiley & Sons, Ltd Nex, F., Gerke, M., Remondino, F., Przybilla, H.-J., Bäumker, M., Zurhorst,A., 2015. ISPRS Benchmark for multi-platform photogrammetry, Joint ISPRS conference 2015, Munich, Germany

ABSTRACT. The New Zealand region lies in the southwest Pacific Ocean overlapping a distinct belt of volcanic and earthquake activity that surrounds the Pacific Ocean. This is known as the "Ring of Fire" and the activity is resulting the structure of the Earth's crust. New Zealand lies on the boundary between the Pacific and Australian plates. To the north of New Zealand and beneath the eastern North Island, the thin, dense, Pacific plate moves down beneath the thicker, lighter Australian plate. Within the South Island the plate margin is marked by the Alpine Fault and here the plates are moved horizontally. Plate movement results in volcanic activity mainly in the North Island and earthquakes that are felt throughout the country (Graham, 2008). On November 14, 2016, a large (moment magnitude [Mw] 7.8) earthquake struck the northeastern part of the South Island of New Zealand. Named after the coastal town near the epicenter, the Kaikoura earthquake had associated surface rupture on more than 20 mapped faults (Stirling et al. 2017), caused widespread crustal deformation (both uplift and subsidence), and triggered more than 10,000 landslides in the complex topography of the affected area (Dellow et al., 2017). Because of this, the earthquake has been described as the "most complex earthquake ever studied” (Jibson et al. 2018). Seismological evidence suggest that the main Kaikoura earthquake of Mw 7.8 was relatively rare for New Zealand with long recurrence intervals Beavan et al. 2010). In fact, the rupture was complex, occurring on intersecting and subsidiary blind thrust faults as well as the dominant east–west strike-slip Greendale Fault (Holden et al. 2011). Since the 1990’s differential repeat-pass interferometry radar (DInSAR) based on SAR SLC images processing has proven an interesting tool for the measurement and observation of ground deformation (Massonnet and Rabaute., 1993). The basic idea of the method is the analysis of the phase of the reflected wave radar from two or more images which cover the same region to observe ground displacement. DInSAR has been widely used to identify ground deformation caused by different natural and anthropogenic phenomena. Many studies are motivated by the potential of SAR interferometry to be applied on a wide range of applications related to seismotectonics. The utilization of an appropriate interferometric dataset allows measuring the various components of the seismic cycle, namely the pre-seismic, co-seismic, and post-seismic deformation (Stramondo et al. 2009; Papanikolaou ei al. 2010, Briole et al. 2015). Nevertheless, significant difficulties are found when using this technique. These difficulties are related to the large variability of slopes (steep and rough topography of prone areas), failure geometries, size of earthquake-prone areas and deformation rates causing phase ambiguity problems and signal decorrelation. Additionally, in regions with strong topographic relief presented local atmospheric variations can in many cases lead to strong atmospheric phase artifacts; all these parameters , often obstract the interferometric pre-processing, making it difficult to estimate surface displacements (Hanssen 2001). This paper aims to combine Sentinel SAR SLC and GRD images from Sentinel 1 satellite in order to overcome the above constrains of DInSAR. This is dome merging results about co-seismic displacement detection from SLC images and measurement from Sentinel 1 GRD data processing. There were used two images, one pre-seismic (Master) sensed on November3rd 2016 and one post-seismic (Slave) sensed on December 3rd 2016. Both SLC and GRD images were acquired on the same days, as the Level-1 Sentinel 1 products provide Single Look Complex images and Ground Range Detected images simultaneously. Level-1 focused data are the generally available products intended for most data users. Level-1 products can be either Single Look Complex (SLC) or Ground Range Detected (GRD). Each acquisition mode can potentially generate Level-1 SLC and GRD products. GRD resolutions will depend on the mode and the level of multi-looking. The SLC images were used in order to measure the displacement through the single-interferometry technique. The GRD images were used to enhance the results of the InSAR technique, which could not measure extreme surface displacement such as landslides. For that matter the Offset tracking method was used. Offset Tracking is a technique that measures feature motion between two images using patch intensity cross-correlation optimization. It is widely used in glacier motion estimation Level-1 Ground Range Detected (GRD) products consist of focused SAR data that has been detected, multi-looked and projected to ground range using an Earth ellipsoid model such as WGS84. The ellipsoid projection of the GRD products is corrected using the terrain height specified in the product general annotation. The terrain height used varies in azimuth but is constant in range (Lu & Veci, 2016). All referred methods were done with SNAP, the open source software for SAR image processing provided by ESA. In order to combine the results of both methods a supervised classification was done in ArcGIS software provided by ESRI. The InSAR technique provides displacement results in millimeters, but the Offset-tracking technique provides results in millimeters per day, so we processed the latter results so they have the same units with displacement. All results were combined in one readable map to provide the total displacement of the affected area in Kaikoura.

ABSTRACT. This study focuses on the sedimentological and morphological features of Vravrona Beach, East Attica, in order to determine the seasonal changes in the textural group classification of the costal sediments, as well as, changes in coastline position (Figure 1). Additionally, Vravrona Beach has been chosen for the assessment of a potential coastal erosion, using the Coastal Vulnerability Index (CVI) through GIS technology, since several incidents of erosion have been identified during the past decades in the broader area of East Attica (Dimou et al., 2010). For the composition of the beach profile in seasonal scale, cross sections were conducted along the beach from landward to seaward until approximately 10 m from the coastline. Beach width as well as the current coastline position for each season were measured with a differential GPS (DGPS). The land use at the landward upper limits of the study area were also measured. Along selected cross sections, sediment sampling was also conducted during January 2018 for the composition of the winter profile of the study area and during September 2018 for the composition of the summer profile of the study area. Sedimentological analyses were based on grain size distribution for the analysis of unconsolidated sediments by sieving and statistical parameters such as sorting, skewness, mean and kurtosis were calculating using GRADISTAT v. 0.4 software in order to determine the sedimentological features of the study area and the transport mechanism at the time of deposition. The textural group of the samples was also determined by Folk and Ward (1957) classification. The grain size analysis of the samples, collected between the upper limit of the beach and the coastline during summer period, show that the majority of grains is described as slightly gravelly sand and gravelly sand, but during the winter period the grains are between gravely sand and sand. The samples collected from the coastline until approximately 10 m seaward are mainly described as slightly gravelly sand and sandy gravel for both sampling seasons (Figure 2). DGPS measurements of coastline position indicate changes that varies between 4.38 m to 7.41 m with a maximum value at 8.27 m. In agreement to field observations, DGPS measurements indicate an accumulation of sediments at the northern part of the beach during the winter period, while during summer period there is an accumulation of sediments at the southern part of the beach.

References Dimou, A., Vassilakis, E., Antoniou, V., Evelpidou, N., 2010. An assessment of the coastal erosion at marathon East Attica (Greece). Proceeding of 10th International Congress of Hellenic Geographical Society, 1579-1587. Folk, R.L. and Ward, W.C. (1957). Brazos River bar: a study in the significance of grain size parameters. Journal of Sedimentary Petrology, 27, 3-26. Pantusa, D., D’Alessandro, F., Riefolo, L., et al., 2018. Application of a Coastal Vulnerability Index. A Case Study along the Apulian Coastline, Italy. Water 2018, 10, 1218 Sammut, S., Gauci, R., Drago, A., Gauci, A., Azzopardi, J., 2017. Pocket beach sediment: A field investigation of the geodynamic processes of coarse-clastic beaches on the Maltese Islands (Central Mediterranean). Marine Geology 387 (2017) 58–73

ABSTRACT. Introduction Beachrocks are consolidated sedimentary formations and are composed of coastal sediments, which are cemented through the precipitation of carbonates. The lithification takes place in the intertidal zone and can include various sediments, such as sands and gravels of clastic and biogenic origin. This study deals with the cements’ mineralogical and geochemical features of a beachrock outcrop and its aim is the contribution for further understanding on the cementation process of beachrocks. (e.g. Vieira and Ros, 2007; Vousdoukas et al., 2007; Karkani et al., 2017). Study Area The site of study is a beachrock outcrop at Peristeria area of Salamis Island which is located at the southeast of the island, 13 km from the city of Salamis. In the coastal area a stream that provides fresh water. The anthropogenic impact is highly evident as there are a number of constructions (basketball court, small piers). The beach has an orientation from East to West and its sediment is characterized as gravely sand. The beachrock slab covers an area of 1.36 Km2 with a length 453m and maximum width of 50m (Figure 1). The examined beachrock has a mean dip of 13.5o seawards.The beachrock mean height (from sea level) is 50 cm and it continues at about 1.5m below sea level. The outcrop has no evidence of vertical to shoreline (channels) erosion but a sea intrusion at its Eastern part. There the sea erodes the beachrock from the landward part and Contributes to new sediment accumulation.

Methodology During the fieldwork detailed mapping of the beachrock slab was performed measuring width, height/depth with respect of the sea level. Additionaly, 12 samples were collected derived by the front and the end of the slabs and sediment bedding. Thin sections were prepared from the beachrocks and samples were studied for their mineralogical and morphological features with a petrographic polarized microscope and confirmed with Scanning Electron Microscope (SEM). Additionally, bulk material was examined for the mineralogical and geochemical composition with X-Ray diffraction (XRD) and Energy Dispersive X-ray Florescence Spectroscopy (XRF).

Results and Discussion From the analysis of the beachrock samples, High Magnesium Calcite [(Ca,Mg)CO3] cement in micritic form is most common (7% wt of MgO in samples) with microfossils. Sparitic formation of cement indicated a well grown crystallization or cement precipitation in the meniscus of sediment by mixing sea water and fresh ground water with higher influence by the marine phase. During the polarized and scanning electron microscopy needles of aragonite have been also observed which reveals a low energy coastal environment. Peristeria beachrock mineralogy is evenly distributed between Mg-calcite, Quartz and Calcite. SEM and XRD analysis also revealed the participation of clay minerals in the matrix cement in full accordance with the mineralogical results that showed the presence of clay minerals in the beachrocks (Figure 2).

Conclusion The Peristeria beachrock outcrop has a very compact and thick morphology with a variety of sediment particles. An alternation in precipitation events seems to have taken place which initiates with a mixed environment of sea water and fresh ground water, was later succeeded with a period of saturation from sea water and lastly with a mixed sea/fresh water environment. The prevalence of the sea water influence in the precipitation of the cement could be due to a sea level rise, for a time period, and then followed by a sea level retreat.

References Karkani, A., Evelpidou, N.,Vacchi, M., Morhange, C., Tsukamoto, S., Frechen, M., Maroukian, H., 2017. Tracking shoreline evolution in central Cyclades (Greece) using beachrocks. Marine Geology, 388, 25-37. ISSN 0025-3227. https://doi.org/10.1016/j.margeo.2017.04.009. Vieira, M.M., Ros, L.F.d., 2007. Cementation patterns and genetic implications of Holocene beachrocks from northeastern Brazil. Sediment. Geol., 192 (3–4), 207–230. Vousdoukas M.I., Velegrakis A.F., Plomaritis T.A., 2007. Beachrock occurrence, characteristics, formation mechanisms and impacts. Earth-Science Reviews, 85, 23–46.

ABSTRACT. In order to study the geomorphological and environmental characteristics of St. George bay, western Naxos, Greece (Fig. 1), a series of 14 beachrock samples were collected and examined. Two transections of the bay, based on field measurements, were designed, in order to provide a deeper understanding of the beachrock development setting. Detailed recording of the beachrocks was accomplished through scuba diving, using a sonar device, measuring tapes, GPS device and Dive Computer. Special attention was given to the cement, as to extract information about the conditions of formation of the beachrocks. Thin sections from the beachrock samples were studied through petrographic microscope in order to investigate their basic characteristics and to obtain information about their basic petrographic and mineral composition. Scanning Electron Microscopy (SEM) alongside with Energy Dispersive Spetrometry (EDS) were used for elemental analysis of the beachrock samples and their cement and Raman spectroscopy was used for identification of the cement crystal structure. For better interpretation of the results, the suggested tool, by Mauz et al. (2015), for reconstructing relative sea level in the far-field was used. In order to estimate the ecological status of the bay, a study of the macroalgae of the area was also accomplished. Macroalgae sampling of two different methods was conducted, destructive (conventional samples) and non-destructive (photographic samples). 57 conventional samples were collected throughout the beachrock reef. These samples were prepared into herbariums and were identified in the best taxonomic level possible using stereoscope and microscope. Photographic samples were taken from the southwestern and northeastern part of St. George bay, from different types of bedrock (beachrocks, granodiorite, aeolianite) for comparison reasons. The percentages of different types of surface coverage (algal, sediment coverage) were counted for each sample, using the program Adobe Photoshop CS6. Finally, a statistical analysis of the data from the photographic samples was conducted, using the program PRIMER 5, in order to have a better evaluation of the algae data. The depth and coordinates of each conventional and photographic sample were recorded. The results regarding the beach rock samples indicate that their formation took place under meteoric and marine vadose zone conditions. Certain results indicate that the development of the beachrocks took place during a sea level rise. Finally, macroalgae statistical analyses indicated that there are no significant differences between beachrocks and other rocks as substrates and the overall ecological status of St. George bay can be characterized as good, according to the Ecological Evaluation Index (EEI, Orfanidis et al., 2003).

ABSTRACT. Introduction The use of water for therapeutic purposes has been known in Greece since the ancient times. The ancient Greeks were the pioneers in the use of warm and cold baths, especially for the hygiene and cleanliness of the body, as well as for the treatment of various diseases. Asclepius was one of the greatest healers of ancient Greece. Cult places for the healing god are uninterruptedly frequented in the Greek world, from the late Classical to the late Imperial period and enjoyed great popularity especially during the Hellenistic and Roman times (Melfi, 2010, Lioulias, 2010). The most characteristic of Asclepius therapeutic practice was the “ritual”, the main part of which was the water, followed by special diet, hygiene and purification rules. The Importance Of Water In Ritual Of Egkoimisis And Purity The location of Asclepieia next to thermal springs is connected with physical therapy. They have been located some distance from the urban settlement, in or near a grove, next to natural springs or the sea. Still, most of the Asclepieia were built in holy places and were considered sacred by the people before their devotion to Asclepius (Chatzinikolaou, 1999, Panagiotidou, 2014). The temples were often protected, located in concavities or in open valleys and hills with water streams, which were passed through the temples and were considered shelters (Vincent, 2009). Dedicated to Asclepius, the Asclepieia were not only temples of worship but also medical care centers. Scattered throughout the ancient world, they were over 300 in number, the largest and most famous being those of Trikke, Epidaurus, Kos, Athens, Corinth, Pergamon and Lebena. Data from ancient literary sources, such as the comedy “Plutus” by Aristophanes and the works of Pausanias, Strabo, Plutarch, Lucian of Samosata and others, and also archeological findings from some of the largest Asclepieia, provide valuable information about the operation of these holy institutions (Christopoulou-Aletra et al., 2010). At Asclepieia, the daily rituals were performed by priests, while the cities organized celebrations dedicated to Asclepius (Panagiotidou, 2014). During the consecration, the priests entered into the Avaton, which was connected to water springs and practiced the treatments as the patients slept (Economidou, 2015). According to Aristophanes, water had an important role in the ritual of incubation (Egkoimisis). There are abundant natural elements of Asclepieia, including those related to slumbers, springs, wells, fountains, small and big cisterns for complete immersion of the body and other water containers. Also, it is not at all clear what kind of water was used exclusively for Egkoimisis, and if the water available near Avaton was intended for cleaning or hydrotherapy or both. The only valid conclusion is that the water at the entrance of a sanctuary was mainly intended for the symbolic cleansing required for those visiting any Greek sanctuary, not only Asclepieia - as suggested by Hippocrates. Usually, outside from the sanctuary (and possibly at a distance from the entrance), there was a small basin serving as a local cleansing bath, since, according to the sacred laws of Asclepius, visitors had to be washed from impurities caused by various activities before entering the sanctuary (Renberg, 2017). Role Of Water In The Sanctuaries Of Asclepius Asclepieia were located next to springs, in holy places, so as to supply the temple with water. The landscape, combined with the holy waters and the groves, had a direct influence on people's health, releasing them from stress and other factors. Patients were relaxing to retrieve their vision or voice or to be cured from breast and foot disorders. In addition, the water was not only medical and beneficial to patients, but even to those who were healthy (Panagiotidou, 2014). Asclepieia were built around springs, e.g. the Asclepieion of Epidaurus and Pergamon, which were built in forest valleys next to springs. Also, the Asclepieio of Lebena, which was built on the southern coast of Crete in a landscape dominated by the harbor and a spring, and the Asclepieio of Kos, which was built near hot springs, with thermal baths (Panagiotidou, 2014), while the Asclepieion of Gortyn was situated beside the river Loussios. Bathing facilities were found in almost all the sanctuaries of Asclepius, such as in Dion, the Asclepieio of Veria and others. The statue of Health was found in Kelepouri, to the south of the sanctuary of Asclepios, where a bath complex was excavated. At the same time, it is not unlikely that the abundance of water in these areas have also been used for healing purposes, resulting from the large number of bathing facilities that were excavated in the area, combined with the particularly intense worship of Asclepius in the city. Four bath complexes have emerged from the city of Dion including the large Thermae (Figure 1): (i) the big thermae near the southern entrance of the city, (ii) the so-called forum thermae in the NE corner of the respective complex, (iii) the thermae of the main road to the east of the sanctuary, and (iv) finally the so-called thermae of the eastern road located in the south of the Dionysus mansion (Lioulias, 2010).

Figure 1. Aerial photography of the great thermae complex at Dion (http://odysseus.culture.gr/h/2/eh251.jsp?obj_id=976)

In addition, the existence of baths is also concerned in the case of Asclepieion of Veria in which it is believed that there should be a set of bathing facilities. Excavations have revealed special architectural elements, as well as statues that indicate the quality of its construction (Lioulias, 2010). Conclusions It is generally accepted that Asclepieia in ancient Greece offered health care, combining experimental therapeutic methods with a variety of religious elements. The holistic approach they used to treat patients was based on the healing properties of the natural environment: knowledge of the life force of the sun, water, minerals, rocks, and knowledge of the properties of medicinal plants. What is now at the core of modern hospital design seems to have been a well-established practice in ancient Greek therapeutic centers. This is evident in the careful selection of the location of sanctuaries of Asclepius, which did not lack running water, and in some cases also healing springs (Christopoulou-Aletra et al., 2010). We can conclude that the importance of "heilig water", which was used for natural and spiritual purification, while offering treatment to patients through its properties, was fundamental in the general holistic philosophy and function of Asclepieia. References Chatzinikolaou, M., 1999. The Asklepieion of Kos. Department of Social Medicine, School of Medicine History, Ph.D. Thesis University of Athens, 373 p. [Dissertation] Christopoulou-Aletra, H., Togia, A., Varlami, C., 2010. The “smart” Asclepieion: A total healing environment, Archives of Hellenic Medicine, 27(2):259-263. [Journal Article] Ekonomidou, E., 2015. The Asklepieion in the sanctuary of Hippolytus at Troizina, Faculty of Philosophy, Department of History and Archeology, Ph.D. Thesis, University of Athens, 487 p. [Dissertation] Lebidaki, M., E., 2003. Small sacred buildings in the Asklipieion of Epidaurus, Faculty of Philisophy, Department of History and Arschaeology, Ph.D. Thesis, University of Athens, 435 p. [Dissertation] Lioulias, S., 2010. The devotion of Asclepios in Macedonia. Faculty of Philosophy, Department of History and Archeology, Department of Archeology, M.Sc. Thesis, Aristotle University of Thessaloniki, 243 p. [Master Thesis] Panagiotidou, O., 2014. Disease and Treatment in the Sanctuaries of Asklepios: A cognitive approach, Faculty of Theology, Theological School, Ph.D. Thesis, Aristotle University of Thessaloniki, 304 p. [Dissertation] Renberg H., G., 2017. Where Dreams May Come: Incubation Sanctuaries in the Greco-Roman World, Volume I, Leiden. [Book] Vincent, E., 2009. Therapeutic Benefits of Nature Images on Health, Department of Environmental Design and Planning, Ph.D. Thesis, Clemson University, 263 p. [Dissertation]

ABSTRACT. The aim of this study is to present a flood hazard assessment and mapping methodology for the Kerinitis River drainage basin which is located in the North Peloponnese. Additionally, the simulation of a flash flood event along the main channel of the river caused by an extreme rainfall event, similar to the storm that took place on January 11th and 12th, 1997 above the nearby catchment of Xerias River, using a surface GIS-based runoff model was attempted. The application of this modeling led to the direct runoff hydrograph along the Kerinitis main channel at the outlet of the basin (the apex of the fan-delta). The proposed methodologies are based on the application of GIS with the integration of various data concerning the study area. Kerinitis is an ephemeral river with a dendritic drainage network, located in northwestern Peloponnese. Its drainage basin has an area of 82.94 km2. For the Kerinitis catchment flood hazard assessment and mapping, a multi criteria model was applied. The model was based on factors controlling the water route when drainage system capacity is exceeded by high runoff. The selected factors include the morphological slope, the elevation, the mean annual rainfall, the flow accumulation, the distance from the main channels of the streams, the hydro-lithology of the geological formations and the land use. Each factor was divided into five classes with specific boundary values. Integer numbers, ranging from 1 to 5, were assigned to every class with 1 representing very low physical vulnerability and rank 5 indicating very high physical vulnerability to flood hazard. To get the final weights for each factor the Analytic Hierarchy Process (AHP) method was applied. For the calculation of the maximum discharge at the outlet of the Kerinitis River catchment (caused by an extreme weather event similar to the storm that took place on January 11th and 12th, 1997, above the nearby catchment of Xerias River), the GIS-based unit hydrograph derivation method was adopted. The results of the flood hazard assessment are depicted on the map of Figure 1. The study area was classified into five sections corresponding to areas of very high, high, moderate, low and very low flood hazard. It is obvious that flood prone areas (of high and very high physical vulnerability to flood hazard) are distributed mostly along the main channels of the Kerinitis River and its major tributaries. Particularly prone to floods are the overbank areas along the lower reaches of the Kerinitis main channel. The model-derived hydrograph follows the mean rainfall pattern above the basin with four discharge peaks. The diagram shows that the basin’s response to the precipitation is very quick. The first peak (~626 m3/sec) occurred almost one hour after the first precipitation maximum (47 mm) and corresponds to the maximum discharge.

ABSTRACT. Abstract In this work, we present a brief description of hydro-chemical data from mineral springs reported in a historical study (Lekkas, 1938). The springs are located in different stratigraphical level and lithological units that outcrop in western Crete. These springs were monitored during the last three years. The outcomes of this monitoring work add to the existing knowledge, which is figured in the map of IGME (Figure 1). Athanassoulis et al., 2009 studied springs in most areas of Greece except Crete and the Ionian islands due to decreased interest and a small number of thermal springs. As shown in the map, four cold springs were recorded in Crete (Figure 1), although no further reference for Crete is mentioned in the technical report.

Figure 1. Geological map of IGME presenting the geotectonic zones of Greece and the distribution of thermal and mineral springs within them (after Athanassoulis et al. 2009)

As mentioned in the historical study on the thermal and mineral waters of Greece (Lekkas, 1938), Crete has 101 mineral springs most of which are saline or ferrous (Figure 2). Although, many of them were used as healing springs during the Ancient, Roman and Byzantine era, they faded into oblivion because the main concern of the authorities were focused in providing drinkable water to every settlement, city and more recently to the touristic infrastructures of the island as a result of the growing demands.

Figure 2. Distribution of thermal and metallic springs of Crete (after Lekkas, 1938)

Water samples were collected during, at least two wet and two dry periods in order to monitor and study the fluctuations in the physical characteristics but also their mineral content. The temperature (T), the pH the electrical conductivity (EC), and the total dissolved solids (TDS) of water samples were measured in situ by portable instruments. The samples were filtered, with 0.45μm filters and were stored in HDPE bottles. The aliquots for major and trace metal analyses were preserved by acidification with 2% HNO3. The analysis of cations and trace-elements was carried out by ICP-MS (7500cx, Agilent Technologies), while the analysis of anions was carried out by phasmatophotometry (Hach DR2800). (i) The springs hosted in the Phyllite Nappe are namely, Ksinonero, Temenia, Arelio and Moustakos: The Ksinonero spring water is cold (14oC, approximately) has pH equal to 3.2 and is connected with ferric depositions at its discharge. The concentration of dissolved iron (Fe) varies from 4 to 6g/l. The historical healing springs of Temenia (Mesa Chorio and Tzanoudiana) are the only springs of Chania and Western Crete that have been recognized and utilized as healing springs with the Royal Decree of 31 August 1957, as diuretic. The temperature of the water of Mesa Chorio spring varies from 14.1-19.3°C, is slightly acidic (pH 5.7-6.4) and has very low TDS (50 mg/L to 140 mg/L). The water of Arelio spring is cold (17o C), and lightly acidic (pH 6.3-6.8), and has very low TDS (50 mg/L). Periodically it contains Copper (Cu) up to 0.3 mg/L. During the Ottoman occupation, Bey’s were transferring the water to the city of Chania, using large glass containers (Lekkas, 1938). Moustakos spring has outlet temperature that varies from 18.7 to 22.5 oC, pH varies from 5.3 to 6, and has also very low TDS (50-70 mg/L). Periodically, it has high manganese (Mn) content up to 1347 μg/L and iron (Fe) up to 0.2 mg/L. (ii) The springs hosted in the Neogene formations are namely Kyrali, Lissos and Kares. The Kyrali spring, located near to the Frangokastello fortress, is coastal and hosted under a relatively large alluvial fan. Moreover, is warm (21-27oC) and connected with travertine depositions. Also, it contains fluorine (F) up to 0.2 mg/L. The remains of a round shaped pool in the sea, indicates that the warm water was used for bathing. Lisssos spring is well known since the ancient era, as it is located to the Asklepius Temple of the homonymous ancient city. The water is hypothermic (20-22oC), has near neutral pH that varies from 7.1 to 7.4, and relatively low TDS which varies from 200-400 mg/L. Periodically it contains up to 200 μg/L of zinc (Zn). Kares Springs have outlet temperature 18.5-20 oC, neutral pH and TDS that varies from 380-400 mg/L. The main dissolved constituents are HCO3 (380 mg/L, approx.) and SO4 (200 mg/L, approx.). Moreover the water contains 0.6 mg/L of dissolved fluorine (F) but also small quantities of trace elements including Li, Mo, Sr, etc. The main characteristics of the waters that discharge from springs in the Phyllite Nappe are their very low TDS and the slightly acidic pH, except from the Ksinonero spring water which is extremely acidic. On the other hand the springs hosted in the Neogene formations exhibit extreme characteristics including travertine deposition or high content in dissolved trace elements. Acknowledgements We would like to thank the director of the laboratory of Hydrochemical Eng. and Remediation of Soil, Prof. N. Nikolaides and the stuff, Mrs Maria-Liliana Saru and Dr Stella Voutsadaki for the chemical analysis of the water samples. References Lekkas, N. 1938. The 750 mineral springs of Greece, Athens, 292 pp., (in Greek). [Book] Athanassoulis, C., Vakalopoulos, P., Xenakis, M., Persianis, D., Taktikos, St. 2009. Integrated Quantitative and Qualitative Study of the Thermal Waters of Greece. Technical Report, IGME, Athens, 350pp. and Supplementary 243pp., (in Greek). [Technical Report]

ABSTRACT. The aim of this study is to calculate the displacement rates of the coastline at the western part of the island, which is characterized of the escarpment coast. The shape of this coastal zone is caused mainly by tectonism which is very frequent in this wider area (Valkaniotis et al., 2018). The western coast of the island from Cape Agios Ioannis (NW) to the southernmost point of the peninsula, Cape Drakato is steep and precipitous, as a result of the high seismicity of the Ionian Sea area (Bornovas, 1964). Along this side of the island, several landslides and rock falls are observed. The situation changes only at the northern part of the island, with a distinctive coastal landform over the narrow zone called "Zostiras" (Leivaditis & Verikiou - Papaspyridakou, 1986). This work was conducted using two different types of data. Historical analogue panchromatic aerial images of high resolution (Zuidam and Van Zuidam-Cancelado, 1979) and contemporary digital high resolution multi-spectral satellite images were combined for extracting the coastline at the time period of acquisition. The acquisition of the aerial photographs took place during 1945 and 2010, while the satellite images where acquired during 2016, 2017 and 2018 (Figure 1). In all cases the images were digitally processed and optically optimized in order to produce a highly accurate representation of the shoreline at each time period. All the data were imported in a Geographic Information System platform, where they were subjected into comparison and geo-statistical analysis (Tsokos et al., 2018). Several transects were drawn normally to the coast and the distance between them was set at every 200 m as the relative displacement of the coastline was calculated for each one of them. In a way to achieve this, an extension of the ESRI ArcGIS v.10.6.1 software was employed as published by USGS and named Digital Shoreline Analysis System v.5 (DSAS). The DSAS extension (Thieler et al., 2009) lets the user define a constant straight line in a specific distance from the shoreline and take transects perpendicular to it among the evolving coastlines. The measurements give quantitative information on the change of the position of the shoreline, as well as more useful statistical data. Even if this seems to be an arbitrary value, it worked rather sufficiently at this almost 12 km long segment of the shoreline as it can be characterized as rather curvy and either a smaller value would result an oversampled area with transects intersect each other mixing the calculations or a larger value would result quite sparse transect locations without any representative outcome.

ABSTRACT. On a global scale, extraction of inert materials from rivers is of great economic importance. Nevertheless, this economic activity can have both immediate and long-term consequences for stability of river system. The scope of the present study is to record and map the location of the extraction sites of inert materials from rivers. The study area is the upper reaches of Pinios river, which is located in Western Thessaly, central Greece. Τhe locations of extraction sites of inert materials were recognized on satellite image and further were verified and mapped by field work. A total number of 18 sites of extraction of inert materials in Pinios river and its tributaries were recorded and mapped. The total area of the extraction sites reaches up to 257,930 m2 and the total volume of removal materials are 1,077,829 m3. The removal materials come either from the riverbed or from the banks of the river and its terraces. In many cases the extractions have caused changes to channel morphology and bank erosion.

ABSTRACT. This study attempts to clarify whether formerly-documented pyroclastic deposits (Keller et al. 2014, McCoy and Dunn, 2002) belong to the Minoan eruption of Santorini or an earlier event. The ‘Minoan’ eruption, occurred in the 17th century BCE (1627–1600 BCE, Friedrich et al., 2006) and had widespread impacts on the civilization of the Aegean an Eastern Mediterranean (Marinatos, 1939). The Anafi island could be a key site for the dispersal of Minoan tephra as it is the most nearby island of Santorini. Despite its proximity, only a few spots with pyroclastic deposits have been found on the island (Keller et al. 2014, McCoy and Dunn ,2002). The occurrence of tephra layers of the Minoan eruption on Rhodes, Kos and western Turkey (Keller, 1980; Eastwood et al., 1999), suggests that Anafi must have covered by Minoan tephra, which was probably eroded and swept away afterwards (Keller et al., 2014). In recent years, a debate has sparked regarding the relation of the Anafi deposits to the Minoan eruption. McCoy and Dunn (2002) associated the thick pumice deposits on Anafi with the Minoan eruption, suggesting “a far larger (Minoan) eruption than previously thought”. In contrary, Keller et al.(2014), after geochemical determination of glass composition by electron microbe analysis on the samples from Anafi, pointed out a strong geochemical similarity with those analyzed from LP2 eruption of Thera at 172 ka, as has been determined by Druitt et al. (1999), excluding any correlation with the Minoan eruptive phase. In this study we attempt to settle the debate of the tephra chronology on Anafi on the basis of numerical dating and specifically by applying the OSL dating method to colluvial deposits that bracket the pumice deposits, reported by McCoy and Dunn (2002) and Keller et al. 2014. It is noted that it’s the first time that the pyroclastic deposits of Anafi will be chronologically constrained, providing indirectly the provenance (Minoan or of an earlier eruptive phase) of the pyroclastic deposits. Our field survey aimed to collect samples from two pumice deposits on Anafi, already studied by Keller et al. (2014) and and McCoy and Dunn (2002, 2004) at Prassa and Vounia, in the western and central part of the island accordingly. We collected 2 samples for OSL dating from the colluvial deposits that cover the pumice layer (Fig 1), as the base of the pumice deposits is not exposed in the section. The sample preparation was carried out at the Department of Geology and Geoenvrionment, University of Athens and aimed at extracting quartz grains from the sampled colluvia. OSL measurements were carried out at the OSL dating laboratories at CEREGE, Aix-Provence, France and the Archaeometry Center, University of Ioannina, Greece. The results derived by the application of OSL dating, demonstrated that the colluvium above the pumice deposition at Prassa was dated about 21.04 ka and in Vounia about 29 ka. According to our new chronological framework from the two sites at Vounia and Prassa, we conclude that tephra deposits in Anafi could not be of Minoan origin as McCoy and Dunn (2002) have suggested, given that the age of the stratum above ranges between 21 ka- 29.ka. The age form Prassa, coincides well with the Cape Riva eruption of Santorini at about 21.8 ± 0.4 ka (Druitt, 1999) On the other hand, we could not unquestionably exclude its LP2 origin as suggested by Keller et al. (2004) as we did not date the base of pyroclastic deposits. More geochemical and chronological analyses on pyroclastic deposits are needed, for the more efficient determination of their provenance and for the better understanding of the effects of Minoan eruption in the Aegean and eastern Mediterranean.

ABSTRACT. Speleothems are useful in detecting past geoenvironmental events and, specifically, variations in their chemical composition on the level of trace elements, constitutes a proxy of volcanic eruptions, enabling both the dating and the assessment of their effects. (Frisia et al., 2005) Several geochemical studies on speleothems have identified well documented volcanic eruptions in the Mediterranean and the Near East, such as the Minoan eruption of Santorini, the Campanian Ignimbrite eruption, as well eruptions from Nisyros and Etna volcanoes etc. (Fleitmann et al. 2009; Bar-Matthews eta al. 1999; Verheyden et al.2008; Badertscher et al. 2014; Gençalioğlu-Kuşcu et. al, 2018). In the speleothem record, volcanic eruptions are generally identified in the carbonate laminae by sharp spikes in the amount of specific major and trace elements. Typically, high concentrations of S, Br, Bi, Zi, Ba, Mo etc can be indicative of volcanic activity (Frisia et al., 2005; Wynn et al., 2008; Bobrowski et al. 2003; Badertscher et al. 2014). This study attempts to clarify possible ‘signatures’ of past volcanic eruptions in speleothems of Santorini. The Santorini volcano has shown significant explosive activity over the last 2 million years, which has not only altered the landscape, but also affected the civilizations of prehistoric and historical ages in east Mediterranean region. Contrary to mainland, karstic systems in Santorini are poor and limited to the carbonate post- alpine sediments to the south-east. Carbonate rocks are exposed on the Profitis Ilias Mountain and Mesa Vouno mainly. (Heiken and McCoy,1984). The most important cave is the Zoodochos Pigi, in the southeast part of the island in the vicinity of Ancient Thera. The presence of a permanent spring inside the cave, had been of immense value to the inhabitants of the Archaic city, as testified through the abundance of Archaic inscriptions (Hiller von Gaertringen et al.1904). Despite the poor decoration, speleothems such as flowstone abound in the cave. During examination of the speleothem deposits in Zoodochos Pigi, we encountered charcoal trapped within the flowstone on a sharp boundary between bioturbated deposits to the bottom and undisturbed CaCO3 precipitation right above it (Fig.1). The unprecedented discovery of charcoal atop a bioturbated horizon shows evidence of sudden cessation of human activity in the cave in far- off times. In order to explore the nature and the timing of the event, material enveloping the charcoal was submitted for mineralogical and geochemical analysis through optical and electron scanning microscopy (SEM-EDS), as well as XRD analysis, whereas the C-14 dating of the charcoal itself is underway. Profiling of the chemical composition of the flowstone in the interface of the bioturbated (lower) horizon and the flowstone laminae, yielded several minerals and inclusions, exotic to typical flowstone composition , such as apatite, ilmenite, muscovite , FeS2 and Bi, Zi, Cu, Ni and Zn S, Ba oxides. (Fig.2). The presence of these minerals tails off sharply upwards going over typical (carbonate) flowstone mineralogy with calcite as the main mineral phase. Specifically elements such as Bi, Ba, S, Zi are associated with volcanic eruptions (Bobrowski et al. 2003). In conclusion, this is the first analysis that has ever disclosed a volcanic eruption in the so far poorly speleothem record of Santorini. Chronological correlation on the basis of radiocarbon dating with the well documented timeline of eruptions of Santorini, as well as assessment of the possible wide - ranging effects on the local-to-regional environment and archaeological record of the said eruption is underway and yet to be announced shortly.

ABSTRACT. Sithonia Peninsula in Chalkidiki is an area dominated by the Sithonia Plouton occurrence and its characteristic geomorphic appearance of granite weathering. In the area of the Akti Kalogrias beach there is a significant number of cavities and surface potholes. Granite caves and tafoni formations have been described from several areas in Greece, such as Serres, Kavala (Lazaridis and Pipera, 2008), Fthiotida (Modianaki 2012) Naxos and Tinos (Evelpidou et al. 2010 and references therein), Paros and Ios (Hejl, 2005). Several opinions, and sometimes controversial, can be found in literature about the formation of caves in granite rocks. The main processes that have been described in order to interpret their development (i.e. vidal romani, 1989; 1990; Cambell 1997; Twidale 2008; Uña Alvarez 2008; Romani 2008, Groom et al. 2015; Klimchouk 2017): 1. eolian deflation; 2. weathering through insolation; 3. frost action; 4. wetting and drying; 5. chemical and salt weathering; 6. biological decay; 7. gravitational forces (imposed by large boulder resting on an outcrop and causing crystal strain at the point or point of contact, eventually leading to rock basins on the outcrop and tafoni on the underside of the boulder); 8. microclimatic conditions; 9. exfoliation; 10. haloclasty [this category emracing crystal growth, hydration expansion and osmotic pressure]; endogenous processes. In the present study two adjacent locations in Akti Kalogrias have been recorded in detail in order to describe the type of the cavities on the basis of their location and morphology, and to discuss their origin. Methods Track and cave positions are recorded with a Garmin GPSmap 60GSx and the track’s length and area are estimated by MapSource software (v. 6.13.7 Garmin). Each cavity was labeled, morphologically categorized, measured and documented. Some of the cavities were surveyed in detail.

Figure 1. Μorphological categories of tafoni in Akti Kalogrias area: A. tafone formed in the side of the rock host with honeycombed erosion; B. tafone formed in the base of the rock form; C. tafone develobed among discontinuities; D. a mushroom-like form; E. a complex tafone form.

Results Their dimensions do not exceed 8 m. Their dimensions range along horizontal axis from 0.9m to 8m (mean 2,4 m); vertically (height) from 0.2 m to 3.0 m (mean 1,2 m); and their depth ranges from 0,15 m to 4.1 m with (1.2 m). Morphologically they can be distinguished in 5 categories that groups cavities with similar number of openings, their location in relation to the boulder and any discontinuities. These categories are the following (Figure 1): 1.tafoni that are formed in the side part of the rock; 2. tafoni that are formed in the base or at the above a horizontal discontinuity and the erosion continues at the inside of the host rock and sometimes resembles a “tortoise shell” form; 3. tafoni that are formed between discontinuities; 4.tafoni that are formed in the base and around of the host rock giving a “mushroom-like shape to that; and 5. combination of the above-mentioned groups. Honeycomb erosion is observed in tafoni from various categories but mainly in basal, and side-wall tafoni. Regarding their spatial distribution, two parameters are estimated: the number of cavities larger than 0.5 m found in the surveyed area; and number of cavities divided to the walked distance. These two parameters are 1/284 cavities/m2 and 1/52 cavity/m2 for the first area and 1/520 cavities/m2 and 1/72 cavity/m2 for the second area, respectively. In total, the two areas covered 21.500 m2 and 3 km of distance that means 1/407 cavity/m2 and 1/63 cavity/m. The hypothesis that a preferred orientation exists was checked with directionality tests. The possibility of random orientation cannot be rejected. The logarithm of the cavity volume and the boulder that hosts the cavity are moderately correlated (n=22). There are 3 main discontinuities recorded in the area (J1: 126/85, J2: 237/85 and J3: 320/20). Their density decreases from J3 to J1. Among 43 tafoni, 21% is formed in boulders that are not in situ. Regarding the in situ tafoni, 29%, 18% and 35% are associated with the discontinuities J1, J2 and J3, respectively. In 21% the cavities are formed along he combination of J1, and J3 discontinuities. In 38% of in situ there is no obvious relation to discontinuities. Concluding remarks With this work the tafoni weathering morphology in Sithonia is described qualitatively and quantitavely. Despite that large caves are commonly unexpected in this setting, it seems that these forms occur in large numbers. This means relatively high values in the estimated parameters. The results is expected to be used for comparisons with other granite tafoni occurrences. References André, M.F. and Hall, K., 2005. Honeycomb development on Alexander Island, glacial history of George VI sound and palaeoclimatic implications (two step cliffs/Mars Oasis, W Antarctica). Geomorphology, 65(1-2), 117-138. Campbell, E.M., 1997. Granite landforms. Journal of the Royal Society of Western Australia, 80, 101. Evelpidou N, Leonidopoulou D, Vassilopoulos A. 2010. Tafoni and alveole formation. An example from Naxos and Tinos Islands, in: Natural Heritage from East to West,Springer, Berlin, Heidelberg ,35-42. Groom, K.M., Allen, C.D., Mol, L., Paradise, T.R. and Hall, K., 2015. Defining tafoni: Re-examining terminological ambiguity for cavernous rock decay phenomena. Progress in Physical Geography, 39(6),775-793. Hejl E. A pictorial study of tafoni development from the 2nd millennium BC. Geomorphology. 2005 Jan 3;64(1-2),87-95. Huinink, H.P., Pel, L. and Kopinga, K., 2004. Simulating the growth of tafoni. Earth Surface Processes and Landforms: The Journal of the British Geomorphological Research Group, 29(10), 1225-1233. Klimchouk, A., 2017. Types and settings of hypogene karst. In Hypogene Karst Regions and Caves of the World. Springer, Cham,1-39. Lazaridis, G. and Pipera, K., 2008. Preliminary report on granite caves in Greece. Cadernos do Laboratorio Xeolóxico de Laxe: Revista de xeoloxía galega e dohercínico peninsular, (33), 101-113. Modianaki, Z., Evelpidou, N., Stamatopoulos, L. and Stamatakis, M., 2012. Tafoni formation at Theologos (Fthiotida, Greece). Revista de Geomorfologie, 14. Romaní JR. 2008. Forms and structural fabric in granite rocks. Cadernos do Laboratorio Xeolóxico de Laxe: Revista de xeoloxía galega e do hercínico peninsular. (33), 175-98. Vidal Romaní, J.R., 1989. Geomorfología granítica en Galicia (NW España). Cadernos do Laboratorio Xeolóxico de Laxe: Revista de xeoloxía galega e dohercínico peninsular, 13, 89-163. Romaní, J.R.V. and Twidale, C.R., 1998. Formas y paisajes graníticos. Universidade da Coruña. Twidale, C.R. and Bourne, J.A., 2008. Caves in granitic rocks: types, terminology and origins. Cadernos do Laboratorio Xeolóxico de Laxe: Revista de xeoloxía galega e do hercínico peninsular, 33, 35-57. Uña Álvarez, De, E., 2008. Description and nomenclature of the tafoni features (cavernous rock forms). Research approaches in granite terrains. Cuadernos Lab. Xeolóxico de Laxe (Coruna), 33, .65-82. Uña Álvarez, De, E., and Vidal-Romaní JR. 2008. Some minor features (tafoni, cavernous forms) in the granite terrains of Los Riojanos (Pampa de Achala, Sierra Grande de Córdoba, República Argentina). Geometric and morphologic properties. Cadernos Laboratorio Xeolóxico de Laxe. 2008,33,3-99.

ABSTRACT. Human activities such as deforestation of slopes, removal of slope support in road cuts, alteration of surface runoff paths, have become important triggers for landslide manifestation.Scope of the present study is to identify the influence of human activities on landslide occurrences. The study area is located in the northern part of Euboea Island, in central Greece. To accomplish this scope, the existing landslides along with anthropogenic factors such as road network and land use were used. Statistical analysis and GIS were applied to process and evaluate the landslides and factors. The results of the applied methodology indicate that the frequency of landslides increases in close proximity to roads.A 100m wide zone along with any type of road corridors is strongly correlated with landslide events. The extensive cultivated land and the bare area of the study area are strongly related to landslide activity.

ABSTRACT. The aim of the present research is to study the sedimentological record of fluvial and coastal landforms of the Filiouris River wave dominated delta plain, during Holocene. Filiouris River crosses the Rhodope plain and flows into Thracian sea (North Aegean), southwards the Komotini City, creating a deltaic plain. A total of 12 samples were collected and analyzed in the Physical Geography Laboratory of Aristotle University of Thessaloniki. Furthermore a geomorphological map was produced using ArcGIS software. From the sedimentological characteristics of the sampling locations, we can conclude that there is a succession of coastal and aeolian depositional environments from South to North. Regarding their positions, the sediments are very well sorted indicating a wave reworking process. Additionally, it indicates a step forward delta progradation. The coastline of Filiouris River is a wave dominated deltaic coast with a succession of coastal and Aeolian landforms.

ABSTRACT. The Agios Georgios show cave is located at a small hill in the town of Kilkis (N. Greece). It has been formed in the Middle- Upper Triassic limestones that belong to the Deve Koran-Doubia subzone of the Circum-Rhodope geotectonic zone (i.e. Mountrakis, 2010 and references therein). Morphologically the cave is an 800 m2 2-dimensional maze with narrow and high fracture-guided passages (Figure 1). Some chambers are mainly formed due to breakdown. Even though the entrance of the cave is artificially opened, there were multiple entrances in the past. These are nowadays obscured by sediment filling of Late Pleistocene age, as it is indicated by large mammal fossils (Tsoukala, 1992).

Figure 1. Characteristic condensation corrosion features of Agios Georgios show cave. A. Solution-smoothed wall with cupolas, cusps and corroded speleothems that delimit cupolas. B. Fracture-guided cupolas on the ceiling of a narrow passage and accompanying forms. C. Ceiling cupolas along bedding and a more susceptible to solution bed in limestone. D. Wall-pockets and corroded speleothems. E. Solution-smoothed wall and remnant of corroded speleothem.

Regarding the (chemical) depositional forms the cave appears moderately decorated. The predominant speleothem in Agios Georgios cave is the coralloids with globular or button-like shape. Other speleothems recorded in the cave are stalactites, stalagmites, columns, draperies, flowstones, eccentrics and shields. A number of studies has been done on stalactites and stalagmites to investigate the paleo-environment of the cave (Antonelou, 2007; Antonelou et al., 2010; Dotsika et al., 2010; Ifandi, et al., 2015). Meso- and small-scale morphology includes cupolas, cusps, partitions, echinoliths, rock bridges and pendants (Figure 1). Some of these dissolutional forms, such as the cupolas, partitions etc., are polygenetic (e.g. Dublyansky, 2013), causing difficulties in the interpretation of speleogenesis. Especially in the broader area of Agios Georgios cave, it has been already noticed that these dissolutional forms are developed over both the speleothems and the limestone (Lazaridis, 2017). This observation dates their formation as post-speleogenetic and means that although the origin of the cave has been considered hydrothermal-phreatic (Lazaridis, 2017), many of the cupolas and related forms have developed when the cave drained and after the deposition of speleothems by seepage water. Thus, these features are the result of condensation corrosion, which is a process of bedrock and speleothem removal from film water that condenses on the rock-mineral substrate, when their temperature is below dew point of cave air (e.g. Dreybrodt et al., 2005). The aim of this study is to document the dissolutional forms by condensation corrosion, their distribution in the cave and set some questions for further investigation. Condensation corrosion morphology The related to condensation corrosion features are widespread all over the cave. However, the significant extend of coralloids in the area that is known as “second floor”, obscures the observation of dissolutional forms. Their dimensions range from few centimeters up to the passage diameter. They are either side-wall pockets (Figure 1-A, D) or ceiling cupolas (Figure 1-B). Accompanying forms, such as cusps and partitions do exist (Figure 1-B,C). Some of them are fracture guided (Figure 1-B). In general they contribute in the formation of solution-smoothed walls or boneyard morphology on the ceiling. Conclusions • This study provided a detailed documentation of condensation corrosion morphology in Agios Georgios cave and verified previous report of the process (Lazaridis, 2017). • The morphological features that are observed are quite similar to those described in other caves (e.g. Dublyansky and Spötl, 2014) and have been attributed to condensation corrosion. • Since Agios Georgios is a show cave, the study of condensation corrosion is crucial because visitors could affect the cave climate and enhance that process. • Among others, in our future goals is to create a data-set with dimensions of these dissolutional forms, measure and estimate the amount of dissolution and possibly the rate, to correlate their formation to the environmental conditions and check if the process is still active. Acknowledgments We thank the geology student and caver Kyriaki Fellachidou for her assistance during the field work. References Antonelou, A., 2007. Study of speleothems from Agios Geogios Cave, Kilkis prefecture: Investigation of paleoclimatic environmental conditions using stable isotopes of C and O. MS. Thesis, University of Patras, Patras, 183 p. Antonelou, A., Tsikouras, B., Papoulis, D., Hatzipanagiotou, K., 2010. Investigation of the formation of speleothems in the Agios Georgios Cave (N. Greece). Bulletin of the Geological Society of Greece 43, 876-885. Dotsika, E., Psomiadis, D., Zanchetta, G., Spyropoulos, N., Leone, G., Tzavidopoulos, I., Poutoukis, D., 2010. Pleistocene palaeoclimatic evolution from Agios Georgios Cave speleothem (Kilkis, N. Greece). Bulletin of the Geological Society of Greece 43, 886-895. Dreybrodt, W., Gabrovšek, F., Perne, M., 2005. Condensation corrosion: a theoretical approach. Acta Carsologica, 34(2), 317-348. Dublyansky, Y.V., 2013. Karstification by geothermal waters, in: Shroder J, Frumkin A, (Eds.), Treatise on geomorphology. Academic Press, vol 6, 57–71. Dublyansky, Y.V., Spötl, C., 2014. Morphological effects of condensation-corrosion speleogenesis at Devils hole ridge, Nevada, in Klimchouk, A., Sasowsky, I.D., Mylroie, J., Engel, S.A., Summers Engel, A., (Eds.), Hypogene cave morphologies, Karst Waters Institute Special Publication, 18, 36-43. Ifandi, E., Tsikouras, B., Papoulis, D., Hatzipanagiotou, K., Antonelou, A., 2015. A new microenvironment for the formation of clay minerals: the example of authigenic halloysite-7Å and gibbsite in a stalactite from Agios Georgios Cave, Kilkis, north Greece. International Journal of Speleology, 44(3), p. 10. Lazaridis, G., 2017. Hypogene Speleogenesis in Greece, in: Klimchouk, A., Palmer, A.N., De Waele, J., Auler, A.S., Audra, P. (Eds.), Hypogene Karst Regions and Caves of the World, Springer 14, 225-239. Mountrakis, D., 2010. Geology and geotectonic evolution of Greece, University Studio Press. Tsoukala, E.S., 1992. The Pleistocene large mammals from the Agios Georgios cave, Kilkis (Macedonia, N. Greece). Geobios, 25(3), 415-433.

