ABSTRACT. The Institute for the Study and Monitoring of Santorini Volcano (ISMOSAV) was established in 1995 as a non-profit entity, with the main purpose of continuing the operation of the Volcanological Observatory and the volcano monitoring networks (seismological, geodetic, geophysical and geochemical) in 1993 in the framework of a European research program. A secondary objective of ISMOSAV was to promote volcanological research in Santorini, contributing significantly to the improved assessment of volcanic hazard and improving the ability to predict any volcanic activity or unrest in a timely manner. In this way, ISMOSAV has filled the gap left by the lack of a public body in Greece (e.g. research institute, etc.) that is responsible for the study and management of volcanic hazard, striving to protect Santorini by maintaining a reliable monitoring system that increases the likelihood of early warning of the volcano's reactivation, while also refuting, when necessary, any unfounded rumors and/or speculation. As a result, over the past 30 years and mainly with the support of the island’s local authorities, ISMOSAV has managed to overcome several problems related to the lack of permanent research infrastructure on the island, maintaining and upgrading installed networks, replacing obsolete equipment, and processing real-time and near-real time information. We present information on the early detection of the 2011-2012 and 2024-2025 volcano-tectonic intra-caldera unrests in Santorini. The presented results verify the critical role of ISMOSAV for the identification of these unrests, as well as on the measures that were taken to handle them. Moreover, they strongly suggest the need to establish the first permanent Volcanological Observatory on the island, operated by a local or other state authority, that will rely on and “assimilate” the existing ISMOSAV infrastructure, as well as monitoring sensors operated by other institutes, allowing to continue and expand on the ISMOSAV’s 30-year legacy.

ABSTRACT. This paper presents certain elements of the neotectonic and active structure of the Santorini island complex. The active structures consist of sets of primarily normal fault systems with right-lateral component in an en échelon pattern, trending at or around N30°E (Mountrakis et al., 1998). Another important and common feature on Santorini is the feeder dykes that are related with those faults. Along the major Columbo fault line, which appears to start at the southernmost tip of Therassia Island (Cape Trypiti) and stretch up to the Columbo submarine volcano and Anhydros Islet, they are primarily concentrated on the northern narrow part of the island, north of Mikros Prophitis Elias ridge.

The Fira normal fault is another active structure that is visible in the caldera walls. Significant tectonic evidence of recent activity may be seen on the Yialos Caldera cliff, including fractured and tilted late Quaternary volcanic layers, as well as new on-land tectonic scarps. A syn-depositional normal fault, it is a significant structure that deforms various volcanic lava layers, scoria, and pyroclastic flows. As evidenced by the microseismic activity during the 2011–2012 crisis and the one ongoing since the end of 2024, this fault is classified as active.

A large scarp of the same strike affects the relief along the fault-line and continues farther to the northeast on the island, even though volcanic material near the topmost part of the fault appears undeformed. It is thought to be a longer, seismically hazardous structure that follows the tectonic line of the Kameni volcano. The fault was modelled by using data from a UAV campaign, that allowed for the construction of a precise DTM (Figure 1, Pavlides & Chatzipetros, 2018). It shows that fault throw episodically declines upward on the caldera's highly steep inner escarpment, from 22 m at sea level to nearly 2 m at the highest point (Pavlides et al., 2025, this volume).

Two extensional contemporary stress phases have been documented, implying that the first is attributed to the tectonic stresses related to the well-established Aegean motion towards SSW, whereas the second, which gives rise to recent microseismicity of the area, is a local stress regime attributed to buoyancy forces relating to magmatic processes of the area (Pavlides & Tranos 2014). Therefore, the combination of these two stress regimes reflects the competition between the tectonic (lithospheric) and magmatic (local volcano-tectonic) forces, in a fault-dynamic regime that could be characterized as extensional-transtentional field.

During the 2024-2025 volcano-seismotectonic crisis, the Fira fault ("Kameni line") is activated producing a shallow sequence which slowly initiated in the beginning of late September 2024 and is still in progress. More than 200 eventst were recorded within the study region for this period and their hypocentres were calculated using the NonLinLoc earthquake location algorithm (Lomax et al., 2000) along with the local 1D velocity model proposed for the region by Dimitriadis et al. (2009). The NonLinLoc algorithm utilizes the equal-differential-time (EDT) likelihood function (Zhou, 1994; Font et al., 2004), which uses travel-time differences between observed and synthetic travel times for pairs of stations, resulting to a more robust calculation of the optimal hypocentral location, due to the fact that the 4-D problem (x,y,z, t) is reduced to a 3-D search over space (x,y,z). Furthermore, mispicked phase data can be identified by the methodology and excluded from the solution. Due to the large number of local seismographic stations at a very close proximity to the sequence, for most of the located events the horizontal error was as low as 0.5km, whereas the vertical (depth) error was between 0.8-1.2 km. The majority of the sequence's hypocentres is located at shallow depths (3-8 km). The strongest earthquake (ML 3.6) occurred on January 25, 2025. The moderately linear horizontal trend of the epicentres is main the characteristic of the sequence.

Figure 1. Digital Terrain Model of the Yialos cliff face, where the Fira fault is observed deforming the layers of lavas and pyroclastics. It was obtained through a targeted UAV campaign (Pavlides & Chatzipetros, 2018). Left image shows the outcrop photomosaic draped over the 3D model, which is shown at the right one.

The majority of earthquakes are thought to be caused solely by tectonic forces, specifically the Fira fault. If we additionally consider the estimation of the volume and depth of the magma intrusion, some of them are most likely caused by the volcanotectonic activity. More specifically, the Fira fault likely both facilitates the magma chamber's upward progress and marks it off to the south.

All evidence, both geological and seismological, indicate that the Fira fault is an active tectonic structure. Its activated length is estimated to about 6-8 km, corresponding to a moderate expected earthquake magnitude of Mw 5.5-6.0, as calculated from known empirical relationships (Wells & Coppersmith, 1994). The fault probably extends bilaterally, i.e. toward the NE, as shown by the seismic activity of the beginning of 2025, and toward the SW as well. Northward onward intracaldera tectonic structures formation example elucidates a swelling of the volcanic edifice.

References Dimitriadis, I., Karagianni, E., Panagiotopoulos, D., Papazachos, C., Hatzidimitriou, P., Bohnhoff, M., ... & Meier, T. (2009). Seismicity and active tectonics at Coloumbo Reef (Aegean Sea, Greece): Monitoring an active volcano at Santorini Volcanic Center using a temporary seismic network. Tectonophysics, 465(1-4), 136-149. Font, Y., Kao, H., Lallemand, S., Liu, C. S., & Chiao, L. Y. (2004). Hypocentre determination offshore of eastern Taiwan using the Maximum Intersection method. Geophysical Journal International, 158(2), 655-675. Lomax, A., Virieux, J., Volant, P., & Berge-Thierry, C. (2000). Probabilistic earthquake location in 3D and layered models: Introduction of a Metropolis-Gibbs method and comparison with linear locations. Advances in seismic event location, 101-134. Mountrakis, D., Pavlides, S., Chatzipetros, A., Meletlidis, S., Tranos, M., Vougioukalakis, G., & Kilias, A., 1998. Active deformation of Santorini. In: Casale et al. (Eds), The European laboratory volcanoes, European Commission, EUR 18161 EN, 13-22. Pavlides, S. & Chatzipetros, A. (2018). The Fira fault (Santorini, Greece) from the French “Expédition de Morée (1829‐38)” to modern scientific approach, In: Koukousioura, O. & Chatzipetros, A. (Eds.), Proceedings of the 9th International INQUA Workshop on Paleoseismology, Active Tectonics and Archeoseismology, Possidi, Greece, 25-27 June 2018, 218-220. Pavlides, S. & Tranos, M. (2012). Fault geometry and kinematics of the broader Santorini area in relation to seismic activity and volcanism. Abst. VOLSAM2012. PavlidesS., Sboras S., LazosI., Mouzakiotis E., & Karastathis V. (2025). The Fira fault, Santorini (Thera): morphotectonic, geomorphological and seismological evidence of fault activity, 17th International Congress of the Geological Society of Greece, Mytilene, Greece. Zhou, H.W. (1994). Rapid three‐dimensional hypocentral determination using a master station method. Journal of Geophysical Research: Solid Earth, 99(B8), 15439-15455.

ABSTRACT. Santorini is an active stratovolcano emplaced within a region of extensional faulting in South Cyclades, Greece. A two-month-long seismic crisis reaching Amorgos (NE of Santorini), together with GNSS measurements made before and during the crisis, provide insights into the relations between the volcano dynamics and its surroundings. The GNSS data show that Santorini inflated since the summer of 2024. We model this inflation with a magma source of ~ 8 × 106 m3 located ~3.5 km under the north-central floor of the caldera, near the inflation centre of 2011-2012. The inflation phase ceased around 20 January 2025. Contemporaneously, the seismic activity, shifted to the north-east of Santorini near the islet Anydros. This phase lasted about ten days, before leading into a most intense phase that produced ground deformation measurable at large distances over the South Cyclades.

ABSTRACT. Expedition DY190 onboard the Royal Research Ship (RRS) Discovery explored the Christiana-Santorini-Kolumbo volcanic field between the 3rd and the 28th March 2025. The primary aim of the expedition was to study the interaction between caldera volcanoes and their hydrothermal systems, to understand the role they play in increasing or decreasing the explosivity of eruptions. However, the expedition was serendipitously scheduled a month after the start of the “Seismic Crisis” in the region and hence provided a unique opportunity to assist in efforts to understand and monitor this seismicity and to assess its impact on both Santorini and Kolumbo volcanoes.

ABSTRACT. The Santorini volcano is associated with one of the most destructive volcanic eruptions in human history, yet it remains insufficiently monitored. This is partly due to its behavioral pattern, characterized by long periods of rest interrupted by short and rapid episodes of unrest. Indeed, the last well-documented unrest episode in 2011–2012, characterized by comprehensive instrumentation and quantitative measurements, occurred after approximately 60 years of quiescence since the 1950 volcano activity. Despite the significance of the 2011–2012 unrest, post-crisis monitoring efforts were limited, sustained mainly by the Institute for the Study and Monitoring of Santorini Volcano (ISMOSAV), and without any coordinated activity at a national level. ISMOSAV is a non-profit organization established in the summer of 1995, with the primary objective of operating volcano monitoring networks and providing informed assessments regarding the state of the volcano. The monitoring efforts over the past 12 years were substantial enough to enable early detection and timely notification to relevant authorities, contributing to the governmental response when a new unrest phase began in mid-summer 2024. We discuss the role of geodetic imaging techniques in volcano monitoring, their advantages, and complementarities with other geodetic and in-situ networks and finally, we emphasize the need to establish a local volcano observatory, involving scientists across multiple domains, integrating diverse techniques and equipment for real-time monitoring of this volcanic region and its surrounding areas.

ABSTRACT. The 2025 volcano-tectonic crisis of Santorini and Kolumbo volcanoes in the Greek Aegean Sea has provided unprecedented insights into the complex, interconnected magmatic systems beneath these neighbouring volcanic centres. Through the integrated analysis of seismological data and geodetic measurements, the migration of magma prior to and during this significant event has been reconstructed. The crisis began with a gradual deformation of the ground within the Santorini caldera from July 2024, with an uplift of about 45-50 mm detected by GNSS and satellite data, accompanied by increased H₂ and CO₂ gas emissions. On 27 January 2025, an intense earthquake swarm initiated 10 km northeast of Santorini, near Kolumbo volcano. The seismic activity continued for a period of over 30 days, during which time the intensity fluctuated. The seismic activity can be subdivided into distinct phases, beginning with deep seismicity (12-18 km) accompanied by strong tremors. This was followed by northward migration of increasingly shallow earthquakes towards Anhydros Island at velocities of approximately 1 km/h. The identification of at least 12 seismic surges, characterised by sharp increases in seismicity rate, magnitude intensification, and concurrent tremor activity, followed by lateral migration of seismic fronts, underscores the complexity of the crisis. A thorough analysis of 180 earthquake moment tensors for events with MW>3.6 revealed a consistent NW-SE-oriented tension axis perpendicular to the earthquake migration path, consistent with normal faulting patterns typical of dike intrusions. Our high-resolution earthquake catalogue, which contains over 28,000 events, shows a segmented, laterally ascending complex dike intrusion characterised by incremental, non-uniform and rapid expansion. Furthermore, periods of dike growth coincided with intense seismicity and large-magnitude earthquakes (MW>5) concentrated at the advancing dike tip. Between surges, when the dike boundary was stationary, seismicity was predominantly lower magnitude (MW 1-3), consistent with gradual pressurisation due to continuous magma inflow. Joint inversion of ground deformation data suggests two primary sources: a volume decrease within a mid-crustal reservoir beneath Kolumbo volcano and a uniform opening along a ~13km long dislocation between Kolumbo and Anhydros, representing the emplacement of a dike. The deflation source has been estimated at a depth of ~7.6 km beneath Kolumbo, with an inferred volume decrease of ~0.08 km³. In contrast, the volume increase in the dike has been calculated at ~0.3 km³. Following the initiation of the dike, there was a rapid increase in the magma inflow rate, which peaked between 4-12 February, with average inflow rates exceeding 200 m³/s, before decreasing to almost zero by 24 February, which is likely to mark the end of the intrusion. The sequential timing of these events – shallow magma chamber inflation at Santorini, followed by dike intrusion into the Anhydros Block with concurrent deflation at Kolumbo – points to coupling between reservoirs of both volcanoes. The interaction between the reservoirs likely occured through crustal stress transfer or pressure changes within the fluid plumbing system at depth, while there is no evidence for direct connection between the shallow magma reservoirs.

ABSTRACT. Positioned in a peculiar paleogeographic regime, near the Hellenic Trench, that is part of the still active subduction process in the eastern Mediterranean, Gavdos island, the southernmost part of Greece and Europe, offers insights, among others, into late Miocene sedimentary and tectonic processes. This study investigates the hydrocarbon generation potential of late Miocene sapropelic and mudstone/siltstones cyclic deposits through geochemical analysis of samples from two outcrops, namely the GL# and GC#. The GL# and GC# outcrops belong to the Tortonian and Messinian age respectively. GL# outcrop represents the lateral equivalent of the basal part of the main section originally described as Metochia-B, while GC# is a new outcrop (probably lateral linked to the Metochia-C), which covers part of the latest deposits that precede the Messinian Salinity Crisis (MSC) onset, firstly presented in this work. To evaluate the organic richness and hydrocarbon generation potential of these deposits, 59 samples were subjected to Rock-Eval VI pyrolysis. Results revealed that the potentiality varied from poor to fair, with most samples containing Type IV kerogen and limited occurrences of Type III, indicating minimal gas-prone source rocks. GL# outcrop samples, associated with the basal part of Metochia-B, exhibited lower organic richness compared to previous studies, reflecting deposition in a more marginal basin sector, where most probably oxygenation of the organic matter was more intense. GC# samples, representing the Messinian deposits, showed decreased organic matter productivity, potentially linked to environmental changes that prevailed prior to the MSC. This work fills a research gap in the geochemical characterization of Metochia-C sapropelic layers and further extends laterally previous analyses of Metochia-B. Although the geochemical signatures indicate limited onshore hydrocarbon potential, findings contribute to refining the hydrocarbon prospectivity map of the eastern Mediterranean. Further studies are essential to explore offshore prospects, where improved organic matter preservation is anticipated in more favorable depositional environments of the deeper sea. This study highlights the value of integrating stratigraphic and geochemical analyses for energy resource assessment in tectonically complex regions like Gavdos and its adjacent basins.

ABSTRACT. Southeast Mediterranean is characterized by the presence of nappes that overthrusted the authochonous Plattenkalk series, during Oligocene to early Miocene. South of Crete, the Hellenic Trench (HT) and the Mediterranean Ridge (MR) were developed during the late Miocene. By Messinian time, most of the MR had been already formed and rose above the neighboring abyssal plains. On the elevated portion of the MR, where fields of mud diapirs (volcanoes) have been discovered, the Messinian layer is significantly thinner than on its deeper southern flank. The comparison of western Greece and western Ionian basin with Gythion/Sparta and Crete Island regions with the Plattenkalk series, showed the same depositional conditions, introducing equivalent depositional conditions between Ionian Basin (western part) and the Plattenkalk series, in south Peloponnesus and Crete Island. Therefore, Crete Island could represents the Ionian basin whereas the HT could be the equivalent of the Apulian Platform Margins (APM); whereas the MR could represents a platform, equivalent to the Apulian Platform (AP). During the Oligocene compressional regime, the Crete Island represents the wedge top area, the Hellenic trench the foredeep area and the area of Mediterranean ridge could be the fore bulge area. Later and during the late Miocene migration of compressional regime southwards the MR represents the wedge top, northwards the HT the extensional backstop areas (e.g. Gavdos Trench), and southwards the Sirte abyssal plain the new foredeep. The presence of nappes in SW Peloponnesus, only in Pylos area, shows how the strike-slip faults influence the nappes development. Furthermore, the presence of reefs, according EDDEY in 2018 announcements, reefs must be developed on the MR. The question is if the nappes overstepped the HT (when they were the APM) and covered the MR (when they were the AP)? or the nappes filled up only the HT and therefore the MR now is without any nappe?

ABSTRACT. This research involves the integrated sedimentological and paleontological analysis of the Neogene tidal deposits in the eastern parts of the Hellenic Fold and Thrust Belt, in South Kefalonia (Paliolinos - Avithos coast) and in NW Corfu (Arillas coast) islands. The study of tidal is supported by illustrative outcrop photographs, with a particular emphasis on two synthetic outcrops. Sedimentary logs were generated to document detailed bed-by-bed measurements, descriptions, and identification of sedimentary structures. Additionally, over 75 samples were chosen for age determination and paleoenvironmental analysis. Micropaleontological analysis encompassed 52 samples from South Kefalonia and 23 samples from NW Corfu and the results point to an Upper Miocene time interval. The sedimentological examination revealed sixteen distinct sedimentary structures within the studied deposits. The study results indicate for NW Corfu that the deposition displays fluctuations between low and high energy episodes, predominantly representing a tidally-influenced continental shelf (Figure 1a); whereas in the South Kefalonia deposition took place in a back-barrier restricted basin and highly active margins (Figure 1b). The different tidal environments, in the two studied regions, were related with the different tectonic conditions. When the tidal environment in a basin mostly controlled either by transfer or strike-slip faults, open shelf tidal environment could be formed; whereas when the major influence is the normal or the thrust faults then a tidal back-barrier environment could be formed.

ABSTRACT. The Apulian Platform Margin (APM), situated between the Apulian Platform to the west and the Ionian Basin to the east, are outcropped in Lefkas Island, on the Ionian Sea, and are characterized by the presence of Jurassic to Eocene deposits. During the middle Miocene, the Ionian Thrust activity produced narrow foreland basins between the Ionian Basin and the Apulian Platform, where carbonate sub-marine fan deposits were accumulated. The APM representing the forebulge area of the Ionian foreland was strongly deformed. The studied section with a NE-SW direction is cross cut by many faults. Some of the faults showed synsedimentary activity and were responsible for the deformation within the outcrops. Bedding planes present an eastward dipping direction, up to 70° angle. In the studied Eocene carbonates, up to 400 m total thickness, the facies analysis showed the presence of four different types of deposits, i.e., pelagic calcilutites, calcarenites, and debris flow deposits. All of them accumulated in slope and toe of slope facies zones. Their microfacies point to deep sea conditions. Additionally, there are also breccia with angular clasts, indicating an active tectonics and very close source. The presence of siliceous concretions within the carbonates supports the above suggestion. Small lenses of red granule-size breccia, with abundant calcareous algae indicate also a proximity of a platform source. The trace fossils Trichichnus, ?Palaeophycus, Zoophycos, crinoids and nummulites in calcarenites were recognized. The Zoophycos appearance, with normal and reverse positions led to the sub-division of the sedimentary succession into two parts (both up to 200 m thick), the lower one with the normal position, and the upper one with the reverse position. The upper part probably reversed due to an intense giant slumping event during the sedimentation, indicating that the deformation of the APM started earlier than the middle Miocene, time of the Ionian Thrust activity. Although Eocene was characterized by deep-sea conditions, the normal fault activity produced many tectonic pulses with the development of slumps and slides, close to the Apulian Platform. Due to this fault activity, diverse sedimentary material (e.g., large foraminifers) was transported from the close extended platform to the slope or to the toe of the slope.

ABSTRACT. In the NW part of the Ionian Basin (Ioannina region, Western Greece), Triassic evaporites and Jurassic to upper Eocene carbonates (interbedded with minor cherts and shales) are overlain by Eocene to Miocene siliciclastics. These deposits reflect the depositional environments that prevailed during the pre-orogenic, extensional stage and the following syn-orogenic, contractional stage, respectively. During the Middle Eocene, a transition from extension to compression and growing of the Pindos Orogen took place. This caused a change of sedimentation from slope carbonate to siliciclastic submarine fan deposits. Clastic deposits accumulated in a pre-foreland basin at the margin of the Apulian microcontinent from the Late Eocene to the early Miocene because of the uplift of Pindos Orogen and the activity of Pindos Thrust. This change is relatively rapid, so the total thickness of the transitional beds is up to 12.67 m in the Mazia village. In the lower 5 m, there are only thinly bedded mudstones, whereas in the upper 7.5 m within the thinly bedded mudstones there are sandstones and marly limestones. The mudstone is thin- to medium-bedded (0.01–0.02 m) and is either structureless or parallel-laminated. The sandstone beds display sharp bases and include sedimentary structures, such as parallel and ripple cross-laminations. Individual carbonate beds may be either structureless, parallel, or ripple-cross laminated calcarenites. Some of them show an upward transition from structureless (base of the beds), through parallel-lamination to ripple-cross-lamination (top of the bed). This facies association is interpreted as deep-water abyssal plain deposits, according to the dominant lithology and sedimentary structures. Within the marly limestone beds, the trace fossils Chondrites intricatus, C. targionii, Planolites isp., Nereites isp., and Avetoichnus are recognized. In the underlying deposits, Zoophycos is present. The overlying clastic deposits in the area contain diverse trace fossils typical of the Nereites ichnofacies. The sedimentological and ichnological features point to the transition from the Zoophycos to the Nereites ichnofacies and slope to abyssal plain deposition.