ABSTRACT. N. Kargopoulou1, G. Lazaridis1, A. Karakosta1 (1) Aristotle University of Thessaloniki, Department of Geology, Laboratory of Geology and Palaeontology, 54124, Thessaloniki, Greece, ntkargop@geo.auth.gr

A small limestone quarry (~0.4 hectares) is located in a low hill in the vicinity of Mandres village, in Kilkis Prefecture (N. Greece). It is 1.2 km east to the village, at about 180 m above sea level (N40.88426 E22.92365). A number of small cavities and cavernous forms are found during commercial works in the NE part of the quarry (Fig. 1). They are opened in carbonates (limestones and dolomite) of Middle to Upper Triassic age (Carnian-Anisian) that are overlain by quartzites. These rocks belong to the Deve Koran-Doubia Unit of the Circum-Rhodope geotectonic zone (Kockel & Ioannides, 1979; Kaufmann et al., 1976; Mountrakis, 2010) that is tectonically placed upon the calcareous flysch of Svoula Unit. The age of the latter is younger than Upper Triassic. These Alpine rocks crop out at higher altitudes and they are surrounded by quaternary sediments. Although the largest cave in the area, the Agios Georgios show cave (Kilkis town), is opened in these carbonates, our knowledge about caves and speleogenesis in the area is quite limited. Methods The cavities are surveyed according to standard cave techniques (i.e. Kalogeropoulos et al., 2008; Trimmis, 2018 and reference therein). Rock discontinuities were measured with CLAR compass. Terms and morphological descriptions of caves can be found in Lauritzen and Lundberg (2000), Gunn (2004) Ford and Williams (2007) White and Culver (2005).

Figure 1. Sketch of the quarry escarpment in Mandres, with the cave entrances depicted and ground plan of the largest cavity.

Description and results The cavities found in the Mandres Quarry (MQC: Mandres Quarry Cavity) are mainly fracture guided by N-S and E-W discontinuities. Their length reaches about 6m and the largest one (MQC4) is located in the eastern escarpment and covers an area of ~30 m2. In the latter, the ceiling and the side-walls coincide with rock discontinuities and are probably related to breakdown that affects the original morphology. Its NE part, however, displays a dissolutional passage that is abruptly terminated. It is poorly decorated with few common speleothems such as stalagmites, flowstone and coralloids. This is commonly the case in all the cavities found in the quarry that are mainly decorated with coralloids. The only exception is a fracture-guided cavity at the northern escarpment that is almost totally filled with thick calcite layers, flowstones, coralloids. The central part of the cavity is partially filled with fine-grained red sediment. All in all the caves are characterized by minimum dissolutional forms of small-scale that means the information about speleogenesis comes from passage-scale forms. The high and narrow, symmetrical and fracture guided passages are indicative of phreatic speleogenesis. This is in agreement with the absence of vadose marks. Furthermore, the orientation, the shape and the filling of the passages in these cavities is similar to those found in the Agios Georgios cave and its surroundings (i.e. in the Quarry to the north of the cave). The latter is considered to have been developed by hypogene speleogenesis (Lazaridis, 2017). Conclusions • A number of small cavities with similar morphological features is investigated and recorded in detail. • Their meso-scale morphology is phreatic and identical to the hypogene caves of the area and thus they probably have been developed under similar conditions. • This group of cavities provides new information and expands the area that has been affected by the processes of hypogene speleogenesis in the carbonates of the Circum-Rhodope Zone. References Ford, D., Williams, P. D. 2007. Karst hydrogeology and geomorphology., John Wiley & and Sons IncInc. Gunn, J. 2004. Encyclopedia of Caves and Karst Science., Taylor and& Francis Inc. Kaufmann, G., Kockel, F., and Mollat, H., 1976. Notes on the stratigraphic and paleogeographic position of the Svoula Formation in the Innermost Zone of the Hellenides (northern Greece). Bulletin de la Societe Geologique de France 18, 225-230 Kalogeropoulos, I., Lazaridis, G., Tsekoura, A., 2008. Methodology of cave mapping: comparing routings. 4th Pancretan Speleological Symposium. Hellenic Speleological Society, Rethymnon, Crete, Greece http://ese.edu.gr/media/seminars/sem_notes/hartografisi/survey_methods.pdf Kockel F., Ioannides K., 1979. Geological Map of Greece, Kilkis sheet. Scale 1:50.000, Institute of Geology and Mineral Exploration, Greece. Lauritzen, S., Lundberg, J. 2000. Solutional and erosional morphology of caves. Klimchouk, A., Ford, D. C., Palmer, A. N., Dreybrodt, W. (eds.) Speleogenesis. Evolution of Karst Aquifers. Huntsville: National Speleological Society. Lazaridis, G. 2017. Hypogene Speleogenesis in Greece. In: Klimchouk, A., Palmer, A. N., De Waele, J., Auler, A. S. & Audra, P. (eds.) Hypogene Karst Regions and Caves of the World. Springer, 225-239. Mountrakis, D. 2010. Geology and Geotectonic Evolution of Greece. University Studio Press Inc, Greece, p. 374 (in greek) Trimmis, K. P. 2018. Paperless mapping and cave archaeology: A review on the application of DistoX survey method in archaeological cave sites. Journal of Archaeological Science: Reports 18, 399-407. White, W. B., Culver, D. C. 2005. Encyclopedia of caves, Elsevier Amsterdam (The Netherlands).

ABSTRACT. The hydrological conditions and development of the epigenetic Stefanina Cave and the maximum paleo-flow discharge in its main passage are investigated on the basis of cave pattern, passage geometry and scallop length. Scallops are small-scale morphological features that form asymmetric dissolution pockets due to turbulent flow of a solvent over a soluble surface. Caves are ideal environment for the formation of scallops that indicate forced flow of unsaturated water along a pressure head. In deep-phreatic setting, where dissolution takes place by convecting water bodies, scallops are absent. Furthermore, these pockets are also indicators of flow direction due to their asymmetry and a reverse relationship between their size and the flow velocity of the fluid (Curl, 1966; Curl, 1974; Lauritzen, 1989). The Stefanina Cave or Lakkia Cave (N40.78183 E23.61357 WGS84; Fig.1) is located NE of the Stefanina Village at about 850 m above sea level (a.s.l.) in the northern slope of the Neromanna stream. The area consists of metamorphic rocks such as marbles and gneisses in alternations that belongs to the almost 3 km thick Kerdylion Series of the Serbomacedonian Massif. The cave is opened in the “upper marble horizon” (20-350 m thick) with white marble (coarse crystalline thick layered), bluish crystalline limestone (fine-grained, thin bedded) intercalated with schists, amphibolites and gneisses.

Figure 1. Ground-plan of the Stefanina Cave

Methods The cave surveyed according to standard cave techniques (i.e. Kalogeropoulos et al., 2008; Trimmis, 2018 and reference therein). Rock discontinuities were measured with CLAR compass. Terms and morphological descriptions of caves can be found in Lauritzen and Lundberg (2000), Gunn (2004), Ford and Williams (2007), White and Culver (2005). The gathered data were processed in the spreadsheet program ScallopEx (Woodward and Sasowsky, 2009). The calculations run for 5℃ water temperature. The estimated flow velocities were statistically analysed in the software PAST 3.2 (Hammer et al., 2001). Description and results The explored part of the Stefanina Cave is 210 m long and covers an area of 1250 m2. Total passage length is 325 m and forms a branchwork horizontal pattern (Palmer, 2000). The height difference between the entrance and the deepest explored part is about 30 m, giving a hydraulic gradient about 0.2. At about 120 m from the entrance a meandering vadose canyon is formed and sediment fill has been eroded revealing the carbonate bedrock. After that point the conduit forms a keyhole passage in cross section and becomes gradually narrow and more canyon like (Fig. 2). In figure 1 survey stations 23-25 where scallops measured are depicted. In addition, a number of measurements are taken between and after these stations. In total about 400 scallops where measured in 30 locations, at different heights inside the passage. The estimated peak flow velocity ranges from 0.4 to 2.7 m/s (mean=1.32; s=0.46, n=30; Fig. 2E). The null hypothesis of normal distribution cannot be rejected. The highest and lowest values appear as outliers. However, the smaller values have been found inside the meandering canyon at locations inside of bends, where lower values are expected. Based on these values and the dimensions of the passage measured from the cross sections, a peak flow discharge equal to 2.2 m3/s is estimated.

Figure 2. A. View of the main passage at the upstream part of the cave; B. Keyohole section with the phreatic upper and the vadose canyon power part; C. bend in the meandering channel; D. wall detail with scallops; E. histogram with scallop-based estimations of flow velocity in the area of survey stations 23-25.

Concluding remarks • The Stefanina Cave has a branchwork pattern in ground-plan that is commonly related to recharge via karst depressions (Palmer, 2000). The passages are both curvilinear and angular, related to foliation and fractures, respectively. It is mainly developed along the foliation of the host rock. • The cross section in the upstream part of the cave indicates a phreatic passage. • Τhe keyhole cross section found in that canyon passage at about the middle part of the explored cave, is indicative of a second stage of developed after water table drop. • The peak discharge estimated in the keyhole cross section is indicative for that area and it is expected to be higher further inside the cave due to the existence of lateral passages. References Curl, R.L., 1966. Scallops and Flutes. Transactions Cave Research Group of Great Britain, 7(2): 121-160. Curl, R.L., 1974. Deducing Flow Velocity in Cave Conduits from Scallops. National Speleological Society Bulletin, 36(3): 22. Ford, D., Williams, P.D., 2007. Karst hydrogeology and geomorphology. John Wiley and Sons Inc. Hammer, Ř., Harper, D.A.T., & Ryan, P.D., 2001. PAST: Paleontological Statistics Software Package for Education and Data Analysis–Palaeontol. Electron, 4: 9. Kalogeropoulos, I., Lazaridis, G., Tsekoura, A., 2008. Methodology of cave mapping: comparing routings. 4th Pancretan Speleological Symposium. Hellenic Speleological Society, Rethymnon, Crete, Greece http://ese.edu.gr/media/seminars/sem_notes/hartografisi/survey_methods.pdf Lauritzen, S.E., 1989. Scallop Dominant Discharge. Proceedings of the 10th International Congress of Speleology, Budapest, Hungary, 123-124. Lauritzen, S., Lundberg, J., 2000. Solutional and erosional morphology of caves. Klimchouk, A., Ford, D.C., Palmer, A.N., Dreybrodt, W. (eds.) Speleogenesis. Evolution of Karst Aquifers. Huntsville: National Speleological Society. Lazaridis, G., 2017. Hypogene Speleogenesis in Greece. In: Klimchouk, A., Palmer, A.N., De Waele, J., Auler, A.S. & Audra, P. (eds.) Hypogene Karst Regions and Caves of the World. Springer, 225-239. Palmer, A., 2000. Hydrogeologic control of cave patterns. Speleogenesis: Evolution of Karst Aquifers. Huntsville: National. Speleological Society, 77-90. Trimmis, K.P., 2018. Paperless mapping and cave archaeology: A review on the application of DistoX survey method in archaeological cave sites. Journal of Archaeological Science: Reports 18, 399-407. White, W.B., Culver, D.C., 2005. Encyclopedia of caves, Elsevier Amsterdam (The Netherlands). Woodward, E., Sasowsky, I.D. 2009. A spreadsheet program (ScallopEx) to calculate paleovelocities from cave wall scallops. Acta Carsologica, 38(2-3): 303-305.

ABSTRACT. Paragenesis (Roth (1937; Renault 1958; 1968; Ford 1971; Ford and Ewers, 1978; Lauritzen and Lauritsen 1995; Bella and Bosák, 2015) is a poorly understood process of cave passage upwards enlargement that results in a variety of geomorphological features. It is observed in phreatic cave systems, when groundwater velocity reduces resulting in permanent deposition of transported sediment that protects the lower part of the passage from dissolution (only negligible dissolution has been observed; i.e. Vaughan, 1998). Theoretically the process is limited upwards to the water table. Such passages are known from caves in carbonates, gypsum and salt (i.e. Frumkin, 1998; Pasini 2009, 2012).Paragenesis has been considered related to periglacial environments (Farrant and Smart, 2011; Lauritzen, 2013). Although, most authors consider paragenesis as a result of dissolution, others (Roth, 1937; Kunský, 1950) a result of mechanical erosion and Pasini (1975, 2009), uses the term “erosion” sensu lato, including mechanical erosion, physical dissolution and corrosion. Farrant and Smart (2011) reviewed the role of alluvation and paragenesis in speleogenesis. However, direct observation on paragenetic processes is obscured either by sediment filling or by their phreatic nature. The aim of this study is to geometrically reproduce the cross-section shape of a paragenetic canyon in order to investigate the controlling factors of the process. Methods In order to investigate the development of a paragenetic passage a geometric perspective is applied in Matlab. The first step starts with the cross section of a circular phreatic passage and the following steps represent the sum of three agents, deposition, corrosion, and corrasion that act simultaneously on the perimeter of the cross section. At the first step, deposits cover the half of the passage height and shields the lower part from corrosion and corrasion. This is an assumption in order to simplify the computations. Although dissolution occur on the covered by sediment passage and within the sediments, its action has been found to be negligible in comparison with the rest passage (Vaughan, 1998) and thus it is ignored. Corrosion acts isotropically at the wet perimeter of the fully flooded passage and actually it is set at a well-accepted maximum of 0.1 mm/year. Corrasion is considered to act upwards due to buoyancy of suspended load. A heterogeneous flow regime with stratification and formation of a bottom layer, mainly stationary is assumed. The abrasion by suspended sediment and kinetic energy flux are estimated according to Anderson (1986); for the relation of suspended sediment and flow velocity a data series from the Blue Hole spring, Central Kentucky, USA is used (Reed et al., 2010). Sediment supply is considered uninterrupted. Illustration of the passage development done in MATLAB environment, attempting to describe the geometrical evolution of the points and the ceiling trace seen in Figure 2. The passage width at each step n is defined as the intersection of the sediment level and the cave ceiling (flooded part of the passage cross section) of the n-1 step. The ceiling is traced as the sum of corrosion and corrasion. Both agents are related to fluid velocity. Sediment level is set as a pseudo-random percentage of the water-filled part of the passage at n-1 step. Results The cross-section of the passage is drawn first as the result of dissolution that gave a continuously widening upwards passage. This shape differs significantly from what is the canyon-like shape of a paragenetic passage. Then the calculation is repeated with the contribution of erosion sensu lato that acts upwards. In this case the result resembles a paragenetic canyon. This is due to the high rate of erosion that is higher than that of dissolution. Furthermore, the rate of erosion s.I. is only indicative since the data for the suspended load come from a spring during flood. However, a key point on these results is that dissolution is directly related to flow velocity, whereas abrasion scales with flow velocity to the fifth power (Whipple et al., 2000). The results are intriguing and largely based on the initial assumptions for the calculations. However, there are some studies on abrasion and dissolution rates in cave passages, such as Newson (1971). In the Cheddar cave in Mendip dissolution is found to be 75 times higher than abrasion, except of years of significant flooding events where abrasion was two times higher than dissolution. Although this seems to be insignificant it is the result of mainly only one flooding event in a year, whereas paragenesis takes place in phreatic fully flooded caves, where these conditions are permanent. Cooper et al. (2014) have similarly shown the paragenesis as the result of dissolution and mechanical erosion. Conclusions • A cross section of a paragenetic canyon is drawn in MatLab by using geometrical relations of passage’s key points, equations for abrasion process and empirical data. • This concept supports that paragenetic canyon is explained by high erosion s.l. rate. • In contrary to dissolution, which is directly proportional to flow velocity, abrasion scales with flow velocity to the fifth power. • Flood-like conditions favour paragenesis, as it is shown by the necessity for high abrasion rates.

Figure 1. Sketch showing the basic concept of geometric development of a phreatic passage during paragenesis.

Figure 2. Modification of passage cross-section due to A. corrosion for a duration of 1000 years and B. abrasion and corrosion for a duration of 10 years.

References Bella, P. and Bosák, P., 2015. Ceiling erosion in caves: early studies and Zdeněk Roth as author of the concept. Acta Carsologica, 44(1). Cooper, M. P., Perne, M., Covington, M. D., 2014. Simple shear stress approximations and a first step in modeling mechanical erosion in caves. 2014 GSA Annual Meeting in Vancouver, British Columbia, 2014. Farrant, A., 2004. Paragenesis. Encyclopedia of Caves and Karst Science. Fitzroy Dearborn. New York, 569-571. Farrant, A. R., Smart, P. L. 2011. Role of sediment in speleogenesis; sedimentation and paragenesis. Geomorphology, 134, 79-93. Ford, D., 1971. Geologic structure and a new explanation of limestone cavern genesis. Transactions of the Cave Research Group of Great Britain, 13, 81-94. Frumkin, A., 1998. Salt cave cross-sections and their paleoenvironmental implications. Geomorphology, 23, 183-191. Ford, D. C., R. O. Ewers, 1978. "The development of limestone cave systems in the dimensions of length and depth." Canadian Journal of Earth Sciences 15(11): 1783-1798. Kunský, J., 1950: Kras a jeskyně. - Přírodovědecké nakladatelství, 163 pp., Praha. Lauritzen, S.-E. Paragenesis: The “Royal Mark” Of Subglacial Speleogenesis. 16th International Congress of Speleology, 2013 Brno. 366 - 367. Lauritzen, S., A. Lauritsen 1995. "Differential diagnosis of paragenetic and vadose canyons." Cave and Karst Science 21(2): 55-59. Newson, M. D., 1971. A model of subterranean limestone erosion in the British Isles based on hydrology. Transactions of the Institute of British Geographers, 55-70. Pasini, G., 1975. Sull’importanza speleogenetica dell’“Erosione antigravitativa”. Le Grotte d’Italia, 12, 297-326.Pasini, G., 2009. A terminological matter: paragenesis, antigravitative erosion or antigravitational erosion? International Journal of Speleology, 38, 4. Pasini, G., 2012: Speleogenesis of the “Buco dei Vinchi” inactive swallow hole (Monte Croara karst sub-area, Bologna, Italy), an outstanding example of antigravitative erosion (or “paragenesis”) in selenitic gypsum. An outline of the “post-antigravitative erosion”. - Acta Carsologica, 41, 1, 15–34. Renault, P., 1958: Eléments de spéléomorphologie karstique. - Annales de Spéléologie, 13, 1–4, 23–48. Renauly, P. 1968. Contribution à l'étude des actions mécaniques et sédimentologiques dans la spéléogenèse. Annales de spéléologie, 530-596.Vaughan, K., 1998. A Quantitative Analysis of Interstitial Fluid-Chemistry and Limestone Dissolution Rates within the Clastic Sediment of a Karst Aquifer Conduit, Mammoth Cave, Kentucky. Whipple, K.X., Hancock, G.S. and Anderson, R.S., 2000. River incision into bedrock: Mechanics and relative efficacy of plucking, abrasion, and cavitation. Geological Society of America Bulletin, 112(3), pp.490-503.

ABSTRACT. Cupola is a term that describes dome-shaped solution cavities and they are accompanied by several features such as terraces, cusps, pendants, pillars, rock bridges etc. Their formation has been attributed to a number of processes summarized by Osborne (2004) and thus they are considered as polygenetic (Dublyansky, 2013). A brief description of the Mesolakkia caves along with a data set with cupola dimensions and images are given. Furthermore, the process of speleogenesis is discussed on the basis of the morphological observations. Methods The study of the Mesolakkia caves is based on their morphological features. They are surveyed in two and three dimensions using standard and paperless speleological mapping techniques (i.e. Kalogeropoulos et al., 2008; Trimmis, 2018 and reference therein). Laser distance meter and Suunto compass were used. Rock discontinuities measured with a Clar compass. Identification and interpretation of morphological features follow Lauritzen and Lundberg (2000), Gunn (2004), Ford and Williams (2007), White and Culver (2005) and of speleothems follow Hill and Forti (1997). Cave description and morphology Three caves have been found to be opened in the marble of the Pangeon Unit (Rila-Rhodope Massif). These are the Disakia Cave, Small Disakia Cave and Disakia shelter-cave, considered all together part of a uniform cave system, called below Disakia Cave System (DCS). Disakia Cave: is a relatively small cave. Its entrance is a 3m deep pothole. It consists of (Fig. 1) small rooms and fracture-guided passages of NW-SE direction that are interconnected to each other with small SW-NE passages and windows. Some passages are characteristically high and narrow (Fig. 1F). There is also a number of abruptly terminating passages. The predominant solution feature noticed are the cupolas that are formed in side-walls and mainly the ceiling. Most of them found to be unrelated to rock fractures and generally wide. Thus, their horizontal diameters appear to be larger than that of the vertical axis. Inside these concave features corroded speleothems, such as stalactites, flowstone and draperies are commonly present. Their length (largest horizontal diameter) ranges from 0.51 to 2.20 m and their width from 0.36 to 1.9 m. Their height is only 0.15 to 0.90 m. Their mean shape is 0.97x0.80x0.48 m. Apart from the small-scale cupolas, there are some cupola-like rooms. In addition terraces, notches, cups, pendants and similar forms are also present. Cave decoration consists of calcite speleothems that in most cases appear to be corroded or damaged and broken by visitors. It is worth to mention that the cave, and especially its deepest parts display numerous inscriptions with mainly names and in some cases dates. They seem to be of the 20th and 21st centuries but the presence of older inscriptions cannot be excluded since a detailed record of them is pending. Table 1. Small-scale cupola measurements from the Disakia Cave. Length(cm) 60 125 120 60 61 51 220 92 83 Width(cm) 36 100 100 57 49 36 190 74 81 Height(cm) 37 90 50 37 27 35 60 15 80

Small Disakia Cave: The entrance of this cave is a small opening on a steep escarpment. Close to the entrance the passage is short and partially filled with fine-grained sediment. In the deepest part there are two rooms interconnected to each other with a small window-like passage, located about two meters higher than the cave floor. The last room is the largest one and displays cupolas and related forms that cut evenly the bedrock and speleothems. The floor in filled with guano. Disakia shelter-cave: Between the above mentioned caves there is a small cavity presently forming a shelter-cave. This small cave remnant has a diameter of few meters and its walls and ceiling consist a chain of cupolas (Fig. 1D). Discussion In the absence of geochemical evidence in DCS, the interpretation of speleogenesis can be grounded only on morphological criteria. In the broader area there are both epigene and hypogene caves (Lazaridis, 2017). DCS consists of chambers interconnected with passages and blind galleries that form a ramiform pattern in ground-plan (see Palmer, 2000). This pattern is indicative of phreatic speleogenesis and genetically placed between spongework and network caves, that means caves formed in mixing zones by aggressive waters of low flow velocity (diffusion dominates) and caves formed mainly related to hydrothermal activity (Dublyansky, 2013). Orientation of passages is strongly affected by discontinuities of the bedrock and especially the more or less vertically dipping groups of joints. Meso-scale features, such as pendants, pillars, cups, terraces, ridges, notches and the predominant forms cupolas that occur on the bedrock are probably related to the main phase of speleogenesis. Small-scale cupolas and the related solution features that intersect vadose speleothems indicating a post-phreatic process due to condensation corrosion. Other, vadose dissolution forms and forms developed in concentrated lateral flow, such as scallops, are absent in DCS.

Figure 1. A. Ground-plan of Disakia cave; B. ground-plan of small Disakia cave; C. Schmidt diagram of rock discontinuities; D. view of Disakia shelter-cave; E. narrow and high fracture guided passage in Disakia cave with cusps and terraces related to cupolas; F. typical flat and wide cupola in Disakia cave; G. cusp and ridge separating cupola-shaped rooms in Disakia cave; H. detail of corrosion on the wall of G; I. cupola that evenly intersects the rock and speleothems in small Disakia cave; J. pendant and partitions in small Disakia cave.

Concluding remarks The meso scale cupolas that form chambers and (e.g. Disakia shelter-cave) and the cave pattern indicate a phreatic origin and dissolution by convecting water bodies. A relation to the hydrothermal speleogenetic phase that has been affected the area (Lazaridis, 2017) cannot be excluded. Small-scale cupolas and the corroded speleothems are due to condensation corrosion that is post-phreatic but not necessarily distinguished from the speleogenetic process; i.e. hydrothermal speleogenesis. Further speleological exploration and geological investigation in the broader area could provide more evidence for the speleogenesis. Acknowledgements We thank the members of the Kavala’s speleological group for indicating the cave entrances and accompanying us during the field work. The MA Architect, Iraklis Kalogeropoulos is thanked for his contribution in the cave survey. References Dublyansky, Y.V., 2013. Karstification by geothermal waters, in: Shroder J., Frumkin A. (Eds.), Treatise on geomorphology. Academic Press, San Diego, (6): 57–71. Ford, D., Williams, P.D., 2007. Karst hydrogeology and geomorphology. John Wiley and Sons Inc. Gunn, J., 2004. Encyclopedia of Caves and Karst Science. Taylor and Francis Inc. Hill, C.A., Forti, P., 1997. Cave minerals of the world (2nd ed.). 1-463, National Speleological Society Kalogeropoulos, I., Lazaridis, G., Tsekoura, A., 2008. Methodology of cave mapping: comparing routings. 4th Pancretan Speleological Symposium. Hellenic Speleological Society, Rethymnon, Crete, Greece http://ese.edu.gr/media/seminars/sem_notes/hartografisi/survey_methods.pdf Lauritzen, S., Lundberg, J., 2000. Solutional and erosional morphology of caves., in: Klimchouk, A., Ford, D.C., Palmer, A.N., Dreybrodt, W. (Eds.), Speleogenesis. Evolution of Karst Aquifers. Huntsville: National Speleological Society. Lazaridis, G., 2017. Hypogene Speleogenesis in Greece., in: Klimchouk, A., Palmer, A.N., De Waele, J., Auler, A.S. & Audra, P. (Eds.), Hypogene Karst Regions and Caves of the World. Springer, 225-239. Osborne, R.A.L., 2004. The troubles with cupolas. Acta Carsologica, 33: 9-36. Davis, G.H., Reynolds, S.J., Kluth, C.F., 2011. Trimmis, K.P., 2018. Journal of Archaeological Science: Paperless mapping and cave archaeology: A review on the application of DistoX survey method in archaeological cave sites. Reports 18, 399-407. White, W. B., Culver, D. C. 2005. Encyclopedia of caves, Elsevier Amsterdam (The Netherlands).

ABSTRACT. Among several thousands of caves that have been reported in Greece, there are hundreds that have developed in non-carbonate lithology (i.e. Lazaridis et al., 2016 and cited references) and non-pure carbonates, such as breccias and conglomerates (i.e. Vlastaridis et al., 2014). Caves formed in flysch sediments have not identified previously in Greece and even in countries with thousands of recorded karst caves, only few examples are known (i.e. Pavuza, 2013). The aim of this study is to document the morphology of the Mavrovouni-1 cave formed in flysch deposits and set the basis for further investigation in caves in this lithology and their speleogenesis.

ABSTRACT. In this project significant geo-morphological structures of the shallow portion of the shelf in the surrounding area of Strymonikos Gulf are mapped, using data from a hydrographic survey taken in July 2015, which included high resolution multibeam bathymetric recording and seismic data from 3.5 kHz. The rising results allowed the Palaeogeographic evolution of the bay of Strimonas during the last glacial period (21,500 BP). In particular there were identified a) the palaeoriverbed of the Strymonas-Nestos River and b) the position of the palaeoshoreline.

ABSTRACT. Background Climate is a constant changing variable, affecting urban development and ecosystems. The Mediterranean, due to complex topography and atmospheric circulation patterns (Tyrlis et al., 2013), presents intense susceptibility to climatic changes (Goubanova et al., 2007). As a part of the eastern Mediterranean basin, the climate and the precipitation regime of Greece has piqued the interest of many researchers (Livada et al., 2008, Nastos et al., 2008, Dotsika et al., 2010, Karavitis et al., 2011). Following the same pattern, precipitation and temperature in Peloponnese vary according to regional characteristics. Precipitation is one of the most important climatic variables in the water cycle and the information it provides is critical for understanding the hydrological balance (Hatzianastassiou et al., 2008). The precipitation regime is significantly affected by the topography of each region. According to Voudouris et al. (2007), the estimation of the annual rainfall distribution in Korinthia prefecture, NE Peloponnese, is controlled by the physiography of the area. However, in the present study, the method that was followed for the spatial analysis, does not take into consideration the variation of precipitation according to the elevation, because this was not possible for such an extended area characterized by a complicated morphology. Objectives The main aim of the present study is the construction of a high resolution map that depicts the spatial distribution of precipitation, as well as the observation of the temporal distribution in the study area, in order to recognize variations throughout the years. Methods Daily rainfall time series from 33 meteorological stations, corresponding to the hydrological years 1985-2015, were processed and the mean annual precipitation was estimated, as well as the minimum and maximum values recorded in each station. The locations of the observation posts were subsequently digitized in ArcGIS 10.1, and each corresponding mean annual rainfall value was inserted. The spatial distribution map resulted from the Inverse Distance Weighting (IDW) interpolation tool. For the temporal distribution, the stations in the eastern, central and western part of the area were compared in groups, as well as all together. Results The precipitation regime presents distinct differentiations in northern Peloponnese. The eastern and northeastern sections of the study area present the lowest values, ranging from 468 to 647 mm/year, while, moving toward the west mean annual rainfall values increase. The highest values, from 1068 to 1505 mm/year, appear in the S-SW region. During the period 1985-2015, the hydrological years 1989-1990 and 1998-1999 were recorded as the driest and wettest years respectively, by the majority of the meteorological stations in northern Peloponnese. It is also observed that 2006-2007 was a dry year for the eastern and central parts of the study area, while 2013-2014 was documented as a very wet hydrological year for the eastern and western regions. Generally, almost all stations, with very few exceptions, seem to have an increased tendency in precipitation over the considered time period. Finally, it is worth mentioning, that the highest and lowest annual precipitation values were recorded by Kastania station in 2000-2001 (2842 mm) and Halkeio station in 1999-2000 (196.1 mm) respectively.

ABSTRACT. This study focuses on both the remediation of the pH values and the removal of toxic load of Fe from pit lakes from Agios Philippos Kirkis mines (southern of Alexandroupoli, Evros Prefecture, Greece) by using a combination of economically and environmentally friendly mineral raw materials such as sterile aggregates (serpentinite, andesite), industrial rocks (magnesite), other natural and organic materials (peat and biochar) in a new experimental electric device. As raw materials for the consolidation of an important acid mine drainage, mainly sterile materials were used which resulted in the execution of laboratory tests to assess such as aggregates, based on sustainable disposal and reuse of sterile materials (serpentine, andesite, magnesite, peat and biochar). The treatment of polluted industrial waste water remains a topic of global concern since waste water discharged from municipalities, communities and industries must ultimately be returned to receiving waters or to the land (Weber et al., 1991). Acid mine lakes have been formed worldwide and are responsible for numerous water quality problems, which severely limit their beneficial uses and may constitute an environmental risk both in the water body itself and downstream environments and water resources (Salmon et al., 2008, Schindler, 1986, Geller, 1998, Geller et al., 2009). Pit lakes or mining lakes, which are unique water bodies, such as this at Agios Philippos form in many places of the world as a consequence of opencast mining. When the activity ceases, the open pit is back filled with groundwater and surface water. The rate of filling is depended on climatic and geologic conditions, as well as the regional hydrologic characteristics. Assessment of the environmental risks of pit lake development is imperative for the mining industry and the public, especially in cases of high sulphidation deposits characterized by high concentrations of heavy metals (Plumlee, 1999). Various mineral raw materials have been used as chemical reagents for the neutralization of pH, as well as for the removal of heavy metals. Several researchers have used experimental columns of batch type to examine the effect of various mineral raw materials. However, a research gap has been observed concerning the remediation of this phenomenon by using electrical driven flow forced device. The up to now proposed approaches for the remediation of this phenomenon include high cost techniques (Amarasinghe and Williams, 2007). For these reasons, in this study a new experimental electric forced device is proposed with the use of low cost mineral raw materials for achieving remediation of industrial waste water. The basic concept for the construction of the experimental electrical device was the simulation of a standard continuous water recirculation system of the treated acidic runoff, in filters with a combination of mineral raw materials. The filters were filled with certain percentages of the selected mineral raw materials. Furthermore, 50 liters of waste water from the pit lake of Agios Philippos were placed into the experimental device. From the beginning of the experimental process periodic measurements of pH values of water were made. During the experimental process, sporadic samples of water were taken for geochemical analysis which it took place after the completion of the experimental process. In the experimental electrical device the combined use of mineral raw materials such as serpentinite, andesite, magnesite, peat and biochar as remediation agents of the acidic effluents of the selected lake with continuous water circulation, was evaluated. The variation of the pH values during the operation of the experiment is listed in Table 1. The pH values showed a continuously increasing trend from the first till the fourth day of the experiment, when pH reached the maximum value of 6.93. The infection of the pH curve after the fourth day indicates a general stability of pH at slightly reduced values of around 6.5–6.8 maintaining a steady trend with very small fluctuations. Regarding the pH adjustment, the experimental device was particularly effective. This happened due to the participation of magnesite and serpentinite which were very effective in pH remediation (Teir et al., 2006). In this study, the serpentinite may release magnesium ions while also engaging more H+. The increase in pH can be attributed mainly to the adsorption of H+ cations on the surface of serpentine crystals as the structure of serpentine consists of silicon tetrahedral which is combined with magnesium. Moreover, the studied serpentinite presents an important advantage in contrast to other lithotypes concerning the specific reaction surface. The Pliocene andesite had positively effected on the normalization of pH values due to its chemical composition, but is less effective than serpentinite and magnesite. The results of the water geochemical analysis during the 7-day operation of the device suggest that the referred combination yielded satisfactory results with respect to the remediation of the removal of Fe. Figure 1 illustrates the concentration of Fe in the water during the seven days of experiment. An increase in the concentration of Fe in the first day is observed explaining by the initial leaching of Fe from the serpentinite and the andesite, which contain small percentages of Fe, as well as to the contamination from the metallic parts of the pumps, as highly acidic solutions, like the initial treated water, promote solubility in the aerobic condition due to the oxidation of Fe2+ to Fe3+ through an increased oxidation potential and the temporarily increased its concentration until the pH increases. In the second day (pH> 4.5), there was a strong decrease in Fe concentration in the solution.

ABSTRACT. The aim of this study is to highlight the impact of the secondary phyllosilicate minerals in mafic and ultramafic rocks used as aggregates on concrete strength and more specifically the influence of microroughness of the aggregates in the adherence of the cement paste. The studied aggregate samples used for the production of concrete, were collected from ophiolite complexes in Central Macedonia. Quantitative petrographic analysis indicates that the tested samples display various percentages of secondary phyllosilicate minerals. Mineral quantification of the studied rock samples was performed by using the Rietveld method on bulk samples. The ocean-floor metamorphism variably affected the collected ultramafic and mafic samples. During this process primary minerals from ultramafic and mafic rocks are often altered to secondary ones as a result of the ocean-floor metamorphism process. Chlorite is the dominant secondary phase in mafic rocks, such as diabase, gabbro and basalt which attributes to their low microroughness and to unfavorable interfaces between cement paste and aggregate particles. On the other hand, in ultramafic rocks, such as serpentinized peridotites, serpentine, chlorite and talc seem to be the dominant secondary phases. Additionally, ultramafic aggregates are characterized by low microroughness contributing on de-bonding between the aggregate particles and the cement paste. Phyllosilicates constitute an important group of minerals which includes serpentine, chlorite, micas, and clay minerals. The basic structure of the phyllosilicate minerals is based on interconnected six-member rings of SiO4-4 tetrahedral that extend outward in infinite sheets. Several researchers have highlighted the impact of secondary phyllosilicate minerals on the engineering properties of various igneous aggregates (Petrounias et al., 2018b). More specifically, Petrounias et al. (2018b) proposed two petrographic indexes Mph and Uph. The petrographic index Mph which is the sum of the phyllosilicate minerals in mafic samples is describing by the following equation Mph= Chlorite (%). On the other hand, the petrographic index Uph (%) which is the sum of the secondary phyllosilicate minerals present in ultramafic rocks is describing by the following equation: Uph = Serpentine (%) + Chlorite (%) + Talc (%). Concrete is the most used man-made material and comprises a mixture of mortar, aggregates and water (Jackson, 1981). Usually, aggregate is considered as inert filler, which accounts for 60 to 80% of the volume and 70 to 85% of the weight of concrete. Aggregates are divided into natural stone aggregates (sand and gravel) and crushed aggregates (crushed stones). The quality of aggregate, including its long-term durability and resistance to cracking, influence the properties of both fresh and hardened concrete. The inhomogeneous structure of concrete can be described as a three-phase system consisting of hardened cement paste, aggregate and the interface between aggregate particles and cement paste. Many researchers investigate the relationship between the percentages of different mineralogical compositions of aggregates and the final compressive strength of concrete. Several researchers (Petrounias et al., 2018a, Petrounias et al., 2018c) investigating various igneous rocks from Greece concluded that the secondary products of serpentinites and andesites largely influence their mechanical properties, which definitely have an adverse effect on their performance as concrete aggregates. However, a research gap is identified concerning the effect of these minerals on the produced concretes by different type of mafic aggregates. Representative mafic and ultramafic rocks were collected from the Veria-Naousa and Edessa ophiolite complexes and were prepared normal concrete cube specimens. The Veria-Naousa ophiolite complex in northern Greece belongs to the Almopias subzone of the Axios geotectonic zone. It consists, from base to top, of serpentinised lherzolite and harzburgite, which are cut by scarce pyroxenite dykes, gabbro, diabase and pillow basalt (Rogkala et al., 2017). The Edessa ophiolite represents remnants of oceanic lithosphere, which was thrust out of one basin during the Upper Jurassic to the Lower Cretaceous time (Rogkala et al, 2019). It is intensively tectonized and consists of several tectonic units. Mafic and ultramafic aggregates used in order to prepare concrete specimens using normal Portland cement (CEM II 32.5N), which is conformed to EN 197-1. Potable tap water, free of impurities such as salt, silt, clay and organic matter, with pH = 7.0, was used for mixing and curing the concrete. In order to keep a consistent composition for all the concrete specimens, we adopted the principle of maintaining the same volume of aggregate per m3 of the mixture. The proportions of the concrete mixtures, by mass, were 1/6/0.63 cement, aggregate and water ratio. The mineralogical characteristics of aggregates were examined in thin sections with a polarizing microscope and their mineralogical composition was also determined by XRD analysis and was calculated using the Rietveld refinement method. Normal concrete cubes specimens (150 mm × 150 mm) were prepared according to ACI-211.1-91. The compression test of concrete was elaborated according to BS EN 12390-3:2009. After the compressive strength test, the textural characteristics of concretes were examined. Thin sections were studied in a polarizing microscope according to ASTM C856–17. In a next stage, 3D depiction of thin sections of the concrete specimens was carried out (Figure 1) showing the adherence between the aggregates and the cement paste as well as the microroughness of the aggregate particles. The influence of secondary phyllosilicate minerals on concrete strength is confirmed by the correlation between the (UCScon) strength of concrete and the percentage of secondary phyllosilicate minerals contained in the tested mafic and ultramafic rocks. Regression analysis is the commonest statistical method for the investigation of the interdependence of the physical and mechanical parameters. Figure 2 shows that as the percentage of serpentine, talc and chlorite in ultramafic rocks as well as the percentage of chlorite in mafic rocks increases, the yield strength of the produced concrete decreases. This is partly due to the ability of the phyllosilicate minerals to absorb water in their structure. In order to perform the regression analysis under a single correlation, UPh values were used as representative phyllosilicate values in ultramafic rocks and MPh values as representative phyllosilicate values in mafic rock formations. The function that links the above sizes is possible to describe by the following relation: UCScon= -0,0667* (UPh /ΜPh)+31,246, R2=0,82. To conclude, as the percentage of secondary phyllosilicate minerals like serpentine, chlorite and talc increases the compressive strength of the produced concretes decreases respectively as more cracks, detachments and de-bonding between the aggregates containing the secondary phyllosilicate minerals and the cement paste.

ABSTRACT. This study examines different types of recycled materials such as beer green glass and waste tile used in different mixtures in order to prepare concrete specimens and more specifically their effect on concrete strength and how their microroughness influences the mechanical strength of the produced concrete specimens. Concrete, a mixture of cement, aggregates and water, is the most used man-made material and has numerous civil engineering applications (Jackson, 1981, Neville, 2005, Taylor, 1994). Aggregates are the major constituents of concrete, typically occupying between 70% and 80% of its volume. The rapid growth of the construction industry has led to environmental problems caused by excessive mining and usage of natural resources such as aggregate and cements (Mo et al., 2016). Therefore there is a need to improve the reuse value of waste materials. Since the usage of conventional aggregates is not environmental friendly and causes depletion of natural resources (Medina et al., 2012), a variety of waste materials such as clay, waste glass, asphalt, waste tile and plastic wastes have been recycled and used as aggregate in concrete blocks. In concrete, most observed faults either in the case of waste glasses or in the cases of asphalt and tiles are due to their smooth surfaces (Abdallah et al., 2014, Meng et al., 2018) which are responsible for the extended cracks and detachments along the rims of the aggregate particles with the cement paste, limiting the final concrete strength (Petrounias et al., 2018). The surface texture of the recycled materials was studied by using Secondary Electron Images. Since the microroughness of materials used as aggregates in concretes plays severe role on their final strength as it is responsible for the adequate bonding between the cement paste and the aggregate particle, artificial increase of microroughness of the recycled materials specimens was carried out using quartz primer for coating the recycled materials three times, one every 24 hours. Normal concrete cube specimens (150×150 mm) were made from the different mixtures containing recycled materials. The recycled materials were crushed through standard sieves and separated into the size classes of 2.00-4.75, 4.45-9.5 and 9.5-19.1 mm and then washed before their used in concrete specimens. These specimens were tested in a compression testing machine. After the compressive strength test, the quality cohesion between the cement paste and the aggregate particles in concretes were examined. The concrete strength ranged from 14 to 20 MPa. The lowest compressive strength values were observed in concrete specimens made by mixtures containing exclusively glass as aggregates (Figure 1a). On the other hand, concretes made by mixtures of glass with primer and tile with primer present the highest compressive strength values. The results of the compressive strength test of the concrete specimens are in accordance to the artificial given microroughness of the recycled materials used as aggregates in concretes. The artificial increase of microroughness seems to positively contribute to all strength values of the studied concrete specimens. The observations of the surface texture of the recycled aggregates show glassy to smooth surfaces for the studied glass, tile and smooth to almost rough for the studied glass and tile grains which have been coated with quartz primer. In general, the quartz primer, as high adherence material, gave microroughness to the recycled materials used as aggregates in concrete specimens and hence increased their final strength. More specifically, among the various produced concrete specimens, these made by the mixture of glass coated with quartz primer in the smaller class and tile coated with quartz primer in other two classes, attributed to the highest concrete strengths (Figure. 1b). This is due both to the artificial increase of and to the optimum interlocking of grains which has been created from the combination of glass coated with quartz primer in the small class tile coated with quartz primer in the bigger classes. Subsequently, concrete specimens made by mixture of tile coated with quartz primer in the bigger class and glass coated with quartz primer in the smaller classes attributed in lower but satisfactory strength. The lower strength is attributed to greater participation of glass coated with quartz primer in concrete specimens. However, its satisfactory strength is due to the artificial increase of microroughness of the aggregate particles as well as due to the good interlocking of grains. The main conclusions of this work are the above: • The artificial increase of microroughness of the used recycled materials used as aggregates in concretes seems to be determinant factor for the final concrete strength. • The mixture of glass coated with quartz primer in the small class and tile coated with quartz primer in other two classes due to the optimum cohesion between the cement paste and the aggregate particle as well as due to interlocking of grains lead to the optimum mixture of recycled materials in concretes.

ABSTRACT. Chromium (Cr) includes two main species in natural aquatic systems, the trivalent (Cr3+) and the hexavalent (Cr6+) one (Richard and Bourg, 1991). The speciation of Manganese (Mn) in aquatic environment is controlled by the prevailing physical and chemical conditions, which includes mainly two oxidation states, the soluble divalent (Mn2+) and the insoluble tetravalent (Mn4+) manganese (Homoncik et al., 2010). Mn mobility, speciation and concentration are controlled by the physical parameters of pH, redox potential (Eh), dissolved oxygen (DO) and also by the aqueous solution chemistry (Homoncik et al., 2010). Mn-oxide minerals, in which trivalent manganese (Mn3+) and/or Mn4+ is accommodated, such as birnessite (Fendorf et al., 1992), pyrolousite (Eary and Rai, 1987), asbolane-type (Fandeur et al., 2009), lithiophorite-type (Fandeur et al., 2009) and cryptomelane (Feng et al., 2007) have been reported to act in rocks and soils as natural oxidizing agents for the redox transformation of Cr3+ into Cr6+ in three (3) main steps (Amacher and Baker, 1982; Eary and Rai, 1987; Richard and Bourg, 1991): (1) Adsorption of Cr3+ on the surface sites of MnO2, (2) Oxidation of Cr3+ to Cr6+ by surface Mn4+, (3) Desorption of the reaction products, Cr6+ and Mn2+ in the aqueous solution The oxidation reaction takes place according to the following equation: Cr3+ + 1.5 δMnO2(s) + H2O → HCrO4- + 1.5Mn2+ + H+ (1) The amount and the surface area of Mn-oxides are crucial factors and control the oxidation rate of Cr3+, which is initially very fast, but through the time it slows down considerably (Eary and Rai, 1987). In addition, the oxidation rate of Cr3+ is highly dependent pH values (Amacher and Baker, 1982). The aim of this research is to examine the speciation of dissolved Mn in groundwater of the Psachna basin, according to pH and Eh conditions, in order to investigate the oxidation of Cr3+ into Cr6+. The Psachna basin - an ultramafic dominated environment- is located in the central part of Euboea Island; the main land use is agriculture. The geological formations of the Psachna basin are the carbonate rocks (limestones, dolomites), the ultramafic/mafic rocks (serpentinites, peridotites, diabases), the Fe-Ni ore deposits and post-Alpine sediments of Neogene and Quaternary age. The main aquifer system of the study area is developed into Quaternary sediments of ultramafic and carbonate origin. A large set of major ions and trace elements of thirty-four (34) groundwater samples were analysed and presented herein. The physical parameters (electrical conductivity-EC, DO, pH and Eh) were measured in-situ immediately after samples were collected according to YSI Professional Digital Sampling System (ProDSS); The analyses of major ions were determined by atomic absorption spectrometry (Ca2+, Mg2+, Na+ and K+), by titrimetry (Cl- and HCO3-) and by turbidimetry (SO42-) and the analyses of trace elements were performed at Analytical Laboratories of Bureau Veritas Commodities Canada Ltd, by means of inductively coupled plasma mass spectrometry (ICP-MS). pH ranges from 7.21 to 8.27 (mean 7.64) indicating slightly alkaline conditions; Eh varies from 135.7 mV to 291 mV (mean 254.7 mV) suggesting an oxidative geological environment. The results of this study showed high concentrations of Cr (up to 161.5 μg L-1), Cr6+ (up to 131.1 μg L-1) and NO3- (up to 540 mg L-1) in groundwater. The majority of the groundwater samples (70%) analysed herein, exceed the limit of 50 μg L-1 for Cr concentration in drinking water of World Health Organization (WHO, 2011). The remarkable extreme values of NO3- are over 10 times higher than the guideline value of 50 mg L-1 (WHO, 2011) and indicate the intense agricultural activities accompanied by extensive use of Nitrogen-bearing fertilizers. The concentrations of Mn (up to 25.53 μg L-1) are below the guideline value (50 μg L-1) for drinking water of WHO (2011).The oxidation of Cr3+ in natural aquatic environment is a process mainly attributed to the Mn oxides (Eary and Rai, 1987; Richard and Bourg, 1991). pH-Eh plots in the Pourbaix diagram for Mn (1966) revealed, that Mn2+ dominates, even at low concentration, in the groundwater samples of the Psachna basin (Figure 1). Besides, Economou-Eliopoulos et al., (2014) identified Mn-oxide minerals (birnessite, asbolane and cryptomelane) in the Euboea soils, which combined with the presence of Mn2+ in groundwater supports the natural oxidation mechanism of Cr3+ into Cr6+ by Mn oxides. The weak to moderate correlation coefficients and the non-linear relationship between physical parameters (DO, EC, pH and Eh) and Mn concentrations indicate an unclear mechanism that is related to the Mn solubility and the spatial distribution of Mn concentrations in groundwater of the Psachna basin. The elevated concentrations of Cr6+ (up to 131.1 μg L-1) may be attributed to the oxidation of Cr3+ by the redox couple of Mn2+/Mn4+. An additional external oxidant agent is likely to affect the water system synergistically with Mn redox couple increasing the Cr6+ concentrations. Previous studies showed that DO could oxidize Cr3+ into Cr6+, but the oxidation rate is very slow and enables Cr3+ to take part in faster reactions such as sorption or precipitation (Eary and Rai, 1987). Therefore, oxidation of Cr3+ by DO seems to be unlikely in soils. An additional potential redox couple except for Mn2+/Mn4+ is NO2-/NO3- , which could make possible the redox transformation of Cr3+ into Cr6+ in natural aquatic environments (Richard and Bourg, 1991; Stamatis et al., 2011). Spatial distribution maps of Cr6+ and NO3- support a possible link between these two parameters; this hypothesis is strengthened by the strong correlation coefficient between NO3- and Cr6+ (r=0.68). However, the exact mechanism that the presence of NO3- results in increased Cr6+ concentration in groundwater has yet to be defined.