ABSTRACT. Introduction This research presents an advanced engineering geological database, designed to comprehensively manage extensive geological and geotechnical data (Kokkala, 2023). Based on the Tunnel Information and Analysis System (TIAS) framework (AGS, 1999; Marinos et al., 2013), the database integrates information from numerous boreholes and geotechnical investigations conducted in Thessaloniki’s urban area, northern Greece, focusing on Quaternary and Neogene sediments, as well as fill deposits. Its primary aim is to reduce geological uncertainties and address geotechnical challenges critical for urban safety and planning, by means of numerous database applications (Kokkala and Marinos, 2022). Emphasizing the utility of big data management, the study explores how geological heterogeneity, subsurface variations, and engineering geological conditions can be better understood to mitigate geohazards (e.g. liquefaction as the application example used here) and support early-stage infrastructure design. Methods In this study, Standard Penetration Test (SPT) and Cone Penetration Test (CPT) results were analyzed to investigate liquefaction susceptibility and potential in an area located at the vicinity of Thessaloniki airport (Figure 1), as a database application for urban geohazard assessment. Based on the outcome arisen by the geotechnical investigation, it was concluded that the subsoil profile predominantly consists of sandy clays and silts, interspersed with medium-density sand layers. Two distinct sub-areas (A and B), differentiated based on their proximity to the stream located to the south, were analyzed to evaluate in situ conditions and liquefaction susceptibility. A series of cross-sections, such as the example shown in Figure 2, was developed to illustrate the distribution of the Soil Behavior Type Index-SBTn (Ic) based on the liquefaction susceptibility criterion proposed by Robertson and Wride (1998). Further analysis involved the assessment of the liquefaction potential index (LPI) alongside estimations of vertical and lateral displacements for each sub-area, utilizing the available CPT data. For this purpose, two distinct seismic scenarios were considered: the first one involves the activation of the Anthemoundas fault, resulting in a seismic event with a magnitude of M 6.9 and peak ground acceleration of 0.4 g, while the second scenario refers to the activation of the Gerakarou fault, generating a seismic event with a magnitude of M 7.0 and peak ground acceleration of 0.5 g (Lin and Smerzini, 2022). Results The analysis revealed stratigraphic differences between the sub-areas. Sub-area A exhibited a higher concentration of coarse-grained materials in places, whereas sub-area B was dominated by fine-grained deposits, reflecting variations in the depositional environment. In most soil columns, LPI values exceeding 5% were observed throughout the study area under the first seismic scenario, indicating a high to very high liquefaction potential. Additionally, vertical displacements ranged from 16 to 19 cm and lateral displacements reached up to 220 cm were estimated under both seismic scenarios for the two sub-areas. Conclusions This study highlights the essential role of integrating primary geological and geotechnical data into a well-structured database for detailed geohazard analysis. The proposed methodology showcases the utility of an engineering geological database in evaluating and mitigating liquefaction, providing critical insights for enhancing urban safety and optimizing infrastructure design.

ABSTRACT. The present study focuses on the assessment of liquefaction potential in an area where numerous liquefaction phenomena were triggered by the 2021 Damasi, Greece, earthquake. The liquefaction features were reported during a field survey conducted few hours after the event along the Piniada Valley (Papathanassiou et al. 2022). They were classified as sand craters, as singular features as well as aligned ones, and ground fissures, from where a mixture of water and fine sandy and silty material was ejected, and lateral spreading phenomena. According to eyewitnesses, the phenomena occurred during the March 3rd mainshock, locally caused mixed fluid fountaining as high as 1 m from the topographic surface. The total area covered by the ejected material (sand blow) at Piniada Valley was estimated as 0.0325 km2, approximately 0.5% of the zone that is delimited by the village Piniada, to the north, and the present-day river channel of river Pinios, to the south (Papathanassiou et al. 2022). This area is covered by Holocene sediments deposited along the meandering fluvial system of Pinios. The characteristic evolution of Pinios River dictates the depositional process of the sediments and contributed to the lateral and vertical heterogeneity of the surficial soil material. That was clearly shown during the 2021 event since liquefaction phenomena preferred to concentrate in specific location forming clusters of liquefaction-induced ground disruption such as sand boils, craters and ground fissures (Valkaniotis et al. 2024). In addition, it is highlighted that within a short distance, the severity of ejecta was totally different. For the purposes of this research, we investigated the role of the stratification of soil deposits for the generation (or not) of liquefaction-induced surface evidence and to the relevant ejecta severity. In order to achieve this, we used data derived by six CPTu tests conducted on an area where liquefaction phenomena were mapped. The liquefaction potential at each site was estimated following the method proposed by Hutabarat and Bray (2022), who concluded that the layer stratification can lead to not producing ejecta.

ABSTRACT. This research serves toward safeguarding airport infrastructure in liquefaction-prone regions. Although airports contribute to socioeconomic vitality of a region and serve as emergency means in cases of seismic events, their functionality remains vulnerable to disruption caused by secondary earthquake effects such as soil liquefaction. Hence, the risk and vulnerability assessment of airport facilities is crucial for their functionality and preparedness during and after the liquefaction events. This study introduces a practical and rapid assessment tool for the preliminary identification of areas prone to liquefaction and the risk analysis of airport infrastructure on a regional scale. As region of research was selected the Nestos delta in Greece, where the critical infrastructure of Kavala International Airport is placed (KVA). According to the results, a significant section of KVA’s runway and taxiways are located on highly susceptible soils of abandoned meanders. Aiming to quantify the impacts of liquefaction in the susceptible areas, FEMA’s HAZUS (FEMA, 2022) methodology is applied, estimating values of 20% of liquefaction probability and 3.1-12.3 cm of expected ground settlements for the class of very high susceptible units. The results of the liquefaction hazard analysis are used for the risk assessment of the airport infrastructure, estimating a total direct loss of €5 million. Validation of the proposed methodology was achieved using datasets from three international airports that sustained extensive seismic damage in the past.

ABSTRACT. Storm (Medicane) Daniel, landed on Greece in September 2023. From September 4 up to September 7 2023, central Greece and especially Thessaly region was severy affected by floods, debris flows and landslides. We used available satellite imagery (Landsat 8/9, Sentinel 1/2, Planet and VHR optical sensors) for mapping landslides polygon over western Thessaly area. A preliminary landslide inventory of 3200 landslides was compiled using high resolution Copernicus Sentinel-2 multispectral imagery ten days after the event. The final Daniel landslide inventory includes 5446 landslides. Most of the landslides are found along the Pindos Mountain range, with additional concentrations in the hilly areas north of Trikala and near Mouzaki. Highest concentration of landslides were located on Triggia Mountain, Trikala and Fanari/Kanalia hills near Karditsa.

ABSTRACT. In this short paper, we update on the findings of a joint geodetic and seismological investigation of Milos (western Cyclades islands, Greece) since 2022 when we published out first short report in BGSG. The integrated monitoring includes the use of geodetic data (InSAR and GNSS) and the continuous recordings of a 24/7/365 local seismic network established by NOA in 2021 and upgraded in 2023. Our objective was to investigate the ground deformation and seismicity patterns and detect activity along fault zones of the island. We present evidence for on-going activity at 5-9 km depths along a NW-SE fault crossing Milos.

ABSTRACT. Geothermal source of energy has become a priority in the energy transition strategy with its great advantage when needed especially in islands with the boost in consumption during the summer period. Legacy data analysis and geological and geophysical surveys can provide in an integrated model for improved understanding how the geothermal fields operate in the subsurface. Analysis of magnetotelluric and regional gravity legacy data as well as old geological studies acted as a feasibility study to design a more detailed geological as well as geophysical survey to unravel the geothermal potential of the Petra area (central northern part of Lesvos Island). The targets were faults and lateral inhomogeneities, which can act as hydrothermal circulation zones and areas of low density and magnetization, resulting from the alteration and oxidation of various rocks. New land gravity and magnetic measurements and four active seismic profiles with vibroseis source and nodal geophones were spread in the survey area to shed light into the subsurface faults and hydrothermal fluid circulations. We present a first-hand result from these surveys in the difficult terrain of Lesvos Island.

ABSTRACT. We report the results of a 3-D inversion of legacy magnetotelluric data collected in the year 2000 at the geothermal prospect of NW Lesvos Island, North Aegean, and co-evaluate the resistivity model with Bouguer gravity anomaly data from the same area. The general outlook of the geoelectric structure is that of a 'mosaic' in which intersecting NE-SW and NW-SE bands of relatively high resistivity (ρ>200 Ωm) engulf zones of relative conductors (100<ρ<5 Ωm). Resistivity is noticeably lower at at shallower depths, where the conductors appear to diffuse laterally to all directions; it increases with depth so that the conductors progressively wedge into the resistive basement and vanish at depths greater than 2 km bmsl. Such configuration of the geoelectric structure is remarkably consistent with that of known (mapped) faulting features of the area, and therefore consistent with the hypothesis that the conductive formations are collocated with intersecting faulting zones of NE-SW and NW-SE orientation, which generate a system of permeable structures capable of storing thermal fluids that ascend and laterally diffuse through the same faulting zones. This interpretation is also consistent with the findings of exploratoty geothermal drilling. A prominent characteristic feature is a NE-SW alignment of gravity and electrical resistivity lows between the broader areas of Stypsi–Petra and Lepetymnos – Sykaminea towns. Low Bouguer anomalies indicate low-density material beneath the surface and low resistivity values indicate the presence of water. Their coincidence indicates the presence of low-density rock filled with water and, in the geological setting of the study area, possible alteration/argillization of volcanic rocks due to hydrothermal activity. Accordingly, the collocated gravity and resistivity lows may be epiphenomenal to the action of faulting due to which the circulationtion thermal fluids depresses the resistivity (epiphenomenon 1) and, hydrothermal alteration/argillization and bleaching of the heavier elements depress the density of the host rocks (epiphenomenon 2). Given the broader tectonic setting of the study area, the above observations indicate the presence of NE-SW fault zones that have at least been contemporary with the volcanic activity 17 – 20 Ma ago; these established well-defined circulation zones which are still operational today, although it is difficult to infer whether they are still active today.

ABSTRACT. The increasing availability of high-resolution satellite data can significantly benefit geothermal studies. Remote sensed data analysis can be employed in the preliminary exploration of geothermal fields, providing valuable insights into the hydrological and tectonic characteristics of the study area. This study reviews the implementation of data derived from two satellites in the exploration of the geothermal system of the Methana peninsula and propose a methodology that is applicable in other geothermal areas. A variety of satellite data was utilized to gain a more comprehensive understanding of the region. Thermal discharges into the sea, structural features, and land cover data were analyzed and presented in maps, along with lithological features, the hydrological network and the system of tectonic discontinuities of the peninsula. The concurrent view of these elements provides insights into the hydrothermal fluid flow in the region, which is crucial if exploitation for potential exploitation of the geothermal resources. Overall, satellite data analysis proves to be beneficial in the exploration of geothermal systems, since it provides useful information with limited financial and time requirements, also including otherwise inaccessible areas.

ABSTRACT. Santorini is one of the most significant islands in the South Aegean Sea and a well-known volcanic center in the South Aegean Volcanic Arc. It is known for its seismicity, caused by active volcanic and tectonic processes, such as the occurrences of 2011-2012 and 2024-2025. This study focuses on estimating the ground deformation velocity of Santorini’s caldera by utilizing Multitemporal InSAR method of SBAS (Small Baseline Subset) and Sentinel-1 satellite imagery. The research found increased uplifting deformation rate in northwestern Nea Kameni and Imerovigli, up to ~ +17.6 mm/yr and ~ +17 mm/yr respectively. A lesser uplifting trend was recorded in Northwestern Thira (Oia) and Thirasia. Significant horizontal westward deformation was seen in south Thirasia and west Oia (up to -20 mm/yr) and Palaia Kameni (~ -39 mm/yr), while an eastward pattern was representing Imerovigli (up to ~ +21 mm/yr), which might signify swelling of the caldera due to magmatic and tectonic processes in the volcanic chamber. Time-series vertical and horizontal deformation diagrams attribute a more impactful effect after June of 2024.

ABSTRACT. Permanent GNSS networks provide valuable information concerning ground deformation monitoring and estimating velocity and strain filed of an area. The Santorini Seismic crisis during 2024-2025 resulted to strong ground deformation, as this was observed from 3 permanent stations operating in the island the last few years. In order to better study, understand and monitor the ground deformation in the broad south Aegean area during this intense seismic activity a joint effort from several academic and research institutions of Greece resulted to the establishment of a dense permanent GNSS network. The network covers not only the Santorini Volcanic Complex, but all the surrounding islands as well as the islets of Anydros and Christiana. Scope of this network is to monitor on a daily basis the ground motion, aiming to provide answers concerning the origin of this seismic activity, and support towards a better organization of the civil protection.

ABSTRACT. The Santorini-Amorgos (SA) region lies within one of the most active segments of the South Aegean Volcanic Arc (SAVA), where complex interactions between tectonic structures and volcanic systems are driven by the ongoing subduction of the African plate beneath Eurasia. This region is characterized by extensional deformation along NE–SW trending faults and includes prominent volcanic centers such as Santorini and Kolumbo. In mid-2024, low-level seismicity began beneath Santorini, gradually intensifying and migrating northeastward by early 2025. This development raised significant concern due to its location along known fault systems and in proximity to active volcanic centers. Historically, the area has shown evidence of tectono-magmatic activity, and the emerging sequence prompted the need for detailed monitoring and analysis. The primary objective of this study is to investigate the evolution and underlying processes of the 2024–2025 seismic sequence using high-resolution seismic monitoring. Specifically, we aim to enhance the existing seismic catalog through machine-learning-driven workflows, resolve spatial and temporal patterns of earthquake occurrence, and assess the physical nature of the events—particularly whether they result from tectonic faulting, magmatic intrusion, or a combination of both. A secondary goal is to develop and implement a near-real-time operational framework to support crisis response and long-term scientific research.

ABSTRACT. The 2025 seismic activity near Anydros Island contributes to understanding the relative roles of tectonic and volcanic processes in the Santorini-Amorgos zone. Here we report on non-shear components of the full moment tensor analyzed in a probabilistic Bayesian framework. This is a continuation of the study preliminarily reported to EMSC and EarthArXiv in mid-February, 2025, during the crisis. We show that the waveform inversion of 25 earthquakes unambiguously provides the full moment tensors with significant non-double-couple components (non-DC), namely with ISO > 0 and CLVD > 0 for most of the investigated events. This indicates robustly resolved non-shear faulting, stable across the events. The positive signs of ISO and CLVD point to the shear-tensile source process, i.e., crack opening. Two (shallower) events represent a shear-compressional process, i.e., crack closing (ISO < 0, CLVD < 0). The DC-part of focal mechanisms of all analyzed events is mostly normal faulting, but strike-slip events were also found. Non-DC components represent sensitive parameters, less robust than strike, dip, rake, and moment. Thus, the uncertainty of non-DC is relatively large. That is why confidence intervals of this study are more reliable than median moment tensors. A warning must be made about simplifying assumptions used by many agencies. In particular, if an earthquake contains a significant ISO component, and is inverted as deviatoric, it may result in an erroneous CLVD. In other words, under the deviatoric assumption, the detection of non-shear-faulting may completely fail.

ABSTRACT. We used the NLL algorithm (Lomax et al., 2000, 2014) and the multiscale high precision NLL–SSST–coherence procedure (Lomax and Savvaidis, 2022) to relocate a manually picked set of earthquakes with data taken from the bulletins from the Geophysics Department of Aristotle University of Thessaloniki (doi:10.7914/SN/HT) and National Observatory of Athens (doi:10.7914/SN/HL) and a set of picks obtained with machine learning (ML). For the ML picking we analysed waveform data during 1 January–28 February 2025, from 21 broadband stations located in distances up 120 km from the seismicity centroid (https://eida.gein.noa.gr/). The earthquake detection and phase picking were performed by Phasenet (Zhu and Beroza, 2018), a deep–neural–network–based arrival-time picker. Phase picks are then associated using the REAL software (Zhang et al., 2019). REAL is a grid–search phase association algorithm that performs phase association and an initial location of earthquakes, primarily through counting the number of P and S picks that appear within a travel–time curve threshold determined by the user and secondarily from travel time residuals (Zhang et al., 2019).

ABSTRACT. During February-March 2025, a seismic swarm occurred near the Santorini-Anydros-Amorgos area, with thousands of earthquakes being recorded with a maximum magnitude of M5.2. Hundreds of earthquakes with magnitudes larger than 3 were recorded and felt by inhabitants of Santorini and neighboring islands, to a tentative self-evacuation of Santorini and the declaration of emergency state by the Hellenic government. In light of these events, we rapidly responded to the ongoing crisis by designing and deploying a new seismic array in Santorini (SantoArray). The collaboration between the Aristotle University of Thessaloniki (Greece) and the Institute of Geophysics, Polish Academy of Sciences (Poland) facilitated the preparation, shipment, deployment, maintenance, and data analysis of 7 SmartSolo units and 117 DATA-CUBE instruments. The network operated continuously for approximately 3 weeks (28 February – 23 March 2025) without instrumentation losses, resulting in a plethora of data recorded by the deployed large-N network. We present detailed information on this newly deployed temporary seismic network along with a preliminary example of data analysis.

Over the last decades, the proliferation of equipment for large-N seismic experiments has provided unique opportunities for extensive investigations aiming at resolving the Earth’s finer structure and towards a better understanding of seismicity. In the case of Santorini, numerous nodal experiments (e.g., PROTEUS; Hooft et al., 2019; Chatzis et al., 2022) have provided local and fine-scale tomographic images of the crust and uppermost mantle (e.g., Dimitriadis et al., 2010, Hooft et al., 2019; Heath et al., 2019; McVey et al., 2022; Autumn et al., 2025; Huftstetler et al., 2025) with the aim of improving our understanding of the deeper structure of the volcanic plumbing system, as well as the geophysical and geological characteristics of the near-surface structure. The presented SantoArray experiment expands over Santorini, Kammeni and Thirasia islands, providing a unique opportunity to better resolve the islands’ shallow structure using land stations.

ABSTRACT. GNSS campaign measurements conducted in February 2025 reveal measurable displacements across the Santorini caldera, with patterns consistent with low-level magmatic deflation. Comparison with 2012 benchmark data confirms ongoing deformation and underscores both the value and the limitations of campaign-based observations relative to continuous GNSS monitoring.

ABSTRACT. The region between Santorini and Amorgos is seismically active and recently has seen a noticeable increase in earthquake frequency, causing significant tectonic deformation linked to active faulting and, potentially, magmatic processes. This extended abstract focuses on the analysis of the coseismic displacement components of Santorini, South Ios, Anafi and Amorgos islands, using Sentinel-1 satellite data and the DInSAR (Differential Interferometric Synthetic Aperture Radar) method, which revealed noteworthy vertical (up-down) and horizontal (E-W) ground displacement. Results indicate uplift in South Thira (+2.1 cm), subsidence near Oia (-2.8 cm), and significant east-west displacement in Santorini, where Thirasia, Nea Kameni and Oia seem to move away from each other. SW and NE Amorgos show a significant westward motion (-4.0 cm in Kalofana, -3.5 cm in Aigiali), while Anafi and Ios exhibit localized subsidence and uplift. These findings seem to reference ongoing fault activity and strain accumulation, presenting the need for continued monitoring of the seismically active area.

ABSTRACT. Reevaluation and analysis of existing and recently collected marine geological and geophysical data along provide insight into the geological and tectonic structure of Santorini-Amorgos Zone and contribute to the understanding of the processes that led to the 2025 seismic activity and their relationship with the longterm evolution of the area. The “Kameni Line” represents the linear distribution of earthquake epicenters that are probably associated with the NW-dipping, steep Akrotiri Fault. The geodetically observed NE-ward movement of Santorini that occurred in the first half of February 2025 affected the hanging-wall of Akrotiri Fault, while the foot-wall of the fault remained more or less stable. The NW-ward tilting of Anydros Island observed during the 2025 seismic activity coincides with the long-term tilting of the entire Anydros Ridge. The earthquake activity and ground deformation observed during the 2025 seismic crisis are compatible with the long-term deformation of Santorini-Amorgos Zone.

ABSTRACT. New fossil discoveries in the area of Thrace offer remarkable insights into the Oligocene vegetation and paleoenvironmental conditions of southeastern Europe. The plant fossil sites, representing some of the oldest Petrified Forests in Greece, preserve a diverse assemblage of both permineralized wood remains as well as leaf imprints of angiosperm trees. The fossil-bearing deposits comprise of successive pyroclastic series mainly consisting of tuffs intercalated with layers of sandstones, clays and marls. The pyroclastic sequence is linked to the volcanic activity in the Rhodope region during the Late Eocene to Oligocene (Georgiev and Marchev, 2005; Voudouris et al., 2007).

Numerous permineralized well preserved wood specimens were identified, exhibiting the dominance of Fagaceae, mainly Quercoxylon sp., and the presence of thermophilic Lauraceae. The occurrence of several leaf litter horizons is recorded within the marl layers of the sequence. Among leaf imprints, the key taxa identified include Fagaceae (Eotrigonobalanus sp., Quercus spp.), Myrica spp., Ziziphus sp., Laurophyllum spp, Dicotylophyllum sp. and representatives of the Leguminosae (Figure 1).Our findings show great similarities to those from the neighboring Bulgarian fossiliferous sites, as well as the petrified forest of Evros (Iamandei et al., 2014, 2016, 2024; Velitzelos et al., 2014; Velitzelos et al., 1999, 2002). In the Bulgarian sites, petrified trunks within tuffs had provided a radiometric age (40Ar/39Ar) of approximately 31 million years (e.g., Iamandei et al., 2014, 2016), confirming the Early Oligocene age of the fossils (Georgiev and Marchev, 2005). The volcanic activity, attributed to centers in Kotyli and Kalotycho (Caracciolo et al., 2011), played a key role in the rapid burial and exceptional preservation of plant material. The studied fossil-bearing area in combination with the petrified forest of Evros (Velitzelos et al., 2014; Velitzelos et al., 1999, 2002) represent some of the oldest occurrences of paleovegetation in Greece.

ABSTRACT. Introduction The calcareous nannofossil biostratigraphy is widely based on the standard zonal schemes of Martini (1971), Okada and Bukry (1980), Bown (1998), Burnett (1998) and the updated schemes of e.g., Backman et al. (2012) and Agnini et al. (2017). In the marginal Mediterranean basin, the fragmentation of the geological record, together with the strong diachroneity of zonal boundary events and/or the absence or extreme rareness of primary marker species, does not allow easily the application of the standard nannofossil zonations. Therefore, regional zonal schemes were developed (e.g., Theodoridis, 1984; Rio et al., 1990; Fornaciari & Rio 1996). In this study, an extended dataset concerning the investigated locations of the Hellenic territory (alpine, flysch, mollasic and post-alpine deposits) and the available published calcareous nannofossil biostratigraphic results, has been constructed, aiming to standardize the available data and provide realistic biochronologic estimations, according to the magnetobiochronology of Berggren et al. (1995) and the more recent astrobiochronological approaches of e.g., Lourens et al. (2004), Raffi et al. (2006), Backman et al. (2012), Agnini et al. (2017). In addition, a series of new locations with their unpublished calcareous nannofossil biostratigraphic determinations (e.g., Triantaphyllou, 2017), are incorporated to the dataset, providing a useful framework for correlations in the eastern Mediterranean and beyond. The geographical distribution of all the available data is presented in a series of geological maps arranged per each nannofossil biozone. A big part of the micropaleontological/geological material associated with the constructed calcareous nannofossil biostratigraphy dataset, is already incorporated into the Micropaleontology Collection at the Laboratory of Historical Geology and Biogeosciences (HG-BioGeoSci), National and Kapodistrian University of Athens (NKUA). The curation of this Collection undergoes the auspices of the newly introduced international MSc Programme “Industrial and Environmental Applications in Micropaleontology” (IdEA-M, https://idea-m.com/) at the Department of Geology and Geoenvironment (NKUA) and the Interinstitutional MSc Programme “Paleontology-Geobiology” directed by the Aristotle University of Thessaloniki. Our aim is to create a free access database of all micropaleontological objects stored in the HG-BioGeoSci, not only for educational purposes but also benefiting all interested parties to visit and study the collections.