ABSTRACT. Introduction/Setting In order to investigate the foundation’s conditions of a construction, it is important to determine the mechanical characteristics of the subsoil and specifically the determination of its shear strength and compressibility. In cases where sandy soils undergo fluctuations in their moisture content, the determination of their shear strength should take into account their behavior in unsaturated conditions (Fredlund & Rahardjo, 1993). This requires, shear tests of soil specimens (in this case direct shear tests) performed with control of the degree of saturation. The present paper presents the subsoil’s mechanical behavior in the Geni Tzami of Edessa under conventional tests as well as tests in unsaturated conditions. The city of Edessa is located in Almopia which is the western sub-zone of the broader Axios geotectonic zone in Central Macedonia. The Geni Tzami is founded on the Quaternary formations of the city which are mainly aluvial deposits and cones of fluvial deposits from the underlying travertines of Edessa. Methodology The restoration of Geni Tzami included a core sampling 15m borehole for the geological and geotechnical investigation of the foundation conditions. The results of the coring showed an interchange between sand and silty sand layers with variable fines content and a small percentage of gravels. The groundwater conditions were dry during the drilling but a low potential groundwater table might develop during the wet season in the coarser deposits. The mechanical properties of the soil samples (c' and φ') were estimated using both empirical relationships from the NSPT values and a specific laboratory testing experimental program. Till recently the production of reliable experimental data for the unsaturated behavior of granular soils using the axis translation technique was difficult. This was due to the lack of sophisticated laboratory equipment for non cohesive soils since most of the used devices required cohesive specimens. The device used for this experimental programwas the GDS unsaturated back-pressure shear boxof the Laboratory of Engineering Geology & Hydrogeology of A.U.TH. Since the foundation soil is mostly under partially saturated conditions the soil specimens were tested for shear strength via consolidated drained shear tests under their natural moisture content and in saturated condition so as to obtain a more accurate picture of the actualin situ shear strength.The unsaturated conditions were simulated using the axis translation technique by applying constant pore-air and pore-water pressure in order to control the matric suction in the samples. The mechanical behavior of unsaturated soils depends on the characteristic for each soil type angle φb as well as the relationship between the soil suction and the degree of saturation as described by the soil water characteristic curve (SWCC) (Fredlund et. al. 2013). Results/Conclusions The test results showed: An increase of soil shear strength with the reduction of the degree of saturation. An increase of the percentage of shear strength variation between saturated and unsaturated conditions with reduced axial stress (Figure 3). An observed cohesion of c'=23,5o under natural moisture content while φ remains almost stable under both conditions. Cohesion presentsanincrease with reduced degree of saturation depending on the matric suction values and the angle φb (Figure 4). The value of φb was estimated as φb=11,08ο using the SWCC to obtain a matric suction value of ua-uw=120 kPa for moisture content m=11.20%. This value is in accordance with similar experimental values in the literature.

ABSTRACT. The survey was conducted in Stavros-Vrasna area which is located in northern Greece at the eastern part of the prefecture of Thessaloniki and covers 11.27 km2. Groundwater sampling took place during the dry season, and the samples were analyzed. Moreover, geophysical survey by the application of geoelectrical tomography method has been conducted. Six (6) geoelectrical tomographies were measured in order to determine the electrical resistivity of underground. The results show 3 different lithological types of aquifers: a) Sedimentary, b) Karstic and c) Fractured. The dominant groundwater aquifer is porous, and most part of it, is confined. In the area of Vrasna, a salinity zone has been detected by geoelectrical survey at a quite large distance from drinking wells, enough to not allow any affection. In opposition with the results of hydrochemical analysis, in the area of Stavros an early stage of seawater intrusion has been detected at the W_St1 well by the geophysical survey. Since the needs of the entire area especially during summer period are limitedly satisfied, mapping of possible salinity zones is very crucial to avoid the quality degradation of the groundwater caused by new drillings in these zones.

ABSTRACT. Greek fibrous clay minerals, Palygorskite from Ventzia basin (Grevena, Western Macedonia) and sepiolite from Solomos village (Corinth, Peloponnese) have been used as adsorbents for nitrate removal. The samples were characterized by XRD, FTIR, SEM and BET methods. Their nitrate removal capacity has been examined through batch experiments, under various conditions of contact time, adsorbents’ mass and initial nitrate concentration. For both clay minerals the highest adsorbent mass was the most efficient, however, palygorskite found to be more efficient adsorbent at low nitrate concentration levels, in contrast to sepiolite. Both examined clay minerals can be exploited for pre- or post- nitrate water treatment however, they found to be not sufficient for the main nitrate removal mechanism at high nitrate concentration levels.

ABSTRACT. Copais lake was the largest lake in Greece, occupying 250,000 acres. Its desiccation has been an issue which puzzled engineers and scientists for ages, as this was the method to develop these acres and cultivate tis land, while parallely avoiding disease caused by stagnant waters of the lake. First historical record the lake was partly desiccated by works completed by the Minyans around 2000B.C. Many researchers were involved in the research for the function and the structure of these works, publishing various theories. The works included embankments, acropolis whose function was connected with them, as well as natural katawothras from which the waters were able to come and thus drain them to the Evoikos Gulf. Two of the last were the entrances of a giant project, the creation of the first tunnel. In this project, a geological, morphological and geotectonic search has occurred researching the region and the local works, having the goal of creating positions related to the function of them, during the archaic period. Finally, is done a comparison of Knausse’s assumption, about operation of the Minyans works, with our research.

ABSTRACT. The coastal karst system of Evia Island, which is developed due to the extended presence of carbonate formations, discharges into the sea in many different locations having a direct relation to the tectonic system of the area. Thermal infrared remote sensing has been proved its capability in monitoring thermal differentiations of coastal water plumes. The aim of this work is to locate the fresh water outflows through remote sensing and specific with the use of Landsat’s 8 thermal images and how this karstification process is controlled by the lineaments of the area.

ABSTRACT. Soil liquefaction is the phenomenon in which a loose saturated soil layer suddenly loses its strength as a result of seismic vibration and instantly behaves as a liquid. Historically, earthquake-induced liquefaction events have occurred in Japan (1964 Niigata), Alaska (1964 Prince William Sound), Taiwan (1999 Chi - Chi), Washington (2001 Tumwater) and Greece (2014 Cephalonia) to name a few. In the wider area of Thessaloniki three geological formations are present (Chortiatis magmatic suite, sedimentary rocks of Neogene and Quaternary deposits). The area is of great interest due to the recent geological deposits and the existence of seismogenic areas in near vicinity. The last century two moderate events occurred triggering failures to the manmade environment at the city of Thessaloniki. For the purposes of this study, data from 64 geotechnical boreholes (figure 1) have been collected and analyzed. In particular, the liquefaction susceptibility per soil layer has been examined according to the criteria of Bray and Sancio (2006); based on the values of Plasticity index (PI), liquid limit (LL) and water content (wc). Afterwards, the factor of safety of susceptible to liquefaction soil layers was computed following the procedure recommended by Youd et al. (2001). The aim of this study is to develop a map showing the value of the critical peak ground acceleration that should be generated, adopting a seismic scenario of Mw = 6.6, in order to classified a site as liquefiable at the central and western part of Thessaloniki. In order to achieve this, two published models of liquefaction hazard are adopted that were developed by taking into account the Liquefaction Potential Index (LPI); the first model was presented by Toprak and Holzer (2003) and the second one by Papathanassiou (2008). According to Toprak and Holzer (2003) sand boils are likely to occur where LPI =5 and lateral spreading phenomena will occur where LPI =12, while according to Papathanassiou (2008) the possibility of liquefaction surface evidences is more than 50% for LPI>14. As an outcome, it is concluded that the liquefaction hazard is relatively high at the area of Kalohori and at the coastal area and at the western region of Thessaloniki, and that the consequences may be quite important for the manmade environment. At these areas, sand boils are likely to occur according to Toprak and Holzer (2003) when the PGA values ranges between 0.1 and .0.3g for a scenario of Mw = 6.6. According to the model of Toprak and Holzer (2003), the thickness of the liquefiable soils varies between 0.50m and 4.00m at the coastal area and the western region of Thessaloniki while at the Kalohori area ranges between 3.50m and 6.85m, reaching at some sites 8.40m. Regarding the model of Papathanassiou (2008), the thickness of the liquefiable soils varies between 0.50m and 4.00m at the coastal area, while at the western region of Thessaloniki ranges between 5.00m and 9.00m and at the Kalohori area ranges between 3.50m and 5.15m. In addition, this study shows that the classification model of Toprak and Holzer (2003) is more conservative than the one suggested by Papathanassiou (2008).

ABSTRACT. Rockfalls are gravitationally driven geomorphic processes that occur rapidly on steep rocky slopes. They can have disastrous effects on human activities and infrastructure and therefore constitute a significant natural hazard. However, due to the complex nature of the phenomenon, the available analysis methods incorporate assumptions that can lead to oversimplifications, since limited parameters are taken into account. This paper presents a new software tool for rockfall trajectory modeling. The software allows the user to choose the analysis method, selecting from: a) the lump-mass model; b) some recently proposed semi-empirical methods; and c) a new neural network algorithm that is trained with the data acquired from an extensive laboratory and field investigation, previously performed by the author (Asteriou, 2016). First, the software is presented and then the well-documented rockfall incident in Ponti, following the Mw=6.5 Lefkada earthquake in 2015, is briefly described and analysed with the software. The outcomes are commented and compared to the actual trajectory. Some interesting remarks on the reliability and accuracy of these methods are discussed.

ABSTRACT. Rockfalls constitute a significant natural hazard that manifests as a sudden and violent downward movement of rock blocks. The design and implementation of appropriate mitigation measures rests on the estimation of the possible trajectories. Once the block comes in contact with a slope, depending on the kinematic state and the contact geometry, it might rebound resulting in a new parabolic trajectory. Alternate response types to rebound are rolling, sliding or a combination thereof. The rebound, which controls the post-impact part of the trajectory, is calculated according to the coefficients of restitution (COR) which are overall values that take into account all of the characteristics of the impact and describe the change in the block’s velocity magnitude. Normal COR (nCOR) is defined as nCOR=-vnr/vni, and Tangential COR (tCOR) is defined as tCOR=vtr/vti, where v is the velocity and the subscripts n, t define its components (normal and tangential to the slope surface respectively), whereas as the subscripts i and r denote the impact and rebound stage. COR estimation in practical applications is based on some suggestive values, which depend solely by the slope surface material. In addition, CORs are adjusted to the impact velocity applying some scaling methods that are also empirically derived. A detailed overview of COR definitions, suggested COR values and the scaling methods can be found in Asteriou & Tsiambaos (2018). However, the rebound is affected by many parameters: (i) the strength, stiffness, roughness and the inclination of the slope; (ii) the strength, stiffness, mass and shape of the block, and; (iii) the translational and rotational velocity, the collision angle and the configuration of the block during impact (Labiouse & Heidenreich, 2009). Therefore, selecting the COR values just by the material type consisting the slope can lead to significant simplifications. It becomes apparent that a better method for selecting the COR is necessary. To attain this necessity, a semi-empirical method is presented hereafter, which considers: (i) the material types of both the slope surface and the block; (ii) the block mass and its incident velocity, and; (iii) the collision angle.

ABSTRACT. Maps and photographs of landscapes have been essential methods to visualize and analyse Earth features and processes. The creation of traditional geomorphological mapping requires intensive fieldwork, qualitative interpretations of remotely sensed imageries and topographic maps, as well as quantitative assessments using detailed orthophotomaps or/ and satellite images . In most of the cases, oblique landscape photographs are used only for the general interpretation of the area under investigation. In this study, we present a robust method for the generation of geomorphological information from various landscape oblique photographs with the use of an open freely available tool, the WSL monoplotting tool. In order to test this method we used historical photographs as well as recent oblique photographs from unmanned aerial vehicles (UAVs – Drones). The results are promising and the methods can be used to retrieve geomorphological information from historical photographs and thus to illustrate geomorphological changes as well as to create relatively low-cost recent geospatial datasets with the used of UAVs. Given the increasing interest in using historical photography, and with the recent high use of Geoinformatics in Earth Sciences, the proposed method can be used to various applications in order to evaluate earth procedures and changes. The article concludes that the proposed approach has a huge potential, although some limitations exist concerning mainly the accuracy of the results as well as the pre-required information about the photographs of the landscape.

ABSTRACT. Interpolation methods categorized either as deterministic or as geostatistical, are based on known values in order to estimate unknown values for any data. They are mostly used for generating spatial distribution maps. Deterministic interpolation methods are based on mathematical equations. The most common deterministic methods are inverse distance weighting (IDW) and radial basis function (RBF) (Varouchakis and Hristopoulos, 2013; Bhunia et al., 2018). Geostatistical interpolation methods are based on statistics of the measured points by means of semivariogram. They quantify the distance among neighboring points. Some of the most important and widely used geostatistical methods in the scientific field of geology are kriging techniques (Krige, 1951; Matheron, 1963). The most frequently used sub-types of kriging are ordinary kriging (OK), simple kriging (SK), universal kriging (UK) and empirical Bayesian kriging (EBK) (Varouchakis and Hristopoulos, 2013; Bhunia et al., 2018). The aim of the present study is to propose the optimum interpolation method by comparing the main deterministic (IDW and RBF) and the geostatistical (OK, SK, UK and EBK) methods on the basis of the parameter of electrical conductivity (EC) in the coastal aquifer of Schinos village, NE Peloponnese, Greece. This study will contribute to reducing the uncertainties in the spatial distribution maps of the hydrogeochemical parameters. The Schinos village is located in NE Peloponnese, Greece and belongs to the Corinth prefecture. The main aquifer system in the area is a granular unconfined alluvial coastal aquifer consisting of sands, gravels and conglomerates of ultramafic and carbonate origin; it is characterized by deterioration of quality due to the seawater intrusion and high concentrations of nitrate (NO3-) and hexavalent chromium (Cr6+) (Papadopoulos and Lappas, 2014; Pyrgaki et al., 2016). A total of twenty (20) groundwater samples were collected from irrigation wells in the alluvial aquifer of Schinos village during the period of November to December 2016. The evaluation of the best interpolated method was achieved by performing the cross validation method, which uses the total number of samples and estimates the value of a known position by means of leave-one-out sample, so there is one measured and one estimated value. This procedure was repeated for the twenty (20) groundwater samples and for all the methods examined herein (IDW, RBF, OK, SK, UK and EBK). Geostatistical methods were performed with semivariogram using Gaussian-model-function, since it produced the most favorable outcome. The root-mean-square error (RMSE) and the mean absolute error (MAE) are two approaches to quantify the predictive performance of different interpolation methods and were calculated using ArcGIS 10.3. The equations for the estimation of RMSE and MAE are: RMSE = MAE = Where Zi is the predicted value, Z is the measured value, and n is the total number of observations. EC constitutes one of the most representative parameter for groundwater quality, since it is a significant indicator of groundwater quality and presents strong to very strong correlation coefficients with the majority of major ions and the total dissolved solids (TDS) (R2=0.90). Furthermore, elevated values of EC, which are directly associated with increased concentrations of Cl-, usually reveal a seawater intrusion regime into the aquifer making explicit the qualitative degradation of the groundwater in the study area (Papadopoulos and Lappas, 2013). EC values in the Schinos village range from 972 to 3943 μS cm-1 with a mean of 2032.35 μS cm-1 and a median of 2017.5 μS cm-1. 95% of the samples have EC > 1000 μS cm-1. The EC has set a maximum guideline value of 2500 μS cm-1 in drinking water according to World Health Organization (WHO, 2011). The physical parameter of EC was interpolated using deterministic (IDW and RBF) and geostatistical methods (OK, SK, UK and EBK). The IDW method was estimated for three (3) different weighting power (1,2,3), since these weights could affect significantly the results. Spatial distribution maps of EC present different spatial patterns for each interpolation method. According to RMSE, the most appropriate deterministic and geostatistical methods are in decreasing order IDW1>IDW2>IDW3>RBF, and UK>SK>OK>EBK, respectively. Lower value of RMSE indicates the better interpolation method. According to MAE, the most appropriate deterministic and geostatistical methods are in decreasing order IDW2>IDW3>IDW1>RBF and SK>UK>OK>EBK, respectively. Lower value of MAE suggests more precise results. Data treatment and cross validation method revealed, that the best interpolation methods for generating spatial distribution maps of EC are RBF and EBK for deterministic and geostatistical methods, respectively. The method with the lowest values of RMSE and MAE was the EBK suggesting that this is the most suitable interpolation method (Figure 1), as also stated by Hussain et al., 2014. The optimum interpolation methods for estimating the spatial variability of the values of EC in the coastal aquifer of Schinos village are geostatistical methods using GIS techniques. Selecting the most appropriate interpolation method is a complex process due to the variability of the examined parameters and the high number of manually-adjusted parameters, which are dependent on the user’s experience. The most crucial factors are: the magnitude and the spatial distribution of the dataset (dependence of the distance), the interpolated qualitative or quantitative parameter since some methods are more suitable for datasets with extreme values (e.g. NO3-, Cr6+), while others are proper for datasets without outliers (e.g. EC, TDS and the majority of major ions).

ABSTRACT. The main purpose of the present study was to produce a landslide susceptibility map based on a probabilistic method, Weight of Evidence, within a GIS framework and also to perform a sensitivity analysis so as to identify the response of the model to small changes in the weights of the selected conditioning factors. In order to evaluate the efficiency of the WofE model, Selinoundas river basin, located at Achaia County, Greece has been selected as an appropriate test site. ArcMap 10.1 software was used for accessing the data and for producing the landslide susceptibility map, whereas data and information obtained from bibliographic references and previous studies regarding the landslide activities in the region were the main source of data. In more details, the methodology which was followed during the present study included four stages of analysis. During the first stage a total of 37 landslide locations were used as training data and 9 landslide conditioning factors were selected, namely: elevation, slope, aspect, profile curvature, plan curvature, geology, topographic wetness index (TWI), distance from rivers and distance from faults. The second stage involved classifying each variable and weighting them according to the results obtained by the method Weight of Evidence. The third stage involved the construction of the landslide susceptibility map, whereas to evaluate the performance of the developed methodology the area under the success curve (AUC) was used. The fourth stage involved the implementation of a sensitivity analysis. Based on the implementation of the WofE model concerning the conditioning factors, slope, profile curvature and elevation are shown to influence more the landslides spatial distribution, while geology is proved to be the most sensitive factor in changes according to the sensitivity analysis. The variable geology, shows the highest fluctuation concerning the relative landslide density that reaches the 7.05% within the zone of moderate susceptibility, 9.71% within the high susceptibility zone and 3.42% within the very high susceptibility zone. This could be attributed to the fact that the scale of the geological maps that were used as the primary source may not had been ideal for the purpose of analysis. Valuable information about the extent of each geological formation may be missing, however, the overall evaluation of the variable do not suggest removing it from the analysis. The performance of the model has been evaluated by estimating the AUC value which was estimated to be 0.78, indicating a satisfactory classifying ability.

ABSTRACT. The main purpose of the present study was to produce a predictive spatial model for landslide susceptibility by using Machine Learning methods and GIS. In particular, a Random Forest (RF) model was used as the base learning algorithm for the development of the predictive spatial model whereas the management of the landslide related variables were achieved using GIS. The developed methodology involved several phases. During the first phase nine variables related to landslide phenomena were selected and the data of 85 landslide events were analyzed. Analytically, the elevation, the slope angle, slope aspect, the distance from the river network, the profile curvature, the plan curvature, the Topographic Wetness Index, the geological formations and the distance from the tectonic features were the nine variables identified as most important and relevant to the landslide phenomena recorded in the research area. The second phase involved classifying each variable and weighting them according to the results obtained by the method Weight of Evidence. The third phase involved a multi-collinearity analysis in order to identify the existence or not of correlations between the landslide-related variables and to decide their usage and the application of the Learning Vector Quantization (LVQ) algorithm, so as to evaluate the predictive ability of the variables. During the third phase, the initial database was separated into training (70% of the total number of incidence) and validating (the remaining 30%) subsets. The last phase involved the implementation of the RF model and the construction of the landslide susceptibility map, whereas to evaluate the performance of the developed methodology the area under the success and predictive curve (AUC) were used. The water basin of the Krikeliotis river located in the Municipality of Evritania, Greece was selected as a test site to evaluate the predictive performance of the developed methodology whereas several R packages were used, based on R a language and environment for statistical analysis and graphical presentation, whereas ArcGIS 10.3.1 was used for accessing the spatial data and generating the landslide susceptibility maps.Based on the results of the multi-collinearity analysis all variables were used during the analysis, since no serious collinerarity was detected, whereas the LVQ algorithm evaluated as the most important and critical variable the variable associated with the geological formations, followed by the altitude and the morphological gradient By analyzing the training and validation data, the RF model showed an AUC value of 0.8670 and 0.7851, respectively, whereas the relative landslide density for the very high susceptible zone was 0.8460 when using the training subset and 0.7242 when using the validation subset. As a concluding remark one can highlight the fact that the identification of areas characterized by very high landslide susceptibility achieved by this study and also similar studies could be considered as a basic process that should precede any implementation of infrastructure development projects since it provides crucial information and knowledge concerning the mechanism responsible for landslide phenomena.

ABSTRACT. Introduction The goal of this research is to evaluate the potential of using hyperspectral airborne data for geological mapping, focusing on rock formations, ore deposits and raw materials identification, hence formations with a significant economic value. Moreover, it aims at identifying the limitations and the key factors in the process. Finally, this work can act as a compass for young scientists that want to combine outcomes from hyperspectral remote sensing methods and techniques with classic geological mapping techniques, as in this paper the linear spectral unmixing steps of the hyperspectral data are outlined.

Study Area The study area of this research is the western part of Milos Island, situated in the southwestern corner of the Cyclades islands in the Aegean Sea, Greece. This area is a part of the Natura 2000 network and the natural habitat of protected species, like the Mediterranean seal and the Milos’ red viper (Liordos et al., 2017). It is also characterized by the existence of very few small villages and hamlets, active or abandoned quarries and extractions sites and a lot of vegetation. Milos island is a part of the active Hellenic volcanic arch and is characterized by calc-alkaline mafic rocks, the most common being andesites, dacites, rhyolites, obsidians and tuffs (Alfieris et al., 2013). Apart from those, the island is one of the most densely mineralized areas in the Aegean Sea, containing economically viable occurrences of both metallic and non-metallic minerals, with reported exploitation since antiquity. These include perlite, bentonite, kaolin, deposits of manganese and barite.

Materials The hyperspectral images, which have been used in this work for the identification and characterization of the island’s surface deposits, have been acquired with a Digital Airborne Imaging Spectrometer (DAIS) 7915 sensor that has 79 spectral bands between 0.5 – 14 μm. (Ganas et. al, 2002). The hyperspectral imagery has 5m spatial resolution, is comprised of 4 independent strips N-S oriented with side overlap of 20% and it was acquired on the 25th of August 1998. Apart from the airborne image, the ASTER GDEM has been also used during orthorectification and atmospheric correction in order to minimize the geometric and atmospheric errors. Due to lack of ground measurements, geological maps of the Institute of Geology and Mineral Exploration (IGME) have been used as the main source of ground truth information, regarding the island formations. USGS Spectral Signatures have been downloaded for these formations as well.

Methods and Results Prior to the implementation of the spectral unmixing, preprocessing took place in order for the data to be homogenous and free of radiometric or geometric errors. Atmospheric correction using ATCOR4 was carried out for the elimination of the atmospheric effects and the estimation of the real surface reflectance. Orthorectification using GDEM and at least 15 ground control points for each image strip has also been carried out leading to a single mosaic image. The first step of the unmixing procedure is the dimensionality reduction. More specifically Principal Component Analysis (PCA) and Minimum Noise Fraction (MNF) were used for this purpose. The PCA method demonstrated that almost all information is concentrated in the first four PCA bands. Aiming at the same purpose, the MNF method was implemented, resulting to 16 MNF bands containing substantial information. The lack of matching between the hyperspectral image spectra and USGS standard signatures for various rock formations led to the selection of spectral targets either from the user using auxiliary sources or by applying endmember extraction techniques, which is the second step of the spectral unmixing. In the manual selection, both training and validation data were selected by the user using the geological map of IGME, due to the lack of in situ measurements. Three main ore deposits that had distinct spectral signatures among them were selected. Namely, two or three pure outcrops of kaolin, barite and pozzolan were manually selected for training areas and another couple or trio (depending on the area) that were used for evaluation. Regarding the automatic extraction of endmembers, three different extraction algorithms were implemented; the embedded in the ENVI program Pixel Purity Index (PPI) method, the Simple Endmember Extraction (SEE) method (Andreou et al., 2011) and the N-FindR algorithm (Winter, 1999). These three methods were tested for two different scenarios, the first including a mask in the aquatic environment and the second a wider mask covering water and dense vegetation areas. The result of this procedure was the extraction of 14 and 16 endmembers (for the sea mask and the mixed masked respectively) through the PPI method and 13 endmembers for the other two algorithms. These endmembers were compared with the user’s targets, in order to identify those that correlated best to each raw material. The assessment was carried out measuring the spectral angle difference between the extracted and the reference spectral signature. The aggregate result (Table 1) was 6 cases (3 different extraction methods with 2 different masks applied for each one), where the total number of endmembers, the closest endmember (number) to each material’s signature and a mean score as a credibility index were identified.

Table 1. Summary table comparing endmembers

It is observed that: • SEE (sea+veg) assigned two different materials for the same endmember. • The PPI method outperformed. • SEE (sea mask) produced satisfactorily results, and detected kaolin with the highest accuracy. In order for the automatic extraction of endmembers to be accurate, the endmembers must be discrete, hence to have wide angle differences. The methods that fulfilled this criterion were PPI and N-FindR, due to the fact that only a few endmembers display an angle difference <0.1. Moreover, the 3 endmembers of the materials of interest, presented wide angle differences with the rest endmembers The final step of the spectral unmixing was the creation of abundance maps for each of the three aforementioned materials (barite, kaolin, pozzolan). For this, three methods, the Constraint Linear Spectral Unmixing method (CLU), Mixture Tuned Match Filtering (MTMF) and Network Based Method (NBM) (Karathanassi et. al., 2011), have been applied. Among these, CLU and NBM produced the most accurate maps.

Discussion and Conclusions The current study had a high difficulty level in terms of mapping due to the wide vegetation areas in Western Milos that hid a wide variety of formations and hinder a complete geological mapping. Another burden was the quite similar formations, since the volcanic island of Milos is characterized by mafic rocks and volcanic tuffs, formations that need in situ mineralogical analysis and higher resolution data, making it quite difficult to be correctly identified with the current remote sensing dataset. Nevertheless, every endmember extraction methodology tested was successful as it managed to produce pure endmembers that matched the user’s endmembers and have wide spectral angle differences between them thus making them easily distinguishable. Regarding the abundance mapping of the pure raw materials, the most reliable method was the ΝΒΜ method, with the CLU being second in terms of accuracy. To sum up, the utility of hyperspectral data in identifying ore deposits is unambiguous, especially when talking about areas with difficult access. It is clear that in order to achieve a high level of accuracy, in situ measurements are prerequisite. Furthermore, an ideal case would be a sensor whose spectral resolution would match the USGS spectral library, so that every mineral in the area could be matched with a mineral of the spectral library.

ABSTRACT. Offering systematic open and free Earth observation data at global coverage (and with an observational continuity ensured for decades), the Copernicus satellite constellation is a game-changer for many different applications, including climate monitoring, environmental changes (atmospheric, marine, land), agriculture, forestry, natural hazards and many others. However, the exploitation of remote sensing data is often computationally heavy and knowledge demanding. With the aim to tackle these issues the RUS Copernicus (Research and User Support for Sentinel Core Products) project, funded by the European Commission and managed by the European Space Agency (ESA), started operations in October 2017. The service is offered free of charge and is operated by CSSI and its partners: Serco Italia SPA, Noveltis, Along-Track, and CS Romania. The main aim of RUS is to enable and increase the uptake of Copernicus data and support R&D activities within Europe. The service provides not only powerful computational environment (up to 40 cores for processing and 50 TBytes of storage capacity) - in the form of customized Linux based Virtual Machines (VMs) preinstalled with a wide variety of open source toolboxes - but also EO expertise and support for application-specific data selection, processing and visualization as well as algorithm development and scaling-up to large amount of Sentinel products. Moreover, users can install additional proprietary tools and SW in case they hold a valid license. The service is exclusively foreseen for training, research and R&D (no commercial use) and is currently available only to the residents of EU (“Copernicus citizens”). Apart from ICT resources and user support, RUS Copernicus has implemented an extensive training programme, led by Serco Italia SPA, and open to everyone (from students to decision-makers and professionals). It is designed to fit users’ needs at all levels of expertise regardless their location or the topic of interest. The training programme covers a wide portfolio of applications and consists of three main pillars: 1) Face-2-Face training (generally up to 2 days in duration, for max. 45 participants); 2) Webinars (regular monthly webinars, special webinars, up to 500 participants); 3) E-learning. All trainings/resources are free and exploit only open source software in order to facilitate repeatability for users (even users not registered for a free RUS VM). By January 2019, more than 2,000 people have participated in RUS training events and the recorded webinars count more than 28,000 views on the dedicated RUS YouTube channel. Additional 1,200 users are registered to the E-learning portal, which enables them to learn and test their knowledge in EO at their own pace.

ABSTRACT. Landslide phenomena pose a major threat to humans and the environment. Due to the complex nature of landslides, a thorough investigation is essential in order to identify and study such disastrous phenomena. The incorporation of innovative tools, such as Unmanned Aerial Vehicles and Terrestrial Laser Scanners is proved to be very effective in the investigation process, in terms of precision, and time-efficient. Moreover, the use of remote sensing techniques in landslide surveys provides information that covers a variety of applications, such as landslide identification and mapping, monitoring, susceptibility and hazard assessment (Scaioni Μ. et al., 2014). This study, by employing both a UAV Photogrammetry and a Terrestrial Laser Scanning approach for data acquisition, focuses on landslide identification and mapping in a vegetated area and provides a comparative analysis of the mapped landslide features on both, UAV and TLS-derived, point-clouds. It is noted that besides the use of these tools, a field investigation was conducted, in order to evaluate the results derived from the point-clouds. Study area The study area is located in Anilio village, in the prefecture of Epirus, Greece. According to the geotectonic zonation of Greece, the area appertains to the zone of Olonos-Pindos, which is composed of Mesozoic carbonate and siliciclastic rocks and Tertiary flysch formations. Pindos flysch consists mainly of sandstones, siltstones and their alternations repeated in several thrust sheets with NW-SE direction. Flysch, in general, is characterized by heterogeneity, presence of members with low strength and a complex structure due to folding, shear zones and discontinuities (Marinos V. et al., 2015). Therefore, its behaviour in slope stability is controlled by these factors in connection with the regional setting, such as morphological and groundwater conditions. The area of interest is formed entirely in a flysch environment, with siltstone formations being predominant, and strongly tectonized by numerous thrusts, being in very close proximity to the Pindos ophiolite nappe, resulting in the degradation of the original rock mass quality. Methodology In order to collect the information, a combination of methods was applied. During a visit in the study area, alongside with in-situ investigation, data were collected using an Unmanned Aerial Vehicle and a ground-based LiDAR system. A series of overlapping high resolution images of the area of interest were acquired by the UAV following a predefined flight path. UAV photogrammetry was used in combination with the Structure from Motion technique, as very detailed 3D models can be obtained from overlapping imagery with SfM algorithms (Lucieer et al., 2014). UAV imagery was used in the Structure from Motion workflow in a software environment and was automatically processed, resulting in the generation of a point-cloud, a Digital Surface Model (DSM) and an orthomosaic. Consequently, a hillshade map was produced, where two main landslides in the region of Anilio are depicted (Figure 1). Furthermore, data were collected by a TLS using the Time of Flight principle for ranging. In order to cover the whole scene and avoid occluded areas, several scans from different points of view are needed (Jaboyedoff et al., 2018). For that purpose, scans were conducted from two different positions. Later, with the aid of a point-cloud processing software (CloudCompare 2.10.2), point-clouds from the multiple scans were used as input and were manually merged in order to generate a single point-cloud of the landslide area. Figure 1. Hillshade map depicting two main landslides in the region of Anilio.

Results The two point-clouds, one derived from UAV data and one derived from TLS data (Figure 2), were used in order to detect geomorphological features of typical landslides, such as scarps, depressions and zones of uplift. These features were identified and mapped on both point-clouds and were later compared. An accuracy assessment of the resulted segments was conducted in order to verify the efficiency of each approach in a densely vegetated area. The main difference between the two methods, which reflects on their derivatives, lies in the fact that the UAV method uses a passive sensor and LiDAR technology uses an active sensor. More specifically, the laser scanner acts as a source of illumination, emitting laser beams, whereas the UAV camera, as a passive sensor, can only capture the scene lit by natural light. This means that, LiDAR technology offers an advantage in landslide studies in vegetated areas as it can penetrate vegetation and reach the ground surface. However, this may not be possible in areas with dense tree canopy and vegetation, but such features can be removed from a TLS point-cloud in a software environment. As a result, the TLS derived point-cloud (Figure 2a) is free of colour and consists of ground points, from the reflection of the ground surface, and non-ground points, from the reflection of trees and vegetation which can be manually removed. The UAV derived point-cloud is colour coded, meaning each point has an RGB value attributed to it and is not free of vegetation as it is produced by imagery processing (Figure 2b). This means it is not easy to identify the geomorphological features of the landslide. Even if filters are applied, to extract the vegetation, or if they are manually removed, shadows will be still shown in the point-cloud.

References Scaioni, M.; Longoni, L.; Melillo, V.; Papini, M. Remote Sensing for Landslide Investigations: An Overview of Recent Achievements and Perspectives. Remote Sens. 2014, 6, 9600-9652. Marinos V., Papathanassiou G., Vougiouka E., Karantanellis E. (2015). «Towards the Evaluation of Landslide Hazard in the Mountainous Area of Evritania, Central Greece». Engineering Geology for Society and Territory, Lollino et al. (eds.), Published by Springer – Volume 2, pp.989-993, DOI: 10.1007/978-3-319-09057-3_173 Lucieer, A., Jong, S. M. de, & Turner, D. (2014). Mapping landslide displacements using Structure from Motion (SfM) and image correlation of multi-temporal UAV photography. Progress in Physical Geography: Earth and Environment, 38(1), 97–116. Jaboyedoff M., Abellán A., Carrea D., Derron M. H., Matasci B. and Michoud C., Mapping and Monitoring of Landslides Using LIDAR. In book: Natural Hazards: Earthquakes, Volcanoes, and Landslides, (2018)

ABSTRACT. This paper deals with a rockfall analysis in the northern steep slope at Eptahori Village, Epirus, Greece, which exhibits extended rockfall instabilities along its face, placing the village at the base of the slope at high risk. Along the examined slope, numerus older rockfall events were recorded. These rockfalls were caused by toppling of overhanging sandstone blocks formed by large tension cracks that were generated due to the erosion of the weak siltstone layers. The geological setting of the study area consists of molassic formations of “Eptahori” and “Pentalofo” units and more particularly by thick sandstone beds (“Pentalofos” unit) on the upper part of the slope, underlied by thin siltstone layers (“Eptahori” unit), which continues to the base of the slope. The structure of the rock mass is blocky, developed by bedding orientation NW – SE, dipping to the slope, which consists the main joint set of the rock mass as well by sub-vertical joints with orientation NNW – SSE within the thick sandstone layers (Figure 1). These joints act as tension cracks along the slope due to the loss of support of the eroded material. These joints are widened due to the high rate of atmospheric precipitation that enters these open discontinuities of the rock mass and to the temperature changes, creating significant unstable blocks along the slope. The objective of this paper is to assess the engineering geological model of the rockfall events, to evaluate the degree of rockfall hazard along the face of the slope and finally propose the protection structures along the slope. A detailed field survey of the geological and engineering geological conditions was executed during July – August 2018 along with field measurements. Moreover, terrestrial laser scanning (Light Detection And Ranging – LiDAR) (Figure 1,c) as well as Unmanned Aerial Vehicle (UAV) flights above the study area were made. According to the resulting images and the generated point clouds, the slope morphology and block structures were precisely determined. The unstable zones were also detected and volume measurements of hanging blocks were carried out so as to develop the engineering geological model of the slope and evaluate the behavior of the formations prior to rockfall. Rockfall analysis were conducted by developing rockfall trajectory simulation models using RAMMS:: Rockfall (RApid Mass Movement Simulation), which stands out to be a usefull and advanced modelling software in simulation of rockfall trajectories in three dimensions. According to these models, all the potential rockfall trajectories along the face of the slope were examined and the trajectories evaluated with high risk were analyzed, estimating the worst-case scenario of rockfall along the slope. Moreover, the parameters of motions of rocks were determined by the simulation results. The resulting model parameters were calibrated according to restitution coefficients in order to improve simulation results. The simulation model was developed by an accurate and detailed Digital Surface Model (DEM) of the terrain of the slope created by the high resolution resulting point cloud data set of LiDAR scanning. The input parameters of the model concerning the type of terrain and vegetation at the slope as well the best-fit simulation of rock bodies were determined in accordance with detailed field observation data (Figure 2). According to the rockfall simulation model, the blocks develop an average jump height of 3 to 4 m with a local maximum of 8 m during bouncing at sandstone benches, where the velocity of the rocks range from 5 to 8 m/s reaching a maximum of 15 m/s. During their motion, the rocks develop high kinetic energy rates (8.000 – 12.000 kJ), which are reduced, as indicated by the values of the restitution coefficients, when sliding on the shale layers of the base of the slope. During this contact, friction forces are developed and provoke the absorption of high amount of kinetic energy. The trajectories are hence stopped at the base of the slope or continue with reduced velocity towards the toe of the slope, placing the residential zone at high risk. The rockfall potential along the slope was assessed as medium to high hazard degree, based on the rock mass quality, the volume of blocks, the history of older rockfalls, the steepness of the slope and the presence of unstable blocks A series of protection measures – both active and passive – are proposed in order to reduce the hazard to the lowest possible level. Active structures aim to decrease the probability of failure by surface drainage of the slope by construction of drainage ditches and protection measures (e.g. sprayed polymer coatings) from the erosion of the siltstone members. Passive protection structures are strongly proposed as effective measures in order to retain falling blocks and absorb impact energy (Figure 3). In particular, the measures proposed are: • Dynamic rockfall barriers (or flexible catch fences) constructed in two lines at the toe of the slope, up to a height of 3 m and energy absorption capacity of up to 10,000 kJ for the first line and a height of up to 2 m and energy absorption capacity of up to 8,500 kJ for the second line. Of course, these very high energies concern the worst-case scenario of the analysis. • Ditches (rock traps) constructed in front of barriers 2 to 5 m wide with depth up to 1 m filled with soil material for the absorption of average energy of 10,000 kJ.

ABSTRACT. Energy production in Greece greatly depends on lignite combustion, therefore exploitation of the indigenous deposits is of great importance. Lignite mainly comes from open pit mines, in whom marly formations are usually found overlaying the lignite accumulation. Due to poor geotechnical parameters, mine’s unique geometry (high temporary slopes in steep angles), combined with the pore water pressure from heavy rainfalls behaving as triggering mechanism, as a result landslide phenomenon often occur. The current research takes advantage of Unmanned Aerial Vehicles and their capabilities to detect, map and with the appropriate process, analyze and discover the basic engineering geological principles (type of failure, triggering mechanism, volume etc.) governing these failures. Specifically, two mine areas have been examined, both of them have undergone rehabilitation (Marinos 2012). The first one is in Florina and the second in Kozani prefecture. These two districts according to the geotectonic units of Greece appertain to Pelagonian nappe and moreover belong in the upper and in the lower part of the elongated intermontaine Florina-Ptolemais-Kozani tectonic graben respectively (Pavlides et al., 1986). Research was initiated with data collection from the in-situ investigation of the mining areas. The UAV, bearing a high-resolution camera with a GPS tracker, was set to fly in a pre-determined flight path to map the plain view of each mine. Meanwhile a thorough field survey to recognize and assess the basic geological and geometrical factors regulating the landslides like marl’s bed dip/dip direction, discontinuity surfaces, geometrical characteristics of landslides, faults, etc. was executed. The Digital Surface Model, Point Cloud and finally Orthomosaic with the contribution of a photogrammetric software was created taking consideration of the desired Ground Sampling Distance (GSD). Methodology continued with the creation of topographic parameters such as Hillshade, Aspect, Slope. With an accurate manual mapping in GIS environment of the Orthomosaic obtained in each case, two individual landslides were identified at Florina’s mine in Amyntaio (Figure 1) and 147 in total at Kozani’s mine in Prosilio (Figure 2). Furthermore, taking into account information derived from the interpretation of the aforementioned topographic tools it was made possible to calculate the fundamental data for each landslide such as slope orientation and dip, discontinuities orientation and dip and finally propose a failure mechanism matching those given by the in-situ investigation. Last but not least, through the application of the prementioned photogrammetric program it was made able to identify and export the volume of each slide with a very good correlation to reality as it was verified by actual data. Finally, for the Amintaio open pit the responsible failure mechanism is the rotational one for both slides. In the Prosilio open pit from the 147 known landslides 109 were identified as rotational and 38 as wedge type failures. Volumetric analysis showed materials movements ranging from 0.28m³±30.00% to 531.71m³±0.74% for the mapped landslides in the area of interest. Concluding, the aim of the research is to designate an effective and simultaneously low-cost method of detecting, monitoring and assessing landslide phenomena. This attribute comes to absolute need regarding open pit mines, where a 24/7 surveillance is essential because of marl’s highly susceptibility to failures. UAV usage checks all the above criteria when it comes in conjunction with proper geological knowledge can truly provide remarkable results.

ABSTRACT. Introduction A landslide constitutes a significant natural hazard that includes mass movement of soil, rocks and/or mud due to the pull of gravity, most of them occurring gradually, but some may be abrupt. It is a phenomenon which most of the times it is not predictable and unfortunately unavoidable and can cause significant casualties and immeasurable economic losses, effecting many aspects of human life. Extensive rainfall, earthquakes, unfavorable geology and human intervention are some potential triggering factors that can induce a landslide event. According the aforementioned, it is necessary to mitigate the landslide hazard to ensure optimum security. As a result, new methodologies are required to develop a better perception of landslide hazards. With the recent advances of technology, various remote sensing methods have been developed providing useful topographic data. In the current study, detailed imagery data has been obtained by using Unmanned Aerial Vehicles (UAV). The UAVs, also known as drones, are aircrafts where are capable of taking high-resolution images and producing via photogrammetric software, precise 3D point cloud, Digital Surface Models and respective Orthophoto. Valuable data source with extended applications on surveillance, inspection, mapping and 3D imaging are now available. The purpose of this study is to investigate and detect potential topographic changes of a mega-landslide by using multi-temporal UAV data. The landslide is induced at the community of Ropoto and constitutes a great risk while a large part of the village has been affected (approximately 280m wide and 750m long) (Figure 1). Ropoto village, belongs to the Municipality of Trikala in the Central part of Greece and according to the geological map (1:50.000), with the title “Mouzakion”, belongs to the geotectonic zone of Pindos (Mountrakis, 1985). The geology of the area of interest consists of the following formations: Paleocene-Eocene flysch formations (transition flysch units in this case) that present a high heterogeneity (sandstones, conglomerates, limestones, siltstones, shales, marls), transition beds consisted of thick-bedded limestones with sandstone and shale (M. Maastrichtian-L. Paleocene) and the thin-bedded limestone formation (Turonian-M. Maastrichtian). The tectonic development of the Ropoto area affected all of the formations and mainly the newer ones (flysch and transition formations), thus isoclinal folds and thrust faults were created. Flysch has thus suffered from compressional forces being highly deformed. Shear zones and smaller faults are also present in the site specific area due to this tectonic disturbance. These geological characteristics produced very weak rock masses which presented the landslide. Brittle rock formations, such as limestones here, created very permeable zones, so very high pore water pressure is often developed triggering the landslide. The latter, explains the water presence between the flysch and thick-bedded limestone formations covered by scree. Consequently, the landslide occurred after 12 hours of intense rainfall within the weathered mantle of flysch depth of the transition beds. As a result, the greater part of the central village infrastructure massively collapsed. Methodology For the detection of surface deformation due to landsliding, field investigation is requisite and typically involve field mapping to characterize the geomorphological conditions. Additionally, there is a number of factors that need to be continuously assessed: the extent of the landslide, detection of fissure structures, topography of the land and the rate of displacements that could be related to the fracture (Niethammer et al. 2010). The latter, depending on the scale of the problem, can take valuable time while rough terrain can constitute access restrictions, therefore the assessment of the landslide is deficient. In order to understand the mechanism of the landslide, horizontal and vertical displacements should be measured. A number of remote sensing methods are valuable tools towards this assessment. Therefore, except the visual interpretation, high resolution images were captured by the UAV while it provides ultra-high spatial resolution and accuracy that is needed to monitor temporal changes. At the community of Ropoto, several movements have been recorded during the last decades., First movement occurred in 1963, while the last episodic large landslide happened in 2012. Ever since the landslide is evolving gradually without perceivable movements. In this survey, in order to detect these changes multi-temporal digital elevation models of the area we quantified and compared. Initially, for change the detection assessment, pre-disaster data is required. The reference data is provided by the Land Registry of Greece where Digital Elevation Models (DEM) - LSO (Large Scale Orthophotos) were created with the use of aircrafts equipped with high-end optical sensors between 2007 and 2009 with pixel resolution of 5 m. Those digital elevation models are specialized database that represents the topographic relief of a surface between points of known elevation. By interpolating known elevation data from sources such as ground surveys and photogrammetric data capture, a rectangular digital elevation model grid can be created. By setting these multi-temporal photogrammetric products under two different procedures, two similar results were given, while according to the visual interpretation they displayed the same volume of movement. In the first procedure the value of the second one has being subtracted from the value of the first one on a cell-by-cell basis and the second one calculates the area and the volume of the region between a surface and a reference plane. As a result, we have two DEM’s of difference involving quantifying volumetric change between these multi-temporal photogrammetric products showing parts with gain or loss material (Figure 2). Especially the crown and the foot of the landslide demonstrate major amount of material removal. On the other hand, several other parts of the landslide reveal an unexpected increment. Concluding, Ropoto landslide constitute an active landslide that shows gradually evolving movements through the years. As so, the continuous monitoring of the landslide in 6 months’ period, it is required to determine the extent, magnitude and style of landslide movement, for risk and even emergency risk management assessments. Last but not least, the need of implementing Unmanned Aerial Vehicles (UAV) in landslide risk assessments is constantly increasing while they provide a safe, quick and potentially more accurate way of inspecting large scale and difficult to access areas, requiring minimal human resources. However, in order to process these results, the contribution and critical evaluation of an expert is obligatory.

ABSTRACT. In many urban areas of the world, the issues associated with rocky slope instability are numerous, ranging from first-time rapid rockfalls to reactivated slow rock mass slides and from minor, localized failures to broader catastrophic events. A variety of factors, such as the topography, geological - geotechnical structure of the formations and environmental conditions control the occurrence of slope failures (Chowdhury and Flentje, 2011). The growth of urban population is responsible for inevitable expansion of urban centres adjacent to hazardous hilly regions. As a result, stability concerns arise for the safety of humans and the infrastructure. The need to predict and prevent these slope failures is critical. Despite the extremely slow rates of hillslope movements, imperceptible to the optical observation, the cumulative displacement over a period of time may cause considerable risk to manmade structures and increase vulnerability. Although authorities have general restrictions prohibiting building on slopes exceeding a certain degree of incline, other effects triggering slope instability should also be considered in mass movement assessments when projecting a complete urban growth plan.

In recent years, integrated remote sensing techniques based on space-based SAR interferometry techniques could become the key method to identify and predict slope instabilities. Since 90’s differential repeat-pass interferometry radar (DInSAR) based on SAR images processing has proven an interesting tool for the measurement and observation of ground deformation (Massonnet and Rabaute, 1993). Nowadays, using large stacks of SAR images acquired over the same area, long deformation time series can be analysed using multitemporal differential SAR interferometry techniques which overcome several limitations of repeat-pass interferometry. The most important advantage of the method is the ability to construct maps of yearly rates of ground displacement or the change to the rates at millimetric scale. Space-based SAR interferometry techniques could become an effective tool for prediction of slope instabilities and identification of locations, where potential slope failures may appear and human interventions could cause instability (Di Martire et al. 2012, Burns S.F. 2015).

The main purpose of this study is the slope stability monitoring of Athens city hills. In the case of Athens progressive residential development has been taking place bellow the shadow of steep rocky hills of the city centre. It is worth mentioning that some of the most renowned ancient monuments in the city are founded on these hills. The Athens Basin represents a complex neotectonic asymmetric graben bounded by NNE-SSW marginal faults (Papanikolaou et al., 2004). The basin is surrounded by the mountains of Aegaleo, Parnitha, Pendeliko and Hymettus. The southern and south-western part of the basin is open towards the Saronikos Gulf forming a shoreline of about 47 km. A number of historical hills are distributed within the basin, Acropolis, Nymphs, Philopappou, Pnika, Areopagus, Lycabettus and Tourkovounia. Based on the comparative evaluation of the geological maps and the available literature it is summarized that the Athens hilltops are formed by light to dark grey, thickly bedded to massive and occasionally medium bedded, recrystallized Upper Cretaceous limestone with numerous joints and karstic cavities. These limestone masses are a member of the upper calcareous horizon of the lithostratigraphic series of the alpine formations that were overthrusted the “Athens Schist” formation that constitute the basement of many parts of Athens Basin. The limestones overlie a marly horizon which covers the Athens Schist series, including schists, shales, sandstones, marls and limestones (Koukis and Sabatakakis, 2000). In places the limestone hills are covered by post-alpine deposits. The neotectonic structure of the broader Athens area comprises a number of major tectonic fractures with E-W and NW-SE strike direction (Papanikolaou et al., 2004). It can be determined that the limestone outcrops were subjected to a NNE-SSW tensile tectonic stress field which formed faults, mainly normal throughout the calcareous mass. Although the limestones have excellent mechanical characteristics they are fractured by numerous joint sets and are intensively weathered forming karstic fissures often 0.5 to 2 m wide and in case of Tourkovounia the voids reach 15m width (Karfakis and Loupasakis, 2006). The karstificated fractured zones represent areas of slope instability and may cause differential settlements of structures and even the failure of the foundation of residences.

Taking into consideration all these points Athens hillslopes’ monitoring is an indispensable and essential issue due to its nature to provide support for slope stability risk assessment in urban and suburban cases. The current research work aims to examine the contribution of high resolution radar satellite images and specifically TerraSAR-X stripmap in the mapping of low rate land displacement over the urban boundary layer of hills in Athens city by means of MTInSAR for the period 2012-2016. In addition, DEM and DEM-derived spatial models have been created and used. Analysis of the results shows that generally the urbanised slopes in Athens hills are stable. Patterns of displacement are locally observed and are of minor importance. Nonetheless, a more detailed knowledge of the local conditions of the limestone outcrops is needed by fieldwork. The methodologies applied proved an effective way to describe the potential behavior of the rock mass with respect to the probability of occurrence of slope displacements.

ABSTRACT. Land subsidence is considered among the most frequent geological hazard that usually occurs as a consequence of a number of phenomena, namely: natural compaction of unconsolidated fine - grained deposits, groundwater over - exploitation, peat - oxidation and collapse of underground cavities (Ziaie et al., 2009). The effects of the land subsidence include damages to building structures as well as loss of functionality of linear and point infrastructures (pipeline and road network deformations, well-casing failures and protrusion etc.) (Osmanoğlu et al., 2011; Cigna et al.,2012). The main purpose of the current study is to investigate land subsidence in the coastal zone of the N. Faliro, Moschato and Kallithea municipalities, by means of advanced DinSAR techniques and to identify the main causes of the observed ground deformations that contribute to the development of the surface fractures affecting the site. Detecting, measuring and monitoring land subsidence is important for the urban and infrastructures planning as well as for the risk management. Repeat-pass space-borne SAR interferometry (InSAR) is a unique tool for large-scale monitoring of surface deformation at a low cost and great precision (Massonnet & Feigl, 1998) and particularly for land subsidence regardless of its cause (Dixon et al., 2006; Herrera et al., 2009; Osmanoglu et al., 2011; Chaussard et al., 2013). The application advanced DinSAR techniques for the detection of land motion phenomena revealed that the area extending between the outlets of the Kiffisos and Ilisos rivers is affected by subsidence with LOS deformation rates of -1.5 to -6.9 mm/yr during the period 1992 - 2001 and of -1.5 to -3mm/yr for the period 2002-2010 (Fig.1a,b).