Materials and Methods The calcareous nannofossils Collection material concerns microscope slides, mounted SEM stubs and filtered water samples, while the majority of the items comes from the Greek territory and the broader Mediterranean area as also other locations worldwide, including samples collected by the global deep-sea drilling programs (DSDP, ODP, IODP etc.). Except from the microfossil content, the raw material comprising rock samples, marine core records, boreholes and drillings, surface sediments, sediment traps, as well as sample residues are recorded in a digital database. The database displays a 2-level classification where all different types of microfossils are documented, labeled with a unique Laboratory code and linked to all available data, i.e., lithology/material type, sampling date and methods, preparation date and analysis techniques, biozone/ biostratigraphic assignment, applied biozonal scheme, age, paleoenvironment type, owner, analyst, references list, repository and notes (e.g., field notes, photos, original drawings, derived publications etc.). The nannofossil biostratigraphy has been accomplished through qualitative, semiquantitative and quantitative analyses.

Results and Conclusions The presented calcareous nannofossil biostratigraphy dataset contributes to a better understanding of the spatiotemporal impact on calcareous nannofossil biostratigraphic assignments of the different geological-geotectonic origin deposits in the Hellenic territory and the factors limiting the distribution and controlling the presence of the widely used nannofossil biostratigraphic indices (examples in Figures 1, 2). The effort to synthesize and critically evaluate all available biostratigraphic data based on calcareous nannofossil analysis contributes to e.g., defining the age of alpine carbonates, the onset of clastic sedimentation in the various geotectonic units, the stratigraphic age of the different flysch and post-alpine deposits, etc.

More than 8.000 available calcareous nannoplankton preparations have been entered in the HG-BioGeoSci Micropaleontology Collection, associated with more than 20.000 entries of sample residues and raw samples. The aforementioned material derived from more than 100 sites, is introduced in the digital database and demonstrated in Figure 3. Most sites are distributed in the Mediterranean area; nevertheless, data from North and South Atlantic Ocean, Gulf of Mexico, Gulf of Aden, Laccadive Sea, etc. are also included, offering a worldwide record.

Up to now, the calcareous nannofossil HG-BioGeoSci Micropaleontology Collection (Figure 4) exhibits mostly Neogene (46%) entities, followed by Quaternary and Paleogene (18% and 17%, respectively). Modern coccolithophore records (water column filtered samples and sediment trap timeseries) are also well represented (13%). The digitization, archiving and storage of calcareous nannofossil and coccolithophore dataset together with (paleo)environmental data are expected to allow us understanding long-term (paleo)ecosystem and ecological dynamics mainly in the Mediterranean area in comparison to the worldwide record. This information is crucial in predicting long-term human-induced environmental and climatic changes.

ABSTRACT. The Lesvos Petrified Forest comprises Lower Miocene silicified tree fossils, both lying and in upright position, as well as fossil leaves, enclosed in pyroclastic and volcaniclastic material deriving from a nearby stratovolcano chain, and interrupted by intercalating palaeosoil horizons on which the successive ancient forests developed. The construction of the new Kalloni-Sigri road, revealed freshly cut artificial sections along the road. These new sections provided the opportunity for detailed stratigraphic research of the volcanic rocks of the Akroheiras Hill area. Twelve sections were lithostratigraphically recorded in detail (Ipsilo section, Toumpeleki north section, Afchenas section, Toumpeleki section, Freatio section, Central Akroheiras section, Vrisaki section, West Akroheiras section, Kotsini/Bachariotaki sections, South Akroheiras Road section and Filakio section). Using the palaeosoil horizons the different sections were correlated allowing the establishment of four Formations (Ipsilo Fm, Afchenas Fm, Acroheiras Fm, Bachariotaki Fm) and fifteen (15) Members bounded by corresponding erosional unconformities. Members correspond to different volcanic eruptions. Thus, at least 15 different eruptive events have been identified. The cessation of each eruption was, most of the times, followed by the formation of a palaeosoil horizon and the subsequent development of a forest on it. This process has been recorded at least 9 times until now in the Lesvos Petrified Forest pyroclastic sequence, indicating an equal number of successive forest forming periods.

ABSTRACT. Abundance and assemblage composition of benthic foraminifera, dinoflagellate cysts and pollen grains were analysed together with sedimentological (grain size) and geochemical (organic and inorganic carbon content, XRF, benthic foraminifera oxygen and carbon isotopes) proxies to investigate paleoenvironmental changes recorded in the Gulf of Corinth during MIS 1-5, from IODP Expedition 381 core M0080. The Gulf of Corinth is a relatively young (<5 Ma) and active continental rift zone in the eastern Mediterranean Sea, with a length of about 120 km (McNeil et al., 2019a and references therein; Gawthrope et al., 2022). The Gulf is currently connected to the Ionian Sea through a shallow sill (Rion sill; 60 m-deep) and to the Aegean Sea via the Corinth Canal (Isthmus; 6 km-wide). The eastern part is divided by the Perachora Peninsula into the Lecheon Gulf in the south, and the Alkyonides Gulf in the north, a shallow semi-enclosed sub-basin within the northeastern part of the Gulf of Corinth, where core M0080 is located (Fig. 1; McNeil et al., 2019b). The closed drainage system and the high sedimentation rates (approx. 0.5-3 mm/yr; McNeil et al., 2019a) make the study area a natural laboratory for the investigation of the complex interaction between sedimentary input, tectonics and climate through the basin’s evolution.The benthic foraminiferal, dinocyst and pollen records are highly variable during both the Last Interglacial complex and the Holocene. Infaunal foraminiferal species characterize these assemblages with high abundances of Bolivina spp., Melonis affinis, Bulimina spp. and Cassidulina carinata, indicating mesotrophic to eutrophic marine conditions, with marine dinocysts (Nemaosphaeropsis labyrinthus, Spinifireties ramosus) and montane trees likely to have occurred during high sea-levels. During glacial and interstadial intervals, benthic foraminifers are very low in numbers or even absent, whereas abundant brackish dinocysts (Pyxidinopsis psilata) suggest a sea-level drop below sill level and the subsequent (semi-)isolation of the basin. Inorganic carbon content and elemental counts varied following the inferred sea-level fluctuations, while the benthic foraminifera oxygen isotope record is discontinuous and conditioned to the presence of well-preserved benthic foraminifera. The beginning of the Holocene is marked by the re-establishment of marine conditions as the sea-level rose above the sill and the basin re-connected to the Mediterranean Sea. Ongoing high-resolution studies and a refinement of the age model will improve our understanding of paleoenvironmental changes in the Gulf of Corinth during glacial and interglacial stages and allow us to define the factors driving changes in this unique active rift of the eastern Mediterranean. Acknowledgements This study is funded through projects GR 5285/3-1 “Late Quaternary dynamics of marine paleoenvironments and ecosystems in the Gulf of Corinth (eastern Mediterranean)” and PA 2664/8-1 “Linking marine and terrestrial ecosystem responses to climate variability since the Last interglacial in the Eastern Mediterranean” of the Deutsche Forschungsgemeinschaft (DFG). References

Fatourou, E., Kafetzidou, A., Marret, F., Panagiotopoulos, K., Kouli, K., 2023. Late Quaternary Ponto-Caspian dinoflagellate cyst assemblages from the Gulf of Corinth, Central Greece (eastern Mediterranean Sea). Marine Micropaleontology 179, 102211. Gawthrope, R.L., Fabregas, N., Pechlivanidou, S., Ford, M., Collier, R.E.L., Carter, G.D.O., McNeil, L.C., Shillington, D.J., 2022. Late Quaternary mud-dominated, basin-floor sedimentation of the Gulf of Corinth, Greece: Implications for deep-water depositional processes and controls on syn-rift sedimentation. Basin Research 34, 1567-1600. Kafetzidou, A., Fatourou, E., Panagiotopoulos, K., Marret, F., Kouli, K., 2023. Vegetation Composition in a Typical Mediterranean Setting (Gulf of Corinth, Greece) during Successive Quaternary Climatic Cycles. Quaternary 6(2), 30. McNeil, L.C., Shillington, D.J., Carter, G.D.O., Everest, J.D., Gawthorpe, R.L., Miller, C., Phillips, M.P., Collier, R.E.LI., Cvetkoska, A., De Gelder, G., Diz, P., Doan, M.-L., Ford, M., Geraga, M., Gillespie, J., Hemelsdaël, R., Herrero-Bervera, E., Ismaiel, M., Janikian, L., Kouli, K., Le Ber, E., Li, S., Maffione, M., Mahoney, C., Machlus, M.L., Michas, G., Nixon, C.W., Oflaz, S.A., Omale, A.P., Panagiotopoulos, K., Pechlivanidou, S., Sauer, S., Seguin, J., Sergiou, S., Zakharova, N.V., Green, S., 2019a. High-resolution record reveals climate-driven environmental and sedimentary changes in an active rift. Scientific Reports 9, 3116. McNeill, L.C., Shillington, D.J., Carter, G.D.O., Everest J.D., Le Ber E., Collier R.E., Cvetkoska A., De Gelder G., Diz P., Doan M.L., Ford M., Gawthorpe R.L., Geraga M., Gillespie J., Hemelsdaël R., Herrero-Bervera E., Ismaiel M., Janikian L., Kouli K., Li S., Machlus M.L., Maffione M., Mahoney C., Michas G., Miller C., Nixon C.W., Oflaz S.A., Omale A.P., Panagiotopoulos K., Pechlivanidou S., Phillips M.P., Sauer S., Seguin J., Sergiou S., Zakharova N.V., 2019b. Site M0078, in Program, I.O.D.P. (Ed.), McNeill, L.C., Shillington, D.J., Carter, G.D.O., and the Expedition 381 Participants, Corinth Active Rift Development. Proceedings of the International Ocean Discovery Program. International Ocean Discovery Program, College Station, Texas.

ABSTRACT. Introduction / Background Long pollen sequences covering the Quaternary period have enabled us to gain insight into the long-term variability and migration of the vegetation in the Mediterranean Basin in relation to climatic cycles (e.g., Magri et al., 2017). Climatic fluctuations and ecological competition led to the gradual disappearance of several tree taxa, including Taxodioideae, Sequoioideae, Sciadopitys, Tsuga, Castanea, Engelhardia, and Diospyros (Suc et al., 1995; Svenning, 2003; Farjon, 2005; Bertini, 2010; Popescu et al., 2010). Deteriorated climatic conditions during glacial intervals forced the most demanding taxa into refugial areas, such as the Pindus Mountain Range, or southern regions of Italy and Greece (Suc et al., 1995; Svenning, 2003; Bertini, 2010; Popescu et al., 2010). Existing high-resolution pollen records from the southern Balkan show that the amplitude and timing of millennial-scale oscillations in temperate tree abundances depend on the latitude and altitude of the study area as well as its proximity to temperate tree refugia. Long pollen records located in mid-altitudes (between 400 and 850 m above sea level) across the Pindus Mountain Range, such as the Ioannina, Prespa and Ohrid Lakes sites suggest the survival of temperate tree populations during successive glacial-interglacial cycles (Tzedakis et al., 2002, 2004; Panagiotopoulos et al., 2014; Sadori et al., 2016). Opposingly, in the Tenaghi Philippon pollen record from the north-eastern Greece, temperate trees often disappear and only occur during interglacial intervals. The vegetation at Tenaghi Philippon seems to have reacted in a more sensitive way to the climatic cycles, possibly due to the reduction in temperature and moisture (e.g., Tzedakis et al., 2006; Pross et al., 2015; Koutsodendris et al., 2023). The Quaternary climate-driven shifts significantly affected ecosystems, particularly at mid-latitudes (Lisiecki and Raymo, 2005; Joannin et al., 2011). In Mediterranean Europe, the shift from the 41,000-year to the 100,000-year climatic oscillations resulted in an increase of in aridity, further impoverishing vegetation communities due to long-term cooling trends (Joannin et al., 2011). This resulted in the gradual extinction of several tree taxa such as Cedrus, Carya, Pterocarya, Juglans, and Zelkova (Suc et al., 1995; Svenning, 2003; Bertini, 2010). However, the sporadic and scattered nature of records only provides a partial chronostratigraphical overview of their distributions and extinctions, necessitating macroregional-scale adaptations. Despite the existence of some long continuous pollen records from the Balkan Peninsula, most of them are either far from tree refugial areas (e.g. the Tenaghi Philippon record that includes the MPT) or do not include the MPT interval (e.g., Ioannina, Prespa and Kopais). The evolution of north-south and west-east environmental gradients over long time scales, notably the sustained west-east precipitation gradient, has profoundly shaped the plant ecosystems in the southern Balkan Peninsula. This is evidenced by the contrasting vegetational responses observed between Tenaghi Philippon (e.g., Tzedakis et al., 2006; Koutsodendris et al., 2023) in the east and other western Balkan sites such as Lake Ohrid (Sadori et al., 2016; Donders et al., 2021), Ioannina (e.g., Tzedakis et al., 2002, 2003, 2004) and Prespa (Panagiotopoulos et al., 2013, 2014). These findings highlight the need for further analysis of long-term pollen archives from the Balkan Peninsula to better understand the evolution of regional flora and the timing of relict species extinctions in the eastern Mediterranean. The Gulf of Corinth pollen record provides significant insights into the persistence of relict taxa such as Liquidambar, Carya, Pterocarya, and Cedrus throughout the Pleistocene. These taxa, key components of temperate and riparian forests, persisted through multiple glacial-interglacial cycles, indicating the Gulf of Corinth region as a refugium in southeastern Europe. The region’s unique climatic, topographic, and hydrological conditions enabled the survival of these taxa despite broader climatic fluctuations. Liquidambar displayed remarkable resilience, with a near-continuous presence from MIS 8 (300 ka) to ~13 ka BP, thriving during glacial phases in humid conditions. Carya persisted from MIS 24 (~923 ka) to MIS 8, with low percentages correlating with localized humid microclimates influenced by marine humidity. Pterocarya was present from MIS 13 (~500 ka) to MIS 3 (~36 ka), reaching higher abundances during glacial periods, indicating stable hydrological conditions in wet environments such as floodplains. Similarly, Cedrus, which gradually disappeared from the central and northern Balkans by the end of the Pleistocene, remained present in Gulf of Corinth sediments, suggesting local persistence rather than long-distance transport. These findings underscore the Gulf of Corinth’s biogeographical significance as a biodiversity hotspot, providing exceptional conditions that allowed the persistence of relict taxa during the glacial maxima and interglacial periods of Quaternary. The study highlights the region’s role as a corridor for species persistence and migration in the Mediterranean. Understanding the resilience of these taxa offers valuable insights into reconstructing past vegetation dynamics, identifying refugia, and predicting ecosystem responses to future climate change. The preservation and further study of this paleoenvironmental archive are important for advancing our knowledge of plant resilience, refugial dynamics, and climatic stability in the Mediterranean region. Acknowledgements The study material was retrieved during the IODP Exp. 381. The research work was supported by the Hellenic Foundation of Research and Innovation (H.F.R.I) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: 1026, Quaternary Environmental Changes in the Corinth Rift Area: the IODP 381 palynological record: QECCoRA). References Bertini, A., 2010. Pliocene to Pleistocene palynoflora and vegetation in Italy: State of the art. Quaternary International 225, 5-24. Combourieu-Nebout, N., Bertini, A., Russo-Ermolli, E., Peyron, O., Klotz, S., Montade, V., Fauquette, S., Allen, J., Fusco, F., Goring, S., Huntley, B., Joannin, S., Lebreton, V., Magri, D., Martinetto, E., Orain, R., Sadori, L., 2015. Climate changes in the central Mediterranean and Italian vegetation dynamics since the Pliocene. Review of Palaeobotany and Palynology 218, 127-147. Donders, T., Panagiotopoulos, K., Koutsodendris, A., Bertini, A., Mercuri, A. M., Masi, A., Combourieu-Nebout, N., Joannin, S., Kouli, K., Kousis, I., Peyron, O., Torri, P., Florenzano, A., Francke, A., Wagner, B., Sadori, L., 2021. 1.36 million years of Mediterranean forest refugium dynamics in response to glacial–interglacial cycle strength. Proceedings of the National Academy of Sciences 118. Farjon, A., 2005. A Monograph of Cupressaceae and Sciadopitys. Royal Botanic Garden, Kew. Joannin, S., Bassinot, F., Nebout, N.C., Peyron, O., Beaudouin, C., 2011. Vegetation response to obliquity and precession forcing during the Mid-Pleistocene Transition in Western Mediterranean region (ODP site 976). Quaternary Science Reviews 30, 280e297 Koutsodendris, A., Dakos, V., Fletcher, W. J., Knipping, M., Kotthoff, U., Milner, A. M., Müller, U.C., Kaboth-Bahr, S., Kern, O.A., Kolb, L., Vakhrameeva, P., Wulf, S., Christanis, K., Schmiedl, G., Pross, J., 2023. Atmospheric CO2 forcing on Mediterranean biomes during the past 500 kyrs. Nature Communications 14, 1664. Lisiecki L.E., Raymo M.E., 2005. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20. Magri, D., Di Rita, F., Aranbarri, J., Fletcher, W., González-Sampériz, P., 2017. Quaternary disappearance of tree taxa from Southern Europe: Timing and trends. Quaternary Science Reviews 163, 23-55. Magri, D., Palombo, M.R., 2013. Early to Middle Pleistocene dynamics of plant and mammal communities in SouthWest Europe. Quaternary International 288, 63-72. Panagiotopoulos, K., Aufgebauer, A., Schäbitz, F., Wagner, B., 2013. Vegetation and climate history of the Lake Prespa region since the Lateglacial. Quaternary International 293, 157-169. Panagiotopoulos, K., Böhm, A., Leng, M. J., Wagner, B., Schäbitz, F., 2014. Climate variability over the last 92 ka in SW Balkans from analysis of sediments from Lake Prespa. Climate of the Past 10, 643-660. Popescu, S.-M., Biltekin, D., Winter, H., Suc, J.-P., Melinte-Dobrinescu, M.C., Klotz, S., Rabineau, M., Combourieu-Nebout, N., Clauzon, G., Deaconu, F., 2010. Pliocene and Lower Pleistocene vegetation and climate changes at the European scale: long pollen records and climatostratigraphy. Quaternary International 219, 152-167. Postigo-Mijarra, J.M., Morla, C., Barrón, E., Morales-Molino, C., García, S., 2010. Patterns of extinction and persistence of Arctotertiary flora in Iberia during the Quaternary. Review of Palaeobotany and Palynology 162, 416-426. Sadori, L., Koutsodendris, A., Panagiotopoulos, K., Masi, A., Bertini, A., Combourieu-Nebout, N., Francke, A., Kouli, K., Joannin, S., Mercuri, A-M., Peyron, O., Torri, P., Wagner, B., Zanchetta, G., Sinopoli, G., Donders, T.H., 2016. Pollen-based paleoenvironmental and paleoclimatic change at Lake Ohrid (south-eastern Europe) during the past 500 ka. Biogeosciences 13, 1423-1437. Suc, J.P., Bertini, A., Combourieu-Nebout, N., Diniz, F., Leroy, S., Russo-Ermolli, E., Zheng, Z., Bessais, E., Ferrier, J., 1995. Structure of West Mediterranean vegetation and climate since 5.3 ma. Acta Zoologica Cracoviensia 38, 3-16. Svenning, J., 2003. Deterministic Plio‐Pleistocene extinctions in the European cool‐temperate tree flora. Ecology Letters 6, 646-653. Tzedakis, P.C., Frogley, M.R., Heaton, T.H.E., 2003. Last interglacial conditions in southern Europe: evidence from Ioannina, northwest Greece. Global and Planetary Change 36, 157-170. Tzedakis, P.C., Frogley, M.R., Lawson, I.T., Preece, R.C., Cacho, I., de Abreu, L., 2004. Ecological Thresholds and Patterns of MillennialScale Climate Variability: The Response of Vegetation in Greece during the Last Glacial Period. Geology 32, 109-112. Tzedakis, P. C., Hooghiemstra, H., Pälike, H., 2006. The last 1.35 million years at Tenaghi Philippon: revised chronostratigraphy and long-term vegetation trends. Quaternary Science Reviews 25, 3416-3430. Tzedakis, P. C., Lawson, I. T., Frogley, M. R., Hewitt, G. M., Preece, R. C., 2002. Buffered tree population changes in a Quaternary refugium: evolutionary implications. Science 297, 2044-2047.

ABSTRACT. Introduction Lake Koronia is located in the western lowland area of the Mygdonia Basin, northeast of the city of Thessaloniki in northern Greece (40° 41′ N, 23° 09′ E, 75 m a.s.l.). It is the remnant of a once larger lake in the region (Psilovikos, 1977) and was formerly the fourth largest lake in Greece, but is now a shallow, hypertrophic and heavily polluted water body (Moustaka-Gouni et al., 2012). It has experienced substantial degradation over time due to human activities, but has also dried up several times in the past two decades (2002, 2007, 2009 and 2014), resulting in its current state (Demertzioglou et al., 2022). Despite its current ecological issues, Lake Koronia is recognised as a protected wetland under international and national legislation, highlighting its importance (Malamataris et al., 2017). The aim of the present study was to investigate the paleoenvironmental evolution of Lake Koronia and the distribution of ostracod assemblages through time using a combination of core and recent surface sediment samples. Methods The KOR-1 core (40o41'45.4" Ν, 23o11'08.8"E; Fig. 1) was drilled at 71 m b.s.l. and reached a sediment depth of 368 cm. A total of 36 sediment samples were studied in order to reconstruct the paleoenvironmental evolution of the lake. In addition, two sediment samples were collected by boat, using an Ekman grabber from the upper 1 cm of the lake bottom for the analysis of the recent ostracod fauna. For ostracod analysis, 50 ml of each surface bottom sediment sample was wet sieved with tap water through a 125 μm mesh size standard sieve. For core samples, 10 g of dried sediment was treated with hydrogen peroxide (H2O2) and wet sieved as described above. The residue was oven-dried at 60°C and all ostracod valves of the >125 μm fraction were hand-picked under a Zeiss Stemi 305 binocular stereoscope. Species were identified, counted, and stored in microslides. Taxonomic identification of the species was based on the morphological features of the carapace. For chronology, radiocarbon dating was performed using accelerator mass spectrometry (AMS 14C; Beta Analytic USA laboratory). Results and conclusions The ostracod assemblage of Lake Koronia, both in the surface sediments and in the KOR-1 sedimentary sequence, consisted of five species: ex gr. Candona juveniles, Cyprideis torosa, Darwinula stevensoni, Heterocypris salina and Limnocythere inopinata. In the recent surface sediments, station Kor-1 had a significantly higher abundance compared to station Kor-2. The Candona species dominated the assemblage, while L. inopinata was the second most abundant taxon of the total ostracod fauna recorded in the lake, with all other taxa showing relatively low abundances. The ostracod valves obtained from core KOR-1 were well preserved and relatively abundant, with the number of valves/g reaching high values in some intervals, while the diversity indices showed relatively low values. The species L. inopinata dominated the assemblages, reaching even 100% in several intervals, followed by ex gr. Candona juveniles and H. salina. The species D. stevensoni and C. torosa accompanied the assemblage with lower but significant values. The resulting dendrogram of the Q-mode cluster analysis performed on the KOR-1 core sedimentary sequence, pointed out three distinct groups of samples associated with different assemblages and thus different paleoenvironmental conditions. The paleoenvironmental record of Lake Koronia revealed conditions of slightly elevated salinity between 2752-1437 cal. yr BP, occurring in a shallow environment with clear water and the absence of benthic macrophytes. After 1437 cal. yr BP, the fauna diverged significantly, and the environment transitioned to a purely lacustrine system, extremely shallow and with extensive macrophyte vegetation. At the top of the sedimentary sequence, the environment undergoes a further change, characterized by a significant increase in diversity, a deepening of the environment, and the establishment of well-oxygenated water conditions. This interval is comparable with the recent surface sediments in terms of faunal composition and diversity, but not in terms of abundance which was significantly higher at the recent stations. Lake Koronia is a severely impacted lake that has faced significant degradation over the past few decades. Over the last 20 years, the lake has experienced a dramatic decrease in volume, surface area, and maximum depth (currently almost 2 meters) due to unsustainable water resource management. Further investigation of the benthic conditions and biota, coupled with the paleoenvironmental record of the lake, will be invaluable in ecological assessment of this important biotope. Acknowledgements Sampling support for the recent sediment samples was provided by the Greek Biotope Wetland Centre. References Demertzioglou, M., Genitsaris, S., Mazaris, A.D., Kyparissis, A., Voutsa, D., Kozari, A., Kormas, K.A., Stefanidou, N., Katsiapi, M., Michaloudi, E., Moustaka-Gouni, M., 2022. A catastrophic change in a European protected wetland: From harmful phytoplankton blooms to fish and bird kill. Environmental Pollution 312, 120038. Malamataris, D., Kolokytha, E., Mylopoulos, I., Loukas, A., 2017. Critical review of adaptation strategies for the restoration of Lake Koronia. European Water 58, 203-208. Moustaka-Gouni, M., Michaloudi, E., Kormas, K.A., Katsiapi, M., Vardaka, E., Genitsaris, S., 2012. Plankton changes as critical processes for restoration plans of lakes Kastoria and Koronia. European Water 40, 43-51. Psilovikos, A., 1977. Paleogeographic development of the basin and lake of Mygdonia (Langada-Volvi area) GreecePh.D. Thesis, Aristotle University of Thessaloniki, Thessaloniki, 156 p.