Fig.1. a) Velocities from 1992 to 2001 as derived by the PSI analysis of ERS1&2 data b) Velocities from 2002 to 2010 as derived by the SVD analysis of ENVISAT data.

In order to further validate and interpret these results, field observations have been conducted exploited. The surface ruptures extent mainly at the area between the riverbeds of Kiffisos and Ilissos river, leading to differential displacements. The visible traces of subsidence affect pavements and numerous buildings (Fig.2).

Fig.2 Field evidence of ruptures in the study area. Coordinates are in UTM WGS84 (projected). Damages witnessed at building (point 1), pavement ( point 2) and natural terrain (point 3).

The outcomes of the performed analysis indicated that the land subsidence phenomena in the study area could be attributed primarily to the natural compaction of the fine grained alluvial deposits. Furthermore, the overexploitation of groundwater reservoir cannot be entirely excluded. Acknowledgments The European Space Agency (ESA) through the Terrafirma project has funded the SAR imagery processing. The authors gratefully acknowledge the German Space Agency - DLR (German) for having processed SAR data for the area. References Cigna, F., Osmanoğlu, B., Cabral-Cano, E., Dixon, T. H., Ávila-Olivera, J.A., Garduño-Monroy, V.H., DeMets, C., Wdowinski, S., 2012. Monitoring land subsidence and its induced geological hazard with Synthetic Aperture Radar interferometry: A case study in Morelia, Mexico. Remote Sensing of Environment 117, 146–161. Chaussard, E., Amelung, F., Abidin, H., Hong, S.H., 2013. Sinking cities in Indonesia: ALOS PALSAR detects rapid subsidence due to groundwater and gas extraction. Remote Sensing of Environment 128, 150-161. Dixon, T.H., Amelung, F., Ferretti, A., Novali, F., Rocca, F., Dokka, R., Sella, G., Kim, S.W., Wdowinski, S., Whitman, D., 2006. Subsidence and flooding in New Orleans - a subsidence map of the city offers insight into the failure of the levees during Hurricane Katrina. Nature 441, 587-588. Herrera, G., Fernandez, J.A., Tomas, R., Cooksley, G., Mulas, J., 2009. Advanced interpretation of subsidence in Murcia (SE Spain) using A-DInSAR data modelling and validation. Natural Hazards Earth System Science 9, 647-661. Massonnet, D., Feigl, K.L., 1998. Radar interferometry and its application to changes in the Earth's surface. Reviews of Geophysics 36, 441-500 Osmanoğlu, B., Dixon, T. H., Wdowinski, S., Cabral-Cano, E., Jiang, Y., 2011. Mexico City Subsidence Observed with Persistent Scatterer InSAR. Journal of Applied Earth Observation and Geoinformation 13(1), 1–12. Ziaie, A., Kumarci, K., Ghanizadeh, K.R., Mahmodinejad, A., 2009. Prediction of earth fissures development in Sirjan. Res J Environ Sci 3, 486-496.

ABSTRACT. Background and Objectives The use of visual models in natural sciences is a commonplace. Physical scale-models of organisms, organs and cells are frequently seen in classrooms and lecture halls. Foraminifera are not an exception to this. D’Orbigny, the scientist who named the group in 1839, was the first to create a set of three-dimensional scale-up models of foraminifera (Miller, 2002). His aim was to make foraminifera available to everybody without entailing the necessity of observing them under the microscope (Heron-Allen, 1917). Since then, several scientists and artists have reproduced scale models of foraminifera (Miller, 2013). However, most of them are treated as museum objects. The reason behind this is simple: foraminifera have complex shapes that are difficult to massively reproduce without loosing the fine detail of the original. Therefore many teaching models of foraminifera usually lack detail and have an unnatural look. The recent development of three dimensional printing technologies enables us to create low cost, yet highly accurate objects. Although 3D printing has been around for decades, only the last years it became affordable to the common consumer. This study examined the impact of a modeling-based instructional intervention on students in primary / early secondary school using different tools: 3D printing, museum objects and microscope images that support modeling. Our aim is to evaluate the use of tactile models could help pupils understand images from the microscope.

Theoretical Framework The literature of the science education offers important data to the scientific modeling. Many researchers agree that modeling should be the main technique of teaching sciences (Mellar et al., 1994). For science education, it is especially important that students learn how to develop models and how to draw explanations of natural phenomena (Coleman, 1998). The modeling process in Sciences’ teaching has been studied via the use of different pedagogic tools: objects from everyday life used for the experiments and technology-based learning environments. The results show that the advantages of different pedagogic tools can contribute to the act of learning the sciences’ concepts taking into consideration the cognitive processes that are involved in the modelling (Smyrnaiou & Weil-Barais, 2005; Smyrnaiou & Dimitracopoulou, 2007). Models can play a role in the learning process when we ask students to construct models. In this “learning by modeling” students are required to construct an external model with the objective to make the model behave as similar as possible as the real system (Penner, 2001). We speak also of “learning from models” when students can interact with the model. Students’ learning processes center around the exploration of this model by changing values of input variables and observing resulting values of output variables. In this process they experience rules from the domain or (re-) discover (aspects) of these rules (de Jong, 2006). Finally, both ways of using models can be combined in what we will call “model-based inquiry learning”. Gerard Vergnaud (1987) has proposed, in a constructivist aspect, a general theoretical framework (schema) which emphasises to the relationships that the student has to construct in order to be able to understand and interpret situations, to communicate their purpose and to make predictions, inferences, etc. He emphasises the role of the student's actions and cognitive resources in the elaboration of knowledge, within a constructivist approach. He distinguishes three functioning registers: a) the register of actions on real objects; the register of mental representations; the register of symbolic representations (maths, language, etc.).

Methods Specimens of Globigerinoides ruber were scanned on a XMCT system (Friedrich-Alexander Universitat Erlangen-Nurnberg, Erlanger, Germany). The specimens were scanned at 80kV, detector array size of 2000*1336, 1500 projections/360o, 2,5s/projection) slice thickness. The 3D reconstruction and visualization of the CT data was performed in AVIZO (www.vsg3d.com). The created 3D meshes were prepared for printing in Autodesk Meshmixer (www.meshmixer.com) and Slic3r (https://slic3r.org). The models were printed on a Prusa i3 MK2S fused filament fabrication printer. Two types of polylactic acid (PLA) filament were used: light gray and semitransparent. The models were printed as complete shells, with the exception of one model, whose shell was sliced in half so that its internal structure can be observed. All printed models were 200 times larger than natural size. We set up an installation with binocular microscopes, foraminifera pictures and 3D models. The fundamental concepts micropalaeontology and using microscopes were explained to the pupils. After that, the pupils were asked to examine foraminifera under the microscope. Then they were given the models and were asked to examine the foraminifera under the microscope again. The research was set out to explore students’ descriptions and manipulations while being exposed to the different mediums: symbolic objects; real objects. Furthermore, students’ models while using “3D printer” and microscope were explored. Finally, the extent to which the combination of the two mediums enhanced students’ understaning was investigated.

Results and Conclusions At the end of the session, the pupils were asked to evaluate the 3D models. In particular the pupils were given a short survey that had the following statements. Nearly all pupils have never used a microscope before and only a small percentage of them (24%) had ever seen a 3D printed object. The 3D printed models helped to the better understanding of the foraminifera structure (97%). However, most pupils were mostly impressed by the microscope itself rather than the 3D models. In many cases 3D printing is used as a support technology in teaching including printing of scale up models of microscopic objects (see for an overview, Ford and Minshall, 2018). As expected, our foraminifera models helped pupils underhand the fine details of the foraminifera shell. The models do not replace the experience of the real object (as that is seen through a microscope), but do contribute to the better understanding of the subject. Fused filament fabrication 3D printing enables scientists to cheaply create teachable objects of high quality. Our experiment demonstrated that the use of objects that are increased in scale, makes them more accessible, and helps the underfunding of microscopic organism and structures. Similar projects in the future should be more complex and thus capitalize on the growing affordability of 3D printing.

Figure 1. A pupil examining a foram under a microscope (left) and looking at a 3D model of the same organism (right).

References Coleman, E.B., 1998. Using explanatory knowledge during collaborative problem solving in science. Journal of the Learning Sciences, 7(3&4), 387-427. de Jong, T., 2006. Computer simulations - Technological advances in inquiry learning. Science, 312, 532-533. Ford, S., Minshall, T., 2018. Invited review article: Where and how 3D printing is used in teaching and education. Additive Manufacturing, 25, 131-150. Heron-Allen, E., 1917. Presidential address, 1916- 1917: Alcide d’Orbigny, his life and his work. Journal of the Royal Microscopical Society, 1917, 1- 105. Mellar, H., Bliss, J., Boohan, R., Ogborn, J., Tompsett, 1994. Learning with Artificial Worlds: Computer Based Modeling in the Curriculum, The Falmer Press, London. Miller, C.G., 2002. Micropalaeontological models at the Natural History Museum, London. The Geological Curator 7(7), 263-274. Miller, C.G., 2013. A brief history of modelling Foraminifera: from d’Orbigny to Zheng Shouyi. The Micropalaeontological Society, Special Publications, Geological Society, London, 337-349. Penner, D.E., 2001. Cognition, computers, and synthetic science: Building knowledge and meaning through modelling. Review of Research in Education, 25, 1-37. Smyrnaiou, Z., Weil-Barais, A., 2005. Évaluation cognitive d’un logiciel de modélisation auprès d’élèves de collège, Didaskalia, 27, 133-149. Smyrnaiou, Z., Dimitracopoulou A., 2007. Ιnquiry learning using a technology-based learning environment. Proceedings of 8th International Conference on Computer Based Learning, Heraklion, Crete, 90-100. Vergnaud, G., 1987. Les fonctions de l’action et de la symbolisation dans la formation des connaissances chez l’enfant. In Piaget J., Mounoud P., Bronckart J.P., Psychologie, Encyclopédie de la Pléïade, Paris, Gallimard, pp. 821-844.

ABSTRACT. Designing An Educational Scenario Aiming To Teach The Concept Of Geological Time To Secondary Education Students With Visual Disabilities.

K. Marmarinos1, A. Antonarakou1, H. Drinia1, F. Antoniou1, (1) National & Kapodistrian University of Athens, University Campus- Zografou, Athens, Greece, kmarmarinos@geol.uoa.gr

Introduction: The understanding of the enormous amount of time in which the Earth has been formed and evolved is one of the most difficult concepts not only for students but for people of all ages (Dodick & Orion, 2003). The difficulty in understanding the geological time is due to its vast scale of events that go beyond everyday experience, as human existence on Earth is very small compared to the temporal scale of the geological events on it (Dodick & Orion, 2006; Trend, 1998). Despite all the difficulties described above the concept of the geological time is taught in the secondary education of Greece as it is necessary for students to understand not only the long-term geological changes but also other processes that occur slowly on the planet, including climate change, oceanography, paleontology, evolutionary biology and cosmology (Dodick, 2007; Dodick & Orion, 2006; Nam, Karahan & Roehrig, 2016; Ravachol & Orange, 2012). Given that in the context of equal opportunities, visually impaired people should have access to the same information as their sighted peers (Aldrich & Sheppard, 2001), Geology teachers are also called to teach geological time to students with visual impairments. The challenge for them is even bigger as in that case visual representations are not an option.

Options-Aim: For students with visual impairments learning is possible through touch (Millar & Al-Attar, 2004). Appropriately designed educational scenarios involving hands-on activities can be used to further enhance teaching (Simone, 2007) and make it in a funy and enjoyable way (Howe, 2006).

Inspiration: Inspiration resources are successful efforts made by researchers to teach concepts related to geological time to students with visual impairments including: • The haptic exploration of actual fossils or replicas, which may include placing them in the correct chronological order (Neuhauser, 2011; Perkins School for the Blind, 2016; Richard, 1967; Travis, 1990; Wild, Hilson, & Farrand, 2013). • The use of materials of different texture that simulate a stratigraphic sequence (Neuhauser, 2011; Ratajeski, 2017). Other inspiration resources are scenarios made for normal vision students like the linear representation of the geological time on the human hand (Borel, 2014) or the proposals for the representation of stratigraphic strata using simple materials in order to teach the principle of superposition. Those ideas have been adapted adequately for students with visual impairments.

Description: A variety of specific haptic educational objects or activities is proposed to be used to teach and stimulate the interest of students with visual impairments in geological time. These haptic educational objects or activities are easily made with low cost materials and do not require much time for their construction. The construction details and teaching scenarios directions are also provided. The Examples are designed for personalized instruction and include: Haptic comparison of recent and fossilized sea cells, haptic exploration of a fictional dinosaur footprint made in clay, simulation of a stratigraphy sequence with pieces of fabric, simulation of a drilling core, simulation of geological timeline in the students hand and the placement of animal toy models in the correct chronological order.

References Aldrich, F. K., & Sheppard, L. (2001). Tactile graphics in school education: perspectives from pupils. British Journal of Visual Impairment, 19(2), 69–73. Borel, B. (2014). The Greatest Animal War. Nautilus, (17). Retrieved from http://nautil.us/issue/17/big-bangs/the-greatest-animal-war Dodick, J. (2007). Understanding Evolutionary Change within the Framework of Geologic Time. McGill Journal of Education, 42, 245–264. Dodick, J., & Orion, N. (2003). Cognitive Factors Affecting Student Understanding of Geologic Time. Journal of Research in Science Teaching, 40, 415–442. Retrieved from https://stwww1.weizmann.ac.il/geogroup/wp-content/uploads/sites/24/2016/10 /jrst_article.pdf Dodick, J., & Orion, N. (2006). Building an understanding of geological time: A cognitive synthesis of the “macro” and “micro” scales of time. In C. A. Manduca & D. W. Mogk (Eds.), Earth and Mind: How Geologists Think and Learn about the Earth (pp. 64–92). Geological Society of America. Retrieved from https://pdfs.semanticscholar.org/de3d/f52f16e01956e531e2ab80bc9ca40a5bdb53 .pdf Howe, M. (2006). A new approach to teaching those with Disabilities : EMBed methodology and the visually disabled. The Triple Helix. Millar, S., & Al-Attar, Z. (2004). External and body-centred frames of reference in spatial memory: Evidence from touch. Perception and Psychophysics, 66(1), 51–59. Nam, Y., Karahan, E., & Roehrig, G. (2016). Native American Students’ Understanding of Geologic Time Scale: 4th-8th Grade Ojibwe Students’ Understanding of Earth’s Geologic History. International Journal of Environmental & Science Education, 11(4), 485–503. Neuhauser, K. (2011). Privilege on Teaching a Totally Blind Student Physical and Historical Geology. In The Geological Society of America (GSA) Annual Meeting. Minneapolis. Retrieved from https://gsa.confex.com/data/handout/gsa/2011AM/Paper_192 703_handout_252_0.pdf Perkins School for the Blind. (2016). Forensic Geology Lab: Digging Through the Sands of Crime. Retrieved June 8, 2018, from http://www.perkinselearning.org/accessible-science/activities/forensic-geology-lab-digging-through-sands-crime Ratajeski, K. (2017). Examples of Tactile Aids for Teaching Introductory Geology Students with Visual Disabilities. Earth Educators Rendezvous, Albuquerque, [Poster]. Ravachol, D. O., & Orange, C. (2012). Scientific knowledge and learning in biology and geology: Between phenomenon and event. In C. Bruguiere, A. Tiberghien, & P. Clement (Eds.), E-Book Proceedings of the ESERA 2011 Conference: Science learning and Citizenship (part 1) (pp. 58–64). Lyon, France: European Science Education Research Association. Richard, B. (1967). Teaching Introductory Geology to a Blind Person. Journal of Geological Education, 15(4), 152–153. Simone, N. (2007). Adapting Hands-On Science Programs for Students with Disabilities. CSIRO Education. Worcester Polytechnic Institute. Retrieved from http://www.wpi.edu/Pubs/E-project/Available/E-project-042907-213933/unrestricted/IQP-HXA-A073-CSIRO.pdf Travis, J. (1990). Geology and the Visually Impaired Student. Journal of Geological Education, 38, 41–49. Trend, R. (1998). An investigation into understanding of geological time among 10- and 11-year-old children. International Journal of Science Education, 20(8), 973–988. Wild, T. A., Hilson, M. P., & Farrand, K. M. (2013). Conceptual Understanding of Geological Concepts by Students With Visual Impairements. Journal Of Geoscience Education, 61, 222–230.

ABSTRACT. The scientific analysis of myths can identify hidden references to geological events in narratives previously viewed as imaginary products of creative storytelling. Although this is the case in mythologies around the World (Vitaliano, 1973), the body of myths originally told by the ancient Greeks is of particular interest (eg. Mariolakos, 2018). Their mythology has an extensive influence on the culture of Western civilization and is widely known to the public. Here we present our ongoing 3-year project, that focuses on the geomythology of ancient Greece. The project, which is entitled INNOVEXPO, aims to the development of innovative applications, incorporating scientifically substantiated content will combine scientific research with the creative industry, to develop multiple levels of interpretation, documentation and content acquisition. As a result, we will develop a prototype methodology, in order to form a complex grid of and their original methodology of interconnection, for the enrichment and interactive presentation of exhibitions. Myths, including geomyths, consist of narratives and stories that lack a material representation. Many previous exhibitions on mythology were designed around objects of material culture inspired by myths (e.g. depictions of heroes and mythical battles). Here we decided to apply a different approach, one that will present myths directly, while minimizing the use of objects of material culture. In order to do so we will use innovative technological applications that act as expressive and conceptual tools for the design of modern museographic practices (Figures 1 and 2). At the same time, it will be easy transportable and adaptable to the specific needs of each exhibition space. Furthermore, we experiential, cognitive, sensory and aesthetic experience. We are currently investigating Greek myths and their potential geological background as a means to discover the references to geological phenomena. This complex project will be the basic model infrastructure for the interactive presentation of exhibitions, contributing to the promotion and dissemination of multidimensional themes of culture, tourism and other thematic areas. Results can be presented in museums, cultural centers and tourist organizations.

ABSTRACT. Background and Objectives Dinosaurs have been the subject of numerous films (Debus, 2016). Despite that nearly all films belong to the science fiction genre, their importance to the promotion of vertebrate palaeontology is rather significant. One of the most famous and frequently shown dinosaurs is Tyrannosaurs rex. In this contribution, we examine the accuracy of the Tyrannosaurus depictions in films. We do so by applying a geometric morphometric analysis of images from films and actual specimens.

Methods The depictions of Tyrannosaurus used in this analysis are profile images selected from 15 movies ranging from 1918 to 2018. Only images displaying a side profile of the head were selected. Some images were mirrored with Adobe Photoshop, in order to have the correct orientation. Those images were compared with photographs of Tyrannosaurus skulls seen from the lateral side. We selected a set of seven landmarks that could be identified both on the anatomical features of the skulls and on the film images. The landmarks on the skulls were the following: (1) most caudal point of the tooth row; (2) most rostral point of the tooth row; (3) point of maximum curvature of the rostal part of the premaxilla; (4) the most ventral point of the nasals; (5) highest point of the postorbital bone; (6) highest point of parietal bone; (7) center of the orbit. The landmarks of the tooth row (landmarks 1 and 2) could be easily identified on most film images. For landmarks 3 to 6, we assumed a negligible thickness of soft tissues covering the skull at those points. Because the eye is filling approximately 65% of the orbit (Stevens, 2006), the eye is considered here as the homologous landmark of center of the orbit (landmark 7). Because in the available film images the mouth is opened at various degrees, we did not collect any landmark on the mandible. Landmark coordinates were digitized using tpsDig2 v.2.17 (Rolf, 2015). For the general Procrustes analysis, principal component analysis, and visualization of shape variation along principal components, we used MorphoJ software (Klingenberg, 2011).

Results and Conclusions The representation of Tyrannosaurus in films has changed over time. From 1918 till the 1980s the cinematographic head of Tyrannosaurus had an outline which was, unlike actual Tyrannosaurus, high over the antorbital fenestra. Despite the fact that the cranial anatomy of Tyrannosaurus was well known since 1908, film makers delayed in applying this knowledge into their creations. As a matter of fact, only after the 1990s, films presented a more realistic depiction of the Tyrannosaurus head. Although some recent dinosaur movies present outdated representations of dinosaurs, the last decade’s trend indicates that as paleontologists continue to make new discoveries about dinosaurs, the way we see them in the cinema will also change.

References Debus, A. 2016. Dinosaurs ever evolving: The changing face of prehistoric animals in popular culture. McFarland & Company. Klingenberg, C.P. 2011. MorphoJ: an integrated software package for geometric morphometrics. Molecular Ecology Resources, 11: 353-357. Rohlf, F.J. 2015. The tps series of software. Hystrix, the Italian Journal of Mammalogy, 26(1): 9-12. Stevens, K.A. 2006. Binocular vision in theropod dinosaurs. Journal of Vertebrate Paleontology, 26: 321-330.

ABSTRACT. The cave is located in a distance of 5 km from Maronia Town, near Komotini City, in Thrace – Eastern Greece. It is considered as an important natural monument which unfortunately has not already developed. According to the Greek mythology, Cyclope Poliphimos is considered that was living in the cave. According to the archaeological research, the cave was used as living and religious site, from the Neolithic until the Byzantine period. The cave is 2000 m long and covers an area of 10.000 m2, according to Petrohilou, A. (1984), who investigated the cave for first time. The present study was a part of a project, of touristic development of the cave, included in the 3rd EU Framework Program. For this purpose, the stability conditions and the more appropriate protection measures of the cave were determined.

ABSTRACT. Along the coast near Neapolis (Peloponnese, Greece) a vast amount of cylindrical and cone-shaped tube like structures can be found within the quarternary und neogene coastal arenitic limestones.The microscopic anatomical study and the large number of samples studied resulted in finding components fossilized palm trees, coniferous and broadleaf trees.At the same time highlighting the uniqueness of the Geopark which epkalyptetai of fossiliferous marine sediments, such as Bryozoans, red algae, molluscs, echinoderms and other categories of animal fossils, giving particular attention to the emergence of the Geopark.All these tubes have to be interpreted as dissolution pipes. The former explanation as “petrified forest” can no longer be maintained. Dissolution pipes are syngenetic karst formations, which can be verified in many young coastal sediments in the Mediterranean as well as worldwide. It can be shown, that the genesis of dissolution pipes is closely related to an intense root growth. Fossilized root structures (rhizoliths, rhizocretions, etc.) are mainly concentrated in places of dense tube distributions as well as along young tectonic fissures. At different places along the coast near Aghios Nikolaos many fracture structures accompanied by rhizoliths can be demonstrated running parallel to the coast for distances of several hundred meters. At the Peninsula of Palaeokastro south of Neapolis dissolution Pipe fields can be clearly identified even in satellite images. Within many different rhizoliths unambiguous cell structures can be detected.The interpretation of the tube forms near Aghia Marina as “petrified forest” is no longer tenable but this does not affect the high geological value of the Geopark of Aghios Nikolaos-Korakas. Due to the very good outcrop conditions in the area of Neapolis, the development of a young tectonically controlled coast with its arenitic sediments und with its different karst phenomena can be a tangible experience. The focused solution process seems a better hypothesis for general interpretation of both isolated pipes, and the dense fields of pipes which are a distinctive feature of dune limestones throughout the world. Note that the four alternative modes of focusing water flow discussed above are not presented as mutually exclusive hypothesises—all could act, either together or separately, according to the local situation in any area.Rhizomorphs are common in dune sands and form around small roots growing through the sand. Such roots would preferentially follow the organic-rich soils that fill the solution pipes and branch out from them. Thus, rhizomorphs could be called petrified roots, but the pipes are not petrified trunks.The Geopark of Aghios Nikolaos represents with its dissolution pipes pseudo forest and with the high concentration of various fossil root structures a nationwide unique selling proposition. Its value and its significance as a national Geotope is on the same level as the other world famous petrified forests.

ABSTRACT. Introduction Geotourism has rapidly developed in the last two decades. One of its most popular segments is cave geotourism (e.g. Garofano 2003, 2010). Transforming a cave into a tourist attraction, or show cave, is complex and it requires modifying the unwelcoming raw underground space. The first step needed to start the process of transformation of a natural cave into a show cave is to recognize its value. This step requires the understanding of both their aesthetic and scientific aspects (Garofano & Govoni, 2012). Galaxidi is a coastal town on the northern coast of the Corinthian Gulf and belongs to the extended municipality of Delphi, Fokida that is located in the region of Central Greece. The Cave of Galaxidi, also known as “Karkaros” is located on the central square of Galaxidi, known as square of Nicholas Mamas. Before 1940, the cave served as an improvised "dump", since from a hole at the top of the rock the inhabitants were usually throwing old objects. Observing the physical properties of the cave (stable temperature), the inhabitants of Galaxidi used it for many years as a refrigerator. In 1965, two Australians turned the cave from refrigerator for cheeses to a disco. In 1980, following a Ministerial Decision by Melina Merkouri on the Protection of Caves, according to which caves are included in the category of Monuments and are considered an integral part of the country's cultural heritage the function of the cave as a place of entertainment was terminated. Since then, the cave remains closed to visitors. The general purpose of this study is to establish the cave of Galaxidi as a cultural organization aiming to the enrichment of the lives of people by promoting research, knowledge and enjoyment through an integrated experience that will be offered to the widest possible audience within and outside of this unique geo- monument. More specific objectives are the presentation of the cave as geological formation, as well as an interest pole of paleontological, archaeological, historical, folklore and aesthetic aspect. Activities and materials developed to promote the geological heritage The cave of Galaxidi has an outstanding potential to promote geotourism and education in Earth Sciences. Its location and accessibility can attract the arrival of a large number of visitors each year. This great potential, however, has not been exploited owing to the abandonment of the cave for many years. As part of the overall redevelopment and reuse of the cave, it is necessary to carry out a series of actions such as site plan, rock mechanics study, removal of all movable components, removal of all wiring etc, aimed at its remediation. The collaboration of scientific staff (geologists, conservationists) is necessary in any work so as not to cause further damage. Approach & Involvement of the local community Community engagement took place in two stages:1st stage: Meeting with the community, its needs and its specific features, presentation of the project to the community, assignment of tasks, participation in the interview process. 2nd stage: Creating a stable, timeless relationship with the community of Galaxidi (Karamani et al., 2019). Proposal for cultural and environmental promotion of the cave Considering that the tourist development of caves due to their particularly sensitive and closed ecosystems should in principle be avoided, a mild tourist development is proposed based on the specific features of the cave and with taking into consideration its protection (Papathanasoglou & Painessi, 2006). All the suggestions of re-emergence and re-use were largely shaped by the limitations and possibilities posed by the monument. The cave system can be divided into four thematic sections while before the entrance of the cave there is an introductory text preceded for the history of the cave. Section 1: Caves and Mythology - Nymphs and Caves - The birth of Jupiter - The birth of Mercury Section 2: Cave and Philosophy - Allegory of Plato's Cave Section 3: The cave in the memories of the inhabitants - The Galaxidians narrate - Photographic archive - Guests “leave” their own thoughts Section 4: Caves and Environmental Education - The uses of caves over time - The development of environmental awareness through educational actions A number of actions will enhance the communication character of the Cave including logo, banner suspension, creation of a vendor, creation of a website and social networking pages, inauguration invitations, inauguration events. Conclusions The case of Galaxidi Cave exemplifies the work necessary in order to promote education in Earth Sciences and promote the appreciation and conservation of important geosites and geoheritage in general. This study showed that the social approach is mandatory. The local population has to be involved in the project, and training is crucial for the improvement of scientific outreach and guidance, where local communities play a central role. Galaxidi Cave constitutes an excellent example of promotion of Earth Sciences education in issues related to geoheritage. Acknowledgements The authors would like to express their gratitude to the Municipality of Galaxidi for the hospitality they offered during the study. The research is part of the postgraduate research of the senior author in the framework of the Postgraduate Program “Museum Studies”. References Garofano, M., 2003. Geoturismo. Scoprire le bellezze della terra viaggiando, DPS edizioni, Genova, 7, 39. Garofano, M., 2010. Geotourism. The geological attractions of Italy for tourists, Geoturismo edizioni, Genova, 5, 34-36, 73-74, 103. Garofano, M. & Govoni, D., 2012. Underground Geotourism: A Historic and Economic Overview of Show Caves and Show Mines in Italy, Geoheritage. 4. 10.1007/s12371-012-0055-3. Karamani, P., Drinia, H., Siakas, S., Panagiaris, G., 2018. Study of cultural and environmental promotion of the cave of Galaxidi, ECHOPOLIS INTERNATIONAL 2018 «Nature and culture-based strategies and solutions for cities and territories : an idea whose time has come !», 26-28 November, 2018, Athens, Greece Papathanasoglou, A. & Painessi, M., 2006. Caves and their protection. Independent Authority, Athens, Greece.

ABSTRACT. Geosites can be considered as the “book of the Earth”, enclosing the geological history of each region, and therefore their preservation and promotion is crucial. Greece, located in the convergence space of two tectonic plates, is characterized by an active tectonic regime and a complex geological structure, exhibiting a variety of geological formations, landforms, geological processes, that are of particular scientific or educational interest, while many of those have high cultural and tourist value. A first attempt to record the “monuments of nature” was made in 1982 by IGME (now HSGME) and continues until today in the framework of several projects. More than 1400 sites have been recorded in the Greek territory, many of which have been classified as of "National Importance" and form the basis of the relevant national registry compiled by the Working Group of the Ministry of Environment and Energy. Moreover, geotrails have been thoroughly mapped in 9 areas, while several more are planned. The HSGME database – updated and complemented by additional data in the frame of the ongoing “GEOINFRA” project (NSRF 2014-2020) – will function as a source of information for every use. Prominent geotopes and designated geotrails will be available for browsing through an online interface and smartphone applications, comprising a useful supplement for the promotion of geotourism.

ABSTRACT. The educational role of a Museum, as well as its goals, are changing and differentiating both in time and in terms of the needs of the time that it is going through. The educational activities of the Museums are confronted with new facts and new challenges and are called upon to take on new roles. The Natural History Museum of the Lesvos Petrified Forest, by expanding its role, has designed and presented to the public a series of temporary exhibitions aiming at enhancing its contact with the public and especially students and young people, as well as its visibility and especially new findings and activities of. In this context, the Natural History Museum of the Lesvos Petrified Forest drew up the periodic exhibition "Gaias’ Memories: UNESCO Global Geoparks of Greece - Cyprus". The exhibition began its tour from Athens and the Eugenides Foundation and then is scheduled to travel to Cyprus, Crete and Lesvos. The exhibition is complemented by educational and informative activities aiming at acquainting visitors of all ages with the UNESCO Global Geoparks, the impressive geological and natural monuments that host the Geoparks of Greece and Cyprus, the geological and natural processes that created the landscapes in conjunction with time and shaped the background for the development of the variety of modern natural ecosystems and culture from prehistory to the present day. The aim of the work is to investigate the role of the educational activities taking place at the temporary exhibition "Gaias’ Memories: UNESCO Global Geoparks of Greece - Cyprus" of the Natural History Museum of the Lesvos Petrified Forest for the development of the contact with the public and the approach of new groups.

ABSTRACT. In the past decades a regular urban geological research program has been initiated in the Hungarian state geological research institute (present official name: Mining and Geological Survey of Hungary, ’MBFSz’). Budapest, capital of Hungary was chosen as target area, because of its complex environmental, social effects which have an extensive interaction with the geological environment under the city. Moreover lots of archive data of previous on-field detections are also available here, which provides an excellent reference base for a comprehensive comparison. Here we present a comprehensive (a) and a small-scale, multi-location aspect (b) of this research program.

ABSTRACT. Geotourism, the tourism through earth features and monuments, is an alternative way of tourism that includes wondering in nature, experiencing the monuments of geology, landscape, environment, history and culture of an area. All these can be found in abundance at the Serifos Island. The Serifos geotopes belong to the Greek mineralogical and geological heritage and can be considered as mineralogical treasures, unique throughout world. The geotouristic development of mineralogical and petrological geotopes at Serifos, ensures the preservation of the geological heritage of Serifos Island and also offers the opportunity for sustainable development. Special geo-trails have been developed in order to discover the natural, geological and cultural treasure of the island.

ABSTRACT. Introduction The Gold Rush of the late 19th and early 20th century was a momentous historical and social event. However, it was also one of the first instances of large scale mining in a remote and yet relative virgin area. The negative effects of mining on the landscape, the flora and the fauna of Yukon in general and Klondike in particular are one of the earliest examples of the environmental impact of extensive and unregulated mining. In the event, the Canadian authorities proved totally unprepared to handle the massive influx of people, issuing miner's certificates without restrictions to aspiring prospectors and allowing them free use of a given site by the river, with no restrictions on tree cutting and fishing. In 1898 alone, 34364 miners' certificates were issued by the authorities. There were two main ways which were followed by individuals and organised groups of people. The seaborne route started from either Seattle or Victoria, to the northwest, in Nome, where then people boarded boats to sail upstream in the Yukon river, all the way to Dawson City. Overland routes started when the prospectors arrived by boat at Skagway and Dyea, and then followed already established trails. Others came through more northern routes staying at all times inside the Canadian borders. In any case, at some point prospectors would have to use either a canoe or a boat - either carried with them during the journey or constructed on the spot - to arrive in Dawson via Yukon River or one of its tributaries. Then began the race to find and claim an area to mine and then the arduous task of placer mining. Following the first report of gold in 1896, the next ten years would mark one of the most radical transformations of local society and environment. Geology of Au Ore Deposits in the Klondike area The gold found in the placer deposits in Klondike is characterised by limited dispersion and originates from the erosion of orogenic gold mineralisation in the Klondike Schists. This mineralising event occurred after regional compressional deformation in the Jurassic, approximately 100 my after a Permian metamorphic event (MacKenzie et al., 2008). Since their discovery, more than a century ago, the goldfields of the wider area have produced around 311 tonnes of gold. The bench and creek placers are fluvial in origin, and their age ranges from Pliocene to Holocene. The goldfields rest upon medium-grade and high-grade metasedimentary rocks, metaigneous rocks of the Yukon-Tanana terrane, and a small amount of ultramafic rocks of the Slide Mountain Terrane. The orogenic gold mineralisation comprises discordant mesothermal quartz veins (Lowey, 2006). Their mineralogy is characterised by anhedral milky quartz, with minor amounts of carbonate, barite, muscovite, pyrite and galena (Rushton et al., 1993), while reported gold grades of up to 9 Kgr/ton have been reported. Gold recovered from the placer deposits of the area manifests in many different forms, from large nuggets to very small grains actually floating on the water. This gold is almost entirely detrital in origin and its source are the aforementioned auriferous quartz veins. The placers themselves are fluvial in origin and their formative mechanisms were controlled by tectonics and climate. A prolonged period of weathering combined with isostatically compensated exhumation turned the quartz veins in a quartz-rich residuum that was then reworked in the Au gravel deposits of the Klondike area. The lower level gravel deposits are richer in Au due to successive circles of aggradation and incision which were related to reconcentration of the placer gold (Lowey, 2006). Placer Mining Methods Usually, in order to get to the gravels containing gold grains, the soil covering them had to be removed. But since the soil, averaging around 2-3 m, was frozen it had to be thawed. This was achieved by lighting numerous fires and when the soil was sufficiently softened it was removed using shovels and buckets. Upon reaching the gravel layer, the miners used mercury in the sluice boxes. Mercury amalgamates with gold and can be used to separate it from the ore. It is subsequently removed during the refining process. Another method was hydraulic mining, which involved using the water of the rivers and streams to strip the overburden of the gravel. Usually, hydraulic concessions were issued, involving 5 mile lengths of the river. The water was transported by wooden flumes or canals and the heated to increase its pressure. In this way, pressurised jets of water were directed against gravel and vegetation on the walls of the river streams. Some companies also employed dredging using suitably modified riverboats. In this way it was possible to recover gold even from submerged riverbeds. This method destroyed the topography of riverbeds, and also in many cases altered the flow of streams or created small lakes. Moreover, the use of mercury during dredging contributed to the pollution of both land and water. Environmental Impact The uncontrollable influx of miners in the years following 1896 resulted in severe degradation to the local environment. In particular, the forests of the area were almost destroyed, since the mass of incoming aspiring gold diggers needed copious amounts of wood for building and boat construction, for cooking and for heating purposes, for boat building, as steamship and locomotive fuel and for infrastructural improvements. Collateral damage by accidental fires destroyed the forests even more. In less than two years, the vast majority of trees had been cut down, radically altering the local landscape. This deforestation resulted in poor water retention properties by the soil, exponentially increasing flash flood probability, and also in a lower water table. Dredging and the melting of the permafrost by fires altered the vegetation and the topography of the area permanently (Willis, 1997). Furthermore, mercury remains in the soil and in the river water to this day, further endangering a host of animal species. Besides these negative effects, intense hunting and fishing almost destroyed the local fauna, altering the balance of the ecological system, creating interrelated side effects that would persist for decades. Finally, for sanitation reasons, waste from Dawson City was emptied on the Yukon River, exacerbating the environmental degradation. Socioeconomic Consequences From the many thousands of people who, upon hearing about stories of unprecedented wealth, set for the area of Yukon, less than half would eventually arrive and an even smaller percentage would actually find gold. Amongst the miners who would persevere through successive harsh winters, coupled with inadequate diets and virtually non-existent sanitary conditions, many would fall victim to a host of diseases, and most notably typhoid fever. Of particular interest is the extensive appearance of scurvy in miners, which further denotes the malnourishment of the people and their negligence for their health. In addition, as the Gold Rush was associated with the seasonal movement of large masses of people, overland or through the river network, there was a cyclic seasonal spread of pathogens, and the emergence of diseases not normally existing in the area. Such was the nature of malaria, which affected many of the people in the area during the Gold Rush (Highet, 2008). Also notable is the transience of miners in the area during the Gold Rush. Most aspiring gold miners rushing to the area of Klondike did not believe that they would stay there more than one or two years. The notion of finding gold in the river streams, via digging and panning, appealed to many relatively poor men who aimed at coming back home with a small fortune with a relatively meagre monetary investment. In reality, not all could find a promising place to stake a mining claim and a good percentage of arriving prospectors worked in pre-established claims, or found employment in other posts in the city (Brand, 2003). Gradually, after 1906, larger companies would buy most private expanses in the creeks and use more large scale and sophisticated dredging methods. In any case, individuals usually lacked the money and technical knowledge necessary to exploit in full their small claims. Thus in the space of ten years there was an almost complete industrialisation of the gold digging process. The state favoured such an outcome, since it was easier to regulate larger companies, and in fact, environmental pollution and degradation were significantly lessened by the application of more effective methods - dredging however would continue unabated until 1966. The expansion of the City of Dawson itself and the acquiring of large tracks of land by westerners had another negative side-effect: the native populations of the area - the Tagish, Tutchone and Han Indians - gradually disappeared from the area. These Indians were ravaged by diseases and faced starvation as overhunting resulted in the disappearance of most animals and overfishing and dredging lead to the fish disappearing from streams and rivers (Willis, 1997). The creation of an extensive mining community within the space of two years meant that more permanent infrastructural ameliorations were necessary. Roads and railways were constructed and regular boat trips from Seattle and Victoria were established, to transport the myriads of prospectors and supply Dawson. Like Dawson, Skagway and Dyea, other towns along the miner migration trails grew from small settlements and ports having no docking facilities, to large scale cities, in a matter of one or two years, due to influx of passing miners and people associated with the rendering of services. Such towns were in the beginning initially lawless and it was a while before the state managed to impose law and order. Conclusions In effect, the expansion of Western culture and associated socioeconomic organisation spread through the vast territories of Canada and the USA through the emergence of local capitalist economies, which were then gradually linked to the wider national socioeconomic network. In assessing the effects of the Gold Rush, it is evident how geology had a formative effect on the creation of a new socioeconomic fabric in an area quite distant and marginal in respect to state interventionism, state control and Western culture in general. The existence of the Klondike gold deposits sparked a torrent of social mobility and proved the focal point for the urbanisation and industrialisation of much of NW Canada. In studying the history of the Gold Rush, the transition from individual to corporate mining also becomes evident. One of the cardinal points of this story however is the danger to man and environment alike, if mining is left unregulated by the state and comprehensive environmental restoration and sustainable mining schemes are not enforced. Today, 113 years after the end of the tumultuous period of the Gold Rush, the damage to the environment and wildlife is still evident. References Highet, M., 2008. Gold Fever: Death and Disease During the Klondike Gold Rush, 1898-1904, M.Sc. Thesis, University of Manitoba, Winnipeg, 176-179 p. [Dissertation] Lowey, G., 2006. The origin and evolution of the Klondike goldfields, Yukon, Canada, Ore Geology Reviews 28, 431-450. [Journal Article] MacKenzie, D.J., Craw, D., Mortensen, J., 2008. Orogenic gold mineralisation in the Klondike goldfield, Canada: Implications for gold exploration in the Otago Schist, AusIMM New Zealand Branch Conference, Wellington, New Zealand, pp. 279-289. [Conference Proceedings] Rushton, R.W., Nesbitt, B.E., Muehlenbachs, K., Mortensen, J.K., 1993. A fluid inclusion and stable isotope study of Au quartz veins in the Klondike district, Yukon Territory, Canada: a section through a mesothermal vein system, Economic Geology 38, 647-678. [Journal Article] Willis, B., 1997. The Environmental Effects of the Yukon Gold Rush 1896-1906: Alterations to Land, Destruction of Wildlife, and Disease, University of Western Ontario, Ontario, 102-105 p. [Dissertation]

ABSTRACT. Introduction The establishment of permanent habitation in Naxos Island, since Prehistory, is strongly linked to the exploitation of the Islands' natural resources. In ancient times, the population of the island tended not to endeavour so much to engage in a seafaring trade like other populations from islands in the Aegean. In general, a sizeable proportion of Naxians remained restricted to agricultural or mining activities and trading activities between different communities. It is entirely possible that the amplitude of agricultural produce and the income generated from emery export lead to the development of a relatively different and somewhat isolationist culture, which is also reflected on the folklore of the island. In this research the aim is to delineate the effect of emery exploitation in the socioeconomic development of the Island from Ancient Greece to the present day, demonstrating how geology contributed to the formation of an insular community. Geology of Naxos Island and Emery Formation Naxos is the largest island of the Cyclades complex and belongs to the Atticocycladic belt of the Hellenides. The Island comprises a metamorphic core complex intruded by a granodiorite during Late Meiocene. Sedimentary rocks and ophiolites are tectonically emplaced upon the granodiorite and the metamorphic rocks. The metamorphic rocks of the island are believed to have been affected by at least four metamorphic events. The emery deposits of the Island are the results of bauxites' metamorphosis. There are widespread metabauxite deposits in Naxos, most of which have a lenticular shape. They are found most commonly inside marbles and sometimes in sheet-like form inside schists. The tectonic deformation is evident and it is believed that the metabauxite lenses were an initially more or less continuous body, torn apart by tectonic procedures (Feenstra, 1985). There is still no consensus on the exact emery reserves of Naxos or the initial amount of emery reserves prior to any exploitation. Τhe general term «emery» is used to describe any rock rich in corundum. The Greek term for emery is «smyris», and is derived from the port of Smyrna, which was the focal point for emery distribution in ancient times. On the other hand, the term «emery» is derived from the Emeri peninsula, where the emery mines of Naxos are located. The principal mineral of emery, corundum, is believed to have been named from the corruption of the Indian word «kauruntaka» which was used to describe the same mineral (Holroyd & McCracken, 1996).The most common mineral assemblage of emery worldwide comprises corundum (Al_2 O_3 ), magnetite (Fe^(2+) Fe_2^(3+) O_4 ), hematite (Fe_2 O_3 ), hercynite (Fe^(2+) Al_2 O_4 ), and trace impurites such as mullite [Al_((4+2x) ) Si_((2-2x) ) O_((10-x) ) ], titania, silica and magnesia. The typical quality of «commercial grade» emery contains less that 10 wt. % silica and is therefore rich in corundum. The commercial grade emery of Naxos contains around 50-80 wt. % corundum and a sizeable percent of FeTi-oxides, while margarite [CaAl_2 (Al_2 Si_2 O_10 ) (OH)_2 ] is the most common silicate mineral (Feenstra, 1985). Regional Use and Export of Naxian Emery from Ancient Greece to the 18th Century The first documented use of emery in tool manufacturing is during the Neolithic period. It is believed that emery was of crucial importance in the creation of the famous Cycladic statues which are amongst the most well known artefacts of the Cycladic Civilisation. Emery is described also in the work of Theophrastus, «Peri Lithon» (Bourdakou, 1997). While under the scope of this research it is difficult to quantify the exact effect of emery exploitation in the economy of ancient Naxos, it is remarkable that Naxos was so wealthy so as to maintain a fleet of four triremes, which took part in the naval battle of Salamis in 480 BC, at a time when most Aegean Islands did not have the ability to maintain even a single warship (Papadopoulos, 1961). In 466 BC Naxos was destroyed by Athens and subsequently very little evidence of the development of Naxian economy is available. No mention of emery mining or export is made during Roman times or the Byzantine era. In 1207 AD Naxos and other Cycladic Islands were conquered by the Venetians, who established the Duchy of the Aegean, with the Island of Naxos as its capital. The first reappearance of emery in historical texts can be traced in 1304, when in Venetian texts it is mentioned that emery was transported to Crete and then on to Venice in small amounts for as yet unspecified uses (Slot, 2008). It was Italian traders who exported emery after 1625 AD, first transporting it with small ships to the port of Smyrna, from where it was transported by ship to other European ports, or by roads to locations in the interior of Asia Minor (Zevgolis, 1947). During this period emery was used for cleaning rusted sword blades. In 1665 C. Huygens mentions that the use of emery dust from Naxos is indispensable in cleaning telescope lenses. It may be no overstatement that had emery from Naxos not existed then lenses of such accuracy would not have been developed at such an early stage (Slot, 2008). During the 18th century, along with its other notable use, emery dust was used for the abrasion of heavy duty sailmaking needles. The alternative was to use a hammer to perfect the shape of every needle individually but this was more time consuming and raised the price of the needles. The emery mines in the NE of the Island, between the gulfs of Moutsouna and Lyona, were exploited by the villages of Apeiranthos, Koronos, Danakos, Mesi, Skado and Keramoti. The inhabitants of these villages alone had been granted exclusive exploitation rights, both by the preceding Venetian administration and by the Ottomans (Glezos, 1989). During the Ottoman occupation of Naxos, there was no tax imposed on emery mining or export as it was not considered valuable enough. Only in 1824 did the Ottomans impose such a tax and this lead the people of Naxos closer to joining the revolution in the ongoing War of Greek Independence. Emery in the Economic and Political Life of the Greek State Worldwide demand for emery reached its peak around the end of the 19th century, following the Industrial Revolution. During the same period, the incremental increase of the iron industry lead to a widespread demand for emery. Emery, whether natural or artificial, is essential for the abrasion of steel tools and machine parts. Among the major emery deposits worldwide in Bavaria, America and Asia Minor, the emery of Naxos stands out in having the highest corundum percentage. This means that comparatively to other emeries, the Naxian emery has the highest value as an abrasive. The importance of this mineral resource for the national economy was recognised early enough by the nascent Greek State which, between 1845 and 1920, regulated the commercial exploitation of emery through a series of «mining law edicts». During those years and afterwards, the quarries belonged to the Hellenic State, which conceded the right for their exploitation to the inhabitants of the Municipalities of Koronis and Apeiranthos. In the first decades of the 20th century, Naxos did not have any ports suitable for loading deep draught cargo ships, and emery was transported using smaller boats to Syros, where it was then transhipped to larger cargo ships. The cost of transporting emery to Syros was borne by the Greek State. It was deemed necessary for the emery mines to be state-controlled, for the better organisation of production, as well as for marketing reasons. At the same time, the State lacked the funds necessary to expand the mining tunnels and finance the proper maintenance and improvement work so as to ensure their structural integrity. In 1922 it was decided to build an aerial cable railway system, so as to alleviate the cost of transporting emery from the mines to the loading station at Moutsouna Bay. Up until then miners had been transporting bags full of emery from the mines to the Bay, on their backs or using donkeys. In 1923, it was decreed that emery would be sold directly to foreign markets, with no mediators, with a fixed percentage of the profits being used for infrastructural improvements. Along with the aerial railway system, wharfs and storehouses were built in Moutsouna Bay, so as to gather and load the emery to barges directly for export, obviating the need, and the associated cost, for transport to Syros. This aerial cable railway system was constructed between 1926 and 1929, for the easier transportation of emery, from the mines, to the bay of Moutsouna; it remained in operation until 1982 when it was replaced by trucks which took advantage of the improving road network. Today, the mining of emery has practically come to an end. The development of artificial abrasives, which are much cheaper than emery, after the 1970s, signalled the gradual decline and eventual halting of systematic mining in the Island. The much greater purity and physicochemical uniformity of synthetic abrasives and their lower cost does not leave any market share for the emery of Naxos. Discussion and Conclusions From the aforementioned it becomes evident that the existence of exploitable emery deposits has been a key factor in shaping the economy and even the culture and the society of the Island. Since antiquity, Naxos had a robust and growing economy which was in large part attributed to its mineral wealth. During the Venetian and Ottoman occupations, the economic importance of emery lead to its exploitation; this was then systematised by the Greek State. For over 2000 years the inhabitants of NE Naxos have maintained their mining rights over the quarries. Over the years, emery miners became a distinct socioeconomic class of the island, while the need for exporting emery gave rise to an extensive trading network, between Naxos, Syros and Smyrna, and other major ports. The economic value of emery was an important contribution to the Greece's gross domestic product up until the 1970s. There is no doubt that without emery Naxos would not have been such a wealthy Island in Ancient times, and would maybe have relied more on commerce. This would in turn have resulted in development of coastal communities with different folklore, traditions and social classes. In addition, in a state level, it is doubtful that the developing Greek State, between 1831 and 1940 would have maintained a viable import-export balance, without the significant profits of emery trade. This is one characteristic example of how ore deposits can be instrumental in shaping the cultural and socioeconomic profile of small insular societies and at the same time in influencing state economy. Acknowledgments I am deeply indebted to Mr. Iordanis Paresoglou for his kind interest in this research and his valuable comments and perspective into the history of Naxos Island. I am also thankful for his providing of historical sources and relative material. This research would have been impossible without his assistance. References Bourdakou, E., 1997. Ancient Greek Terminology - The Problem of the Naxian Earth, ELETO, Athens, Greece, 187-195. [Conference Proceedings] Feenstra, A., 1985. Metamorphism of Bauxites on Naxos, Greece. Ph.D. Thesis, Instituut voor Aardwetenschappen, Rijksuniversiteit te Utrecht, Utrecht, 23, 33p. [Dissertation] Glezos, P., 1989. The State Exploitation of the Naxian Emery - The Collaborative Mining of the Mineral and the «Reconstruction», Aperathitika 1.IV, 69-108. [Journal Article] Holroyd, W., McCracken, D., 1994. Emery, in: Carr D. (Ed.), Industrial Minerals and Rocks, 6th Edition, Society for Mining, Metallurgy and Exploitation Inc., 425-428. [Book Chapter] Papadopoulos, N., 1961. The Naval Battle of Salamis, Bookshop of Estia. [Book] Slot, B., 2008. The «original Naxian emery» in international economy (14th-19th century), Flea 19, 17-19. [Journal Article] Zevgolis, A., 1989. History of the Naxian Emery, Aperathitika 1.IV, 61-68. [Journal Article]

ABSTRACT. Introduction

After 1960 the association between radiation and adverse health effects has come to the foreground. Epidemiological research indicates that even low doses of radiation over an appreciable amount of time are distinctly connected to a quantifiable increase in cancer incidence rate. Such low and constant doses of radiation often come from natural sources, namely from the rocks exposed on the surface of the area, or from the drinking water of the aquifers contained within radioactive rocks. Here cancer incidence data from areas with high background radiation and radioactive water sources in India and Norway is examined, so as to demonstrate the correlation between geology and public health hazards. Radiation and Associated Induced Damage on DNA In nature, uranium, thorium, radium and radon are the most common sources of ionizing radiation. These radioactive elements tend to concentrate in highly fractionated magmas, so they are commonly found in acidic rocks, such as granites. Uranium exists in three naturally occurring isotopes, (_92^234)U, (_92^235)U, (_92^238)U, of which the latter is the most abundant in nature and has a half life of 4.51 • 〖10〗^9 years. Thorium can be found in nature in 30 different isotopes, but the most stable one is (_90^232)Th with a half life of 13.9 • 〖10〗^9 years. As far as radon ((_86^222)Rn ) is concerned, it is derived from the parent radionuclide (_88^226)Ra, which has a half life of 1620 years, and is a member of the (_92^238)U decay series (Banks et al., 1995). While radon is chemically inert, being a noble gas, it accumulates in groundwaters and more importantly becomes airborne, thus being quite a potent radiation source. Based on the half life values mentioned it becomes evident that even rocks of Precambrian age, containing sizeable amounts of uranium or thorium will be significantly radioactive. All of these radioactive elements emit alpha, beta and gamma radiation during their decay series, which is potentially hazardous to humans, depending on the dose, the dose rate and the time span of exposure. It is a general axiom that the rate of mutagenesis depends upon the dose rate and the total absorbed dose of ionising radiation. For a given dose and dose rate, the biological effects also depend upon the linear energy transfer (LET), a quantity used to describe the «quality» of radiation (Hall, 1991). As far as radiation protection is concerned, and regarding low LET radiations, experimental results indicate that the same dose delivered in a protracted period of time results in reduced biological effects. This is known as the dose rate effect or DRE, which however only applies to low and intermediate LET radiations (Hall, 1991). Even so, for some types of cells, at different ranges of low dose rates, an inverse DRE is observed, meaning that even low background radiation doses may be quite more dangerous than originally thought, in some cases. Low and intermediate LET radiations, such as electrons, positrons and photons, cause a small number of ionizations per unit of distance traversed into matter. Gamma radiation, i.e. photons, causes mostly indirect effects in cells. Indirect effects are those associated with the molecules produced during water radiolysis. Such molecules are the hydroxyl radicals and other free radicals, which interact with and damage DNA and other biomolecules. However, newer data (Goodhead, 1994) indicate that even low LET radiations cause some degree of focused damage on DNA, creating small clusters of double strand breaks (DSB) which may not always be repaired by the cell, thus leading either to cellular death or to proliferation of potentially cancerous cells. High LET radiations, like alpha radiation, i.e. helium nuclei, deposit a high amount of energy in fewer cells, leading to significant DNA damage, and cellular death. In contrast to photons or electrons, where most irradiated cells survive, alpha radiation leads to a higher percentage of cellular death, albeit surviving cells may have a higher carcinogenic potential, due to more significant DNA damage (Hall, 1991). The consequences are understandably more far reaching if the mutations happen, and are not repaired, in germ line cells, instead of somatic ones. The continued exposure of individuals to even low LET radiations and dose rates not only is hazardous for inducing more and more damage, but for hindering DNA repair by N-glycosylases, endonucleases and purine imidazole-ring cyclases (Téoule, 1987). Cancer Incidence and Background Radiation in India and Norway Looking at the annual cancer incidence rate map in the states of India, for the last 26 years (Dhillon et al., 2018) it can be observed that there are significant differences between the rates of different regions. If such a map is correlated with the geology of India, it can be observed that areas, which comprise carbonatites, are also characterised by relatively elevated cancer incidence rates. Interestingly, if the cancer incidence map of India (Dhillon et al., 2018) is overlaid upon the isodose map of India (Sankaran et al., 1986) it can be observed that areas characterised by elevated background radiation levels roughly correspond to areas with elevated cancer incidence rates. Recent research on the carbonatites of Tamil Nadu indicates background radiation well in excess of the safe background radiation exposure levels. One other relative example is the region of Kerala, where much of the soil contains almost 10 wt. % thorium and uranium oxides (Chougaonkar et al., 2004), exhibits the highest cancer incidence rate in India. It is reported that the maximum outdoor dose in this region is 39.1 mSv/a, which is higher than the maximum allowed for a radiation worker, where the limit is 20 mSv/a, and around 13 times the mean human background radiation exposure, which is about 3 mSv/a (Brenner et al., 2003). Another study in the region of Kerala (Forster et al., 2002) proved that the background radiation of the area accelerates point mutations in mitochondrial DNA. By implication, the amount of radiation absorbed could lead also to mutagenesis in the nuclear DNA of the cells, potentially leading to changes in gene expression, in protein structure and functionality and higher risk of cancer incidence. Norway is an example comparable to India, due to the existence of rocks of comparable age and also of carbonatites of comparable geochemical characteristics. Looking at the cancer incidence rate map of Norway (Patama et al., 2014), it can be deduced that higher cancer incidence rate correspond roughly with locations where there are outcrops of the Precambrian basement, which are mainly granites and gneisses, containing relatively high amounts of radionuclides, leading to elevated levels of background radiation. In addition, Cambrian shales in some areas of Norway are characterised by elevated uranium levels. The potential for adverse health effects has been studied in the Fen carbonatite complex in Telemark (Sundal & Strand, 2004). There are about 350 dwellings in the area which according to measurements are characterised by increased radiation emission. The carbonatites in the area contain the highest amounts of Th ever recorded in a bedrock in Norway. Both the indoor and outdoor radiation values are higher in the areas where the carbonatite is exposed. Another acute problem in Norway is the concentration of radon in groundwater. According to extensive sampling by Banks et al. (1995) groundwaters in gneissic and porphyry rocks have radon levels exceeding the maximum acceptable threshold of 100 Bq/lt, with some samples approaching 1000 Bq/lt. Samples from the granite in Iddefjord have a radon concentration of 8500 Bq/lt. Already radon exposure has been estimated to account for around 10 to 20 % of lung cancer cases in Norway (Banks et al., 1995). Samples from the same area also exceed the safe thorium and uranium concentrations. Discussion and Conclusions The association between background radiation and health effects has long been established. However, there is no large scale research correlating cancer incidence with background radiation attributable to geological factors at a national or even continental level. How the soil formed by such radioactive rocks contributes to the introduction of radionuclides in the food chain has not been examined here, but this is surely another contributing factor to the dose received by the locals, which has to be studied extensively. In any case it is demonstrated how cancer incidence rates in a national level do exist, at least partially, as a function of background radiation and by implication of regional geological setting. There is still a lot of research to be undertaken on how exactly different radioactive rocks affect public health, and how governmental public health policies should be formulated taking notice of the petrological and geochemical characteristics of each particular area. In these last decades the effects of radiation on nucleic acids have been thoroughly studied, although there are still many questions and uncertainties, regarding cell sensitivity in particular cell cycle phases and radiation-induced cell signalling and its ramifications for the survival of complex cellular systems. Finally, it would be useful to assess how prolonged relatively small doses of radiations inhibit the function of DNA repair enzymes. By combining such research data it will hopefully be possible to quantify the effects of background radiation at different levels in multicellular organisms in general and humans in particular. References Banks, D., Røyset, O., Strand, T., Skarphagen, H., 1995. Radioelement (U, Th, Rn) concentrations in Norwegian bedrock groundwaters, Environmental Geology 25, 165-180. [Journal Article] Chougaonkar, M., Eappen, K., Ramachandran, T., Shetty, P., Mayya, Y., Sadasivan, S., Venkat Raj, V., 2004. Profiles of doses to the population living in the high background radiation areas in Kerala, India, Journal of Environmental Radioactivity 71, 275-297. [Journal Article] Dhillon, P., Mathur, P., Nandakumar, A., Fitzmaurice, C., Anil Kumar, G., Mehrota, R., Shukla, D., Rath, G., Gupta, P., Swaminathan, R., Thakur, J., Dey, S., Allen, C., Badwe, R., Dikshit, R., Dhaliwal, R., Kaur, T., Kataki, A., Visweswara, R., Gangadharan, P., Dutta, E., Furtado, M., Varghese, C., Bhardwaj, D., Muraleedharan, P., Odell, C., Glenn, S., Bal, M., Bapsy, B., Bennett, J., Bodal, V., Chakma, J., Chakravarty, S., Chaturvedi, M., Das, P., Deshmane, V., Gangane, N., Harvey, J., Jayalekshmi, P., Jerang,, K., Johnson, S., Julka, P., Kaushik, D., Khamo, V., Koyande, S., Kutz, M., Langstieh, W., Lingegowda, K., Mahajan, R., Mahanta, J., Majumdar, G., Manoharan, N., Mathew, A., Nene, B., Pati, S., Pradhan, P., Raina, V., Rama, R., Ramesh, C., Sathishkumar, K., Schelonka, K., Sebastian, P., Shackelford, K., Shah, J., Shanta, V., Sharma, J., Shrivastava, A., Tawsik, S., Tyagi, B., Vaitheeswaran, K., Vallikad, E., Verma, Y., Zomawia, E., Lim, S., Vos, T., Dandona, R., Srinath Reddy, K., Naghavi, M., Murray, C., Swaminathan, S., Dandona, L., 2018. The burden of cancers and their variations across the states of India: the Global Burden of Disease Study 1990-2016, The Lancet Oncology 19, 1289-1306. [Journal Article] Forster, L., Forster, P., Lutz-Bonengel, S., Willkom, H., Brinkmann, B., 2002. Natural radioactivity and human mitochondrial DNA mutations, PNAS 99, 13950-13954. [Journal Article] Goodhead, D., 1994, Initial events in the cellular effects of ionizing radiations: clustered damage in DNA, International Journal of Radiation Biology 65, 7-17. [Journal Article] Hall, E., 1991. Weiss Lecture, International Journal of Radiation Biology 59, 595-610. [Journal Article] Patama, T., Engholm, G., Klint, Å, Larønningen, S., Ólafsdóttir, E., Christensen, N., Storm, H., Pukkala, E., 2014. Small-area based map animations of cancer incidence in the Nordic countries with new entities, 1971-2010, Nordic Cancer Union, astra.cancer.fi/cancermaps/Nordic_18. [Electronic Publication] Sandal A., Strand T., 2004. Indoor gamma radiation and radon concentrations in a Norwegian carbonatite area, Journal of Environmental Radioactivity 77, 175-189. [Journal Article] Sankaran, A., Jayaswal, B., Nambi, K., Sunta, C., 1986. U, Th and K Distributions Inferred From Regional Geology and the Terrestrial Radiation Profiles in India, Bhabha Atomic Research Centre. [Book] Téoule, R., 1987. Radiation-induced DNA damage and its repair, International Journal of Radiation Biology 51, 573-589. [Journal Article]

ABSTRACT. Introduction The carbonate replacement ore deposit of Lavrion and the methods through which Ancient Athenians and subsequently Romans mined for silver have been the subject of many detailed researches. Also, many authors have correlated the course of Athens in Antiquity with the profits gained from the exploitation of Lavrion. In addition, contemporary researchers have written about the crisis that came about in the 1870s and its repercussions in Greek economy. Here, we attempt to present a collective assessment of the impact of this, the most famous ore deposit of European Antiquity, in the course of the Greek Nation through the ages. Geology of the Ore Deposit of Lavrion The diversity of the ore deposits of Lavrion is well known, and the ore is preferentially concentrated between contacts of rocks with different permeability.The Kamariza ore district, which was mined in ancient times (Gelaude et al., 1996) is a carbonate replacement system whose development is attributed to the exhumation and formation of a Miocene metamorphic core-complex, in the Atticocycladic Crystalline belt. The ore bodies at Kamariza occur as infillings along fracture zones and faults and also as massive stratabound replacement sulfide bodies and chimneys. The fractures and faults were the pathways for the ascending mineralising fluids (Voudouris et al., 2008). The minerals of the carbonate replacement system are pyrite, arsenopyrite, sphalerite, galena and chalcopyrite. The ores are enriched in As, Sb, Ag, Bi, Sn and Au. Galena is the principal carrier of Ag, with enrichment reaching up to 3000 gr/t (Voudouris et al., 2008). This, in brief, is the nature of the ore deposit mined in antiquity and in modern times. Lavrion and its Importance in Antiquity It is not precisely known when the first mining activities at Lavrion occurred. Archaeological finds of the Minoan Era indicate that this happened around 3000 BC. Organised mining activities are believed to have started around the 8th century BC, with silver production starting around the 7th century BC (Economopoulos, 1996). In the 5th and the 4th century BC silver production reached its peak. The mines of Lavrion were controlled by the City of Athens and were leased to private contractors, who paid for exclusive mining rights of smalls sections of the galleries. Slaves were also used to mine for galena inside the galleries. To extract silver from lead ore a two step process is necessary; initially the ore is smelted and silver-rich lead is produced while the remaining slag is discarded. In the second part of the process, the so-called «cupellation» the lead is ignited and burned in a furnace with a strong influx of air. Then only pure silver remains at the bottom of the furnace. Thus, 99 % pure silver is produced while large amounts of litharge, the monoxide of lead, are discarded (Rehren, 2000). In part, the income generated from the mines made possible the construction of the temples at Acropolis. Colonated temples were amongst the most expensive buildings in antiquity, not to mention the cost of the metopes, the murals, the statues and the towering gold-ivory statue of Athena Promachos itselt (Stuttard, 2013). Combined with the tribute of the Delian League, the income from Lavrion made Athens the wealthiest city-state in the Ancient World. The creation of the vast Athenian fleet in 482 BC was the result of the Lavrion mining activities, and was initiated following a public dispute over the exploitation of a recently discovered silver vein at the mines. With the generated wealth directed to the addition of 100 triremes the Athenian fleet now reached the unprecedented number - for a single Greek city-state - of 200 triremes manned with trained oarsmen and hoplites. Two years later, during the naval battle of Salamis, the Greek fleet numbered around 380 triremes, of which more than half were the triremes of Athens. The wealth generated by the mining activities at Lavrion was one of the main factors of Athenian strategic dominance during much of the Peloponnesian War. In peacetime, Athens maintained and manned a fleet of about 300 triremes, building 20 new each year, as old ships were in constant need of replacement. Such a fleet was manned by 60000 seamen and supported by 20000 dockyard workers. Each ship needed one talent to be constructed and an additional one for crew wages and ship maintenance for each month at sea. During one naval campaigning season - 8 months - having around 2/3 of its ships at sea, the city had to pay around 1600 talents - more than twice the annual tribute of the whole Delian League. Undoubtedly, paying for an entire ship and its crew - around 200 men - entailed a sizeable expense. Such a large fleet enabled Athens to coerce more than 200, mostly maritime, city states, to join its alliance. Athens entered into the war with a reserve of 5000 talents. Not until the last stages of the war did the Lacedemonians succeed in disrupting the mining activities and thus cutting off Athens from the last major source of its income. The income from the mines allowed the Athenians to sustain a fleet out of all proportion to the realistic capacity of any city state of the era. Supplemented by smaller navies of other members of the Delian League it gave Athens an insurmountable advantage. Even after the complete disaster and the loss of most of the Athenian fleet at Sicily in 413 BC Athens was able to rebuild her fleet. All in all, Athens built and lost two entire fleets during the Peloponnesian War and went on to fight for 27 years (Davis Hanson, 2005). The mining activities at Lavrion continued well into the Late Roman period with more advanced mining techniques involving drainage procedures for extending the galleries below the water table. Interim Years and Mining in the 19th and 20th Centuries Despite the absence of mining activity since Roman times, the existence and possible economic potential of the mines did not go completely unnoticed. British explorer G. Wheler who visited Attica during 1675-1676 reports that there were older people remembering a lead mine in the area, which was abandoned for fear that it would be taxed by the Ottomans. In fact, the same people reported that there were traces of silver within the lead mined. In 1790, the British explorer Hawkins reported that there might be economic potential in mining the Ag-Pb ores at Lavrion. German surveyors brought by the Greek Government in 1835 and 1841 gave conflicting opinions about the possibility of exploiting any ore at Lavrion and what ores could be exploited. The ancient slags remaining at Lavrion since Antiquity were recognised as economically important by the geologist A. Kordellas in 1860. Since the nascent Greek State did not have the organisational and financial capacity to found a State Mining Company, in 1864 Jean-Baptiste Serpieri founded the Italian-French Company Roux-Serpieri-Fressynet C.E. This year marks the creation of the modern day Lavrion. However, despite acquiring the lease of some 15000 acres from the Greek State, the Company also bought illegally heaps of slags from the Municipality of Keratea, without permission from the State. Besides this, the Company expropriated all kinds of slags found in the area, with no State permission and ignoring courts' decisions. The Italian-French company behaved with a cavalier attitude, more reminiscent of a colonial affair. This behaviour enraged the Greek State while the ambassadors of France and Italy issued a proclamation defending the company's interests. In the end, the appearance of French warships of Lavrion resulted in Greece accepting an unprofitable settlement. In 1873 Roux-Seprieri-Fressynet C.E. was bought by the Bank of Constantinople's co-owner Andreas Syggros, and was renamed to Lavrion Metallurgy Company. Many people rushed to buy the new companies' shares only to discover soon enough that many of them were fakes. This triggered a downfall of the shares' price and ultimately a collapse of the Stockmarket. Thousands of individuals soon discovered that they had worthless stocks at their hands, having spent thousands of drachmas to no real gain. In addition, the Company actually decreased its slag production output and Syggros successfully blackmailed the State to lessen the annual tribute of the Company to State. The stockmarket crisis and the significant reduction in state profits from the mines of Lavrion were amongst the contributing factors for the bankruptcy of the Greek State in 1893. Meanwhile, Serpieri founded the Compagnie Française du Laurium which acquired the sole right of exploitation of the area's underground mineral wealth. As the amount of slags was exhausted in 1917 the Greek company was forced to close, while the French Company continued its activities until 1977 (Dermatis, 1994). Conclusions By the aforementioned we have demonstrated the significance of the presence of Lavrion throughout the Greek history as another example of how geology and history intertwine. It can be stated with certainty that had this ore deposit not existed Ancient Athens in particular and Ancient Greece in general would have followed radically different historical courses. For it can be considered as a sacrosanct principle that to civilisation and war making, these two driving forces of human history, a steady influx of money is a prerequisite. From the military exploits of Ancient Athenians who checked the Persian invasion time and again to the exquisite temples at Acropolis, the mark of Lavrion's ore deposit is resplendent. In modern times, the mineral wealth of the area became the locus of initially international and subsequently national enterprising and corporations. It shaped the international relations of Greece with France and Italy through the 1860s to the 1880s and was one of the major steps leading to the financial crisis of 1893. This then is the complete story of the importance of Lavrion for Greece, a tumultuous saga of ever increasing mining profits and their management and allocation. Acknowledgements We are deeply indebted to Mr. Iordanis Paresoglou for his invaluable interest in our research and for the rare sources which he provided. We are also thankful for his incisive comments on the matters regarding the historical aspect of Lavrion in ancient and modern times. References Davis Hanson, V., 2005. A War Like No Other, How the Athenians and Spartans Fought the Peloponnesian War, Random House Editions. [Book] Dermatis, G., 1994. Scenery and Monuments of Laureotiki, Publication of the Municipality of Laureotiki. [Book] Economopoulos, J., 1996. Mining Activities in Ancient Greece from the 7th to the 1st Centuries BC, Mining History 3, 109-114. [Journal Article] Gelaude P., van Kalmthout P., Rewitzer C., 1996, Laurion, The Minerals in the Ancient Slags, Janssen Print. [Book] Rehren T., 2000, Roads to riches: making good the silver ore at Lavrion in Greece, Archaeology International 4, 31-34. [Journal Article] Stuttard, D., 2013. Parthenon, Power and Politics on the Acropolis, The British Museum Press. [Book] Voudouris, P., Melfos, V., Spry, P.G., Bonsall, T.A., Tarkian, M., Solomos, C., 2008. Carbonate-replacement Pb-Zn-Ag±Au in the Kamariza area, Lavrion, Greece: Mineralogy and thermochemical conditions of formation, Mineralogy and Petrology 94, 85-106. [Journal Article] Wheler, G., 1682. A Journey into Greece, vol. 6, William Cademan, Robert Kettlewell and Awnsham Churchill Eds. [Book]

ABSTRACT. Introduction In South America, covering mostly the area of modern day Peru, the most developed sociopolitical entity of the Precolumbian Americas, started as the small city-state of Cusco. At the height of its power, the Inca Empire covered vast expanses of land from Ecuador to the North to Chile to the South, while the Andes formed its Eastern frontier. The population of the Empire at that time is estimated at around 16 • 〖10〗^6 people (Pemberton, 2011). While the economic system of the Incas did not include any concept of money and was based on mutual trade, the role of precious metals, namely silver and gold, as well as of other metals and minerals was pivotal in establishing distinct social strata and a domestic trading network. The Incas built upon an already rich pre-existing tradition of mining and metallurgy, which was assimilated from the peoples they conquered. By capitalising on mineral wealth and relatively advanced ore extraction and processing techniques, they created a civilisation which is remembered as being amongst the wealthiest in historical record. Of course, such sumptuousness was to prove the undoing of the Incas, as it drove the relentless Spanish conquest. In this research the quantification of the cumulative effect of the availability of different ores in the socioeconomic fabric of the Incas is attempted, so as to demonstrate how geology shaped the Age of Discovery. Geological Setting and Ore Deposits of the Andean Cordillera The Andes constitute the richest source of mineral wealth in the New World and are characterised by a rich metallurgical tradition since 700 BC (Cooke et al., 2009). In terms of metallic ores, the Andes represent one of the richest orogenic belts, and are a source for many metals, such as Sb, Be, Bi, Cu, In, Mo, Pt, Re, Tr, Al, W, Zn and Sn. The Fe-Cu skarn deposits of the Andahuaylas-Yauri zone in Peru, are associated with quartz monzonite stocks and also contain native Au. At the Northern and Southern ends of the Andean belt there are a lot of copper deposits, dating from the Upper Palaeozoic to the Pleistocene. Most porphyry copper deposits are related to dacitic-granodioritic porphyry stocks (Oyarzún, 2000). Within modern day Peru - in the centre of the erstwhile Inca Empire - there are numerous Cu ± (Fe, Au, Zn) skarn deposits, Cu-Fe manto-type deposits, and widespread Cu vein deposits, which are considered to be the first exploited copper source (Oyarzún, 2000; and references therein). As far as Au deposits are concerned, there are epithermal Au-Ag veins, Au quartz veins, Au placer deposits, Au skarn deposits and Cu ± Au porphyry deposits in Ecuador and Peru (Noble & Vidal, 1996). In the Western Cordillera, in modern day Peru and Chile, there are numerous deposits of Ag, either in primary or secondary form and as inclusions of Ag-minerals in galena (Bellido & Montreuil, 1972). Tin is found in Tertiary deposits related to sub-volcanic intrusive bodies, which crosscut Palaeozoic clastic formations (Sillitoe et al., 1975). Gold and Silver in the Context of the Inca Society The main source of gold of the Incas can be traced back to placer deposits, which were the first to be exploited by man. However, both porphyry and vein deposits are known to have been exploited. In general, the Inca Empire had abundant gold resources within its borders, both in its central part, in modern day Peru, as well as in Ecuador, Chile and Colombia (Petersen, 1970). While native gold was extracted from quartz veins, placer deposits in Peru were exploited at the valleys of Rio Chinchipe, Rio Mariñón, Rio Santiago de Montaña, Rio Aguarrica, Rio Morona and Rio Chachapoyas. It must be mentioned that a substancial percent of Incan gold ornaments where not made of pure gold. Rather, using a depletion gilding treatment (Petersen, 1970) objects made from a Cu-Au-Ag alloy were given an even superficial golden layer. Interestingly, due to the importance of gold and silver extraction, and for purposes of production intensification the Inca employed the mit'a labour system, using «mitmaqkunas» - the Inca term for resettled labourers - which in conjunction with local labourers lead to the creation of mining micro-communities in fairly remote places, such as those recently investigated in the Atacama Desert. This is an excellent early example of how local ore availability has social and economic consequences on a regional scale. As far as Ag is concerned it was exploited both in its native form, from Ag-bearing veins, and also extracted from complex ores. The Inca Empire also had access to Cerro Rico de Potosí, which was until fairly recent times the world's richest silver mine (Cooke et al., 2009). Use and Mining of Mercury, Copper and Tin Cinnabar (HgS) and native mercury occurrences of Colombia, Chile and Ecuador have been known since ancient times and one of the largest cinnabar deposits in the world is found at Huancavelica in Peru (Brown, 2001; and references therein). Cinnabar had various cosmetic and ornamental uses in the Inca society in addition to its use for pigment manufacturing, while native mercury was mined between 1400 BC and 1450 AD, reaching its peak around the time of the Incas. However, as the health hazards associated with mercury, which was also used for silver amalgamation, were realised, the Incas abandoned its use. It is tempting to assume that the coexistence of exploitable gold deposits and exploitable mercury deposits made it possible to produce such vast amounts of gold and silver plated objects. Copper was the earliest metal used in smelting, as evidenced by the copper slags, dated between 900 and 700 BC, which were found in the Highlands of Bolivia. The Incas made extensive use of alloys, namely arsenic bronze and tin bronze, which are alloys of arsenic and copper and tin and copper respectively (Cooke et al., 2009), while evidence of bismuth bronze have been found at Machu Pichu; the existence of Cu-Au and Cu-Ag-Au alloys has also been noted (Cooke et al., 2009). Tin was obtained from the altiplano - the Andean Plateau - where cassiterite (SnO_2 ) occurrences are abundant and it was widely used throughout the Inca Empire. It is still doubtful if the Incas knew of the existence of tin as a pure element, despite using it, in the form of cassiterite, to create alloys (Petersen, 1970). Discussion and Conclusions Within the context of the Inca civilisation, it is possible to approach ore mining and processing as a formative factor of social and economic differentiation, which in turn had ritual and religious connotations, as noted by van Gijseghem et al. (2013). A principal aspect of any empire's economical policy is the acquisition of revenue, which drives imperial expansion, which in turn leads to a further increase in revenue, in a circular scheme repeated so often in the course of human history. Revenue was extracted by taxation, tribute and plunder, and by intensification of productive activities. The latter can be achieved by infrastructure improvements, technological innovations and new production methods, and local socioeconomic reform. All such measures result in the symbolic and political integration of provinces, which will in turn expedite road construction, administrative infrastructure establishment and as such the imperial control structure will be physically and notionally expanded. From the abovementioned reasoning it becomes evident that the need to increase the influx of ores, and especially of precious metals, was a cardinal factor if not in fuelling directly the expansion of the Inca Empire, then in accelerating the assimilation of provinces rich in specific resources. This trend continued up until the Spanish conquest in 1532, when the abundance of ore deposits was to be in essence the cause of the Empire's collapse. After the discovery of America by Christopher Columbus in 1492, Spain and Portugal, the two great seafaring nations of the 15th and 16th centuries divided the as yet undiscovered or otherwise unexplored world in two, with the Treaty of Tordesillas (McKee, 1987). What followed was arguably one of the most frantic exploration attempts in the history of mankind, influenced in a not inconsiderable degree by tales of immeasurable wealth and of the existence of El Dorado (Harrasta, 2014). However, such vast amounts of treasure were a mixed blessing. On one hand, Spain used them to expand her empire, her military and her navy. On the other hand, it was often that despite the massive influx of precious metals, the Spanish Crown was not capable to pay the soldiers guarding it. Ultimately, the existence of the undefended Spanish galleons off the Peruvian coast prompted the legendary raiding voyage of Sir Francis Drake in 1577 which, in tandem with other covert or apparent acts of hostility paved the way for the war of 1588 between the two nations (McKee, 1987). Of how and why the discovery of the Americas transformed the existing status quo, historical conclusions have been reached long ago. What has not been adequately put forth, however, is the importance of the «geological background» in the existential battle of the contemporary nascent empires and colonial powers. For can it be said that had the Americas not possessed such phenomenal natural wealth the Spanish Empire would have so rapidly flourished? Or is it a foregone conclusion that even if such ore deposits existed, albeit being not accessible by the indigenous populations which would consequently be relatively poor, the Spanish would have rushed to such a frenetic conquest, especially given the fierce native resistance and the adverse environmental and geomorphological conditions? It can be therefore concluded that the fortuitous discovery of a new continent so rich in natural wealth was the fulcrum of colonialism and expansionism of the Old World, shaping the course of human history for centuries. It is, accordingly, evident how the interplay between man and geology is a formative factor of human history. References Brown, K., 2001. Worker's health and colonial mercury mining at Huancavelica (Perú), The Americas, The Academy Franciscan History 57, 467-469. [Journal Article] Cooke, C., Balcom, P., Biestar, H., Wolfe, A., 2009. Over three millennia of mercury pollution in the Peruvian Andes, Proceedings of the National Academy of Sciences 106, 8830-8834. [Journal Article] Harrasta, J., 2014. El Dorado, The Search for the Fabled City of Gold, Charles River Editors. [Book] McKee, A., 1987. From Merciless Invaders, The Defeat of the Spanish Armada, 2nd Edition, Grafton Books [Book] Noble, D., Vidal, C., 1994. Gold in Perú, SEG Newsletter 17, 7-17. [Journal Article] Oyarzún, J., 2000. Andean metallogenesis: a synoptical review and interpretation, in: Cordani, U., Milani, E., Thomas Filho, A., Campos, D. (Eds.), Tectonic Evolution of South America, 725-753. [Book Chapter] Pemberton, J., 2011. Conquistadors, Searching for El Dorado: The Terrifying Spanish Conquest of the Aztecs and Inca Empires, Futura. [Book] Petersen, G., 1970. Minería y Metalurgia en el Antiquo Perú, Arquelógicas 12, Publicaciones del Instituto de Investigaciones Antropologícas, Museo Nacional del Antropología y Arqueología [Book] Sillitoe, R., Halls, C., Gran,t J., 1975. Porphyry tin in Bolivia , Economic Geology, vol. 70, pp. 913-927. [Journal Article] van Gijseghem, H., Vaughn, K., Whalen, V., Linares Grados, M., Olano Canales, J., 2013. Economic, Social, and Ritual Aspects of Copper Mining in Ancient Peru: An Upper Ica Valley Case Study, in: Tripcevich, N., Vaughn, K. (Eds.), Mining and Quarrying in the Ancient Andes, Sociopolitical, Economic, and Symbolic Dimensions, 275-298. [Book Chapter]

ABSTRACT. Introduction The oldest major settlement of Mesoamerica, Teotihuacan, was build mainly from pyroclasts extracted via quarry tunnels, from the basaltic flows underlying the superficial volcanic tuffs, for approximately 300 years, between 150 BC and 150 AD. These tunnels are still in existence today and were subsequently used by the inhabitants of the city for ritualistic and burial purposes (Manzanilla et al., 1996). Another such example is the city of Xochicalco, where there are tunnels originally used for limestone mining. So, from an early stage, the indigenous populations of Mesoamerica build their major settlements in places where there was a relatively easy procurement of building materials, and constructed the buildings virtually on top of the quarry tunnels, which were then converted to other purposes. The Aztecs themselves claimed their descend from the Toltecs, which in turn believed themselves to be ancestors of the inhabitants of Teotihuacan (Pemberton, 2011). As far as metallurgy and use of processed metal objects is concerned, modern research maintains that metalworking was introduced gradually in Mesoamerica through maritime trade with South America, and more specifically with Ecuador between 650 and 700 AD (Hosler, 2009; and references therein). In this research we present a general description of the metallogeny of Mesoamerica, and we document how the Aztecs mined for or collected as tribute gold, silver, copper, turquoise, jadeite and obsidian, how the availability of such commodities shaped their civilisation and how in the end lead to their demise. Metallogeny of Central America The oldest ore deposits of the area date back to the Proterozoic (Camprubi, 2009), but here the main interest is in the metallogenic province of the Pacific margin, which is the greatest silver province of the world (Camprubi, 2009). The intense Mesozoic to Cenozoic magmatism resulted in a host of porphyry and epithermal deposits, as well as skarn deposits. Many surface manifestations of porphyry deposits were mined for Cu and Au. Examples of such deposits are San Juan Mazatlán in Oaxaca, Tiámaro in Michoacán, Bacamari and La Azulita in Sinaloa, Caborca, El Promontorio, La Mariquita and El Alacrán in Sonora and many others (Camprubi, 2009; and references therein). For most of these deposits there is no evidence proving that they were the locus of Aztec mining activity but it is reasonable to assume that quarrying of some scale must have taken place in some of them, although tunnels are yet to be discovered or have since collapsed. Uncommonly, for such an extensive metallogenic province, there are very few high sulfidation epithermal deposits, while intermediate sulfidation epithermal deposits are dominant. Many such deposits are Ag/Au-rich or polymetallic, while high sulfidation deposits cluster in the NW Mexico (Camprubi, 2009). Mining and Use of Obsidian within the Aztec Society Perhaps the most well known rock coming to mind when seeing Aztec murals, weapons and everyday tools, is obsidian. Indeed, it can be argued that it was the most important natural resource of the Mesoamerican indigenous populations, since it was first exploited by the Olmecs (Pastrana & Domínguez, 2009). The physical properties of obsidian, namely its sharpness, durability and predictable cleavaging, made it an excellent material for a number of uses. The main sites for obsidian extraction, of the Aztec Empire, were Sierra de las Navajas, Otumba, Paredón, Tulancingo and Pico de Orizaba. The extraction of obsidian could be accomplished directly from the available outcrops, or via shallow trenches, open pits and tunnels. Obsidian was used for the creation of most implements of everyday life, be it weapons, ritual tools, everyday tools, jewels, vases and sculptures. Such was the importance of obsidian for the Aztecs that every source was assiduously exploited, while need for continuous mining and processing of obsidian lead to the gradual delineation of distinct socioeconomic strata, i.e. miners, knappers and obsidian traders. Copper Mining and Importance for the Aztec Civilisation Archaeological research has discovered remnants of ancient quarries in Zocotallan, Cerro del Aguilar, Tasco and in the Zapotec country (Phillips, 1925). Ayutla and Ayutlan in Jalisco and Inguaran and Bastan in Michoacán are settlements associated with copper mining and processing, while similar settlements have been found in the area of Guerrero (Hosler, 2009). However, the Aztecs did not most probably have any knowledge of bronze, as exhibited by the chemical analyses of various copper objects found in Mesoamerican archaeological sites (Phillips, 1925). While the metallurgy of the Aztecs was pretty advanced, they never progressed to the Bronze Age sensu stricto, as they did not intentionally use tin in conjunction with copper to produce bronze. It appears that the main focus of Aztec in particular and Mesoamerican metalworkers in general was to alloy Cu with other metals to produce religious and ornamental items which would be durable and shiny having a yellowish golden colour. Use of Ornamental Stones and Minerals The two principal ornamental minerals of the Aztecs, which shall be examined here, were turquoise and jadeite. Turquoise [Cu(Al,Fe^(3+) )_6 (PO_4 )_4 (OH)_8 •4H_2 O] was used in a variety of applications, from jewelry and ornaments, to mosaics, shields and knife handles, for the upper echelons of the Aztec society. Current research (Thibodeau et al., 2018) indicates that turquoise most probably was mined in SW Mesoamerica, from locations in West and Central Mexico, where copper mining has also been documented (Hosler, 2009). Since turquoise forms in the oxidation zones of copper deposits, it is reasonable to assume that in many cases turquoise and copper were extracted from the same mines. Regarding jadeite [Na(Al,Fe^(3+) ) Si_2 O_6 ] was used by almost every Precolombian civilisation of Mesoamerica in some form or another. In the case of the Aztecs, jadeite had acquired a mythical status and was restricted only to upper social classes, as they valued jadeite even more than gold and silver. The sources of jadeite are believed to be the Motagua River Valley in modern-day Guatemala and the Balsas Valley in Guerrero, while possibly more sources remain to be identified (Howard, 2001). Gold and Silver in the Aztec Society The abundance of gold and gilded items used and possessed by the Aztecs is described by many historians and chroniclers of the 16th and 17th centuries, and is verified by archaeological discoveries. According to descriptions by Cortés and Pizarro, the gold of the Aztec Empire came from Çoçolan, Malinaltepec, Tenis, Tochtepec, Zacatula and Xaltepec. The majority of gold was extracted from placer deposits and the term «placer» itself is most probably of Spanish origin and refers to deposits of detrital and residual material, such as sand or gravel, which contain a valuable mineral as a result of weathering and preferential mechanical accumulation (Yeend & Shawe, 1989). The descriptions of the Aztecs to the Spanish, about gold procurement, present gold mining as little more than picking gold grains from the sand which they gathered from the bottom of riverbeds. The need to furnish with gold and gilded items the upper echelons of their society lead to the creation of a separate and elite class of goldsmiths. Silver is a different story altogether, as it appears to have waded its way through the Aztec society and metalworking tradition through marketing networks. Discussion and Conclusions In effect, the existence of many different valuable minerals and rocks, and the constant need of the upper socioeconomic classes of the Aztecs for a display of precious ornate jewels and accessories lead to the formation of different professional classes of craftsmen, who occupied a distinct spot in the social fabric of the Aztec Empire. However, gold did not have a monetary value and it is interesting to observe that entire civilisations of Mesoamerica, who had regulated their everyday life without using any metal implements, shifted their focus on associating available metals with ornamental, religious and ritualistic maters (Hosler, 2009). This is a clear formative effect of geology, as had ore deposits of particular metals not existed, a whole aspect of the Aztec civilisation - and the preceding and contemporary ones for that matter - would be significantly different if it had existed at all. Additionally, the constant demand of the Aztec society for precious stones, which could not be found in their entirety within the borders of the Aztec Empire, lead to an ever increasing need for expansion, and therefore constant warfare. However, the display of wealth, and especially of gold, or of gilded items was the catalyst of the Aztecs' downfall by Cortés and his conquistadors (Pemberton, 2011). Interestingly, the presence of gold and silver contributed in altering the perception of the Spanish about the association between land ownership and wealth. In the Old World, the ownership of arable lands meant a steady income, roughly commensurate with the productivity of said agricultural expanses. However, the conquistadors virtually destroyed local societies, and as a result local production capacity (Harrasta, 2014). So, the conquest of more land was simply the means to an end, namely in acquiring gold and silver. The influx of enormous amounts of gold to Europe in the end had negative effects for European economies, since it caused a rapid drop in the nominal value of gold, and, since currency at the time was based on a country's gold reserves, widespread inflation. Despite that, the Spanish economy was, in the short term, benefited, since it overcompensated for the partial devaluing of its gold reserves by the huge increase in the net amount of gold available (Harrasta, 2014). A more far reaching consequence of the real and imaginative wealth of Mesoamerica in particular and the New World in general, was the Treaty of Tordesillas in 1494, the race for colonisation and the eventual war between England and Spain, in 1588 (McKee, 1987). References Camprubi, A., 2009. Major metallogenic provinces and epochs of Mexico, SGA News 25, 1-32. [Journal Article] Harrasta, J., 2014. El Dorado, The Search for the Fabled City of Gold, Charles River Editors. [Book] Hosler, D., 2009. West Mexican Metallurgy: Revisited and Revised, Journal of World Prehistory 22, 185-212. [Journal Article] Howard, K., 2001. Jadeite, Canadian Institute of Gemology. [Book] Manzanilla, L., López, C., Freter, A., 1996. Dating Results from Excavations in Quarry Tunnels Behind the Pyramid of the Sun at Teotihuacan, Ancient Mesoamerica 7, 245-266. [Journal Article] McKee, A., 1987. From Merciless Invaders, The Defeat of the Spanish Armada, 2nd Edition, Grafton Books. [Book] Pastrana, A., Domínguez, S., 2009. Cambios en la estrategia de la explotación de la obsidiana de Pachuca: Teotihuacan, Tula y la Triple Alianza, Ancient Mesoamerica 20, 129-148. [Journal Article] Pemberton, J., 2011. Conquistadors, Searching for El Dorado: The Terrifying Spanish Conquest of the Aztecs and Inca Empires, Futura. [Book] Phillips, G., 1925. The Metal Industry of the Aztecs, American Anthropologist 27, 550-557. [Journal Article] Thibodeau, A., López Luján, L., Killick, D., Berdan, F., Ruiz, J., 2018. Was Aztec and Mixtec turquoise mined in the American Southwest?, Science Advances 4, doi: 10.1126/sciadv.aas9370. [Journal Article] Yeend W., Shawe, D., 1989. Gold deposits in the Virginia City-Alder Gulch District, Montana, in: Yeend W., Shawe D., Wier K. (Eds), Geology and Resources of Gold in the United States, U.S. Geological Survey, Bulletin 1857, pp. G1-G13. [Journal Article]

ABSTRACT. About 30 show caves exist in Greece, which are scattered in both the mainland and the islands. Some of them are temporarily closed to the public due to maintenance reducind their number to 25. Show caves are the most important geotouristic feature according to Cigna and Forti (2013). They exist for at least 400 years and provide an income to more than 100 million people around the world (Cigna and Forti, 2013). In any case a viable development is crucial for any show cave and their environments. This study investigates the status and the conditions of show cave development in Greece from the perspective of a geologist. Methods In order to collect data a survey has been created with questions based on the UIS Management Guidelines for Show Caves (see Cigna and Forti, 2013) about the suggested prerequisites of show cave development. In addition to that form, a second one has been added with information about the cave visitors per year and a number of fields related to the dimensions and geology of each cave. The questions were of varied content about the cave visitors, the materials that have been used, the ideal lighting that have no effect in the biology and climate of the cave, the cave monitoring of parameters such as temperature, humidity or carbon dioxide, and how these data are treated and interpreted. Results In total 25 completed forms provided information about the conditions of cave development in Greece. Regarding the entrance to the caves, the natural entrance is used in 56%, in which it has been opened and modified in 43%. Independently of whether an artificial entrance is used or not, a double set of doors it is used in only 28%. The materials used in the caves are commonly compatible with the cave environment. However, at least in 21% non-compatible materials have been used and in other cases compatible materials have been used in a way that has a negative effect on the cave environment. The pathway is only in less than 21% a continuous route, which means that visitors use another exit and do not repeat parts of the route. This results in twice the time spend in cave that has a negative impact on the cave environment. The group size varies from 8 to unlimited persons and depends only to the cave size. Furthermore, the breaks between groups vary from 5 minutes to unlimited, and depends on the visitors per day. The lights along the pathways is a parameter that show improvement of the Greek show caves. Many of them have already installed proper lighting and others have included such changes in their plans. However, in 52% of the caves the lights are on during the working hours, independently of the visitors’ presence. The cave environment is monitored in only 40% of the Greek show caves for the parameters of temperature and humidity (unknown instrument precision) and only 28% report a carbon dioxide monitoring system. However, none of them reported a use of these records or scientific staff responsible for the data evaluation. Furthermore, only occasional collaboration with geologists has been reported and mainly with the Ephorate of Paleoanthropoloy and Speleology (Ministry of Culture and Sports) and with some Universities. The guides are part-time staff and they are mainly shelf-educated on speleological subjects (this may include also the attendance of seminars in speleological clubs). The aim in cave management are in most cases the advertisement of the cave (76%), the protection and conservation of each environment (20%) and new employment (4%). The visitor volume ranges for about 40% with data available, from 2.500 to 200.000 providing more than half a million euros income. Concluding remarks On the basis of this survey, the Greek show caves are important geotouristic destinations. However, it seems that Greek show caves do not conform perfectly to the standards of UIS Management Guidelines for Show Caves and the related literature (Cigna and Burri, 2000; Gillieson, 2009; 2011; Cigna and Forti, 2013; Cigna 2016). Entrance-related problems may be a closed natural entrance or an artificial one without an efficient air lock system. Pathways that doubles the visitors’ stay inside the cave, combined with group size and frequency based on demand instead of environmental studies, is also a potential hazard. In addition, the absence of monitoring systems and scientific staff makes difficult the evaluation of the conditions in each cave. Acknowledgements We would like to thank all the people who work in the show caves for their good-will to help in the survey and the Ephorate of Palaeoanthropology and Speleology, Ministry of Culture and Sports for the provided information. References Cigna, A.A., 2016. Tourism and show caves. Zeitschrift für Geomorphologie, Supplementary Issues 60, 217-233. Cigna, A. A., Burri, E., 2000. Development, management and economy of show caves. International Journal of Speleology 29, 1. Cigna, A. A., Forti, P., 2013. Caves: the most important geotouristic feature in the world. Tourism and Karst areas 6, 9-26. Gillieson, D. S., 2011. Management of caves. Karst management. Springer. Gillieson, D., 2009. Caves: processes, development and management, John Wiley and Sons.

ABSTRACT. Germinal is considered to be one of the ten greatest novels in the French language and is a story of a miner’s strike, taking place in a coal mining area in northern France in the mid. 1800’s (Zola, 2004). The novelist, Emile Zola, lived himself for several months in this area, thus providing accurate descriptions of the miners’ life. This literary work provides indeed important information on the history of coal mining in Central Europe during the 19th century. Zola, being a naturalist novelist, addresses in an explicable way all aspects of coal mining (legislation, labour types, health and safety issues, environmental problems, mining conditions, mineral processing etc.), which could be very useful for educational purposes. All the information mentioned above is emphasized in our study. The contribution of coal utilization in the so-called industrial revolution is indisputable. The industrialization of a coal mining area is evenly described in the following parts, comprising sugar refineries, flour mills, blast furnaces, construction and cable works, glass factories and coke-ovens: Over in Montsou the Fauvelle sugar refinery was still working; the Dutilleul flour mill and the factory at Bleuze that made cables for the mines were managing to keep going; the Sonneville construction works had received only a third of its usual number of orders; of the three blast-furnaces the ironworks in Machiennes only two were lit; at the Gagebois glass factory there was a threat of a strike; only two batteries of coke-ovens still going; …the blast furnaces and the coke-ovens. These last, batteries of a hundred slanting chimneys, stood all in a line like ramps of red flame; nineteen pits they have, with thirteen producing coal and six for drainage or ventilation. Ten thousand workers, concessions stretching over sixty-seven communes, a production level of five thousand tons a day, a railway linking all the pits, and workshops and factories. Founding and Management of coal mines resemble the modern ones as seen in Zola’s descriptions: concession-holders were to found the Anzin Mining Company; people were busy taking soil samples; companies were set up and concessions were materialized overnight; the new mines that he had to be abandoned after long months of toil, mine-shafts closed by rock-falls, miners drowned by sudden floods, hundreds of thousands of francs draining away down a few holes in the ground; problems of managing the business, the panicking shareholders, the tussles with the hereditary landowners of ancient estate; After establishing the company, the pits were beginning to yield meagre returns; almost ruined with the ferocity of the competition of other Companies; A settlement had been reached between the three concessions and they were amalgamated; a distribution of shares; the total capital value represented a sum of nearly three million francs; faced with the crisis, the Company had been forced to reduce its costs, naturally the workers were the ones to tighten their belts; the Company would gradually whittle their wages down; Coal had been piling up at the pit-heads for two months now, since all factories were idle; the Company didn’t lay off its workers because it would be ruinous not to maintain its plants; a strike would bring its workforce to heel and leave it less well paid than before. Different types of colliers are illustrated in several parts of the book (Figure 1): the hewers were wedged between the face and the ceiling and kept grazing their elbows as they extracted the coal; Each afternoon the shifters came and fetched the rubble left at the end of each tunnel by the hewers and then disposed of it in the cavities where the seam had already been mined; Simple pit-boy to start with, then putter once I was strong enough to push the tubs, and then hewer for eighteen years; Banksmen of each deck would drag the tubs out and replace them with others; The onsetters were busy wheeling the full tubs roughly across the cast-iron flooring; After that they put me on maintenance work, filling in seams, repairing the roads; they had to bring me up and give me surface job...they made me a driver; The engineman standing by the operating lever was listening out for the signal bells; a large white horse, pulling a train of coal tubs; Each full tub reached the surface marked with a special token so that the checkweighman could credit it to the appropriate team of miners; The haulage roadway had not yet been widened by the stonemen; a full tub could only just pass underneath, with the putters having to get down on their knees and push so as not to crack their skulls open; The tubs of coal came directly from the pit-head and were then emptied out by tripplers on to the screens; To the right and left from these chutes, the women and girls who did the screening; a deputy shining his lamp in their faces; A stoker shovelling coal into one of the boilers that powered the drainage-pump; which the engineers had had no inkling of despite their extensive knowledge of the terrain. All these categories of mine workers are clearly elucidated by Bulman and Redmayne (1906). The mine machinery on the surface along with coal processing plant are also illustrated in the following novel fragments (Figure 2): The screening-shed with its asphalt roof; the headgear over the pit-shaft; the huge engine house and the square tower containing the drainage pump; The winding-engine was setback some twenty-five metres from the shaft and housed at a higher level; working at full steam and producing every one of its four-hundred horse power; The engine would start up each time a cage departed and the spools-two enormous wheels measuring ten metres in diameter, around the hubs of which two steel cables wound unwound in opposite directions; did the screening equipped with a rake and shovel; the clean coal fell through funnels down into the railway wagons standing on the line beneath the shed.

Figure 1. A collier standing next to a mega xylite trunk (left) and hand-made manufacturing of briquettes (right).

Figure 2. Coal mine with primitive excavators and drainage problems (left) and a drainage pump (right).