ABSTRACT. This paper briefly reports the new results on Miocene gymnosperm fossil wood assemblages from Lesvos, including two families and nine genera: Tsuga, Pseudotsuga, Keteleeria, Larix, Pinus, Lesbosoxylon (Pinaceae), Metasequoia, Sequoia, Taxodium (Cupressaceae). Among them, Pinaceae exhibits the highest taxonomic richness, Pseudotsuga, Keteleeria and Metasequoia were found in Greece for the first time. At present, the Lesvos fossil wood flora is one of the Miocene wood floras with highest diversity found in Greece and even in the Mediterranean, which enriches the fossil record of gymnosperms in the Miocene of Greece. The occurrence of abnormal growth rings and traumatic resin canals in Lesvos fossil woods reflects the short-term climate fluctuations, natural hazards or the interaction between plants and the associated organisms in the forest ecosystem. Further study of this fossil wood flora will provide important evidence for understanding the evolution and development history of modern gymnosperms in the Mediterranean as well as their palaeoenvironment and palaeoclimate background.

ABSTRACT. The teeth of hippariorine horses have a structure of high complexity, consisting of heavily plicated enamel, which forms fossettes and a protocone (in upper premolars and molars), in addition to peripheral enamel. This structure, along with hypsodonty, are traits that helped them adapt to dietary conditions. Enamel structure can be of aid to distinguish differences among taxa, and to track evolutionary changes in regard to dietary adaptations. Twenty-four dental samples (upper cheek teeth) from the fossiliferous locality of Pikermi (Attica, Greece) were acquired from the NKUA Museum of Paleontology, to test if there can be a distinction between the two subgenera that are part of the Pikermi fauna, Hippotherium brachypus and Cremohipparion mediterraneum. Samples of each group were selected, and were examined via stereoscope and Scanning Electron Microscope, regarding possible distinctive traits. In general, the three main enamel types found in Hipparionines were present in all the samples. Type I enamel was present mostly closer to the EDJ (enamel – dentine junction), and sometimes at the EDJ Type III enamel appeared, transitioning to Type I while moving away from the EDJ. When going towards the ECJ (enamel – cement junction), Type I enamel gave its place to Type II enamel. However, in some of the samples that was not always the case. There were some occurrences in samples with 1 pli caballin, where Type II enamel was absent from some areas and Type III enamel was at the ECJ, transitioning later to Type I as we went closer to the EDJ. There was also a slight difference in maximum enamel thickness between the two groups. There was no conclusion regarding distinguishing the two subgenera, as the enamel microstructure in all samples was quite similar, although further investigation with a larger sample group needs to take place, in order to get definitive answers.

ABSTRACT. Research Highlights: Strontium isotope analysis (87Sr/86Sr) of enamel from Late Pleistocene ungulate teeth reveals a predominant local habitat range of these ruminants within the Mani Peninsula with only minimal migration. Results reveal insights into human subsistence strategies, with hunting focused on fauna from nearby areas. Introduction Determining the mobility and provenance of Late Pleistocene fauna are crucial for understanding past ecosystems, predator-prey dynamics, and human-animal interactions. Among geochemical methods, strontium isotope analysis (87Sr/86Sr) has proven to be a powerful tool, offering the ability to trace geographic origins and movement patterns through the isotope composition of tooth enamel (Bentley, 2006; Britton and Guiry, 2020). The bioavailable 87Sr/86Sr, which varies with composition and age of the underlying bedrock geology, enters the food chain through soil, water, and vegetation and is subsequently recorded in the biological (hard) tissues of consumers of higher order (Ericson, 1985). This study examines the 87Sr/86Sr in tooth enamel of ruminant species excavated from the Melitzia Cave in Mani Peninsula, Greece. The faunal assemblage includes species such as Cervus elaphus (red deer), Capra ibex (ibex), and Dama dama (fallow deer), these species were hunted and consumed by the cave’s occupants (Homo sapiens) during Upper Pleistocene (Darlas and Psathi, 2016), who lived in the numerus cave sites of Mani Peninsula. By comparing 87Sr/86Sr in tooth enamel of archaeological faunal remains to a bioavailable baseline derived from modern plant samples, this research aims to establish provenance and assess the habitat use and mobility of the human prey animals. It also seeks to contextualize these findings within the broader palaeoecological and geological framework of Mani Peninsula. Material and Methods To construct the bioavailable strontium (BASr) baseline, modern plant samples were collected systematically across 13 geological formations in the Mani Peninsula. A total of 36 leave samples, representing 12 different species of shrubs and trees, were processed. The sampling design accounted for variations in altitude, geology, and vegetation type. The spatial strontium distribution map was created by the Inverse Distance Weight (IDW) method in ArcGIS. Isolated third and second molars from three ruminant taxa were analyzed to investigate animal mobility. In total, 42 bulk enamel samples were analyzed, and 13 of these teeth were also sequentially sampled to assess seasonal habitat changes. Results and discussion The 87Sr/86Sr from plant samples, ranging from 0.70801 to 0.71749, were used to create an isoscape map representing the spatial distribution of bioavailable 87Sr/86Sr across the region (Figure 1). Enamel 87Sr/86Sr of ruminant teeth from the cave deposits range from 0.70852 to 0.71014 and nearly all of them fall within the range of the Upper Cretaceous to upper Eocene marine limestones (in which Melitzia cave formed) and modern seawater (i.e., sea spray effects) (Figure 2). The average 87Sr/86Sr of the enamel samples vary for C. ibex between 0.70852 and 0.70861 (mean: 0.70871, 0.000006 SD), for C. elaphus between 0.70860 and 0.70911 (mean: 0.70878, 0.0001 SD) and for D. dama between 0.70856 and 0.71014 (mean: 0.70894, 0.0005 SD). The lowest ratio occurs in C. ibex and the highest in D. dama although most of the enamel ratios lie within the narrow 87Sr/86Sr range of the limestone rocks in which the cave formed, except for one D. dama individual (0.71014) that lies outside of this range. This suggests that most of these animals likely spend their early lives (i.e., the time of tooth mineralization) in the vicinity of the cave. The identification of one individual with a higher 87Sr/86Sr value, indicates a short-term migration, suggesting that the individual possibly moved across different geological formations during its lifetime. This non-local value likely fits to 87Sr/86Sr of a region with metamorphic bedrocks, that are exposed in the peninsula’s north-eastern part. The findings suggest that this animal either migrated into the area or was hunted there and then transported to the site by predators. Altogether, the enamel 87Sr/86Sr range indicates that humans hunted mainly in the surroundings of the Melitzia Cave and do not show any spatial niche partitioning. C. ibex exhibited the least isotopic variability, consistent with its narrow ecological niche, its preference for rugged, steep terrains likely restricted its movement to local areas. While C. elaphus and D. dama show slightly broader variations in their 87Sr/86Sr isotope ratios compared to C. ibex, the variations show still a narrow range. This indicates that their movement was limited to areas with isotopically similar bedrock. By integrating strontium isotope analysis with palaeoecological investigation, this study sheds light on the movement and habitat use of Late Pleistocene ruminants in Mani Peninsula. It underscores the utility of isotopic methods in unravelling past faunal behaviours and contributes to broader discussions of human-animal interactions and ecological stability in Upper Pleistocene Mediterranean ecosystems.

ABSTRACT. Assessment of liquefaction susceptibility of Holocene sediments in alluvial plains is one of the first step for regional planning, hazard mitigation, and land use management in seismically active regions. Subtle geomorphological features resulting from recent depositional processes can significantly improve mapping liquefaction likelihood since they also express the lithology and distribution of Holocene sediments. As we compiled a detailed geological map for the purposes of this investigation and correlated it to the spatial distribution of the earthquake-induced liquefaction phenomena, we observed that liquefaction surface occurrences (ejecta, craters. ground fissures, lateral spreading) are highly correlated to point bars and abandoned river channels formed during the last century.

ABSTRACT. After the seismic sequences of 2021 in Damasi (Greece), 2023 in Kahramanmaraş (Türkiye) and 2010-2011 in Christchurch (New Zealand), extensive liquefaction phenomena were induced in the floodplain and point bars of the associated meandering rivers. As the identification of paleoenvironmental features plays a pivotal role in the assessment of the liquefaction susceptibility of an area, this research aims to statistically investigate the spatial distribution of liquefaction phenomena within point bar formations. By combining historical and remote sensing data, reconstruction of the evolution of each meandering fluvial system took place to delineate the different types of lithofacies encountered in point bars. Afterwards, correlation of the density of liquefaction manifestations (ejecta and lateral spreading) with sand- and mud-prone sediments occurred, based on a relationship proposed in this study. The outcome that arose from this procedure resulted in the attribution of weight values for each heterogeneity type, according to which, most of the liquefaction phenomena are correlated with the sandy sediments deposited on the upstream flow direction.