The mining techniques and the working conditions in the underground coal mine are described as follows: Five hundred and fifty-four metres deep, but there are four loading-bays on the way down; The shaft itself is divided vertically into three sections by wooden planks. In the middle are the cages, on the left is the emergency shaft where there are ladders; the miners crossed pit-bottom, a cavity hewn out of the rock, which was reinforced with masonry vaults; oak props supported the roof and retained the crumbling rock behind a wooden framework; Ventilation doors open with a bang and then slowly closed again; the temperature reached thirty-five degrees; there was no circulation of air, and the suffocating atmosphere was potentially fatal; Each man hacked into the shale bedrock, digging it out with his pick; they had to drag themselves forward on their elbows and knees and were quite unable to turn round without banging their shoulders; the atmosphere became even more poisonous from the asphyxiating firedamp. Health problems and accidents of the miners and their families connected to coal exploitation are often emphasized by Zola: The old man spat black phlegm; It’s the water that’s got under my skin, what with getting soaked all the time down at the coal-face; with his frail limbs and huge joints, swollen from scrofula; soaked to the skin and shivering, their lungs a prey to the pneumonia; the anaemia that was gradually eating away at them; They’ve dragged me out of there three times now, barely in one piece. Once with my hair all signed, once full to the gills with earth, and once with my belly full of water, all swollen like a frog’s; a rock-fall it was, completely flattened him, swallowed him whole, bones, flesh, blood, the lot. Two of his uncles and then, later on, his own three brothers had all lost their lives down there. Environmental pollution caused by coal exploitation is depicted in quite a few parts of Germinal: The spoil-heap was already covered in grass, while at the other end it was being eaten away by an internal fire, which had been smouldering for a year now and gave off a thick pall of smoke; beneath a dun-coloured sky; the road were coated in mud, the thick, glutinous mud of coal-mining regions that looks as black as liquid soot; factory buildings with tall chimneys that belched out soot and filthied what remained of the countryside. Overall, it is evident that substantial information is inhered from this literary work, Zola’s Germinal, regarding coal mining in the mid. 19th century in Central Europe. The latter is not only important for comprehending the history of coal mining, but may be useful for teaching mining subjects in educational institutes. References Bulman, H.F., Redmayne, R.A.S., 1906. Colliery Working and Management, 2nd Ed. London (first published in 1896). Zola, E., 2004. Germinal, Penguin Books Ltd (first published in 1885).

ABSTRACT. The most deadly flood in Greece in the last 40 years occurred on November 15th 2017 in the western part of the region of Attica. A high intensity convective storm with orographic effects reaching up to 300 mm in 8 hours (200mm in only 3 hours) locally in a small area (18 km x 4 km zone) of the western and southern slopes of Pateras mountain caused flash floods along the streams of Agia Aikaterini, Soures and Koulouriotiko with extensive damages in the towns of Mandra and Nea Peramos and the loss of 24 people. The most severely affected by the extreme flash flood event area is the western part of the Thriassion plain in west Attica. Thriassion plain hosts one of the largest industrial units in Greece including refineries, metallurgical industries, factories, shipyards as well as the waste landfill of the Attica prefecture.It covers a total area of 812.95 km2 and is bounded by Pateras mountain (1016 m) to the west, Parnitha mountain (1413 m) to the north and Aigaleo mountain (468 m) to the east while the southern border of the plain is the Eleusis Bay. The Bay of Eleusis is a small and deep basin between the north coast of Salamina Island and the mainland. It has a coastline of approximately 15 km and receives the sediment load of a series of streams that drain the surrounding mountainous area. The upper reaches of the streams have relatively steep slopes resulting in high stream erosion capacity and transfer ability. Due to very high water flow velocities during the event (since in certain areas the terrain was very steep) and bottom shear stresses, the flash flood caused significant soil erosion and carried away not only large quantities of solids (practically it was a mud-flow), but also extremely large and heavy objects, such as buses and cars. Additionally, debris flows occurred along the steep coastal fan of the Koulouriotiko Stream which passes through the settlement of Nea Peramos. The main objective of this study is to identify the effects of the 15 November 2017 flash flood event along the north shore of Eleusis Bay using remote-sensing observations. These effects concern mainly the deposition of large amounts of sediments transported by the streams that flow into the Eleusis Bay. Images from Copernicus Sentinel 2 and Planetscope Dove microsatellites are used. For this purpose images before and after the flood event in the area have been collected also only one Planetscope image dated 15/11/2017 which is the only one in which a part of the coastal zone is displaced due to cloudiness. Research based on optical satellite images are simple to interpret and easily or free obtainable.

ABSTRACT. Introduction – Location - Geology The study area is located at coastal area of the Ancient Harbor of Lechaion, at the area of the outer harbor moles (Figs. 1-2), in order to investigate a possible extension of the existing ancient settlements. It is located on the southeastern coast of the Corinthian Gulf, 3km to the west of the modern city of Corinth, Greece. The construction of the Ancient Harbor dates to the 6th-7th century BC and archaeological evidence suggest that its use continued throughout the Roman period (Rothaus, 1995; Stiros et al., 1996). Lechaion harbor site lies in the southern coastal area of the Lechaion Gulf (Fig. 1). The broader area comprises alluvial and coastal deposits including loose materials, sands, pebbles and gravels (Papanikolaou et al., 1998). The geophysical survey was carried out in an area lying approximately 3 km west of the modern city of Corinth and consisting of recent beach deposits including sands and gravels (Papanikolaou et al., 1998). They are cohesive at places making up beach rocks. Geoelectrical research Three (3) profiles were carried out (Fig. 2) by applying the Electrical Resistivity Tomography technique, which is indicated for the investigation of buried archaeological settlements (Alexopoulos et al., 2014). The total length of investigation was 224 meters. Section “Lexaio-1” was 96 meters while sections “Lexaio-2” and “Lexaio-3” were 64m length each one. The roll-along technique was applied in order to reach the desired length and depth of investigation. The Wenner array was chosen with minimum electrode spacing equal to 0,40 meters. A total number of 3.610 data points were collected from all three ERT sections, investigating the subsurface resistivity distribution. The instrument used for the field measurements was Terrameter SAS 300C along with the ES464 electrode selector, supported by the Lund Imaging System. The resistivity data points that were collected during the field campaign were processed with Res2DInv Software (Geotomo). During the processing, the software tries to minimize the misfit error of an arbitrary model, checking the raw data points. The inversion process is continuously repeated until the minimum possible misfit is reached. The robust inversion was used, as the most appropriate for such geoenvironments and targets. During the set-up of the two geoelectrical lines, the coordinates of each electrode have been determined using Differential Global Positioning System (dGPS) and Real-Time Kinematics (RTK) technique. The topographic relief must be taken under consideration in such investigations and should be embodied in the inversion procedure of the ERT measurements. The geodetic system used for the coordinates was the local (Greek) EGSA’87 (Datum GGRS’80). Results and Discussion In Section 2 (Fig. 3), a dominant geoelectrical formation of low resistivity (<50 Ohm.m) has been investigated, from the depth of 2m up to the maximum depth of investigation which is equal to almost 6,0 meters. At shallow depths (<2 meters), resistant formations (500-2000 Ohm.m) have been determined along the section (Fig.3-red dashed rectangulars). It should be mentioned that along the main resistant formation (17,0-40,6m.) the highest resistant zones are adumbrated clearly (reddish colors) illustrated with almost sharp boundaries. In Section 3 (Fig. 4), even though the general image is similar, the resistant formations are quite bigger in size. The dominant geoelectrical formation of low resistivity (<100 Ohm.m) has also been investigated, extending mainly from the depth of 2,5 meters to the maximum depth of investigation which is equal to almost 6,0 meters. In this section, between 38,4-51,0 meters the aforementioned conductive formation is interrupted by a relatively resistant zone with values close to 400 Ohm.m. At depths less than 3,0 meters, highly resistant formations (550-6500 Ohm.m) have been determined along the section (Fig.4-red dashed rectangulars). It should be mentioned that two main resistant formations have been investigated (5,6-28,6m. and 30,0-64,0m), from depths 0,2-1,8m. and 0,4-4,0m equally. Along the first main resistant formation the highest resistant zones (>1500 Ohm.m) are adumbrated clearly (purplish colors) and are illustrated with almost sharp boundaries. Concerning the second major resistant zone, almost all the resistivity values are above 2000 Ohm.m (purplish colors). The geoelectrical boundaries here are also quite sharp and clear. Conclusions The results of the geoelectrical survey seem to adumbrate some zones (Figs. 3-4, reddish & purplish colors) that could be interpreted as archaeological remains of the coastal installations of the ancient foreharbor. These are presented and discussed by Mourtzas et al. (2014) in the context of the geoarchaeological approach of the ancient harbor of Lechaion. Acknowledgements The authors would like to thank Mr. Spyridon Mavroulis and Ms. Helen Kaplanidi for their contribution in the field campaign.

ABSTRACT. In this abstract we briefly discuss the results of a 5-year long measurements program, regarding bedload transport in Vouraikos River. We compared our measurements against the outcome of some of the bedload equations included in B.A.G.S. (Bedload Assessment for Gravel-bed Streams) software. Another equation, that has been developed for the Little Granite Creek, in Wyoming, USA, by Ryan & Emmett was also considered. Finally, we developed a site-calibrated equation based on the procedure outlined by Wilcock (2001). In the long term (a decade), all equations (except Parker90) predict the same mass of dislocated material. We can conclude that, given good quality hydrological, topographic and sedimentological data, these three equations from BAGS can give credible results. The most critical point is the choice of D50.

ABSTRACT. In this abstract we briefly present the results of a 5-year long measurements program, regarding suspended sediment transport in Vouraikos River. In particular, we discuss - and strongly encourage - the use of a transparency tube, a cheap and easy to use turbulometer, as a reliable alternative to more sophisticated and expensive instrumentation for monitoring sediment transport in rivers and streams. The rating curve that we developed predicts values of suspended sediment transport that average 22 thousand tonnes per year, with a maximum of 68 thousand tonnes in 1983.Depending on the estimation of the upstream contributing basin, the above value can yield anything from 1300 to 120 t/y/km2.

ABSTRACT. The principal objective of this study is to quantify the post 1945 changes of the shoreline of the Evinos River delta in Western Greece using geo-referenced aerial photographs, a detailed Digital Elevation Model (DEM) and Landsat imagery. Quantitative assessment of recent delta shoreline changes is a part of the coastal monitoring that helps significantly in long-term predictions of shoreline positions, which is particularly useful for the design of future shoreline management and development strategies. The Evinos River delta is located on the northern shore of the Gulf of Patras. It covers an area of about 92 km2 and belongs to one of the most significant ecosystems in Western Greece, the Messologi wetland, which is protected by the Ramsar Convention. In order to detect and quantify diachronic changes of the Evinos delta shoreline, comparative observations of the coastlines of 1945, 1969, 2016 have been made utilizing GIS techniques. In an attempt to quantify land loss and/or land gain for the time periods between 1993, 2002 and 2018, the broader deltaic area of the mouth of the river was divided into three parts (Figure 1) and three Landsat TM images, acquired on July 1993, August 2002 and August 2018 respectively, with a spatial resolution of 30 m, were collected. The comparable analysis of the 1945, 1969 and 2016 delta shorelines shows that the main process along a significant part of the delta front is intense erosion. In particular the coastline of the eastern abandoned part of the delta is retreating since 1945. The main cause of the east delta erosion are the exposition of the shoreline towards the predominant waves and long-shore currents (Piper et al., 1982) in addition to the lack of sediment supply since 1959 after the artificial closing of the river mouth. The only area where the delta progrades today is west of the present river mouth which consists of dynamic, gradually changing sandy barriers. The comparative analysis of Landsat TM images showed a significant land loss for the broader area of the active delta and the part of the delta east of the present river mouth, especially after 2002. Land loss is primarily associated with severe decline of fluvial sediment discharge due to the construction of the dam (in 1997) in the upper reaches of the river. Another important reason for the erosion is the uncontrolled sand and gravel mining activity from the distributary channel of the river.

ABSTRACT. The present study aims at a better understanding of the prevailing processes which contributed to the recent geomorphic evolution of the Kerinitis River fan-delta, located in the North Peloponnese (Central Greece), during the Late Holocene through geomorphological mapping and fieldwork. One of the objectives of this study was to assess mean shoreline change rates along the apron of the fan-delta using remote sensing data and GIS techniques. The fan-delta of the Kerinitis River is located along the southern coast of the western Gulf of Corinth and has been prograding in deep waters since the deceleration of sea-level rise during the upper Holocene like all the fan-deltas of the broader area of the northern Peloponnese. It has an area of 6.16 km2 and the mean slope of its plain is 0.03. In order to determine the dominant processes responsible for the evolution and configuration of the fan-delta, detailed geomorphological mapping was carried out, which includes the identification and depiction of the dominant landforms of both the fan-delta plain (such as modern distributary channels, natural levees, abandoned channels, etc.) and the fan-delta coastal front (sandy and pebbly beaches, low cliffs, etc.). For the study of the recent changes of the fan-deltas shoreline, comparative observations of the coastlines of 1945, 1969, 1996, 2009 and 2017 have been made. The coastlines of 1945 and 1996 have been digitized from georeferenced aerial photo-mosaic obtained from the Hellenic Millitary Geographical Service (HMGS) and the Greek Ministry of Agriculture respectively. The coastlines of 1969 and 2009 have been derived from the topographic diagrams of the HMGS and the detailed DEM of the Hellenic Cadastre while the most recent coastline of 2017 has been obtained from digitization in Google Earth. This comparison allowed us to identify areas of progradation and parts of the fan-delta plain that are being eroded as well as to estimate mean annual progradation and erosion rates for the last 72 years. Numerous presently inactive abandoned linear distributaries were recognized across the fan-delta plain. Old maps of the area along with aerial photographs of 1996 as well as the detailed DEM of the area have been particularly useful in identifying and mapping these traces of the abandoned river courses. A palaeochannel has been identified flowing along the east Eliki fault segment leading to the eastern border of the fan-delta. A migration of the river after the 1861 earthquake event towards the central portion of the east Eliki fault segment occurred but then the main channel changed its course flowing along its present position, which is similar with its 1700 AD path. These changes of the main channel indicate that Kerinitis River appears to have been strongly affected by tectonic movements related to the westward propagation of the east Eliki fault segment. The comparable analysis of the 1945 and 2017 fan-delta shorelines shows that the main process along a significant part of the fan-delta front is intense and rapid erosion. Progradation (with a maximum mean rate of +1.46 m/yr) is observed only at the area around the presently active mouth of the river and at the easternmost edge of the fan-delta. A significant segment of the fan-delta shoreline is currently undergoing erosion with a maximum mean rate of -0.57 m/yr for the time period between 1945 and 2017.

ABSTRACT. Akrotiri Penisnsula is located west of Limassol at the Southern end of the Island of Cyprus. It covers an area of approximately 100Km². The development of the peninsula started with the deposition of calcareous marls in to the Episkopi grabben during the Miocene which resulted the Akrotiri High in the form of an isolated island. The maritime space between the Akrotiri Island and the mainland eventually closed during the Quaternary and several geomorphic features were developed. Beachrocks identified at three continuous pocket beaches at the southwest part of the Akrotiri peninsula. Detailed GNSS measurements and GIS analysis revealed that the area is uplifted. A direct relationship between the development of the beachrocks and the paleogeographic evolution of the area is apparent. Additionally, results from Petrographic, mineral and sedimentary analysis on beachrock samples are indicating a continuous supply of material from the nearby Kouris River. A gradual reduction of the sediment granulometry consists the beachrock is observed. Also the transition of the texture of the samples from non-uniform to uniform is observed. The sample mineralogy varies eg quartz, alkaline feldspars, carbonate minerals, ortho and clino pyroxenes, serpentinites, hornblende, muscovite. A reduction in the contribution of overbearing minerals (according to their hardness) was observed from North to Southern beachrock slabs and the increase of carbonates, quartz and feldspart. It should be noted that there is a strong participation of fossils fragments were a number of them was preserved in good condition. SEM-EDX analysis were conducted and showed that the micritic and sparitic crystals of cement are consisted by High Magnesium Calcite +(>4 mol% CaCO3 or 1.2 wt.). The cement agent forms an isopachous coating around the sediment grains and with meniscus forms connect all the sedimentary particles which leads to the formation of a high density beachrock slabs.

ABSTRACT. A large percentage of the coastline in Greece, with strong tourist, economic and natural interest, is Pocket Beach. In the present study, the processes of coastal erosion, existing on Platys Gialos beach, are described and examined due to: (i) limited river stereo transfers, (ii) the construction of a protective wall along the coastline, but also (iii) the construction of a fishing shelter. In particular, are being analyzed the geological and sedimentological composition of the background, the geometrical characteristics, the morphological peculiarities, the orientation towards the prevailing oceanographic conditions and the coastline development in two seasonal periods (winter/summer), focusing on the existing morphodynamic condition of the coast. The methodology followed in the study included: (i) long-term geomorphological evolution of the coastal zone through the analysis of satellite images, in order to estimate the intensity of coastal erosion, (ii) data of the numerical recomposition of the wind and wave conditions of the study area, (iii) topographic sections at the surface and the subsea of the coastal zone, through D-GPS, perpendicular to the coastline, (iv) collection of surface land and marine sediments, and (v) analytical recording and mapping of the summer and winter shorelines via the D-GPS. Taking into account the results and identifying the morphodynamic environment of Platis Gialos beach, a "soft" invasive method is proposed on the beach, such as artificially beach nourishment, in order to restore disturbed balance and achieve its protection from the erosion.

ABSTRACT. Mt Athos, Northern Greece, is a monastic community with life since ~1000 AD, a UNESCO worldwide cultural heritage site that repeatedly hit by large earthquakes. On 8 November 1905 Mt Athos suffered a lot from an earthquake which shook the Balkan peninsula and had estimated magnitude ranging from 6.8 to 8.3. However, this important event remains little known since only very few documentary sources have been utilized so far. We collected a set of new documentary sources, ignored so far by the seismological community, including contemporary press reports, letters and manuscripts. Based on these sources we reconstructed the earthquake impact field and organized a data base which contains assignment of macroseismic intensity in 42 observation points, at epicentral distances up to ~660 km, and an identification of several sites where a variety of co-seismic ground failures were reported, the most important being landslides and sizable rockfalls. From magnitude-intensity relationships based on data of instrumental Greek earthquakes, macroseismic magnitude of ~7 equivalent to Ms was estimated, which is close to the most recent, reliable instrumental estimates of ~7.2. The examined sources revealed for the first time that earthquake-triggered landslides occurred in the southern tip of Mt Athos producing a local but powerful tsunami of ~3 m run-up. Eleven persons were reportedly killed.

ABSTRACT. A Feasibility Study Layout Masterplan of the Tekhuri River located on the south-west slopes of Caucasus Mountains, in North-west Georgia, had been prepared in 2015. That Masterplan included five (nr. 5) individual hydro-electric projects containing five (nr. 5) dams (one rockfill type embankment dams with central clay core and four of the RCC gravity type dam), their height varied between minimum 23m over to 47m without taking into account the foundations excavations. In addition, the full initial project, included five (nr. 5) headrace tunnels, of diameter ranging between 2.5m to 4.0m with their lengths ranging between 3.6 over to 5.0km linking the reservoirs with the relevant provided five (nr. 5) power houses downstream, of total then provided installed of 112MW. The prevailing engineering geological conditions of the three upstream dam and their reservoirs are geologically characterized by the presence of a volcano-sedimentary folded sequence of, thick to medium layered, sandstones, siltstones, mudstones, andesitic lavas and tuffs. From the engineering geological point of view, the aforementioned sequence is characterized by relatively high strength, generally low deformability and low permeability, that practically secure both the dam and reservoir feasibility. However, the two downstream dams and their reservoirs geologically develop over karstic limestone formations outcrops which from the engineering geological aspect are characterized by very high permeability, with serious potential reservoir water-tightness and associated dam stability problems. In the beginning of 2016, a private investing company undertook the carrying out of the missing designs and the submission of the relevant application to get the permission for the implementation of the whole cascade hydro project to the Georgian Authorities. Within the obligations of the application procedure for obtaining the relevant concession permission by the Georgian authorities, there was carried out the necessary Feasibility Study by a local (Georgian) consulting company. The candidate Developer for the concession contract, just before the submission of the official application to the Georgian authorities, assigned to an Austrian consultancy the carrying out of the Technical Due Diligence Study of the Feasibility Study of the project which had been carried out by the local Georgian consultancy, focusing in particular on the Hydrological, Hydraulic, Geological and Geotechnical and the Energy aspects of the design. Within the framework of the Due Diligence study, a Greek team of Geologists and Geotechnical Engineers from the Greek branch office of an Italian consultancy based in Thessaloniki, Greece, undertook the geological and geotechnical part of the aforementioned study. In the presentation, there are described, first, the unsuccessful ways of the input and the essential incorporation of the geological information in the Feasibility Planning and Design of the Project Masterplan and in general, all of the hydroelectric projects in Georgia. Then, there are presented the final evaluation of the proven “non-feasible” of some of the provided dams and reservoirs of the previously developed project Masterplan. Finally, there are presented the Masterplan modifications based on the geological proposals to be in full alignment of the hydrological, hydraulic and energy considerations of the project, in order to achieve the technical and financial feasibility of the General Masterplan of the Hydro-electric Development of the river Tekhuri in the area of the South Caucasus mountains of Georgia.

ABSTRACT. The Cyclades islands have been experiencing over time problems of water scarcity, due to limited water resources. The last decades precipitation over the south Aegean islands displays generally a larger variance and has a tendency of becoming dryer, compared to long-term climatic normal (Nastos & Zerefos, 2010) because of climate changes. Reduced precipitation can affect the sustainability, quantity and quality of water resources. The natural shortage of water resources is exacerbated by increasing water consumption for human needs, such as the expansion of irrigated land and the development of urban, industrial and touristic areas. These conditions reinforce the necessity to improve water management in order to ensure the necessary quantity of water supply. This necessity becomes stronger in areas with complex geological setting, with relatively small aquifers and tangential (with hydraulic communication) to the sea, where overpumping and the expected minimum natural renewal due to the dry climate, leads to a significant drawdown in water table, resulting sometimes in the salinization of groundwater. The municipal water supply of Ios Island has been reinforced by a series of projects and interventions, mainly focusing to the summer period due to tourism where water demand surpasses by far water availability, consisting of: • New deep boreholes. • Construction and operation of the water reservoir of Mylopotamos with a total capacity of 215,000m3. • Construction and operation of Mylopotas desalination plant with a total capacity of 1,000m3/day. Given the climate change that has taken place in recent years, there is a continuous quantitative and qualitative degradation of Ios Island water resources. Indicatively, it is reported that it has been recorded: • Partial or total recession of springs discharges. • Significant drawdown of wells and boreholes water tables. • The water reservoir of Mylopotamos was totally empty in 2000 and 2018, due to the prolonged drought. The Ios Island almost entirely comprises of metamorphic rocks and Quaternary formations unconformably cover them (Van Der Maar & Jansen, 1981). The metamorphic rocks are including the dominant unit of the Cycladic Blueschist Unit (CBU) which is located mainly in the north part of the island and in scattered outcrops in the south. The CBU is tectonically overlying the Cycladic Basement Unit which constitutes the Variscan basement and is demonstrated in the central and south part of the island. Three main aquifer systems developed on Ios Island include (Kourmoulis, 1980; Papadopoulos & Stergiopoulos, 2000; JV of Aegean Watersystems, 2005; Giannoulopoulos & Lappas, 2010): • The shallow aquifer system in porous Quaternary formations. • The karstic aquifer system in the carbonate rocks of the Cycladic Blueschist Unit (CBU). • The aquifer system (both shallow and deep) in the fractured hard rocks mainly of the Cycladic Basement Unit. Precipitation is the direct recharge of the three aforementioned aquifer systems. It should be mentioned, that the overlying, shallow aquifer system is also indirectly recharged from the streams runoff during the winter months and from the formations of the Cycladic Blueschist Unit (CBU) and mainly of the Cycladic Basement Unit (augengneiss and garnet-mica schists). However, even this indirectly recharge depends on the precipitation. The shallow, porous aquifer system of Mylopotas, Manganari, Psathi, Koumbara and Kato Kambos is encountering continuous quantitative and qualitative degradation, due to restriction of precipitation during the winter months and overpumping during the summer months. The karstic aquifer system of the north part is being discharged in the Aegean sea and therefore, it is not of particular hydrogeological interest. The aquifer system in the fractured hard rocks mainly of the Cycladic Basement Unit occurs in the weathered zone (shallow) and in the fractured zone (deep) of the garnet-mica and the augengneiss and is encountering continuous and over time quantitative degradation since: • The great majority of small springs which discharge the weathered zone has suffered partial or total recession through the years, due to the restriction of the precipitation and the prolonged drought. • The time fluctuation from 1976 until today of the springs discharges, named Epano Desi, Kato Desi, Psathi and Aghia Theodoti, which discharge the fractured zone of the augengneiss shows both continuous recession and flow, covering even today the water supply of some settlements. It should be mentioned, that in the recharge areas (hydrogeological basins) of the aforementioned springs there are no wells and boreholes and therefore, their continuous discharge recession is due to restriction of the precipitation and the prolonged drought. • The time fluctuation from 2005 until today of the fractured zone water table of the augengneiss shows drawdown which exceeds 35 meters in the west and southwest of Kastro or Pyrgos and is almost 15 meters in the south margin of the Mylopotas alluvial basin. In conclusion, a continuous quantitative and qualitative degradation of Ios Island water resources is being recorded which is the result of both the restriction of precipitation during the winter months and therefore of the limited recharge and the overpumping during the summer months of the three main aquifer systems. Furthermore, the direct consequence of the climate change is the often occurrence of extreme hydrometeorological phenomena that favors the runoff instead of infiltration which leads to the restriction of the recharge of the three main aquifer systems. For the sustainable water resources management of the Ios Island new projects must be planned, such as: • Artificial recharge for both the shallow, porous aquifer system and the aquifer system (shallow and deep) in the fractured hard rocks mainly of the Cycladic Basement Unit. • Construction and operation of new water reservoirs. • Construction and operation of new desalination plants.

ABSTRACT. Three main aquifer systems developed on Kythira Island include (Pagounis, 1981; Pagounis & Gertsos, 1984, Danamos, 1991; Koumantakis et al., 2006): • The porous aquifer system in Neogene and Quaternary formations. • The karstic aquifer system in the carbonate formations of the Pindos and Tripolis units. • The aquifer system (both shallow and deep) in the fractured hard rocks mainly of the Phyllites – Quartzites unit. The main discharge of the aquifer systems takes place in coastal and submarine brackish springs around the island, except for its northern part where the Phyllites – Quartzites unit outcrops and its central part where springs of small capacity discharge the carbonate formations of the Pindos unit. The municipal water supply of Kythira has been reinforced by a series of projects and interventions, focusing on the summer touristic period, when water demand surpasses by far water availability, mainly consisting of new deep boreholes. Precipitation is the direct recharge of the three aforementioned aquifer systems while indirectly lateral discharge occurs in places between adjacent and tangential aquifer systems and from the streams runoff as well. On August 4, 2017 a shrub, rather a forest fire broke out close to the island hospital; it expanded rapidly due to strong winds blowing in the area and raged out of control for four days, inducing considerable damage. The size of the fire-affected area was about 20km2, 16km2 mainly of shrub and 4km2 of agriculture land. For the detailed evaluation of the geo-environmental impact of the aforementioned fire to the aquifer systems of the Kythira Island concerning the quantitative and qualitative degradation seventeen municipal water points were finally selected for further hydrogeological study. The water points monitoring network were used in September 2017, June 2018 and October 2018 for measurements of the water tables heads and springs discharges while water samples were collected and chemical, trace elements and microbiological analysis were carried out. The impact of the fire on the quantity of the aquifer systems of the wider fire-affected area could not be fully clarified and there was indirect evidence of their recharge (it remains unknown its rate compared to the recharge before the August 2017 fire) during the three field trips such as: • Fluctuation of the measurements of the water table heads. • Fluctuation of the measurements of springs discharges. • Fluctuation of the measurements of boreholes hydrometers. • Changes to the hydrochemical facies of the Piper’s, Durov’s and Stiff’s diagrams of the collected water samples. The results and the evaluation of the chemical and trace elements showed that there was no impact of the fire on the quality of the wider fire-affected area aquifer systems. However, microbiological analysis from the Mylopotamos spring showed qualitative degradation, due to human activities in the wider area preexisting the August 2017 fire (Pagounis, 1981). For the sustainable water resources management of the wider fire-affected area new projects were proposed in order to prevent phenomena that favors the runoff instead of infiltration which lead to the restriction of the recharge of the three main aquifer systems, such as works of artificial recharge.

ABSTRACT. As one of the world’s largest users of fresh water resources, irrigated agriculture has a profound effect on the water cycle, water availability, distribution of water, and water quality. Irrigated croplands are essential contributors– they comprise 15% of arable land yet provide 36% of food (FAOSTAT Statistical Database, http://www.fao.org/statistics/en/). However, they are also large consumers of fresh water resources. Despite high yields and relatively low risk (relative to rain fed lands), the large amounts of water used for irrigation often conflict with competing demands. In semi-arid lands these conflicts are exacerbated by already strained resources, climate change, and population growth. Accurate information on agricultural water needs and withdrawals at appropriate spatial and temporal scales remains a key limitation to joint water and land management decision-making. Addressing these problems require assessments of irrigation practices to ensure that farms are currently using water efficiently and the development of tools to facilitated additional water saving strategies at farm to irrigation district scales. These assessments and tools could be implemented by using medium resolution remote sensing data, which are being increasingly used to monitor, manage, and forecast agriculture water use at different spatial scales. The coverage of the water needs of the Thessalia plain remains a landmark issue for the country and the local and central authorities. The area under consideration is unique: Numerous research programs and studies, concerning the management of water resources, have been realized. The major irrigation projects have been designed since 1925 up to contemporary times. The scientific community has presented different estimates in relation to the reserves and the real needs. This paper does not attempt to approximate the size of water needs, nor does a reassessment of inventories. It is undertaking a review of the possibility of further exploiting local water resources. The most recent updates to the water balance carried out by IGME, add significant new results have been derived from the major hydraulic parameters. It must be emphasized that the above mentioned hydraulic parameters consist a vital criterion for the most suitable selection of the technical interventions which must be followed. The output will determine the technical interventions that can be carried out in order to upgrade the underground water reserves through artificial enrichment.

Summarizing, a key element of the present work is that underground aquifers are easily amenable to artificial enrichment at depths of <100 m in the selected region of Thessalia Basin. Aim of the study is to introduce the following points:

a) The selection of a pilot area is located in Thessalia plain, (Figure 1) which has high water permeability (region of the stream sediment cones). In addition, 23 cone areas are presented in the 1:50,000 scale IGME geological maps, of total surface area of 12.9 km2 which have been analysed. b) Applying mild forms of "artificial enrichment", utilizing the local hydrographic network and working in shallow aquifers, "peripheral hydraulic loading". Different hydrologic parameters have been estimated using the Digital Elevation Model of Ktimatologio S.A. with 5 m. resolution: Bifurcation Ratio, Length Ratio Drainage Density, Constant of Channel Maintenance, Length of Overland Flow Stream Frequency, Basin Length, Form Ratio, Elongation Ratio, Basin Relief, Relief Ratio, Ruggedness Number and Mean Stream Slope. Furthermore, basins directly related with their outflow to the cones that have been selected. Actually, 62% of all basins have an altitude that varies between 138 to 414 meters, while 98.86% of the total area of the basin includes slopes that vary between 0 to 35 degrees. c) A total length of 815 km for the streams running the area have been mapped and analysed, 190 km are directly related with their flow to cones (Figure 1). A number of basins of a total area of 73. 6 km2 contribute to surface flows towards the sedimentary cones. Drainage density of basins varies between 0.0024 to 6.29. d) No disturbance to existing land uses by the development of technical enrichment interventions. Land uses are effectively monitored using medium resolution satellite data. e) Exploitation of surface run-offs in non-flood time periods to avoid accumulation of sediment within the enrichment channels. f) Using a combination of satellite and vector data in appropriate and homogenized geospatial databases to monitor and support the operation of these mild technical projects. This is possible after the estimation of significant environmental indicators on a weekly basis (NDVI, NDWI, Chlorophyll A, e.t.c), which are directly related to the status of the crops.

It could be generally agreed that results of the present work are important and critical for the sustainable artificial enrichment of ground water aquifers. Furthermore, remote sensing techniques can be used to support watershed implementation plans to satisfy future water needs.

ABSTRACT. The Aghia Sub-Basin (ASB) is located at the eastern boundary of the River Pinios Basin and covers an area of approximately 45 km2. It constitutes a rather important local basin for Thessaly due to the intense agricultural activities. Regarding water resources management status, irrigation constitutes the major water consumer for the watershed, and demands are almost exclusively covered by groundwater. Agriculture constitutes a dominant factor for the hydrogeochemical conditions of the wider area, as reflected by the locally high NO3 concentrations observed in the alluvial groundwater system. Moreover, the irrational irrigation practices applied, are reflected by locally increased salinization, which is attributed to irrigation water return. The results from two sampling campaigns (n=24) revealed that general water quality is good, with local deviations. All groundwater samples have the same water type (Ca-HCO3), which is evident from their common hydrodynamic characterization, which classifies them as recharge waters. Based on the combined evidence of hydrogeology and hydrogeochemistry, 4 different hydrodynamic zones (Z) may be identified (Fig.2). Specifically, Zone 1 is composed by fractures-weathered formation, with no groundwater abstractions and lateral crossflows. Zone 2 is a transition zone with groundwater abstractions, which receives inflows from Z1 and discharges outflows to Z3. Zone 3 is consisted of alluvial deposits, with significant groundwater abstractions and inflows from Z2. Finally, Zone 4 is mainly composed of serpentines and limited karst formations and a relatively small contribution of inflows to Z3.

ABSTRACT. The Normalized Difference Vegetation Index (NDVI) indicates the existence of vegetation in the area of interest and is the most widespread and acceptable of vegetation indices. Its calculation is made by utilizing the Near-Infrared (NIR) and Red spectral bands, calibrated in TOA Reflectance values, according to the following equation (Rouse et al., 1973): NDVI=(NIR-RED)/(NIR+RED) The linear regression analysis between NDVI (2007 satellite image) average values for the agricultural areas of interest and known water consumption for these areas (estimated by electric power consumption of irrigation pumps) produced the following equation: y=1.647*Χ-0.313 , with R2=0,7896 Where: y: mean annual water consumption ( m3/m2) x: NDVI average values Additional to this the linear regression analysis between NDVI2007 and NDVI2018 is the following: NDVI2018=NDVI2007*0.571+0.286 with R2=0.85 Applying the previous equations to the average NDVI values (15 July 2018) satellite image the irrigation water consumption was estimated at least 35.000.000 m3 for the year 2018 with mean annual consumption 0.73 m3/m2. An analogous estimation was deduced introducing to Blaney Criddle water consumptive use equatrion Kc calculated by the following equation: Kc=1.18*NDVI+0.05 (Masahiro, 2005) Applying the previous equation to the average NDVI values of 0.57 returns a coefficient Kc equal to 0.72. The study concludes that there is an annual increase of 1.000.000 m3 for irrigation use. The results reinforce the arguments of Public Power Corporation of Greece (PPC) that the amount of water that is being pumped for lignite exploitation water inrush and geotechnical protection purposes, is negligible in comparison with the water consumption for irrigation and therefore the water balance of Sarigiol aquifer is mainly affected by farmers water pumping.

ABSTRACT. Carbonate rocks in Greece occupy about 35% of the surface area of Greece and are mainly located in the western, central and southern parts of the country. The carbonate rocks can be divided into sedimentary formations (limestones and dolomites) and metamorphic rocks (marbles). They mainly date from the Triassic to the Cretaceous periods, whereas marbles have a Paleozoic-Mesozoic age. Within the carbonate rocks are hosted karst aquifers which are the main supply source for domestic use in many sites of Greece. However, integrated management plans of karst aquifers in Greece are only focused on extraction limitations, while detailed monitoring, vulnerability assessment and modelling are neglected. According to the EU Directives and new Greek legislation of management plans of aquifers in Greece require the determination of protection zones of springs and wells used for domestic uses. The delineation of protection zones is not a straightforward and one-dimensional process. It should be a part of an integrated management plan of the aquifer system (Burgess and Fletcher, 1998). The process is much more difficult dealing with karst aquifer due to their anisotropy and uncertainty of their structure and function. A sustainable management of karst aquifers includes the following steps (Biava et al., 2014; Kazakis et al., 2018): a) Detailed hydrogeological observations (temporal and spatial data). b) Data analysis applying advanced statistical methods. c) Application of integrated models depending. d) Vulnerability and risk assessments. Although in Greece, many studies deal with statistical analysis of karst systems (Panagopoulos and Lambrakis, 2006), vulnerability assessment (Kazakis et al., 2015; Nanou and Zagana, 2018) and time series analysis (Manakos et al., 2019) there is a methodological gap for the delineation of protection zones in Greek karst aquifers. It is pointed out that karst aquifers are highly vulnerable to pollution, precisely because of their specific structure (Biava et al., 2014). In this study we suggest a methodological approach for the delineation of protection zones in karst aquifers. The process includes basic hydrogeological research, hydrochemical and isotopic analysis, statistical analysis, simulation process, and vulnerability and pollution risk assessment. Obviously, the delineation of the protection zones of the karst systems constitute the final step and maybe the most important step for the sustainability of the systems. In this study we provide the methodological framework in simple research steps in order to delineate protection zones to karst aquifers. This protocol has been developed during the study of four karst aquifers in the municipality of Kozani, in western Macedonia, north Greece (Fig. 1). The water demands of the municipality are covered by exploiting of these karst aquifers. Hence, the sustainability of these hydrosystems is of the outmost importance for the water security of the area. The suggested methodology to delineate protection zones in karst aquifers includes the following research steps: Literature review: A detailed literature review of the existing geological and hydrogeological studies is essential for the delineation of protection zones. The literature review could provide the initial hydrogeological conceptual model of the karst aquifer, the missing data and determine the field work. Data base development and digitization in Geographic Information System (GIS) environment: All available maps (geological, geomorphological, hydrogeological) including geological and hydrogeological information should be digitized. Hence, a data base can be created in G.I.S. environment in order to elaborate and analyse the various spatial data and create the corresponding thematic maps. Hydrogeological observation: The hydrogeological research includes field measurements, data collection and analysis. More specific, field measurements include: a) hydrogeological-geological mapping of karst features, springs, aquifer boundaries, faults using both field measurements, satellite images and UAS (DRONE) images, b) geophysical research applying electrical resistivity tomographies in order to determine the structure of the aquifer, c) hydrochemical analysis to determine the quality of groundwater, and d) isotopic analysis of stable isotopes and tritium in order to determine the recharge zones and groundwater age. Statistical analysis: The statistical analysis includes methods such as cross-correlation, autocorrelation and phase function of rainfall and discharge of the karst aquifer. The main contribution is to understand the functioning of the hydrosystem and determine the lag time of the system. Modelling: The modelling process contributes in the prediction and exploitation of the quantities of the system. The modelling process include both lumped (e.g. Karstmod) and spatial models (e.g. Modflow-CFP). Groundwater vulnerability and pollution risk assessment: The vulnerability and pollution risk assessment are the final step to delineate protection zones and suggest land use changes. The PaPRIKa method and the corresponding plugin have been widely used for the vulnerability assessment of karst aquifers (Ollivier et al., 2019) and hence, it has been included in the suggested methodological approach. The holistic approach of the suggested methodology can ensure high reliability in the delineation of protection zones in karst aquifers. It can be adopted in different hydrosystems according to the data availability. Additionally, the integrated approach of this method ensures the reliability of the results and the social acceptance of the protection zones. It should be mentioned that the application of different methods give different results as regards to the extension of the protection zones. Hence, the proposed methodology would be benefit by improvement in hydrological data monitoring and the application of isochrones method to compare the results.

ABSTRACT. Active landslides can be monitored using many different methods such as classical geotechnical measurements including inclinometers, topographical survey measurements with total stations or Global Navigation Satellite Systems (GNSS) receivers. Newer methods include Airborne Light Detection and Ranging (LiDAR) systems, Terrestrial Laser Scanners (TLS), photogrammetric techniques using airphotos or high resolution satellite images, Differential Interferometry using radar images (DInSAR). A recently emerged methodology is the computer vision technique using data from Unmanned Aerial Vehicles (UAVs). The advantages and drawbacks of those different methodologies for landslide monitoring are described and analyzed in several studies highlighting the existence of a high resolution and accurate representation of the relief as a prerequisite in order to achieve a proper displacement identification (Nikolakopoulos et al., 2017; Nikolakopoulos et al., 2018; Nikolakopoulos and Koukouvelas, 2017; Kyriou and Nikolakopoulos, 2016; Kyriou and Nikolakopoulos, 2018). Additionally, all the studies agreed that a key point in active landslide monitoring is the performance of repeated surveys, as the transient geomorphology of the sliding area changes resulting in the requirement of precise mapping over time. The current study presents the exploitation of new technologies including TLS, UAV and DInSAR for landslide monitoring that were applied in different sites within the Greek territory.

ABSTRACT. The purpose of this research is to combine two state-of-the-art technologies in surveying for extracting the rock thickness above a cavity. By combining Lidar technology for indoor surveying and photogrammetric processing of Unmanned Aerial Systems (UAS – drones) data, we managed to calculate and project with high accuracy the rock thickness of the roof of the underground environment of Koutouki Cave (Peania, Greece). Usually, cave systems are complex and unique because of their distinctive geometry and compound geomorphology along with natural harsh conditions such as constrained accessibility, limited light, high humidity and possible existence of water. Such environments make mapping difficult and further complicated (Kershaw, 2012). Nowadays, the state-of-the-art in surveying of open surface is based on LiDAR technology. Lately, similar technology has started to be used for indoor surveying and consequently in cave mapping, especially where the underground space allows it. Our research was based on the use of a recently released piece of equipment introducing a lightweight mobile handheld laser scanning system (GeoSLAM ZEB – REVO) that has the ability to produce a quite dense point cloud within an underground cavity. The x, y, z point cloud is generated while the operator walks through the cave (Zlot and Bosse, 2014). The specifications of this equipment include a 360o rotation, a (class 1 eye safe) 100Hz laser – making 100 rotations per second with the collection of 43,200 points per second. The maximum effective range is around 25-30m for indoor environment and data over 30m are usually excluded.

ABSTRACT. Rockfalls consist one of the most dominant geological hazards in mountainous rocky regions with the potential to turn catastrophic if occurs in the anthropogenic environment. Due to that fact, the identification of the possible locations to produce the phenomenon is of high importance. Susceptibility is the parameter describes these locations and the qualitative and quantitative assessment of it is necessary for the timely treatment of a possible rockfall occurrence. However, this approach requires some critical rock mass characteristics to be known. These ones that govern the phenomenon and so the more detailed acquisition of them increases the calculations reliability. Such data acquisition can be achieved by implementing conventional mapping methods as well as remote sensing techniques like LiDAR (Light Detection and Ranging) scanners. The LiDAR technology is extremely preferred the last decades in the field of Geosciences, providing many advantages against the pre-existing methods (Abellán et al., 2009; Lato et al., 2009; Kromer et al., 2018). In the current study, LiDAR technology was implemented to extract the appropriate parameters can be used for the rockfall susceptibility assessment. The study area was the limestone slopes in Perissa area at the southeastern part of Thera island at Santorini complex. After data processing, joint orientation parameters, joint spacing and block volumes were extracted. Parameters which are usually either statistically or at confined areas estimated considering homogeneous rock mass in them respect. The extra element this methodology provides is the creation of spatial distribution maps of the above-mentioned parameters, taking into account the fluctuation of their values along the slopes. Thus, the produced result can be used in the spatially-specific susceptibility assessment without considering each slope or formation as an entire susceptibility mapping unit. The data processing is extensively analyzed step by step providing the reader with the desirable view of the whole procedure. Finally, the results produced by the current methodology are validated and interpreted according to in-situ records and measurements as well as manually extracted measurements on the point clouds. Study area In particular, the study area is part of the internal Hellenic Volcanic Arc and geologically belongs to the Atticocyladian geotectonic zone’s bedrock. Located on the southeastern part of Thera, represents one of the two pre-alpine bedrock exposures on the island, and specifically the indigenous unit, as the rest is covered by the later volcanic activity’s products. Perissa’s cliffs belong to the wider carbonate formation of Profitis Ilias that consists of Early Cretaceous recrystallized limestones which compose the semi-metamorphosed bedrock of the Atticocycladian zone and specifically the South Cyclades Unit. The landscape of the coastal Perissa area is in general very steep with dipping up to 70 degrees, heights up to 50 m and face towards the SW and SSW. Data acquisition The LiDAR data was obtained by using an Optech ILRIS-3D long-range terrestrial laser scanner and the survey planning aimed to acquire a dense and high-resolution dataset for the detailed mapping of all necessary parameters required in the direction of rockfall susceptibility. In specific, five predefined scan locations were used to cover the different slopes formed along the entire cliff with the most feasible overlapping, given the buildings that exist in a small distance from the slopes, in order to minimize the orientation bias and occlusion effect. The obtained point clouds were merged and geo-referenced by utilizing on-slope-placed targets and their absolute coordinates measurements taken from a total station as they were easily identified within the dataset due to the high resolution. The entire dataset consists of more than 15 million points. Methodology The proposed methodology initially aims to the orientation estimation of the individual slopes formed along the cliff as well as the discontinuity sets, following aproaches proposed by Riquelme et al., 2014. Sequentially, joint spacing values are extracted for each discontinuity set according to Riquelme et al., 2015 and based on these geometric parameters the block volume distribution is estimated. Furthermore, a spatial distribution map (Figure 1) for each of the above-mentioned parameters is created providing the desirable spatial information which a further analysis could be based on in order to produce a spatial-aimed result rather than a single susceptibility value for each individual slope. Current methodology’s implementation was carried out by using CloudCompare and ArcGIS software as well as numerous Matlab algorithms on DSE software package. Results Principal discontinuity sets orientations extracted from the used semi-automated methodology are presented and compared with the conventional compass measurements taken in-situ. Furthermore, statistics, graphs and maps illustrate the distribution of each discontinuity set orientation, spacing value, as well as the block volume, are listed. It is commonly accepted that the block volumes formed along a slope are the very critical parameter for the rockfall susceptibility assessment. Moreover, further space-resolved stability analyses for the susceptible-defined areas can be carried out utilizing the spatial distribution maps produced by this methodology. The authors also utilized the extracted orientation data in order to create the corresponding stereoplot to each slope and detect the governing failure mechanism on each of them. The parameters being extracted from the proposed LiDAR data processing methodology are spatially independent and display fluctuations along the cliffs. Thus, the main aftermath earned here is the fact that the rock masses are not represented realistically when being treated as homogenous and isotropic in respect of parameters such as joint spacing and/or block volumes. Sequentially, susceptibility is not represented any more by a specific value for an entire slope or a formation considered as a united mapping unit. Contrariwise, it can be changing defining the more and the less susceptible areas along the slopes. That fact leads the focus of interest, for additional analysis, only to certain areas and prevents the consumption of unnecessary funds and time in the entire united unit investigation.

ABSTRACT. A strong, shallow depth, earthquake (Mw=6.5) occurred onshore Lefkada island on November 17, 2015 with the focal depth estimated at 10 Km (Ganas et al., 2016). Lefkada has been repeatedly struck by earthquakes during the last century (1911-2015). The surface magnitude (Ms) of instrumentally recorded earthquakes ranges between 5.3 to 6.4. (Papathanassiou et al., 2005; 2017). The 2015 seismic fault is a near-vertical strike-slip fault running along the western coast, which is part of the CTF zone (Cephalonia Transform Fault). Landslides and ground cracks were mainly reported at the western part of the island, inducing structural damages. High severity slope failures occurred at Egremnoi and Gialos areas that both are located at western coastal regions. This study aims to investigate the engineering geological conditions at those areas assigned based on GSI classification, and assess the characteristics and physical quantities (eg. type, area-m2, volume-m3) of the instabilities. In order to achieve this, a field survey was conducted in July 2016 and landslide characterization was conducted in Eggremnoi and Gialos areas with the use of UAV imagery in relation with engineering geological mapping (Grendas et al., 2018). Furthermore, types and dimensions of slope failures were evaluated in order to estimate the total volume of the mass movement. Structure-from-Motion models produced by UAV images (using Agisoft Photoscan software) permitted the accurate and detailed identification and mapping of co-seismic failures. Moreover, all the field data from the engineering geological mapping, have been digitized and rasterized at 5 m grid spacing using ArcGIS. The outcome of the present study is the precise calculation of the area-m2 and volume-m3 regarding the slope failures and the correlation among the pre mentioned failures with the existing engineering geological conditions. The limitations of UAV surveys at the specific region are also presented.

ABSTRACT. According to the World Atlas of Natural Hazards (McGuire, 2004), landslides are the most frequent and widespread natural hazard on Earth. They can occur on any terrain, particularly hilly and mountainous areas and mostly given the suitable conditions of soil or bedrock, groundwater, and the angle of slope (Varnes, 1978). Landslides can be characterized by low probability of evolution into a catastrophic event but can have very large direct and indirect impacts on man-made structures (Klose et al., 2014). Mapping of existing landslides in areas of known slope instability produces maps that can potentially deliver knowledge for landslide risk management strategies. Landslide activity maps represent a shortcut in the assessment of the hazard related to slope movements (Parise and Wasowski 1999), and show the areal extent of slope subject to failure, probable maximum extent of ground movement and highlight areas where more detailed studies should be conducted. “Traditional” ground motion monitoring methods are based on field surveys. These methods include mainly geodetic/levelling measurements and Global Positioning System (GPS) networks, extensometers etc. However these methods of ground deformation monitoring except that provide information only about a few points present furthermore many disadvantages, such as high costs, time consuming and most of the monitoring systems require installation by experts of special equipment which in many cases is impossible nor are they able to produce knowledge of the past (retrospective products). Earth Observation (EO) satellites, a non invasive source of knowledge, host a diverse range of sensor types that utilize different parts of the electromagnetic spectrum (optical and radar sensors), a very rich archive of scenes and different techniques to provide a range of measurements from space offers several opportunities to map and monitor natural and human-induced Earth hazards from space (Cigna, 2018). Specifically, for landslides the ability to quantify them from space using repeat imagery depends, in principle, on the precision of the method used, the total displacement between two data acquisitions, the rate of displacement, and the existence of corresponding features in phase data (for radar) or amplitude data (for radar and optical sensors) that can be tracked over time (Delacourt et al., 2007, Kääb and Leprince 2014). Since 90’s differential repeat-pass interferometry radar (DInSAR) based on SAR images processing has proven an interesting tool for the measurement and observation of ground deformation (Massonnet and Rabaute., 1993). The basic idea of the method is the analysis of the phase of the reflected wave radar from two or more images which cover the same region to observe ground displacement. In recent years using large stacks of SAR images acquired over the same area, long deformation time series can be analysed using multitemporal differential SAR interferometry techniques which overcomes several limitations of repeat-pass interferometry. These coherent methods exploit either permanently coherent Persistent Scatterers (PSs) or temporally coherent Distributed Scatterers (DSs) known by names Persistent or Permanent Scatterer Interferometry (Ferretti et al., 2001, , Werner et al.,2003 ) and Small Baseline Subset (Berardino et al., 2002) Both techniques have been widely applied for monitoring of slope instability with millimetric precision (Raucoules et al., 2013, Casagli et al., 2017). The most important advantage of the method is the ability to construct maps of yearly rates of ground displacement or the change to the rates. Nevertheless, significant difficulties are found when using this technique. These difficulties are related to the large variability of slope (steep and rough topography typical of landslide-prone areas) instabilities in terms of mechanisms of movement, failure geometries, size of unstable areas and deformation rates causing phase ambiguity problems and signal decorrelation. Additionally, in regions with strong topographic relief presented local atmospheric variations can in many cases lead to strong atmospheric phase artifacts; all these parameters , often obstract the interferometric pre-processing, making it difficult to estimate surface displacements (Hanssen 2001, Delacourt et al., 2003, Strozzi et al. 2005). Monitoring and measurement of landslide activity using optical satellite sensors is also an efficient method which has been used since the end of 70’s (Sauchyn and Trench 1978) mainly based on visual interpretation.The increasing of Very High Resolution (VHR) optical sensors, since beginning of 2000, led to the increase of new methods to monitoring land motion including landslides although that optical images are strongly dependent on atmospheric conditions. The methods can be split into two categories, pixel-based and object-based, both containing techniques applicable to single and multi-temporal images and frequently making use of additional data. In recent years and from the beginning of the anvailability of high resolution optical data different methods with processing differentiation and in order to improve the accuracy of the measurements under different conditions have been developed. The current research work aims to examine further contribution of medium resolution of free optical satellite images and specifically Sentinel 2 in the mapping of landslide of moderate and/or rapid velocity of travel regardless of the cause induced them in three different area specifically in USA (Yakima County, WA), Italy (Ponzano, Central Italy) and Greece (Amyntaio, Northern Greece). Also validate the results based on knowledge derived from other sources of knowledge. For the purpose of this study the normalized cross-correlation (NCC) method of image matching was used (Debella-Gilo and Kääb 2010, Heid and Kääb, 2012). References Bamler, R.; Hartl, P. Synthetic aperture radar interferometry. Inverse Probl. 1998, 14, R1-R54 Berardino, P., Fornaro, G., Lanari, R., Sansosti, E., 2002. A new algorithm fro surface deformation monitoring based on small baseline differential SAR interferograms. IEEE Transactions on Geoscience and Remote Sensing 40 (11), 2375–2383 Casagli N,Frodella W,Morelli S,Tofani V,Ciampalini A,Intrieri E,Raspini F,Rossi G,Tanteri L, Lu P(2017) Spaceborne, UAV and ground-based remote sensing techniques for landslide mapping, monitoring and early warning. Geo Environ Disasters 4.1(9):1–23 Cigna F., 2018. Observing Geohazards from Space. Geosciences, 8, 59, doi: 10.3390/geosciences8020059 Debella-Gilo M. and Kääb A. (2010): Sub-pixel precision image matching for measuring surface displacements on mass movements using normalized cross-correlation. Remote Sensing of the Environment, 15(1):130-142. Delacourt, C., Allemand P., Berthier E., Raucoules D., Casson B., Grandjean P., Pambrun C., Varel E., (2007). Remote-sensing techniques for analysing landslide kinematics: A review. Bulletin de la Societe Geologique de France. 178. 89-100 Ferretti, A., Prati, C., Rocca, F., 2001. Permanent Scatterers in SAR Interferometry. IEEE Transactions on Geoscience and Remote Sensing 39 (1), 8–20 Hanssen, R.F. 2001 Radar interferometry: data interpretation and error analysis. In Remote Sensing and Digital Image Processing; Kluwer Academic: Dordrecht, Netherlands, Heid T. and Kääb A.(2012): Evaluation of existing image matching methods for deriving glacier surface displacements globally from optical satellite imagery, Remote Sensing of Environment, 118, 339-355. Kääb A. and Leprince S. (2014): Motion detection using near-simultaneous satellite acquisitions. Remote Sensing of Environment, 154, 164-179. DOI: 10.1016/j.rse.2014.08.015 Massonnet , D.; Rabaute, T. 1993 Radar interferometry: limits and potential. IEEE Trans. Geosci. Remot. Sen., 31, 455-464 McGuire, B. (2004). World atlas of natural hazards, London: Arnold, 120 p Parise M., Wasowski J., 1999 Landslide activity maps for landslide hazard evaluation: three case studies from Southern Italy. Natural Hazards, Vol. 20, 2-3, 159-183 Raucoules D., de Michele M., Malet J.-P., Ulrich P., 2013, Time-variable 3D ground displacements from high-resolution synthetic aperture radar (SAR). application to La Valette landslide (South French Alps), Remote Sensing of Environment, Volume 139, 198-204. Sauchyn D. and Trench N. (1978) Landsat applied to landslide mapping. Photogrammetric Engineering and Remote Sensing 44, No.6, pp. 735-741. Stumpf, A.; Malet, J.P.; Allemand, P.; Ulrich, P. 2014 Surface reconstruction and landslide displacement measurements with Pléiades satellite images. ISPRS J. Photogramm. Remote Sens., 95, 1–12. Strozzi, T., Farina, P., Corsini, A., Ambrosi, C., Thüring, M., Zilger, J., Wiesmann, A., Wegmüller, U., Werner, C., 2005. Survey and monitoring of landslide displacements by means of L-band satellite SAR interferometry. Landslides 2 (3), 193–201 Varnes, D. J. (1978). Slope movement types and processes. In: Special Report 176: In: Schuster, R. L. & Krizek, R. J. (Eds.) Landslides: Analysis and Control. Transportation and Road Research Board, Special report 176: 12-33, National Academy of Science, Washington D. C. Werner, C., Wegmüller, U., Strozzi, T., Wiesmann, A. (2003). Interferometric point target anaysis for deformation mapping. In Proceedings of the IEEE International Geoscience and Remote Sensing Symposium, Toulouse, France, July 2003, 7, 4362–4364

ABSTRACT. During the last decade, there has been an increasing demand in geo-engineering society for automatically monitored areas susceptible to landslide and catastrophic rockfall events. Traditional methods were supplemented, mostly by in-situ observational methods held by experts or by point-based approaches such as inclinometers and GPS measurements. Lately, we were given the opportunity to apply active sensors such as Terrestrial Laser Scanning (TLS) technology or passive ones such as Unmanned Aerial Vehicle (UAV) photogrammetry, as a result of the introduction of innovative remote sensing technologies as a common practice. This change has led to more accurate, precise and time-effective local scale modelling of the landslide event. Specifically, Structure from Motion (SfM) methodology enabled the production of ultra high-resolution orthomosaic and Digital Terrain Models (DTMs) of hazardous regions, via detailed point clouds. The current research demonstrates a powerful approach to precisely foresee potential rockfall hazards in the area of interest, based on a multi-temporal change detection procedure in time intervals in order to prevent any undesired consequence via the integration of innovative remote sensing tools and the suitable analysis of their results. The investigated site is located in Santorini island, Greece and is called “Apothikes”. Specifically, the area is situated in the southern part of the island, east of the Akrotiri village, on a road that leads to the only beach that lays inside the caldera region. Various rockfall incidents of significant magnitude have been recorded in the slope over the years, mainly connected with external triggering factors and especially occurring after heavy rainfall. These rockfalls have caused numerous destructions on the road and have concluded to its temporary disruption in the past. These blocks are not only confined along the road but can also reach the seacoast. The significance of this specific region in which the research is held originates from the notable human activity (hotel, residences) that takes place at the top of the slope as well as the restlessness tourist activity during the year which is especially observed in the area of the beach located directly under the prone area. Specifically, “Apothikes” comprise one of the most tourist destinations in the whole island. Consequently, it is indispensable to provide accurate and precise precognitions of any potential rockfall hazard because of their significant environmental and commercial impacts. In general, the volcanic complex of Santorini belonged to the volcanic arc of South Aegean and is the most active globally. The commission of this complex is based lengthwise in two main volcano-tectonic lines with a NE-WS strike. The area is geologically characterized by successive alternations of volcanic beds of strong ignimbrite and soft layers of pyroclastic materials with different engineering properties. The morphology consists of very steep slopes (≤80°) with highly steep dip discontinuities (76°-90°) which have significant persistence. All these parameters constitute to differential erosion and undercut in the base of the slope which develop tensile tenses and eventually lead to the loss of the rockmass cohesion and finally the failure of the previously suspended unstable blocks of ignimbrite (≤4m³) from a notable height (≅15m). The main failure mode comprises rock pillar detachment followed by toppling or planar sliding failure, which result to their fragmentation. The fallen blocks reveal fresh surfaces and as a result, the laterally blocks exhibit a lack of confining stress. Consequently, new cracks begin to emerge and the same process accelerates. Analytically, in this particular case, multi-sensor fusion and multitemporal change detection techniques were performed among three different datasets derived from i) a Terrestrial Laser Scanner (TLS) during summer 2014 and ii) a UAV platform during summer of 2018 and spring of 2019 respectively. The aim of this procedure is to monitor and characterize topographical changes between different epochs for robust modelling of the rockfall’s dynamics. The proposed approach of multi-sensor change detection was accomplished with the correlation of the 3 multi-epoch models in order to quantify the rockfall’s displacements with computer-based methods. With the results of this comparison it was possible to classify the whole investigated area into sub-regions based on rockfall susceptibility. In order to precisely predict potential rockfall hazards in the area we proceed to a trajectometry simulation in the prone sub-regions. The produced Digital Surface Model (DSM), from the latest acquired dataset, was converted to hillshade via QGIS3.0. The prone blocks, that we have already spot, was analyzed and their potential trajectories was specified in both 3D and 2D display. This analysis gave us the capability to estimate the outcome (energy, velocity, height and travel time) of any potential rockfall event pre and post the implementation of remedial measures. It gives us confidence, that through this in-depth risk assessment we can mitigate potential miscarriages of the protection measurements that can be possibly applied in these certain sub-regions. To conclude, all these innovative remoting sensing technologies provide the researcher many benefits compared to conventional methods. For instance, they pose great data transferability, completeness, precision and accuracy in the research study. Additionally, due to their capabilities they can produce holistic region measurements, which constitutes very important parameter for the whole geo-engineering society in order to scale up research area without degrading the measurement quality. At last, it is important to highlight UAV ability to eliminate user’s risk to get harmed in order to gain access in some inaccessible areas via their remoted technology. This study demonstrates that, they could be considered as a valuable supplemental tool in engineering geology to investigate the quantification of rockfall hazard via a multitemporal change detection analysis and to create an accurate potential failure mechanism model. However, it is significant to mark the importance of fieldwork, site investigation and the geological judgment of the researcher because it is essential to be able to test the validation and the quality of the obtained information.

ABSTRACT. Ore reserve estimation is traditionally developed using a model of selected deposit attributes, created by discretizing them into small blocks. Among these attributes, the thickness and the grade are the most critical for the ore reserve estimation. The thickness and the quality characteristics of the deposit are determined by several factors related to the usually complicated geological process which led to the deposit formation. Many of these factors are not well known and cannot be brought easily into a conventional mathematical model. Any attempt to model the geometrical and quality characteristics of a deposit inevitably requires simplifications and assumptions of the spatial variation. The existing methods are mainly based on either geometrical reasoning or statistical techniques and generally assume that the spatial distribution of the modelled parameters is a function of distance. Artificial Neural Networks (ANNs) have provided a new approach for the estimation of the reserves of a deposit. Since the ANNs are not only trainable nonlinear dynamic systems but also adaptive model-free estimators, no assumption concerning the spatial variation of the deposit attributes need to be made. The basic approach for developing ANN model for the ore reserve estimation is to train the model using an existing borehole data set and appropriate learning methods. The way that available data are divided into training, testing, and validation subsets can have a significant influence on the performance of an ANN. This study presents methods for dividing borehole data into these subsets considering spatial and quality criteria. These methods are compared with the conventional approach commonly used in the literature, which involves an arbitrary division of the data.

ABSTRACT. A. Tompolidi1,2, O. Sykioti1, K. Koutroumbas1, S. Xenaki1, I. Parcharidis2 (1) Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, V. Pavlou & I. Metaxa, Penteli, Greece, atompolidi@noa.gr (2) Harokopio University of Athens, E. Venizelou Avenue 70, Kallithea, Greece.

The aim of this study is to investigate the potential of detecting and mapping hydrothermal alteration from Sentinel-2 data, using an innovative clustering algorithm, as well as the interpretation of the resulting clusters using spectral indices (SIs) linked to the hydrothermal alteration within the caldera of Nisyros.

Geological setting Nisyros is a small, almost circular, island, which constitutes the youngest volcano of the South Aegean Active Volcanic Arc (SAAVA) with a central caldera depression of 4km diameter (Fig. 1a). The volcanic edifice, entirely formed during the Late Quaternary, lies above an Alpine basement of Mesozoic limestones and is characterized by calc-alkaline series (from basaltic andesitic to rhyolitic composition) (Francalanci et al., 2005). In historical times, several hydrothermal eruptions took place in the south-eastern part of the caldera generating hydrothermal craters. Nowadays, various fumarolic fields are present in the hydrothermal crater area (Gorceix synthem) with the major fumarolic vents to be located in the craters of Stephanos, Polybotes (Micros Polybotes and Megalos Polybotes) and Phlegethon and the minor fumarolic vents in the Kaminakia craters area (Marini et al., 2002). In these areas, steam-heated, acid sulfate hot waters are formed, due to O2-driven oxidation of H2S to H2SO4, where ascending hydrothermal gases condense, in shallow groundwaters or surface waters. These acidic solutions react with the host rocks and form advanced argillic alteration.

Materials Recent studies have shown the capabilities of Sentinel-2 MSI data in geological and lithological mapping (Van der Meer et al., 2014, Ge et al., 2018). For the purpose of this study, a Sentinel-2A MSI L1C image was used, acquired on 22/7/2017. The image has been atmospherically corrected with the Sen2Cor tool within ESA’s SNAP software. The resulting bottom-of-the-atmosphere reflectance dataset, consisting of 12 spectral bands with 10m spatial resolution, was then subset to the caldera area.

Methodology The adopted methodology consists of the following processing steps: a) Projection of the data on the space spanned by the first three principal components. b) Application of the Online GAPCM (O-GAPCM) clustering algorithm on the projected data. The O-GAPCM is a possibilistic clustering algorithm, which has the ability to recover the true number of clusters, while, in addition, it can identify hyperellipsoidally-shaped clusters, formed in the feature space (Xenaki et al., 2018). c) Comparison of the clustering results with the georeferenced simplified geological map of Nisyros (1:12.500) (Volentik et al., 2005), in order to investigate whether the hydrothermal alteration area of the Gorceix synthem is identified. d) Interpretation of the clusters covering the Gorceix synthem and the surrounding area, using the hydroxyl-bearing alteration (SI-i), the all iron oxides (SI-ii) and the ferric iron oxides (SI-iii) spectral indices (Van der Werff & Van der Meer, 2016).

Results The O-GAPCM algorithm has produced five clusters within the Nisyros caldera (Fig. 1b). In the sequel, we focus on the following three clusters: Clusters 1 and 2, which according to the simplified geological map exhibit significant overlap (69%) with the hydrothermal area (Gorceix synthem) (Fig. 1a) and Cluster 3, which covers the surrounding area. As shown in Figs. 1b-1c, Clusters 1 and 2 differ from Cluster 3, in terms of hydroxyl-bearing alteration (SI-i), all iron oxides (SI-ii) and ferric iron oxides (SI-iii) presence. Cluster 3 is mainly characterized by the presence of iron (both ferric and all iron oxides), which is in accordance with Seymour and Lalonde (1991). In particular, all iron oxides (west of the Gorceix synthem) are mainly detected οn post-calderic dacitic lava domes (Profitis Ilias synthem) and ferric iron oxides (east of Gorceix synthem) on lacustrine intracalderic deposits (talus, aluvion and beach) (Fig. 1a). In contrast, Clusters 1 and 2 exhibit stronger hydroxyl-bearing alteration than Cluster 3 (Fig. 2). Focusing on Clusters 1 and 2, the former is characterized by a strong presence of both all iron oxides and hydroxyl-bearing alteration, while the latter is mainly characterized by strong hydroxyl-bearing alteration (Fig. 1c). Concluding, Sentinel-2 data seem to contain the necessary spectral information for the detection of hydrothermal alterations in a geothermal volcanic environment, which can be extracted using clustering methods. Current investigations include the examination of the mineralogical content of the alteration zones inside the Nisyros caldera, utilizing Sentinel-2 and/or other multispectral data.

Acknowledgements We acknowledge support of this work by the project “PROTEAS II” (MIS 5002515), which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure,” funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014–2020) and co-financed by Greece and European Union (European Regional Development Fund). The authors would like to thank Dr G. E. Vougioukalakis, for providing additional field information on Nisyros.

References Francalanci, L., Vougioukalakis, G.E., Perini, G. and Manetti, P., 2005. A West-East Traverse along the magmatism of the south Aegean volcanic arc in the light of volcanological, chemical and isotope data. In Developments in Volcanology (Vol. 7, pp. 65-111). Elsevier. Ge, W., Cheng, Q., Tang, Y., Jing, L. and Gao, C., 2018. Lithological classification using sentinel-2A data in the Shibanjing ophiolite complex in inner Mongolia, China. Remote Sensing, 10(4), p.638. Marini, L., Gambardella, B., Principe, C., Arias, A., Brombach, T. and Hunziker, J.C., 2002. Characterization of magmatic sulfur in the Aegean island arc by means of the δ34S values of fumarolic H2S, elemental S, and hydrothermal gypsum from Nisyros and Milos Islands. Earth and Planetary Science Letters, 200(1-2), pp.15-31. Seymour, K.S. and Lalonde, A., 1991. Monitoring oxygen fugacity conditions in pre-, syn-and postcaldera magma chamber of Nisyros volcano, Aegean island arc, Greece. Journal of Volcanology and Geothermal Research, 46(3-4), pp.231-240. Van der Meer, F., Hecker, C., van Ruitenbeek, F., van der Werff, H., de Wijkerslooth, C. and Wechsler, C., 2014. Geologic remote sensing for geothermal exploration: A review. International journal of applied earth observation and geoinformation, 33, pp.255-269. Van Der Werff, H. and Van Der Meer, F., 2016. Sentinel-2A MSI and Landsat 8 OLI provide data continuity for geological remote sensing. Remote sensing, 8(11), p.883. Volentik, A., Principe, C., Vanderkluysen, L. and Hunziker, J., 2005.Explanatory notes on the "Geological Map of Nisyros Volcano (Greece)". In: Hunziker JC, Marini L (eds): The geology, geochemistry and evolution of Nisyros Volcano (Greece). Mémoires de Géologie (Lausanne), No.44 : 7–25. Xenaki, S.D., Koutroumbas, K.D. and Rontogiannis, A.A., 2018. A Novel Online Generalized Possibilistic Clustering Algorithm for Big Data Processing. In the 26th European Signal Processing Conference (EUSIPCO), Rome, Sept. 2018.

ABSTRACT. Introduction The Ingessana hills in the southern Blue Nile of Sudan consist of serpentinized and highly silicified dunites in contact with the intruding Bau granite. The observed chromite mineralization zones are associated with NE-SW trending shear-zones. The mineralization associated with ophiolitic belts includes podiform chromite, asbestos, talc, and base metal (Cu, Ni, Co) mineralization. We applied Linear Spectral Unmixing algortithm on a 10m spatial resolution Sentinel-2 images in order to detect and map the chromite mineralization and the associated mineralization of ophiolitic belts. The resulting abundance maps show the capabilityof Sentinel-2 for detailed mineral mapping and detection of potential chromite ore depositlocations.

Background and Object The study area is located at the Ingessana Hills, in Blue Nile Province of Sudan (Fig. 1). The dominant basement rocks consist of serpentinised hartzburgites and dunites with metadolerite, epidiorite and gabbro surrounded by psammopelitic metamorphic rocks and cropping out around the hill (Fig.1). The chromite mineralization is mainly concentrated in the western side of the Ingessana Hills as lenses, veins, in irregular patches and disseminated deposits, in the serpentinites and talc carbonate rocks of the dunite –peridotite gabbro (Ibrahim, 2003 ). The lenses and the veins generally strike NNW with steep dips.

(a) (b) Figure 1.(a) Colour composite of the mosaic Sentinel-2 image after equalization stretching of the study area [R:12 (2,19μm), G:8Α (0,86μm), B:3 (0,56μm)]. The red lines correspond to the main faulting. In the cyan box is the area of the abundance images that are shown in fig.2. (b) The red box indicates the location of the study area in Sudan.

Methodology In this study, we used two adjacent Sentinel 2 (S2B) images Level 1C, acquired on19/02/2019 and on 29/02/2019. After atmospheric correction, the two images were mosaicked (Fig.1). The output reflectance image has 12 spectral bands and 10m spatial resolution.We then performed Linear Spectral Unmixing (LUN). The LUN approach assumes that the reflectance of each pixel is a linear combination of the spectral signature of each material (endmember) present in the pixel (Keshava & Mustard, 2002) and determines its relative abundance, based on its spectral characteristics.Compliant to the geology of the area, the spectral signatures of talc, chlorite, chromite, limonite, hematite, antigorite, epidote, quartz, tremolite, chrysotile and dolomite were retrieved from the USGS Spectral Library. We applied a Least Squares LUN with a positivity constraint. The abundance map for each endmember was calculated (Fig. 2). The abundance values were then normalized between 0 and 1.

Results and Conclusions Chromite is detected west and east of the Ingessana Hills (Fig. 3). The easternmost outcrops of chromite are accompanied by high limonite abundances, indicating that they are rich in iron (Fig. 2a, b). Limonite has also been detected at an extended area aligned to the NE SW faulting of the Ingessana Hills. Antigorite, seems to have the same spatial extent with chromite (fig.2c), while chrysotile (fig.2d) is detected at the fringes of serpentinised rocks in contact with metasediments. Τhe proposed areas for further investigation are presented in fig.3.The results are in a good agreement with literature, unpublished reports and with the geological map, including locations of current mining sites.

(a) (b) (c) (d) Figure 2.Spectral Linear Unmixing (LUN) result. Abundance images of (a) chromite, (b)limonite, (c) antigorite, (d) chrysotile. Black and white areas correspond to low and high mineral abundances correspondingly.

Figure 3. CCF image of the abundances of: R: Chromite G:Vegetation B:Antigorite. The proposed locations for further investigation are shown (red squares).

References Babiker I. M., 1982. The chromatiferous ultrabasic rocks of Jebal El Ingessana, Eastern Sudan. Precambrian Research Volume 16, Issue 4, p.p. A44-A45. Ibrahim M., 2003. Information about Ingessana Hills artisanal Gold Mining Sites chosen for the environmental and health assessment. Global Mercury project Eg/GLO/01/G34. Keshava N. and Mustard J.F., 2002. Spectral unmixing, IEEE Signal Process., vol. 19, no. 1, pp. 44–57. Mohamed-Ali M.A., Simos J., Kheiralla K.M.,2017. Chromite exploration using electrical resistivity tomography in Ingessana Hill, Blue Nile, state Sudan. Proceedings of 119th the IIER International Conference, Putrajava, Malaysia, 4th – 5h September 2017 . Yassin A., Khalil F. A.,GadirA. S., 1984. Explanatory note to the Geological Map at the scale 1.200.000 of the DemographicRepublic of the Sudan.Department of Energy and Mining Geological & Mineral resources Department, Bulletin 35.

ABSTRACT. A Risk-based analysis of Engineering Geology Failures in Pipeline Corridors Investigations

P.–M. Spanidis¹, C. Roumpos², K. Liakoura²

⁽¹⁾ ASPROFOS Engineering S.A., Division of Project Management, 284 El. Venizelou str., 17675 Athens, Greece.

⁽²⁾ Public Power Corporation S.A. of Greece, Mines Central Department, 29 Chalkokondili str., 10432 Athens, Greece.

Pipelines are safe and environmentally friendly means for transportation of oil and gas over long distanced areas ^{(1), (4)}. The investigation of the terrestrial corridors within which the pipeline systems are developed is a multidisciplinary and multitasking process of high complexity ⁽⁴⁾. This process is iterative and starts with examinations in a wide ‘corridor of interest’ and then narrows down to a more defined route at each engineering/design stage insofar more data is acquired to a final zone (also known as: ‘Right of Way’-ROW) that is finally identified as appropriate for the pipeline erection/construction. The scope of this process is the performing of an integrated assessment of various corridor alternatives by considering critical environmental, geological, geotechnical, social factors and natural hazards as well. For this reason, teams consisting of experts from various disciplines of science and technology (managers, geologists, environmentalists, archaeologists, sociologists, surveying engineers, piping designers, etc.) make all necessary evaluations to produce appropriate assessments from which the most advantageous corridor can be demonstrated and selected in relation to criteria of technical feasibility, constructability, safety, environmental compliance, cost effectiveness, public acceptance and permitting.

Engineering Geology ⁽⁶⁾ constitutes a significant, crucial and sensitive part of that process. The objective of geological investigation is the analysis of the consistency of stratigraphic and soil formations, the geographic, terrain and landform features and the determination of soil geotechnical properties within the corridors under examination. The interpretation of geological layouts and laboratory results from tests performed on material collected from boreholes and site tests, constitute an instrument providing inputs valuable for the structural designs of the buried pipeline sections. These inputs derived from investigations of pipeline route encroachments of instable/loose formations, active faults, erosive or rocky sites, steep slope locations, soils prone to buoyancy or liquefaction and water crossings. Even important for the quality and efficiency of the pipeline design studies is the consideration of historical seismic data and determination of the seismic action parameters ⁽⁵⁾ in determining the earthquake effects to the pipeline body at the wider areas where the alternative corridors are to be developed ⁽¹⁾.

The investigation of pipeline corridors is a combination of desktop studies, extended field surveys as well as soil sampling and laboratory testing works. It is common practice the route corridor investigations to be performed in the early stage of the pipeline projects, where various supply chain scenarios are under examination and the technical philosophy of the pipeline system at hand has not yet come to a level of solid technical maturity. This fact combined with a number of other factors such as, managerial deficiencies, lack of appropriate expertise, low cost investigations, tight time schedules, non-completely developed project organization and planning schemes and low reliability baseline data/studies, might generate failures with potential effects to the quality of the engineering and design studies. In terms of the Engineering Geology, these failure risks represent any low quality/reliability data of surface/subsurface geology, hydrogeology, tectonics and seismicity, which, once they have inserted in the designs and calculations of other technical/technological studies, generate risks inserting the entire pipeline project time and cost overruns.

There are several types of Engineering Geology failure causes observed pipeline route corridors investigations with crucial impact in the elaboration of basic and detailed engineering studies (topographical, civil, mechanical, pipeline crossing and environmental design, structural and stress analyses ⁽⁵⁾. The main categories of risk generating failures are:

1. Incomplete or low performance site surveys: refers to failures in field data collection, improper fieldworks logistics, omissions in visiting areas of geological/geotechnical/hydrogeological concern, inadvertent soil sampling and drilling works, insufficient experience of site personnel, inappropriate evaluation of crossings morphology, non-availability of field instrumentation/equipment, reactions of local communities, landowners or stakeholders reactions against the geotechnical research, permitting dysfunctions and weather conditions;
2. Desktop Analysis failures: refers to failures related to inappropriate spatial analysis of baseline geographical data of the under evaluation corridors, lack of remotely sensed and satellite imagery/spectral data, limitations of GIS/software capabilities, information technology (IT) equipment and hardware defects, time elapsing in transforming conventional mapping products to digital form, etc.;
3. Poor scientific background and evidence: refers to non-availability of previous substantial geological studies and surveys ⁽¹⁾, misuse/misinterpretation of baseline maps, satellite imagery and remote sensing products and ortho-photo-rectified maps, poor literature reviews and scientific knowledge acquisition;
4. Managerial dysfunctions: refers to failures caused by budgetary limitations, lack of managerial capabilities, poor planning, organizational limitations, non-finalized project scope definition, unjustified delays in decision-making, uncontrolled delays in obtaining permissions, lack of interface management and poor quality controls;

In view of the above, some reasonable research questions are raising up: is there any method of analyzing the nature of Engineering Geology failures and quantifying the associated risks? Is there any instrument of representing those failures into an ontology enabling probabilistic estimation(s) of risk failures? Are there any methods of examining risk-based scenarios analysis developed as a tool for project management improvement in pipeline contexts?

The objective of this paper is to suggest a methodology aiming to the better understanding/management of Engineering Geology failures based on application of quantitative methods and structured according to the following main tasks:

1. Understanding, identification and classification of Engineering Geology Failures that insert risks in multidisciplinary investigations of pipeline route assessments;
2. Developing a Risk-based analysis of Engineering Geology failures using the Analytical Hierarchy Process (AHP)^{(3), (4), (7)} technique for obtaining the probability of occurrence of failure risk factors/sub-factors based on knowledge aggregation and empirical evidence of pipeline route experts and engineering geologists (see Table-1);
3. To represent the identified failure causes in a Fault Tree Analysis (FTA)^{(2), (3), (8)} ontology enabling a top-down and bottom-up probabilistic analysis (see Figue-1);

The methodology is supported by a Case Study showing how the results of probabilistic analysis produced by the AHP and the FTA ontology provides an integrated approach of estimating time and cost overruns using the Expected Value (EV) function in engineering geology investigations. The methodology is advised as a low cost and soft computing solution, however, its techno-economic views and limitations have to be considered.

  Table-1: Probabilities of Failure Risks - AHP results                                    Figure-1: FTA Ontology

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[7] Saaty, T. L., (2008). Decision making with the Analytic Hierarchy Process, International Journal of Services and Sciences, vol.(1) No.1, pp. 83-98

[8] Vessely, W. E., Goldberg, F. F., Roberts, N. H., Haasl, D. F., (1981). Fault Tree Handbook, NUREG-0492, US Nuclear Regulatory Commission, Washighton DC.

ABSTRACT. Variography is an important step in any geostatistical resource estimation study. Calculation and modelling of experimental variograms using samples from irregular sampling patterns is a painful and time-consuming task. The more random the sampling pattern is, the more difficult it becomes to find directions and basic spacings (lags) that have a high enough number of sample pairs to produce reliable variogram points. Even after the application of directional and spacing tolerances, fixed lag variography can fail to produce interpretable experimental variograms that can be used to derive a model of the underlying structure. Finding directions that produce interpretable variograms can also be a fairly difficult task, even with the interactive and dynamic interfaces that most modern geostatistical packages provide. Variable Lag Variography (VLV) based on k-means clustering of sample pairs has been successfully used in the past to address the deficiencies of applying fixed lags and lag tolerances to irregularly spaced data. Sample pairs are grouped into clusters based on their sample distance, with the centre of each group representing a single variogram point lag, and the maximum difference in the group from this centre representing the particular variogram point lag tolerance. The study presented in this paper, takes the concept of variogram sample pair clustering one step further, using a k-means clustering process to derive the most populated directions in the sampling space. Sample pairs are first grouped into clusters based on their azimuth and plunge. Each cluster has a centre representing a particular azimuth and plunge (direction), and a radius representing azimuth and plunge tolerances. In these automatically produced directions, VLV is then applied to produce the experimental variogram, making maximum usage of the available sample pairs. This two-step automated approach can significantly reduce the time and effort required in producing the most interpretable experimental variograms from a set of irregularly spaced samples.

ABSTRACT. Management of groundwater recourses has been one of the most critical challenges facing human beings in the past few decades. Mapping groundwater levels and fluctuations provide a valuable source of information for various applications of human and urban activities as well as their impact on the environment. Al Ain region in the United Arab Emirates has been facing serious problems with the depletion of its groundwater resources in the past few decades. This problem has been intensified by the rising urban population, and expansion in agricultural activities. It has been judged to be prudent to continuously monitor groundwater levels from different observations well. Such study shall be useful for integrating water resources management, planning groundwater development, and sustainable water resources for agricultural and urban utilization. The water table levels from different observation wells around Al Ain city were interpolated using deterministic and stochastic interpolation techniques to predict the spatial distribution of water levels for the period between 2014 to 2017. It has been observed that groundwater level ranges from 2 m inside Al Ain city to 154 m at Remah district western of Al Ain city. The fluctuations of the groundwater level during the mentioned period will be presented and discussed. Furthermore, the study will provide the necessary steps in generating a hydrogeological model for sustainable water resources management.

In the Arabian Peninsula and particularly in United Arab Emirates (UAE) groundwater is a major source of fresh water supply particularly to agriculture. More recently, the socio-economic development, the high population growth and expansion in agriculture have placed enormous strains on the limited available water resources. Achieving sustainable water use and management practices is thus of vital importance. The development of an integrated water management strategy based on the long-term monitoring of changes in groundwater storage and its seasonal dynamics is a first step towards this goal.

Groundwater level in Abu Dhabi, United Arab Emirates (UAE) has been continuously subject to changes in both level and salinity. Due to the arid characteristics of the region, the enormous water consumption to meet the intensive urbanization and expansion processes comes mainly from the groundwater and desalinization plants. In addition, demands from agriculture, domestic and industrial sectors participate with more than 65% of the water consumption mainly from groundwater resources. A decrease of the groundwater level by as much as 80 m has been reported in some areas in Abu Dhabi emirate. Furthermore, the arid climate in UAE with less than 100 mm a year in average combined with the high evaporation rate (2-3 m/year) and the low groundwater recharge (4% of total annual water use) are more contributing to the scarcity of these resources.

Water wells in the study area offer information about depth to water provided from Environmental Agency of Abu Dhabi, some of these wells are productive wells which they use for farming and some are observation wells to monitor water table dynamics. Information obtained from both types of wells were used for studying aquifers parameters (permeability, porosity, storativity, so on), groundwater exploration, and furthermore for investigating land surface deformations. In recent years deterministic and stochastic interpolation techniques have been utilized to predict the spatiotemporal variability of water table levels inside the GIS environment. The benefit of using GIS environment that is providing better use of interpolation techniques to predict the spatiotemporal variations. This paper is focusing in identifying the variations of water table levels over space and time in Al Ain region to provide better understanding of groundwater dynamics in the study area.

Both stochastic and deterministic techniques provide a means for studying the spatiotemporal variability of water levels from close points. Stochastic interpolation methods import the spatial variability of the variable by using the spatial autocorrelation property, while deterministic interpolation methods use the values of the variable only. Stochastic interpolation techniques use both statistics and mathematical functions for interpolation, while deterministic interpolation techniques use only mathematical functions. The main methods of deterministic interpolation available in GIS software include triangulation with linear interpolation, Inverse Distance Weighted (IDW), spline and spline modified.

Stochastic methods have the capability of producing a prediction surface, but they can also provide some measure of the certainty or accuracy of the predictions. Ordinary kriging is a stochastic method that is common in GIS analysis tools. Kriging is similar to IDW (deterministic method) in that it weights the surrounding measured values to derive a prediction for each location. However, the weights are based not only on the distance between the measured points and the prediction location but also on the overall spatial arrangement among the measured points.

When using Kriging interpolation technique, the spatial autocorrelation is studied using the empirical semi variogram to investigate that close points are mores similar than far away points. Empirical semi variogram has variety of models that use to fit the plotting between semi-variance and the distance between points. The best fit model should be selected carefully because it will affect the prediction surface.

The provided water table levels data were in form of depth to water in meter with lithological description. These data were processed in ArcGIS software package to create point map showing the spatial distribution of water wells. In order to generate interpolated surface using stochastic technique the Geostatistical wizard of ArcGIS has been used to utilize interpolated surface of water table levels. Geostatistical wizard allows to construct and manipulate semi-variogram model to optimize the interpolation process and Kriging type used was Ordinary Kriging. Generating interpolation surface using Kriging method provide additional benefit of creating standard deviation surface to evaluate the accuracy of the interpolated surface. On the other hand, the interpolated surface using deterministic technique was generated using IDW method. A comparison between both methods have been conducted.

This study showed that depth to water increased during May to November (drought season) and return to decrease between December to April (rainy season). Interpolated surfaces generated from stochastic interpolation technique showed higher accuracy than surfaces generated from deterministic interpolation technique. Standard deviation surface maps from Kriging method showed a consistent value to consider the generated surface as optimum results. The trend of water table levels during this period showed a significant decrease and this can be result of the consistent drop in rainfall at the study area between 2014-2017 coupled by increase in groundwater withdrawals.

Acknowledgement This work is supported by a grant from the National Water Centre of the United Arab Emirates University under Grant number 31R155-Research Centre- NWC -3-2017.

ABSTRACT. In recent years Synthetic Aperture Radar Interferometry (InSAR) has proven to be a valuable tool for monitoring surface deformations occurred naturally (landslides, earthquakes, and volcanoes) or due to anthropogenic activities (extraction of underground materials such as groundwater, oil and gas) with acceptable accuracy. This research provides a general background behind InSAR technology and how it can be effectively used for detecting surface deformations; Persistent Scatterer Interferometry, Small Baseline Subset, Stanford Method for Persistent Scatterer, and Offset Tracking. Moreover, the research highlights and discusses the different strengths and weaknesses of InSAR techniques. The availability of SAR data from various satellites significantly improved this technology especially with collecting data from different radar frequencies (X-, C-, and L-band) and along both ascending and descending orbits. Furthermore, the research focuses on determining surface deformations over different types of landcover and highlighting the optimum methodology and data needed. The main challenges faced by the use of InSAR for mapping land surface deformations are summarized and discussed.

ABSTRACT. Hydrochemical diagrams aim at interpreting any evolution occurring in the groundwater systems. This paper is an effort to assess the groundwater quality and the geochemical processes using a diagram based on Chadha’s work (Chadha, 1999), who classifies natural waters, documenting Piper’s and extended Durov’s diagrams. The example of hydrochemical analyses were given from groundwater samples of Thriassion Plain. The study area (Figure 1) is located 25 km west of Athens and has undergone uncontrolled urban and industrial development. Geologically, it is dominated by alpine sediments represented by Palaeozoic volcano-sedimentary complex, Triassic phyllites and sandstone, limestones, dolomitic limestones and dolomites, and Cretaceous limestones. Post-alpine sediments of Neogene-Quaternary marls, clay and marly limestones conglomerates as well as Holocene clay, sands and gravels have filled in the basin (Katsikatsos et al., 1986). The post alpine tectonic activities (Papanikolaou et al., 1999) combined with the Pleistocene sea level fluctuations (Lambeck, 1996) is responsible for the current landscape: firstly a sequel of Pliocene to Lower Pleistocene movements gave born to the main neotectonic fault of Mt. Parnes (Lekkas, 2001; Mariolakos et al., 2001) at the northern edge of the study area. Later, in M. Pleistocene the extension fault of Aspropyrgos defined the basin of Eleusis; this activity goes on to date. As a result, a complex hydrogeological regime has been established in which a multi-layered confined aquifer system has been formed (Hermides, 2018). To attend our objective, sampling of 45 wells and boreholes along with measurement of basic physico-chemical parameters took place. The target anions Cl- , SO4-2 and cations Ca+2, Mg+2, Na+, K+, were identified with Ion Chromatography, while the HCO3- anion was characterized with titration. Then, hydrochemical sections, XY diagrams, distribution maps of ionic ratios as well as Gibbs diagrams (Gibbs, 1971) were used to identify origin of salinity and geochemical processes. Based on the relationship between TDS (meq/l) and Na/Na+Ca, Cl/Cl+HCO3 meq/l ratios these diagrams have shown that evapotranspiration (ET) and rock-water interaction that dominate the study area play an important role to the increase of groundwater salinity. All data were illustrated on a Chadha diagram (Figure 2) to interpret groundwater geochemical processes: this diagram uses simple spreadsheets excel file. Concentration meq/l % of (Ca+Mg)-(N+K) and HCO3- (Cl+SO4) are displayed onto X and Y axes respectively. The diagram is divided into 8 fields. The geochemical processes that occur in groundwater such as mix of fresh water with modern seawater (red dashed line and arrow 3 in Figure 2), refreshening (arrow1), mix of fresh water with aged water and possible ancient seawater influence (arrow 2), reverse cation exchange (double arrow 4) and base ion exchange are mainly presented in the fields 5, 6, 7, 8. The interpretation of the produced diagram highlights the stratigraphic factors and especially the clay strata occurrence that have isolated fresh groundwater from seawater. The abundant occurrence of clay deposits to the depth of the plain work as barriers to sea intrusion. Good quality groundwater has been identified which confirms the role of clay strata, showing evolution of saline to fresh water. References Gibbs, R.J., 1970. Mechanisms controlling world water chemistry. Sci. J. 170:795–840. [Journal Article] Hermides, D., 2018. Hydrogeological conditions of the Thriassion Plain basin with emphasis on the geohydraulic characteristics of the aquifers and the groundwater quality. PhD thesis, Agricultural University of Athens, pp 283. [Dissertation] Katsikatsos, G., Mettos, A., Vidakis, M., Dounas, A., Pomoni, F., Tsaila-Monopolis, S., Skourtsi-Koroneou, V., 1986. Geological map of Greece, in scale 1:50.000, ‘‘Athina-Elefsis’’ sheet, IGME publication, Athens. [Journal Article] Lambeck K (1996) Sea Level change and shore-line evolution in Aegean Greece since Upper Palaeolithic time. Antiquity 70(269):588–611. [Journal Article] Lekkas, E., 2001. The Athens earthquake (7 September 1999): Intensity distribution and controlling factors. Engineering Geology, Publ. Elsevier Science Ltd., Vol.59, 297-311. [Journal Article] Mariolakos, H., Theocharis, D., 2001. Shifting shores in the Saronic Gulf during the last 18,000 years and the Kychreia paleolimni. Proceedings of the 9th International Conference, Athens, Bulletin of Hellenic Geological Society XXXVI 1: 405-413. [Conference Proceedings] Mariolakos, H., Fountoulis, I., Sideris C., Chatoupis, T., 2001. Morphoneotectonic structure of Parnes’ Mt of Attica Proceedings of the 9th International Congress, Athens, Bulletin of the Geological Society of Greece, XXIV/1, 183-190. [Conference Proceedings] Papanikolaou D, Lekkas E, Sideris Ch, Fountoulis I, Danamos G, Kranis CH, Lozios L (1999) Geology and tectonics of Western Attica in relation to the 7-9-99 earthquake. Newsletter of E.C.P.F.E., Council of Europe, 3: 30–34. [Journal Article]

ABSTRACT. This article deals with the hydrochemistry of coastal aquifers of the Oropos plain, Attica, Greece (Fig. 1). The geological structure of the study area is complex consisted of: (i) alpine sediments of Permo-Triassic volcanosedimentary and carbonate rocks, ophiolites and Cretaceous limestone and flysch (Katsikatsos, 2000); and (ii) post-alpine lacustrine, lagoon and torrential Miocene sediments, Pleistocene conglomerate/breccia and clay and Holocene clay, sand and conglomerate (Parginos et al., 1971, Perissoratis, 1989; Mettos, 1992). The Oropos plain is a NE-SW oriented neotectonic depression affected by W-E, NE-SW and NW-SE striking tectonic and neotectonic faults (Papanikolaou et al., 1986; Perissoratis, 1989; Papanikolaou et al., 1989) as well as by the Pleistocene sea level fluctuations (Lambeck 1996). The interaction of tectonic and stratigraphic factors combined with eustatic changes established a complex hydrogeological regime where successive unconfined and confined aquifers have been formed. In total, four aquifers occur in the study area (Dounas et al., 1980; Pagounis 1994). The upper aquifer occurs in the Holocene sediments which is unconfined and locally confined. The second aquifer, which is confined, occurs in the Pleistocene sediments. The third aquifer occurs in the Miocene conglomerate and the last one in the Mesozoic carbonate. The objective of this article was to highlight the occurrence of good quality groundwater which is hosted in the confined aquifer of the Pleistocene sediments located adjacent to the coastline of the Oropos plain. The hydrochemistry of Oropos groundwaters has been investigated using major and heavy metal constituents. Groundwater samples from 36 wells and one sample from Asopos River surface water were collected. Physico-chemical characteristics of Temperature T (oC), pH and Electrical Conductivity EC (μS/cm) were measured in situ. The method of titration was used for Ca2+, Mg2+, HCO3-, and Cl- determination and Hack Dr 3000 Spectrophotometer was used for NO3-, PO43-, NH4+ and SiO2 determination. The concentration of Na+ and K+ was determined using the CORNING Flame Photometer 410. Heavy metals Sr, Cd, Cu, Fe, Mn, Ni, Pb, Cr VI και Zn were determined using AAS GBS 908 Atomic Absorption Spectrophotometer. Ion balance error was better than 5%. Hydrochemistry of groundwaters in the Holocene, Miocene and Mesozoic sediments indicated seawater influence. Electrical conductivity (EC) values ranged between 526 and 3770 μS/cm with a median at 2098 μS/cm. Chlorides ranged between 31 and 993 mg/l with a median at 260 mg/l. On the contrary, groundwater quality of the Pleistocene conglomerate was very good. The EC values which ranged between 766 and 971μS/cm with a median at 854 μS/cm and chlorides which ranged between 95 and 163 mg/l with a median 121 mg/l led to the conclusion that this coastal aquifer is protected from seawater intrusion, despite the fact that it is located adjacent to the coastline. The NO3- and PO43- concentrations were increased in the agricultural area which is attributed to fertilizers. Most of the heavy metal concentration such as Cd, Fe, Pb and Ni exceeded the EU limits which they have been determined at 82, 2500, 817, 217 μg/lit respectively. Groundwaters were categorized into 2 main water types based on the expanded Durov diagram (Fig. 2) (Lambrakis, 1991): (i) the first group was mainly depicted on the field 2 indicating fresh groundwater of Ca-Mg-HCO3 type; and (ii) the second group was depicted on the field 8 that is Ca-Mg-Cl type indicating reverse cation exchange of old Na-Cl waters (Lloyd, et al. 1985). The Asopos River surface sample was projected on the field 9 indicating Na-Cl type contaminated by seawater. Based on the Piper diagram most of the samples showed Ca-Mg-Na-HCO3 type and some samples showed no dominant type which means mixing processes are in progress. It is worth mentioned that the Pleistocene aquifer resources represent a reserve of good quality water which needs to be properly managed.

ABSTRACT. The purpose of this study is to examine the isotopic composition of the typical alluvial aquifer system of Tirnavos sub-basin and compare it with the isotopic composition from previous studies for the wider region. For this purpose, totally 26 samples for both groundwater and surface waters were collected in two sampling periods. Results were plotted and the Local Groundwater Isotope Line and Local Surface Isotope Line were compiled. The slope and the d-excess values compared to the Thessaly Meteoric Water Line (Dotsika et al., 2010) showed no significant deviations; thus, demonstrating that the study area follows the general composition of the wider region isotopic ratio. Τhe low value of d-excess compared to the GMWL value may be attributed to the environmental conditions. Regarding the Local Surface Isotope Line, the slope of the regression line and the d-excess value show the effect of the evaporation on these surface receptors. It could also be argued that due to the difference in the isotopic ratio between groundwater and surface water, there seems to be no (or not significant) hydraulic interaction between them.

ABSTRACT. INTRODUCTION Pollution from organic and inorganic pollutants is very frequent in places with industrial activity. The existence of pollution plumes in shallow or even in deeper aquifers is inevitable. Pollution can be due to raw materials that are used during treatment of industrial products, during the storage of intermediary products and from the remains (wastes). The cost of risk assessment for the polluted regions, with the existing geochemical environmental techniques, is judged expensive, time-consuming and does not provide results for the entire region. Imaging of the pollution of waters in rural regions, recording the pollution in places of industrial wastes deposition, imaging of salination of underground water regions, imaging of the water-bearings stratum pollution from petroleum products and other environmental problems have been identified using lot of geophysical techniques. The fast cover with dense network of measurements in the entire region that offers the possibility of extension is one of the main advantages of the geophysical methods. In opposition, the geochemical techniques cover parts of the polluted area with specific samplings and chemical analyses.

GEOLOGICAL AND HYDROGEOLOGICAL SETTING The tanneries of Thessaloniki established in 1970. Then they were developed arbitrarily. Surface channels with polluted liquids, storage of dangerous chemical substances without particular precautions etc. had resulted the pollution of subsoil and underground waters and the progressive demission of the environment. The geophysical research was realized in 3 selected places A, B and C. The geological and hydrogeological conditions in region A, as these were recorded the shallow drillings (BH1, BH2 and BH3) are as follow: Unconsolidated geological formations (sediments) up to 5 m in depth, consisting of sands, fluvial and torrential deposits, red clays with limestone conglomerates (figure 1). Underground water measurements showed that the pH values are normal and the electric conductivity values are between 3,41 and 6,95 mS / cm. Low concentration values (0,5 - 6,8 mg/l) of free oxygen prove the existence of organic pollutants. The chromium (Cr+3), the zinc (Zn) and the arsenic (As) are the inorganic pollutants in the soil and the dichloromethane and the acetone are main organic. The chromium (Cr+3) is also observed in the underground water while the petroleum products (TPH) are main organic pollutants (Atzemoglou et al. 2003).

GEOPHYSICAL RESEARCH AND RESULTS We applied the electric resistivity tomography (ERT) at the region of tanneries of Thessaloniki (Greece), aiming at the investigation of subsoil and underground water in-depth up to 5 meters. The research was realized with the LUND system of ABEM that supports many electrode configurations and 42 electrodes (max.). Data were initially plotted in pseudosections and bad quality data points were rejected. Subsequently the data were processed using a non-linear 2-D inversion scheme and the results of the region A are showed in figure 2.

The geophysical identification of the pollutants present in the underground water depends mainly on the contrast between the rock porosity properties, when it is saturated with water, and when it contains various humid pollutants. The rock resistivity depends also from the rock’s electronic conductivity and the electrolytic (ionic) conductivity of the water contained in their pores. Thus the measurement of resistivity is decisive. The organic and inorganic substances can cause decrease of the resistivity of the materials. This decrease could be referred to the increase of the total dissolved salts (TDS) found in the rock. The content of soil samples in chromium, at 1-meter depth, is 5 to 10 mgr/l and is lower (1%) than the surface chromium values. That content does not influence considerably to the electronic conductivity. The content of samples of water in chromium reaches the 0,2 mgr / l percentage that according to relation TDS and conductivity (Driscoll, 1986) cannot increases the conductivity of water above 0,4 mS/cm. If we take into consideration that the measured conductivity of water is 3.000 until 7.000 mS/cm (salination), we could conclude that the effect of Cr concentration to electric resistivity measurements is very small. With the same reasoning, the content in hydrocarbons of petroleum products does not affect the measurements of electric resistivity. The content in NaCl in studied region is too high (noise) that the previous concentrations does not affect decisively to measured resistivity values.

REFERENCES Atzemoglou, A., Skianis, G. (2003). Geophysical research in Thessaloniki tanneries, IGME, internal report. (text in Greek). Driscoll, F. (1986). Groundwater and wells. Mower House publications.

ABSTRACT. One of the most significant outcomes of soil erosion in drainage basins is the extensive deposition of sediment within dam’s water-reservoirs. This procedure could lead to an increased aggradation rate in the dam’s water-reservoir which results in a reduced water storage capacity. World widely, soil erosion is calculated with the use of the Revised Universal Soil Loss Equation (RUSLE) adopted in a Geographical Information System (GIS) framework. In the current study, RUSLE and GIS were used for predicting soil erosion rate of Pineios dam drainage basin, before and after the wildfires of August 2007 occurred in the Ilia regional unit; thus examining the aggradation rate in the dam’s water-reservoir. Factors that control RUSLE equation were imported in the GIS framework and applied on a Digital Elevation Model (DEM) map of Pineios River basin with 85m accuracy. Soil erosion rates were calculated before and after the wildfires by using as a dependent variable the cover management factor C, which is strongly influenced by large destructive fires.

ABSTRACT. Mediterranean Temporary Ponds (MTPs) are shallow water bodies which are characterized from a short wet period and their small size. MTPs of Europe have are under an effective protection status, as a result of their identification as a priority habitat in the EU Directive 92/43/EEC. These ponds are very delicate ecosystems regarding their hydrological and geochemical characteristics. Due to their small size, they are open to random destruction or other unpredictable dangers. Although small in size, MTPs are complex ecosystems where topography, soil, water and hydrological conditions and microorganisms are closely connected. The conservation and restoration of such ecosystems is very difficult because of their unique characteristics. The most common threats for MTPs include destruction of the hosting area through human and animal pressures, hydrological disturbance, fire and generally changes in ecological conditions resulting in an increase of competitive plants, nutrition influx, toxic contaminants and wastes, sedimentary deposit filling, exotic-invasive fauna and flora and negative effects from domesticated or hunted fauna. The study was carried out in the MTPs area of the National Forest Park of Mt. Oiti (GR2440004) and Mt. Kallidromo (GR2440006). The National Forest Park of Mt. Oiti covers an area of 7.210 ha, extends at altitudes of 400-2.116 m and encompasses a small network of four temporary ponds (TPs) of natural origin. The protected area of Mt. Kallidromo extends at altitudes of 43–1.393 m. and includes several streams which are tributaries of Spercheios River. Mt Kallidromo covers an area of 6.685ha and also encompasses a small network of three temporary ponds. Overall, the survey has included seven small and independent MTPs of high altitude in the areas of Mt. Oiti (Louka, Livadies, Greveno and Alikaina) and Mt. Kallidromo (Nevropolis, Mourouzos and Souvala). The current study aims to present a dataset of the geo-environmental parameters in order to assess the potential hazards for these priority habitats. Furthermore, it is also worth mentioning that MTPs are unevenly studied, regarding their geological, hydrological, hydrochemical, geochemical and mineralogical characteristics and this work provides a first report on an integrated evaluation of these parameters regarding the qualitative and quantitative risk identification of the MTPs in Central Greece. A 3-year sampling campaign took place at the temporary ponds (TPs) of the Mt. Oiti and Kallidromo, over two different time periods, autumn and spring, by doing so, we ensured that the data were representative and comparable to the conditions during the wet and the dry period. Bottom sediments and water samples were collected from each pond. Sampling was carried out at the bottom of the outer part of the habitat, from designated sampling points, with a maximum uppermost of 15cm and side inspection of the plant communities. The analytical methods used on the sediments consist of granulometric characterization, mineralogical analysis (powder XRD), chemical analysis of major and trace elements (ICP-AES and ICP-MS) and organic matter determination. Water measurements include pH, Eh, conductivity and TDS values and were performed in situ. The water samples were also analyzed for NO2-, NO3-, NH4+, PO43-, HCO3- and SO42-. Regarding mineralogical analysis, Kallidromo bottom sediment samples revealed high participation of quartz and clay minerals, mostly montmorillonite. High clay mineral participation in Kallidromo, results in mostly fine gained fractions. Oiti samples consist of quartz. However, albite, iron-rich smectites and clay minerals have also been defined. Furthermore, in terms of granulometry, Oiti samples composed mostly of sand. The studied MTPs develop hydrochemical fluctuations as a result of annual hydrological changes. The MTPs of Mt.Oiti present very low dissolved salts concentrations. On the other hand, ion concentrations in Mt. Kallidromo MTPs are higher due to its geological background. The geochemical results and the water chemistry coupled with temporal analysis indicated that precipitation (meteoric water) is the main mechanism for the Mt. Oiti MTPs formation. Hydrochemistry suggests that there is no interaction between the ponds and the geological background. On the other hand, Mt. Kallidromo MTPs show a strong affection to the local geological background, exhibiting higher Fe concentrations compared to those of Mt. Oiti. Fe presence is related to high concentrations of As and Co, which indicate a strong correlation to the geological formations of the area. pH variation is controlled by processes such as photosynthesis and oxidation of organic matter. These processes can succeed one another in short time. Bottom sediment samples from Mt. Oiti present high concentrations of SiO2 in comparison to the Kallidromo samples, but show lower Fe2O3, MgO and CaO rates. Trace elements in the samples from the Oiti bottom sediments show lower Ni numbers, but all the other trace elements are in comparable numbers. The MTPs present sporadic sensitivity regarding ammonium and phosphate ions, derived from decomposition of organic matter (mostly cattle feces in Oiti and cattle and horse feces in Kallidromo). Pb enrichment noticed in the second sampling campaign of Nevropoli pond in Mt. Kallidromo, which might come from buckshot during hunting activity in the area. The same enrichment determined to the respective bottom sediment sample. The morphology of Mt. Oiti and Mt. Kallidromo MTPs is unaffected from anthropogenic factors. Animal manures affect the nutritional status of the examined Mediterranean Temporary Ponds. It is noticed that animal manures increase the area’s fertility and could result in the invasion of competitive flora species that might reduce the endemic flora of the ponds. A monitoring procedure would be important for this type of ecosystems. This procedure may be implemented based on the geological, hydrochemical and geochemical parameters of the MTPs. Some of the parameters that need monitoring are: i) the pond surface area, ii) the climatic conditions, iii) the anion and cation levels, ammonia and phosphorus concentrations, iv) water pH, Eh and conductivity together with total dissolved salts and oxygen saturation in the pond’s water and v) the fluctuation of the organic matter in the bottom sediments.

ABSTRACT. In many countries protection measures have been introduced for specific geological monuments and protected areas have been created that include sites of special geological - geomorphological value, but the management of these areas has not had as priority the protection of geological - geomorphological sites. In Greece until recently the elements of the abiotic environment were referred to in Law 1650/1986 as objects of protection without being subject to management. The locations containing special geological monuments are mainly protected in the context of the archaeological or forestry legislation. As a result, there was a lack of protection of geological - geomorphological sites. Law 1650/1986 and especially law 3937/2011, which regulate the management of protected areas and biodiversity conservation include provisions on the conservation of biodiversity. In Law 3937/2011 for the first time the concept of geosites and geoparks are introduced into the Greek legal order. The subject of this paper is the presentation of an integrated methodology and criteria for the evaluation of geosites that constitute the basic unit of the geological and geomorphological heritage and the use of this methodology for the implementation of an integrated geo-conservation policy. A special point is the incorporation of the methodology of quantitative evaluation of the geosites and its results as a basic tool for the management of the geoparks of Greece, as well as for its application in a geopark internationally. An essential component of the research was the development and implementation of the geosites’ assessment methodology that assessed the locations and structures of geological and geomorphological interest in Lesvos Island UNESCO Global Geopark in order to define the priorities for protection, promotion and management and ultimately select those sites which are exploited in the context of the different actions of the Geopark of Lesvos in the fields of awareness raising, education and tourism. Taking advantage of the data collected, the criteria necessary for the creation of a framework for the evaluation of geosites and the definition of parameters for a system of evaluation of the geosites of Greece were defined. In conclusion, the main results of the research carried out are: • the proposal for an integrated methodology for the evaluation of geosites and the use of this methodology for the implementation of an integrated geo-conservation policy. • the incorporation of the methodology of quantitative assessment of the geosites and its results as a basic tool for the management of geoparks of Greece, as well as for its application in geopark internationally.

ABSTRACT. Geosites are outcrops with significant geological value that can contribute to the restoration of the geological evolution of an area (Gray, 2004). All together constitute the geological heritage of a territory. Areas of outstanding geological value including geosites of international significance that are under a holistic conservation and management plan for the local sustainable development can be nominated as UNESCO Global geoparks (UGGp). Since 2015 Crete hosts two among the five UNESCO Global geoparks of Greece, those of Psiloritis and Sitia. Core aim of the UGGps is the conservation and promotion of geological heritage and incorporation them with other natural and cultural values for the development of geotouristic activities (UNESCO, 2019). In addition, geoparks have to develop educational and training activities to inform visitors and inhabitants on the value of their natural environment and raise awareness on critical geological issues and geohazards. Under the GEOIN project (www.geo-in.eu) that supports the Geotourism in insular Geoparks of Greece and Cyprus, the Natural History Museum of the University of Crete has undertaken the development of three web-based applications to promote geoheritage, support visitors’ needs and educate through entertainment, at Psiloritis and Sitia UGGps. The first application is a web-gis based interactive map of each of the two areas. It has been scheduled to be compatible with desktop and mobile devices connected with the web, but are also used for static digital displays with touch screens. This WebGIS application is separated in two distinct parts, the map panel on the left and the side panel on the right, which interact with each other. The side panel is further distinguished in major units, each one of them comprising points of interest and other information related to the geological, environmental, cultural and religious heritage of the two geoparks. Clicking upon every unit will add the correspondent layers on the map panel, while the content of that unit slides down as an accordion. All the information is presented as an interactive list in harmony with the map. When clicking on a point on the map, the side panel automatically scrolls until the equivalent information appear on top and vice versa, when clicking on a specific information on the side panel, the map zooms in to that location. The geosites of the two UGGps of Crete have been assessed and categorized in various types following international standards and procedures (Fassoulas et al., 2011; Fassoulas et al,. 2013). Based on these categories the geosites are presented in the application both in the core map and the interpretation part offering simple information of their type and features and an accompanying image (Figure 1). This application may be used thus as a geography book with interactive chapters and to perform a virtual tour in the Psiloritis and Sitia Geoparks. The second application comprises the development of Storytelling maps for Psiloritis and Sitia geoparks. Story telling maps are widely used nowadays for the complete and interactive presentation of a story using various multimedia means such as videos, animations, spherical panoramas and images (ESRI 20019). A good example for the use of Story maps to interpret and promote geological heritage using web-gis tools is the Santorini Volcano Story map produced by Staridas (2018) that received the First place at the 2019 ESRI contest for the Travel, Recreation and Destination category. One story telling map has been produced for each of Psiloritis and Sitia UGGps that presents the geological heritage of the areas along selected routes. Each map is built up with data gathered from the two geoparks but also data acquired during the project such as, earth based and aerial spherical panoramas that combine site interpretation information through text, sketches and animations. Scrolling down through the various chapters of the story telling maps, information is displaced at the left part of the web page, while interactive maps alternate with videos, images and animations appear at the other side, to fully present the geological content of each route. The third application developed, is the e-geodiscover educational application. This is developed as an app compatible with android devices that can be downloaded for free and stored in a mobile device to run, even without Wi-Fi access. The educational approach is based on the treasure handing games, forcing users to discover an area using a digital map with location tracked through the device’s gps, identify geosites and other locations of natural and cultural importance, and select the correct answer in selected spots. The proximity of the device in a predefined buffer zone around a spot area is identified by the gps permitting the pop up of introductory information for the site and then of predefined answers in the form of simple phrases, images, or true/false options. Correct response within three tries enables the appearance of complementary information about the site and guidance to discover the next. The application has the ability to trace players’ response and can count the first provided answer per site to evaluate the total performance of the player at the end. The applications have been scheduled along three of the geo-routes of the two geoparks; the Migias and Gonies trails at Psiloritis, and the Upper Zakros trail at Sitia. All applications will be hosted at and accessed from the new geoparks websites that are under development. These application not only contribute in the promotion of the geological heritage of each geopark, increase of their visibility and attract visitors of young ages, but being web-based can serve the needs of future visitors to schedule and design their trip in the two geoparks. Moreover, these applications can serve the needs of disabled people, especially those with mobile disabilities, to visit remote sites being inaccessible to them, explore the nature and geology values of the two geoparks from their home places, and possibly trigger them to visit other accessible places of the two areas. Finally, as all applications will be also available at geopark’s info centers, and educational facilities, will strengthen the provided environmental education and enrich their didactic methodologies.

ABSTRACT. In the present work, an attempt has been made to highlight the contribution of the Museums of Natural Sciences to the teaching of the Geosciences through designing and presenting an educational program whose subject is derived from the field of Geology and specifically from Paleontology and Historical Geology, aiming at understanding the geological time and its comparison with historical time. For this purpose, three different models of depicting geologic time have been designed, for the construction of which participated a group of pupils. In addition, an attempt of designing 3d visualization of microfossils and 3d printing is presented.

Introduction The knowledge gained in informal learning environments is particularly important (Hann & Jackson 1995), taking into consideration the fact that in such environments there is a change in attitudes to the subjects under study, psychomotor skills are developed and the social interaction between the team members is promoted (Ioannidou et al 2002) Thus, school teachers choose visits to museums when they think that they are linked to curriculum subjects and are educationally relevant to the pupils' age (Papadopoulou.) Several museums try to make their educational programs be directly linked to the school curriculum (Allard & Boucher, 1998). This cooperation can be achieved at various levels, such as the complementary level where the museum complements school education. (Koliopoulos, 2005) The Museum of Natural History of Philekpaideftiti Etaireia is considered to be a Museum of this type, which is located within the area of the Arkakeia Schools in Psychiko. The aim of this Museum is to make the Museum become a school and its target is to offer knowledge through experiential education programs which are linked to the curriculum of the subjects, depending on the pupils age and as it is suggested by the Analytical Program of Studies (Tripolisitsou et al., 2018) The educational program presented in the present work is entitled: "The Time period before humans", and was designed and carried out in this Museum. The program which is still in progress takes place in 3 stages and so far it has been attended by 250 students aged 9-15 years as well as individual adults. Methodology Prior to the design of the educational program " The Time period before humans ", a survey had been conducted among 450 students concerning pupils of the 4th grade of primary school to the 2nd grade of Senior High School who responded to a question about the geological time on the geologic time scale, in order to collect data on whether students are able to understand geological time.

The objective questions we have posed based on the results of geological time research are as the following: • What are the mental representations of the students in relation to geological time, how do they perceive it? • What is the relationship between geological and historical time? • Can the participants categorize the fossil organisms into basic categories? (bivalves, gastropods, corals ..) • After completing the training program which they attended, which ideas do they express about fossils, and geological time? Table1: Teaching Model Before Classroom Preparation Submit Study Subject Was the form of the Earth always the same as we see it today? During Museum Implementation Subject study and data collection Attendance of Educational program - knowledge enrichment and activities. Collection of data in the Museum After Classroom Extension Analysis and synthesis Discussion and knowledge building

In this training program, the Allard & Boucher, (1998) & Paquin (1995) teaching model is applied (Table 1) In addition to this teaching model, the Pre-Post teaching model is also used, according to which the participants fill in a questionnaire before starting the program and the same one immediately after its completion in order to record the students' initial ideas on the theme of geological time.

Description of the program Initially, the students at the Museum fill in a questionnaire aiming at recording their initial ideas on fossilization and understanding of geological time. Then through interactive presentation and fossilization models they learn about fossils and the ways of fossilization. Furthermore, there are activities based on experiential learning aiming at the identification and classification of fossils. For this purpose, models of depicting geological time have been designed for the acquaintance and understanding of the geological ages, giving emphasis on the Phanerozoic Eon. The students observe the fossilized exhibits of the Museum and examine fossils that belong to the museum exhibits as they are able to touch them. In addition, by using geological time models, participants try to understand the minimality of historical time as compared to the duration of geological time. With the help of a group of seven students, enlarged 3-dimensional models of microfossils have been designed using computer programs aiming at getting students to get acquainted with the fossils, since they can touch and observe them in a better way. Conclusions The final questionnaire as well as the students' comments show that there is a positive response to the program and an understanding of geological time depending on the pupils' age. The older the age the better and the understanding of geological time. An unexpected positive outcome is that the students are impressed with the extent of geological time and are concerned about the impact of human activities on the environment during the time of human existence on Earth.

References

Allard, M & Boucher, S (1998). Eduquer au musée. Un modèle theorique de pédagogie muséale. Cahiers du Québec Hann, K. and Jackson, R. (1995). Learning from experiences: approaches to research in the informal sector, Paper presented in the European Conference on Research in Science Education, Leeds UK Koliopoulos D., (2004) Teaching Approach in Physical Museums, Metaichmio pub Paquin M, (1995) Modèle didactique d’ utilization d’ instutition culturelles quebecoises a des fins educatives. Loisir et Societe Education p.81 Tripolitsiotou F, Drinia H., Antonarakou A, (2018). Searching for the lost paleontological thesaurus. An educational program of the Natural History Museum of Phileakpaideftiki Etaireia. Neos pedaegogos proceedings, pp 778-785

ABSTRACT. The Lesvos Petrified Forest was formed by silicification process of plants during the Lower Miocene era, when intense volcanic activity occurred in that region. It is situated in the western part of Lesvos island (NE Greece) and consists of hundreds of standing and lying fossilized tree trunks, covering an area of 150 km2. It is one of the most important natural heritage monuments in the world and in 2004 the area was included in the Global Geoparks Network (Zouros, 2010). The Natural History Museum of the Lesvos Petrified Forest is the management body of Lesvos Geopark. The numerous visitors of this geopark are impressed by the fascinating colours of the fossilized trunks. A palette of vivid colours is often evident in the silicified stems (Figure 1). Variable colours are noticed not only in fossil plants from the same locality, but within a sole fossil plant itself. Several factors affect the distribution of different colours within the fossilized plants: the nature of pyroclastic rocks and the hydrothermal solutions produced during the volcanic activity; the silicification process itself (replacement of cell-wall structure or void filling, i.e. permineralization process); the possibility of a multi-stage petrification and the subsequent mobility of chemical elements therein; the palaeoenvironmetal conditions (hydrology, pH, Eh etc.); the type of species and the variability of plant tissues within the same species. The aim of the present study is the investigation of the origin of these natural colourants by determining the chemical and mineral abundance of fossil plant samples. Seventeen fossil plant samples were collected from the Sigri pyroclastic formation within the Lesvos Petrified Forest. Polished block sections of each sample were prepared for analytical purposes. A Philips QUANTA 200 Environmental Scanning Electron Microscope (ESEM), coupled with an Oxford INCA Energy 200 Energy Dispersive System (EDS) was used for imaging and chemical (both in area and spot) analyses. For the Raman spectroscopy, a Thermo Scientific DXR Raman Microscope with a 780 nm laser beam was employed. The power value of the sample irradiation was ranging from 6 mW to 12 mW. The average spectral resolution in the Raman shift range of 100-3000 cm-1 was 5cm-1 (grating 400 lines/mm, spot size 2μm). The main colours determined are black, milky white, transparent white, green, red, orange, brown and yellow. The presence of black carbon was clearly estimated in the black zones by the characteristic Raman spectra bands at 1378 and 1536 cm-1 (Figure 2). However, pure silica was only detected by EDS in the black colour of some samples. Thus, black colour is attributed either to the relicts of organic matter in the silicified sample or may simply be related to the low reflectance of translucent silica oxides (Musteo & Acosta, 2016). Raman spectroscopy confirmed the presence of opal in milky white and quartz in transparent white colours. Quartz was revealed with its intensive band at 465 cm-1 and the secondary bands at 123, 203 and 497 cm-1, while opal showed a characteristic hump between 200 and 500 cm-1, with distinct strong peaks at 350, 784 and 1590 cm-1 (Iordanidis et al., 2014). The EDS analysis of green, yellow, orange, brown and red colours revealed that iron (Fe) is the primary colourant, with the intensity of colour proportional to the abundance of that element. Consequently, lower concentrations of Fe were found in the green colour, while higher contents of iron were determined in the red colour and intermediate contents for orange, brown and yellow tints (Sileo, 1979). Similarly, the presence of iron oxides and hydroxides was determined in the red/orange/brown/yellow and green colours by Raman spectroscopy (Figure 2) and particularly hematite (Fe2O3) for the red hue, lepidocrocite [γ-FeO(OH] for the green colour and goethite [α-FeO(OH)] or mixtures of the aforementioned iron oxides/hydroxides for the brown/orange/yellow tints (Musteo & Acosta, 2016). Hematite showed characteristic bands at 223, 296, 402, 658 and 1315 cm-1, goethite presented peaks at 243, 298, 389, 550, 681 and 1298 cm-1 and lepidocrocite displayed characteristic bands at 170, 256, 285, 440, 525 and 694 cm-1. Trace amounts of the chemical elements Mn, Ti, V, Hg, Ba, REE were also detected by EDS. Some of these trace elements, such as Mn and Ti are known as natural colourants (Sileo, 1979). However, they were determined in all colour hues and therefore could not be consider as colour creators. It should also be noted that the chemical analysis of this study refers to a spot or area (up to some hundreds of μm2) EDS analysis and not to a bulk sample analysis. In conclusion, the complementary use of ESEM-EDS and Raman microscopy techniques provided significant information on the natural colourants, accountable for the fascinating colours of the fossilized stems from Lesvos petrified forest.

ABSTRACT. Vikos-Aoos Geopark is part of the European and Global Geopark Networks of UNESCO since 2010 and it is located at the NW part of the Pindus Mountain Range at Epirus Region, northwestern Greece. The Geopark extends in an area of 1.200 km2 from the area of Northern Pindus National Park to the Greek-Albanian borders. The area is characterized by a mountainous continuous and rugged terrain which is interrupted by steep gorges, elongated narrow valleys, and alluvial plains. Smolikas (Geros peak: 2637 m a.s.l.) and Tymfi (Gamila peak: 2497 m a.s.l.) Mountains host the highest peaks of the Geopark, while Vikos and Aoos Gorges as well as Konitsa plain control the lower relief morphology. Except of the major geological, geomorphological, and natural aspects, the Geopark hosts also significant cultural aspects. Sixty one traditional settlements belonging to the municipalities of Zagori and Konitsa, most of which are protected culturally and architecturally, are found within the Geopark area. These settlements bear a total population of 9954 inhabitants (Hellenic Statistical Authority, 2018). Nevertheless, 6362 of these inhabitants reside at Konitsa town, thus the Geopark area could be characterized as depopulated (Telbisz et al., 2019). In these publication we further discuss on the special geological aspects of the Vikos-Aoos Geopark, the Gamila peak spherical concretions and the Oxia hanging valley which are located at the Tymfi mountain massif, based on the recent publications made by authors (Chatzipetros and Stergiou, 2016; Telbisz et al., 2019).

ABSTRACT. Story maps are widespread as an interactive tool used for science and spatial data communication, information and dissemination. A web-based application using story mapping technology is here presented to show the walking paths and routes of Nisyros volcano, Dodecanese, Greece (Figure 1). A tailored story map that combines thematic webmaps, scenes (3D webmaps), narrative text and multimedia content was created to highlight the geological and cultural environment of Nisyros. The webmaps and scenes were entirely created by a Geographic Information System (GIS) having a great impact on web-based visual presentations. The island of Nisyros was selected as it presents unique characteristics. It is one of the smaller islands of Dodecanese islands in the eastern Aegean Sea covering an area of 42 km2 and having an almost circular shape with a total width of 8.5 km and a coastal circumpherence of about 25 km,. It is composed of Quaternary volcanic rocks with a central caldera diameter of approximately 2.8 km surrounded by volcanic domes and thick lavas averaging about 550 m height with Profitis Ilias mountain having the maximum altitude of 698 m (Nomikou & Papanikolaou, 2011). The history of Nisyros is strongly connected to the volcano, and impresses the visitors with its steaming hydrothermal craters, intensive smell of sulphur and fumarolic gases and hot springs on its northern and southern shores (Dietrich, 2018). Due to its volcanic morphology and geographical position, in the southeast corner of the Aegean Sea, which make it a rather inaccessible island, the cultural and historical heritage of the island have been unchanged in time. Nisyros Island combines the volcanic history and natural beauty with the splendor of art and civilization, expressed through prehistoric and historic locations and monuments. The interpretations vary regarding the names of the island: Porphyris, Kisiris and Nisyros. The first references are present from Early Neolithic times, in the form of relicts from the “Cycladic and Minoan” civilizations. Historical records start from the Hellenistic epoch continuing through Roman, Byzantine, Venetian and Ottoman eras till modern times (Dietrich, 2018). All these periods bequeath to the island plenty of churches, monasteries with hagiographic frescoes, castles, caves and spas. In the presented application, the aim was to present the geodiversity, the cultural environment and the biodiversity (unique flora and fauna) along the paths of the volcano. Using Story Maps, this relative new geographical approach, having open source code, provides many possibilities, as it is easy to be used both from the developer and from the end user and allows integration of new functions combining many scientific fields in order to disseminate and understand scientific findings to broader non-technical audiences (Janicki et al., 2016; Wright et al., 2014). Furthermore it is responsive, and it can be also as interactive as the developer wishes. Users can navigate easily through the content, using either the sequence of the predefined tabs or jumping from one to another according to their will. The developed application can be an ideal way for presenting the geological, geomorphological and historical contents of other places, especially places which can be characterized as geotopes or protected areas worldwide (e.g. Natura 2000 areas) (Antoniou et al, 2018). Finally, as Nisyros volcano portrays a geotope, this application provides a quick access of the available information to a wide audience, developing the interest and possibly motivating the public to learn more about the volcanic landscape of Nisyros, or even to visit it.

ABSTRACT. On July 20, 2017 at 22:31 UTC (01:31 local time) a shallow earthquake of Mw6.6 magnitude occurred in Gökova Bay at a depth of ≈10Km (Fig. 1). The epicenter of the earthquake, located between Bodrum, Turkey and the island of Kos, Greece, SE Aegean Sea. In particular, according to Kandilli Observatory and Earthquake Research Institute (KOERI) the epicenter was at 36.9620oN 27.4053oE, while according to the National Observatory of Athens (NOA) at 36.9643oN 27.4332oE. The fault plane strikes N280°E and dips to the north with an angle of about 40 degrees in a nearly E-W direction with surface deformation that reached about 20cm onshore islet Karaada (Ganas et al. 2017, Karasözen et al. 2018). Preliminary inversion results of geodetic data, as constrained by InSAR observations, suggest that the upper edge of the fault (14km length and 12km width) is offshore (near the Gökova ridge bathymetric feature) at a shallow depth (2±0.5km - Ganas et al. 2017, Karasözen et al. 2018).

The recorded acceleration at the city of Bodrum, which is located at an epicentral distance of 12 km was 158.76 cm/sec2. Based on the preliminary distribution of peak ground acceleration (PGA), provided by ITSAK, 2017, the PGA values at the city of Kos and cape Louros were estimated as 0.2 g and 0.25 g, respectively (ITSAK, 2017).

The primary goal of this study was to document the earthquake-induced secondary effects and to provide quantitative data regarding the characteristics of the liquefaction related phenomena at the island of Kos. In order to achieve this, a post-earthquake field survey conducted on 13-14 August, 2017.

Based on the field observations, it can be summarized that the earthquake caused damages to the building stock of the town of Kos, mainly to Ottoman and Venetian-era constructions, including partial collapses that killed two people and seriously injured several others (Papathanassiou et al., 2019). Damages were also reported in the city of Bodrum. Focusing on the island of Kos, the most remarkable type of environmental effects is the liquefaction related phenomena that induced severe damages to the port facilities and to the custom building at the new port of Kos, and at the old harbor of the city. Moderate liquefaction-induced structural failures were induced at the marina of Kos, while at cape Louros ejected material due to liquefaction covered more than 450m2 (Papathanassiou et al., 2019). Furthermore, a tsunami wave was reported indicating that the generation of tsunami-related phenomena e.g. flooding and structural damages is likely in the Aegean Sea. In particular, the tsunami effects were observed at the south coast of Bodrum peninsula and at the northeast coast of Kos Island, with a maximum run-up measured at 1.9 m at Bodrum area (Yalçıner et al., 2017). Small-scale size rockfalls were reported in the southern part of the island of Kos.

Taking into account the quantitative characteristics of the earthquake-induced secondary effects e.g. liquefaction phenomena and tsunami, the macroseismic intensity was evaluated by applying the Environmental Seismic Intensity (ESI-07), a scale based only on environmental effects introduced by Michetti et al. (2007). Thus, according to Papathanassiou et al. (2019), the macroseismic intensities at the coastal area of cape Louros and the at waterfront area of the city of Kos were assessed as VIII taking into account i) the dimensions of liquefaction manifestations in the former case, ii) the lateral spreading and subsidence at the port and at the old harbour of the city of Kos, and iii) the characteristics of the generated tsunami documented by Yalciner et al. [4]. Details regarding the liquefaction related phenomena are presented in sections 5.1 and 5.2 in this article.

The secondary goal of this study is to investigate in detail a lateral spreading site, located at the old harbor of the city of Kos. This was achieved by performing traditional ground measurements as well as an image-based survey following the Structure from Motion (SfM) technique in order to virtually measure the deformation. The novelty of this study is related to the fact that the applied SfM technique for measuring the lateral spreading displacement was based on a simple handheld digital camera instead of a UAV. Comparing the obtained measurements by these two methods, it is resulted that the deviation of the measurements on horizontal axis e.g. width of cracks, between the virtual (SfM-based) and the manually field observations is less than 1%. Thus, it can be concluded that the SfM-based technique provide reliable data regarding the lateral displacement and accordingly, could be used for the purposes of a rapid post-earthquake field survey (Papathanassiou et al., 2019).

References

Ganas A, Elias P, Valkaniotis S, Briole P, Kapetanidis V, Kassaras I, Barberopoulou A, Argyrakis P, Chouliaras G, Moshou A.2017. Co-seismic deformation and preliminary fault model of the July 20, 2017 M6.6 Kos earthquake, Aegean Sea; 2017. https://www.emsc-csem.org/Files/event/606346/Kos_report_30-7-2017.pdf ΙΤΣΑΚ. 2017. Earthquake Μw6.6 July 21, 2017, Preliminary report, ITSAK, OASP; 2017. Thessaloniki, 20 pages (in Greek) - http://www.itsak.gr/uploads/news/earthquake_reports/EQ_COS_20170721_M6.6.pdf Karasözen, E., Nissen, E., Büyükakpınar, P., Cambaz, M.D., Kahraman, M., Ertan, E.K., Abgarmi, B., Bergman, E., Ghods, A., Özacar, A.A., 2018. The 2017 July 20 Mw 6.6 Bodrum–Kos earthquake illuminates active faulting in the Gulf of Gökova, SW Turkey. Geophys. J. Int., 214 (1), 185-199 https://doi.org/10.1093/gji/ggy114 Michetti AM, Esposito E, Guerrieri L, Porfido S, Serva L, Tatevossian R, Vittori E, Audemard F, Azuma T, Clague J, Comerci V, Gurpinar A, McCalpin J, Mohammadioun B, Mörner NA, Ota Y, Roghozin, E. 2007. Intensity Scale ESI 2007. Mem. Descr. Carta Geol d’Italia. 74, Rome; 2007 Papathanassiou G., Valkaniotis S., Pavlides S. 2019. The July 20, 2017 Bodrum-Kos, Aegean Sea Mw=6.6 earthquake; preliminary field observations and image-based survey on a lateral spreading site, Soil Dynamics and Earthquake Engineering, 116, 668-680, https://doi.org/10.1016/j.soildyn.2018.10.038 Yasuda S, Morimoto I, Kiku H, Tanaka T. 2004. Reconnaissance report on the damage caused by the three Japanese earthquakes in 2003. In proceedings of the 11th ICSDEE and 3rd ICEGE. Berkeley CA USA;1:14-21. Yalçıner Α, Annunziato Α, Papadopoulos G, Dogan G, Guler H, Cakir T, Sozdinler C, Ulutas E, Arikawa T, Suzen L, Kanoglu I, Guler I, Probst P, Synolakis C. 2017. The 20th July 2017 (22:31UTC) Bodrum/Kos earthquake and Tsunami; Post Tsunami Field Survey Report. 2017; http://users.metu.edu.tr/yalciner/july-21-2017-tsunami-report/Report-Field-Survey-of-July-20-2017-Bodrum-Kos-Tsunami.pdf

ABSTRACT. The nature and extent of the risk associated with rockfall in steep terrains is a function of the local terrain conditions such as the structure of the rock, the slope stability and the geological processes that lie underground. Furthermore, climate, and weather-related phenomena can alter the local conditions and affect an area’s risk. These variables make the assessment of hazard more difficult, especially when specific infrastructures are situated at the site and support measures are required to be adopted. The HSGME has performed numerous studies on rockfall hazard assessment at cliffs of broken, faulted or jointed rock. Among them there exist cases of steep bedrock layers undercut by activities of man for infrastructures developments, mining works etc. In these last cases humans and infrastructures are subjected to serious threat from detached falling rocks (Konstantopoulou et al., 2015). The available support systems for mitigating this risk have the ability either to stabilize the slope or to dissipate the kinetic energy of falling rock. Due to the lack of an official design code, these systems are designed primarily by experience and engineering judgment which often makes the design rather conservative. In this study, assessment of rockfall hazard along a 300m long manmade cliff at Tolo, Naflio (Greece) is presented. The area is of specific interest due to fact that the foot of the 10 to 110m high cliff hosts the local wastewater treatment plant (WTP) of Tolo, consisting of clarifiers, aeration tanks and other supplementary infrastructures. The WTP plant was decided to be situated at the specific site, a few meters from the seaside of Tolo, to minimize wastewater transportation cost for disposal to the sea.

ABSTRACT. Epirus is a region having a high density of active landslides and numerous areas prone to slope instabilities due to its particular geology and large annual precipitation. In such conditions, blasting operations performed in the context of seismic surveys have to be planned in such a way that there is no risk of triggering ground instabilities or generating significant ground deformations. Herein, we present a summary of a methodology for landslide susceptibility assessment developed and applied in the context of the seismic survey operations in the Ioannina hydrocarbon exploration block. The project took place under the supervision of Repsol and Energean Oil & Gas Joint Venture, which have been awarded the specific block. The study area covers an extensive part of Northern Epirus (Fig. 1), which is dominated by carbonate and clastic sedimentary rocks. Of particular importance are the outcrops of the flysch of the Ionian Zone, as well as the outcrops of Posidonia shales and Miocene marls, which all are characterized by low strengths. The study was implemented in three stages: a) preliminary desktop analysis, b) field survey, data collection and sampling and c) evaluation of ground failure hazard using a deterministic approach.

ABSTRACT. This paper describes the landsliding behavior of highly weathered and tectonically decomposed flysch in characteristic landslides in Western Greece, focusing on its mechanical parameters, such as shear strength. Generally, the most serious landslide movements in Western Greece are often observed in the upper weathered zone of flysch and they often constitute translational and composite landslides. Large shear box tests were performed on selected samples of weathered flysch zone, under different moisture and density conditions. Three varying normal stresses were applied in each sample to determine the effects upon shear resistance and displacement. The results show that an increase of moisture content ensue an appreciable decrease in apparent friction angle. Furthermore, a dilatant behavior in dense samples was exhibited in contrast with the loose ones. A clear effect of composition - structure as well as moisture - density is also observed on the shear strength variation.

ABSTRACT. Because of the fact that Rockfalls cause human lives’ loss and extensive damage to the human structures, the assessment of Rockfall risk is considered to be very crucial along roads and on other geotechnical works. Especially, in Greece owing to the complexity of geological structure, the tectonic characteristics, the climate, the human activities as well as the seismic loading, this assessment is of great importance. For this reason, eight representative positions of “Kakia Scala” area (part of the one of the most major highways in Greece) are examined and the Rockfall Hazard Rating System values are calculated. Two of them are of high risk and so urgent remedial actions must be taken.

ABSTRACT. The excavation of tunnels produce ground settlements (“ground loss”) which result in subsidence, tilting and occasionally damage to overlying structures. The above is known since many decades ago (Terzaghi, 1942) and till now systematic recording of ground deformation is a common practice for decision making about the development of the excavation or about measures for ground and/or structures stabilization. In this study we summarize geodetic monitoring data from tilting of two brick chimneys in the Technopolis area and ground subsidence at Sepolia area during the construction of the Athens Metro in 1997 and 2003, respectively.

ABSTRACT. This research focuses on accessing the suitability of specific igneous rocks for their potential use as aggregates in road pavement layers. During the current research several quality control tests were carried out on andesite and dacite rocks, obtained from the areas of Methana and Agioi Theodoroi, approximately 60 Km West of Athens. The quality control test were conducted under the specific guidelines of Hellenic Technical Specifications ELOT and EN for aggregate properties’ determination, while the procedure was referred to the estimation of the following parameters: • Geometrical properties (grain size analysis, flakiness index and sand equivalent value) • Physical properties (apparent density and water absorption) • Mechanical properties (Micro - Deval index, Los Angeles Abrasion Value, Aggregate Impact Value) The laboratory testing results led to the general conclusion that the samples obtained from the andesite and dacite rocks cannot be used as aggregates in road pavement layers, due to their high Los Angeles Abrasion Values (LAAV). High values of LAAV represent a low strength in mechanical corrosion and crush and contribute to the low quality of these geomaterials as aggregates. Only the sample obtained by a basaltic andesite outcrop proved to be suitable for use as aggregate in road pavement layers.

ABSTRACT. Meteorology is a branch of Physical Sciences. It is mainly applied physics and every branch of physics finds an application in it. What gives rise to our weather is an extremely complex set of interactions involving fluid mechanics and thermodynamics. Physics also comes in to play when we use the principles from optics to explain how the atmosphere reflects and refracts light giving rise to phenomena as rainbows, coronas, glories, etc. and we use electrodynamics to try to understand lightning and phenomena associated with it, like red sprites and blue jets. Weather phenomena influence everyday live and economy while severe weather phenomena may cause serious property and infrastructure damages, disruptions in economic and social activities, and human fatalities. The education of the citizens and namely of the pupils on the risks from natural hazards related to weather events and the increase of awareness on preparatory measures and precautions to protect themselves is actually needed. The NOA’s (National Observatory of Athens/ meteo.gr) scientific team of educational meteorology, named “Peri Anemon & Ydaton”, has started in 2016 its effort to popularize the science of Meteorology for Junior and Senior High School pupils. The developed program aims to help the pupils understand how weather phenomena occur, based on the Physics’ curriculum of each school grade. The “Peri Anemon & Ydaton” is currently under assessment through the completion of questionnaires by both teachers and pupils. In the frame of this presentation we will also discuss the results of the program assessment scores, by the teachers of the participating schools.

ABSTRACT. The CREATIONS EU Program aims at creating and producing innovative teaching approaches being recognized as best practices in the European community, by observing the scientific framework of creativity and combining science and art. Responsible Research and Innovation and the principles of Science with and for Society act as a catalyst to new developments on Science Education. In this paper a demonstrator entitled "The Ghost Particle" is presented. This scenario is framed by the scientific, pedagogical framework of Effective Learning Environments, Creativity and Inquiry-Based Approach, the principles of the European Framework of Responsible Research and Innovation and is in line with the Creations Features and the principles of Science with and for Society.

ABSTRACT. This paper analyses Greek students’ alternative ideas, both initial and synthetic, on geodynamic phenomena. More specifically, it presents their concepts on Earth structure, earthquake occurrence, volcano formation and relief change. An indicative curriculum and textbook evaluation is attempted in order to specify their involvement in concept construction. A new synthetic mental model on earthquake occurrence is revealed. New synthetic alternative ideas on geodynamic phenomena are presented. Finally, (a) the characteristics of initial and synthetic alternative ideas on geodynamic phenomena are outlined separately, and (b) the factors that control their development are highlighted and grouped, hoping that their revelation will lead to alternative ideas’ decomposition

ABSTRACT. Background and Objectives The limited exploitation and low understanding of geological notions, in modern education in physical sciences, motivated the design of research procedures about the understanding of rock formations, of recognizing rocks, of informing about geological potential, using techniques entailed in the scientific/educational methodology by inquiry, suggesting educational walking paths through historical center of Athens. From the geological point of view, the basin of Athens is bounded to the east by Mountain Hymettus which is built by metamorphic alpine formations (marbles and schists), constituting the lower tectonic unit, and to the west by the overlying tectonic unit of Mountains Egaleo and Poikilo, which include non-metamorphic formations like limestones, volcanosedimentary sequences and ophiolites. The tectonic contact of these two units includes a low gradient detachment fault. The major part of the basin is covered by neogene and quaternary formations (terrestrial, marine and lake deposits of conglomerates, sandstones, marls and pelitic rocks, but also laterally extended debris and scree deposits). Below the neogene formations, small alpine low-grade metamorphic rock formations (crystalline limestones and phyllites) are emerging forming small individual hills (Turkovounia, Lycabettus, Acropolis, Philopappus etc.), overlying both the metamorphic formations of Hymettus and the non metamorphic formations of Egaleo. In this paper, the geology of the city of Athens and in particular the area of the inner city (historic center) is mainly studied. The designed geological walk trail is a practical endorsement, where the students will use fieldwork skills to identify a range of rocks and geological materials in the built environment and can also be informed about geological features of the area. Someone would think that urban area is poor for geological study and contains few useful geological data. This thought derives from the fact that primary surface of a city has been built and sharpened artificially, streets have been constructed, hydrographic networks have been shaped and hide, natural surface has been degraded.

Research Methology This work is an attempt to follow research steps forth by inquiry – based learning : a) trigger of interest, b)reminding of basic knowledge/formulation of hypotheses, c) experimentation/trials d) formulation of conclusions, e) applications/generalization according to learning. We designed the walk trail: Syntagma- Monastiraki-Kapnikarea-Pantanassa-Library of Hadrian -Roman Market (figure 1) and we pursued the educational research with an experimental group of students of secondary school of Attica.

Results and Conclusions The results of our research were compared with a control group of students of secondary school of Attica who visited our paleontology museum in Faculty of Geology and Geoenvironment of School of Science of National & Kapodistrian University of Athens. We noticed that students’ understanding, creativity, cooperation and critical thinking were spectacularly improved. They learned about the river Eridanus, they could recognize white marble of Pendeli, grey Hymettus’ marble, green marble of Karystos, granites and limestones with fossils. The most interesting point of the research was when the students realized that the complexity of the natural world arises from the combinations of few simple procedures.

Figure 1. The walk trail: (1) Monastiraki (2) Kapnikarea (3) Pantanassa (4) Library of Hadrian (5) Roman Market.

Acknowledgements The authors would like to thank the Director of Paleontology-Geology Museum, Professor Vassileios Karakitsios.

ABSTRACT. Introduction The research team of ΜΕΤΕΟ Gr at the National Observatory of Athens has implemented an educational program for secondary schools named “Peri Anemon & Ydaton” since 2016. The content of the educational program is in line with the curriculum of the Middle and High Schools and its structure is based on the constructive model of Driver & Oldham (Driver, 1986). The curriculum aims to provide to students acquisition of knowledge on severe weather phenomena, with emphasis on their impact on individuals and the society. The curriculum has an interdisciplinary as well as a holistic character. The interdisciplinary approach ensures the synthesis of knowledge, concepts and approaches from different sciences, natural and human, with the aim to unify the knowledge (Flogaiti, 2006). The evaluation of a educational program is a prerequisite as it helps to improve the program and determine if the program meets their stated goals . The purpose of this paper is to present the preliminary results of the evaluation of the educational program “Peri Anemon & Ydaton”.

Methodology Evaluation is a systematic process of collecting, analyzing and interpreting information to determine the extent to which students achieve instructional objectives (Gronlund, 1990). In the evaluation process, the first step is to determine the objective of evaluation and to quantify the achievement of the educational goals. The program “Peri Anemon & Ydaton” aims to present and discuss the weather phenomena, which affect students in the Mediterranean area, emphasizing in the severe weather phenomena and the related protection measures. The main objectives of the program are the explanation of the following weather phenomena: A. the creation of cyclonic and anticyclonic systems B. the formation of the cold and warm fronts C. the water cycle and the creation of clouds D. the stability and the instability in the atmosphere E. the cloud classification F. the creation of thunderstorms G. the creation of cloud-to-ground lightning strikes H. the formation of tornadoes.

The dominant tool for teaching strategies is the didactic tool of the model, since the student can confirm or reject his perceptions about the development of the weather phenomena. Furthermore, the students can discover the factors that influence the meteorological phenomena, such as the creation of high intensity rainfall and thunderstorm, the formation of a tornado and the creation of lightning, while developing psychomotor skills. During the educational program, the cooperative approach is applied to ensure students' cooperation. In parallel, modern teaching tools (educational videos, interactive tablet applications, experimental devices) are implemented, aiming at the experiential approach of knowledge. For the above objectives, Bloom’s taxonomy was used, while the program targets 8 overall goals. A multiple-choice questionnaire with 20 questions pertaining to the whole cognitive approach is used as an evaluation tool. To ensure student’s participation in the evaluation, the questionnaire is given as a software application and students are informed of their success score at the completion of the questions. In this paper, we used the results of the 257 questionnaires completed by Middle and High Schools students, from all over the area of Greece.

Conclusions Among the 257 questionnaires completed by the students and analysed, the correct responses average is 67%. The number of the sample can be characterized as satisfactory in order to obtain reliable results. The total percentage of correct answers was calculated in relation to the relative frequency percentage (pi) and the cumulative frequency percentage (Pi), as indicators of evaluation (Figs. 1, 2). A total of 78% of the sample provided answers with an accuracy exceeding 50% (Fig. 1). To assess the achievement of the above eight (8) learning objectives, twenty (20) questions formed the questionnaire and were categorized by objective (A to H) as follows: A: Q1, 2, B: Q3, 4, 5, C: Q7, 8, 18. D: Q6, E: Q9, 10, F: Q13, 14, 15, 16, 20, G: Q12, 19, H: Q11, 17. Every question is an evaluation criterion relevant to the cognitive goal. The main preliminary results of the educational evaluation of the program are presented in Figures 1 and 2.

Figure 1 presents the relative frequency of correct answers, while Figure 2 presents the cumulative frequency of correct answers. for the analysis of the above results, the assumption that the 5/10 grade (or 50%) is considered successful was adopted. As it is obvious from Figure 1, the majority of students gave correct answers from 50% - 85%, proving that the educational program achieves its educational goals, at a satisfactory level. The percentage of correct answers in the range of 50 - 70 % ranged from 8-10 %. The corresponding percentage of correct answers from 70% - 85% was 10-12%, showing that this is the dominant range of students with correct answers. On the contrary, the percentage of correct answers which ranges of 30- 45% and 90% - 100% was less than 5%. The percentage of students with correct answers follows a Gauss distribution (Fig.1), revealing that the sample is representative, and that the questionnaire was built according to the educational programme and the average cognitive level. Figure 2 shows that the cumulative percentage of correct answers with a success rate lower than 35 % is less than 6%. The percentage of correct answers with a success rate lower than 45% is 13,6%, while the corresponding percentage for success rates lower than 50%, 60%, 70% and 80% are 21,4%, 38,3%, 58% and 82%, respectively. Consequently, it is once again shown that the predominant range of students with correct answers is 50-85%. The obtained results prove that the overwhelming majority of students had successfully answered to the questions, consistently to a normal (Gauss) distribution (Spiegel, 2000). Based on the above preliminary results of evaluation of the educational program "Peri Anemon & Ydaton", it is evident that the program is achieving at a great extent its cognitive goals. It should be noted that the evaluation is underway and it will be completed by May 2019.

References Driver, R., Oldham, V., 1986. A constructivist approach to curriculum development in science, Studies in Science Education, 18, 105-122 Gronlund, N.E. and Linn, R.L. (1990) Measurement and Evaluation in Teaching. McMillan Company, New York. Flogaiti, Ε. (2006). Education on Environment and Sustainability, Hellenic Grammata, ISBN 978-960-9552-26-4. Fraenkel R. Jack & Wallen E. Norman (2009). How to Design and Evaluate Research in Education.McGraw‐Hill, ISBN 978‐0‐07‐352596‐9. Matthews, M.R. (1994). Science Teaching: The Role of History and Philosophy of Science. New York: Routledge Press. Spiegel, M & Stephens, L, 2000.Θεωρία και Προβλήματα Στατιστικής. 3η έκδοση. Αθήνα: Εκδόσεις Τζιόλα. ISBN 960805012X

ABSTRACT. Developing educational material based on satellite remote sensing technologies, information and methods, is a key trend in modern pedagogy of Earth System Sciences. Here, we present “MICE”, a classroom activity on Melting ICe Effects, that utilizes remote sensing information to demonstrate the value of Earth Observation (EO) as a context to teach the STEM (Science, Technology, Engineering and Mathematics) school curriculum. The activity focuses on the subject of polar ice melting as a main climate change effect and the different impact of land and sea ice melting on sea level rise. Students, have the opportunity to discover the above experimentally and subsequently, to observe the diachronic change on polar ice through sequences of satellite images and discover the positive climate feedback on global warming. The activity was translated and adapted to the Greek curriculum from the freely available classroom resources of the European Space Agency (ESA, “Teach with Space” collection). MICE, has been enriched with Greek scientific material, including up-to-date information on climate impacts, localized for the extended region. As part of an evolutionary process, the activity was pilot-tested with 6th grade primary school students and adjusted according to the trial findings. This work is considered as the first step towards the development of original Greek educational material that will utilize EO and climate change as the context to teach STEM school curriculum, capitalizing on the pedagogical role satellite remote sensing and inquiry-based teaching methods, can play.

ABSTRACT. Greece is characterized by a complex geological setting and evolution and was subjected to a variety of geological and geomorphological processes, resulting in a high geodiversity. As a result a large number of spectacular landscapes and rock outcrops form today a great number of geosites, some of them indicative and representative of the geological evolution of Greece, characterized thus as of national importance. In spite of their intrinsic value for the natural and human environment and the legal framework created by the L.1650/1986 for the protection of the environment and especially its revision law 3937/2011, till now the majority of geosites has not been awarded any kind of legal protection due to their scientific, educational and aesthetic value. The Committee for the Conservation and Enhancement of the Geological Heritage of the Geological Society of Greece took an initiative in October 2016 and invited all its members to identify and register in form proposals of geosites which present special geological interest and needs for protection. In December 2018 a special committee was created by the Ministry of Environment and Energy aiming to a proposal of measures for the protection of the geological heritage. Among the proposal was the establishment of a catalogue of the 100 geosites of national importance as a first step for the protection of the most important geosites of Greece. The Committee for the Conservation and Enhancement of the Geological Heritage of the Geological Society of Greece contributed to this effort with the submission of a catalogue including 108 geosites. This Catalogue was formed taking into account the existing geosites catalogues: the geosite catalogue of IGME (2016), the Atlas of Geological Monuments of the Aegean (2002), the catalogues of the five areas recognized as UNESCO Global Geoparks, published scientific papers as well as the list of the geosites submitted by the Committee members. The catalogue includes the following geosite categories: a. Geomorphological geosites b. Stratigraphic geosites c. Tectonic geosites d. Palaeontological geosites e. Mining geosites f. Petrological geosites g. Volcanic geosites h. Human made geosites To select the sites which were included in the Catalogue six criteria have been used: 1) scientific and educational value (integrity, rarity, representativeness, and exemplarity); 2) natural beauty and aesthetic value; 3) cultural value; 4) geodiversity; 5) potential threats and protection needs (legal protection, vulnerability); and 6) potential for use (recognizability, geographical distribution, accessibility, and potential for generating economic activities). The proposed catalogue is a first effort for the legal protection of the important geological heritage sites of Greece and should be further developed and increased.