ABSTRACT. Introduction

Landslides are among the most pervasive and destructive natural hazards, threatening lives, infrastructure, and ecosystems worldwide. Triggered by factors such as intense rainfall, earthquakes, volcanic activity, and human-induced changes, landslides are inherently complex phenomena influenced by dynamic interactions between geological, hydrological, and climatic conditions. Effective prediction and risk mitigation are critical to minimizing their societal and environmental impacts. However, traditional modeling approaches, which often rely on deterministic or statistical frameworks, face significant limitations in capturing the multifaceted and nonlinear processes underlying landslide occurrence. In recent years, artificial intelligence (AI) has emerged as a transformative tool in addressing complex problems across various scientific domains (Catani, Nava, and Bhuyan 2025). In the field of landslide modeling, AI-driven approaches leverage machine learning (ML), deep learning (DL), and advanced data analytics to process large, heterogeneous datasets, uncover hidden patterns, and make predictions with unprecedented accuracy (Sun, Bocchini, and Davison 2020). These technologies offer new opportunities to improve landslide susceptibility mapping, hazard assessment, and early warning systems. The integration of AI into landslide modeling is particularly timely given the increasing availability of high-resolution remote sensing data, real-time sensor networks, and global climate models. These data sources provide the foundational input for AI algorithms to identify correlations and interactions among diverse variables such as slope angle, soil properties, rainfall intensity, and vegetation cover. Moreover, AI’s adaptability allows models to evolve with changing environmental conditions, making them highly suited for long-term hazard management in a rapidly changing world (Dahal and Lombardo 2022). Despite its promise, the application of AI in landslide modeling is not without challenges. Issues such as data quality and availability, model interpretability, and uncertainty quantification remain significant hurdles. Furthermore, the successful implementation of AI requires interdisciplinary collaboration, bridging expertise in geosciences, computer science, and engineering, and transparency for decision-makers. Addressing these challenges is crucial to unlocking the full potential of AI in landslide risk reduction. This study aims to explore the opportunities and challenges associated with AI-driven in landslide modeling. It provides a review of methodologies, evaluates effectiveness, and highlights emerging trends and research directions.

Challenges and Opportunities In recent years, the integration of AI with geotechnical and environmental sciences has opened new avenues for enhancing landslide modeling accuracy and effectiveness. AI approaches leverage computational algorithms to learn from data, enabling the extraction of hidden insights and the development of robust predictive frameworks (Zhao et al. 2024). Data complexity and availability remain significant barriers in landslide modeling, largely because these models require input from diverse datasets spanning geological attributes, hydrological dynamics, land cover, and climatic variables. The heterogeneity of these data sources often complicates their integration into cohesive models. Geological maps, satellite imagery, rainfall records, and field measurements vary in scale, resolution, and format, necessitating extensive preprocessing pipelines to harmonize inputs. This process can be computationally intensive and prone to errors. Additionally, data scarcity in remote or underdeveloped regions limits the accuracy and scope of modeling efforts. For instance, in areas without detailed geological surveys, proxy variables are often used, introducing uncertainties. Noise and errors in data, such as interference in remote sensing imagery due to cloud cover or inaccuracies in manually collected field data, further exacerbate the challenge. High temporal resolution data, critical for capturing dynamic triggers such as rainfall or seismic events, are frequently unavailable, reducing the model's ability to identify precursors to landslide events. The temporal and spatial variability of landslide occurrences adds another layer of complexity. Landslides are influenced by short-term events like extreme rainfall, as well as long-term processes such as progressive slope deformation driven by climate change. AI models must therefore be capable of addressing these overlapping timescales. On the spatial front, landslides range from localized slope failures to regional mass movements, and models trained on small-scale events may not generalize well to larger-scale phenomena. Variability in lithology, vegetation, and human activities such as deforestation and construction introduces nonlinear and region-specific interactions, complicating predictions further. Capturing these dynamics requires multi-scale modeling approaches capable of representing both broad regional trends and localized instabilities (Dahal, Huser, and Lombardo 2024). Uncertainty in AI-driven landslide models is another critical challenge, stemming from both the inherent unpredictability of landslides and limitations in data and algorithms. Quantifying uncertainty is essential for practical applications, as decision-makers must understand the confidence level of predictions. Probabilistic approaches, such as Bayesian neural networks or ensemble methods, can address this need but often demand substantial computational resources. Validation of model outputs against historical landslide inventories is another challenge, as such inventories are frequently incomplete or biased toward more visible events. This bias can reduce the reliability of model predictions. Furthermore, high-dimensional AI models risk overfitting to limited training data, underscoring the importance of rigorous cross-validation and feature selection to ensure generalizability. Despite these challenges, AI offers transformative opportunities for advancing landslide modeling. One of the most significant benefits is enhanced prediction accuracy. AI algorithms can analyze large, complex datasets to uncover intricate patterns and nonlinear relationships that traditional methods often overlook. For example, deep learning models can extract geomorphological features indicative of slope instability from high-resolution satellite imagery, leading to improved landslide susceptibility mapping. These models also provide insights into the relative importance of input variables, such as rainfall intensity versus slope angle, which can guide future data collection and mitigation strategies. The scalability of AI further enables the development of regional and global models with unprecedented detail. Real-time monitoring and early warning systems represent another area where AI can have a profound impact. By integrating with data sources such as Internet of Things (IoT) sensors (Mendoza-Cano et al. 2021), AI models can continuously update landslide risk assessments in near real-time. Advanced algorithms, including recurrent neural networks and long short-term memory networks, excel at detecting anomalies in time-series data, serving as early indicators of potential slope instability (Zhao et al. 2024). These systems can also facilitate community engagement by delivering timely warnings through mobile applications, empowering at-risk populations to take preventive action and minimizing casualties. AI-driven models are inherently adaptive, evolving with new data inputs and changing environmental conditions. This adaptability is particularly valuable in the context of climate change, where shifting weather patterns and land-use practices continuously alter landslide dynamics (Ajraoui et al. 2024). Continuous retraining ensures that models remain relevant and accurate over time. AI can also simulate hypothetical scenarios, such as the impact of land-use changes or extreme weather events, aiding long-term planning and resilience building. Moreover, by automating data analysis and hazard mapping tasks, AI reduces the cost of landslide risk management, making advanced solutions accessible even to regions with limited resources. Numerous open-source libraries e.g. for R and python, such as the Scikit-learn library, and the implementation of AI algorithms in GIS platforms or Google Earth Engine make AI methods highly accessible. AI is being used in a variety of ways to improve landslide modeling, including data collection and integration, real-time monitoring, predictive modeling and early warning systems.

Figure 1. Conceptual schematic plot of landslide modeling where different conceptual elements are integrated (created in Gemini).

Discussion This review has examined the burgeoning field of AI-driven approaches for landslide modeling, highlighting their potential to revolutionize our understanding and management of these geohazards. We have observed a growing body of research demonstrating the superior performance of AI algorithms, particularly deep learning models, in capturing complex non-linear relationships within landslide datasets. This has resulted in improved accuracy, enhanced prediction capabilities, and the ability to handle high-dimensional and heterogeneous data. However, several critical challenges persist. Data scarcity and heterogeneity remain significant hurdles, hindering the development and validation of robust AI models. The lack of standardized data collection and sharing protocols exacerbates these issues. Furthermore, the inherent "black-box" nature of many AI models raises concerns regarding interpretability and the potential for unintended biases. This lack of transparency can hinder trust and limit the widespread adoption of AI-based landslide prediction systems. Despite these challenges, the potential benefits of AI are substantial. AI-driven approaches can significantly enhance early warning systems, enabling more accurate and timely predictions of landslide events. This can facilitate proactive evacuation procedures and minimize human casualties. Moving forward, several key research directions are crucial. • Data-centric workflows: Prioritizing the development of robust data acquisition and sharing frameworks, including initiatives to improve data quality, standardize formats, and enhance data accessibility. • Cognitive AI: Developing and implementing techniques to enhance the interpretability of AI models, such as feature importance analysis, visualization methods, and rule extraction algorithms. • Hybrid approaches: Exploring hybrid models that combine the strengths of AI with traditional geotechnical and statistical methods, leveraging the interpretability and domain expertise of traditional approaches while benefiting from the predictive power of AI. • Real-world applications: Focusing on the practical implementation of AI-based landslide models in real-world settings, including their integration into operational systems and decision-making processes. Ultimately, the successful application of AI in landslide modeling requires a multidisciplinary approach. Collaboration between researchers, practitioners, policymakers, and the public is essential to address the challenges, maximize the benefits, and ensure the responsible and ethical development and deployment of AI-based landslide prediction and mitigation systems.

ABSTRACT. This paper proposes a risk and hazard assessment system for rockfalls in fire-affected areas. The system has the ability to efficiently prioritize hazardous sites and evaluate post-fire rockfall risks, supporting rapid decision-making for mitigation actions.

ABSTRACT. Rockfall and landslide hazards pose significant challenges for mountainous road networks in Central Greece, particularly in the region of Evritania, which is recognized as one of the most susceptible areas to landslides in Greece (Marinos et al., 2015). In cooperation with the Region of Central Greece, the NTUA Engineering Geology & Geohazards Research Group initiated a targeted research program focusing on several key sites in the region. These areas were selected due to their geological complexity, different mechanisms of failure, challenging terrain, and history of documented landslides. Detailed investigations have been conducted to assess slope stability and analyze the mechanisms contributing to slope instability. Building on these investigations, this study highlights advancements achieved through the research program over the past three years, focusing on the application of innovative technologies and the development of methodologies for geotechnical analysis and hazard monitoring. By leveraging advanced 3D reality capture technologies, the research integrated high-resolution aerial and terrestrial data to produce precise digital replicas of the investigated areas. These replicas enabled the extraction of critical engineering geological information and supported the development of advanced digital tools for terrain analysis and hazard assessment. Furthermore, the digital replicas formed the foundation of a comprehensive monitoring program designed and implemented by the research team. When combined with ground-based instrument monitoring (e.g., inclinometers), this program provided a continuous stream of data, enabling regular updates to datasets and significantly improving the accuracy and reliability of detailed 2D geotechnical simulations. These analyses, along with 3D numerical simulations, offered valuable insights into slope behavior, advancing landslide hazard assessment and informing the development of site-specific mitigation measures. Finally, the study evaluates key limitations encountered during data acquisition, processing, and analysis. These insights are examined in the context of each site, demonstrating how challenges were addressed or remain to be resolved to further enhance hazard assessment and optimize mitigation strategies.

ABSTRACT. Deep gravitational slope deformations (DsGSDs) are geological and engineering challenge with important implications for slope stability, reliability of existing infrastructures, land use and, above all, the safety of settlements. This work focuses on the DsGSD phenomenon that affects a large part of the Borrano hamlet, located in the municipality of Civitella del Tronto (Teramo, Abruzzo, Italy). The results of the study provide an essential basis for the development of strategies aimed at planning mitigation and/or relocation measures, which are crucial for the protection of infrastructure and the safety of local communities. The work also highlights the importance of integrated spatial planning, which can combine innovative detection technologies with traditional methods. This approach also makes it possible to optimize land management, making it more effective and sustainable, especially in geologically complex and vulnerable contexts.

ABSTRACT. Coastal slope failures are major geological phenomena that often lead to environmental degradation, land loss and destruction of property and infrastructure. These failures occur predominantly in regions with weak geological formations, steep slopes and dynamic coastal processes. The Kalamaki coastal zone in Western Achaia, Greece, is a representative example, featuring a stratigraphy of friable sandstone formations overlaying cohesive clays and marls, which are inherently prone to weathering, erosion, and slope instability. The susceptibility of these geological formations to failure is exacerbated by structural discontinuities in the sandstone layers, allowing water infiltration and subsequent slope destabilization (Zhang et al., 2020). Since 2014, progressive slope instability in Kalamaki has been observed through satellite imagery, aerial surveys, and field investigations. The main causes of this instability include natural processes such as wave action and erosion, combined with anthropogenic activities such as irrigation and excavation for road and building construction. In addition, water infiltration along vertical cracks in the sandstone, combined with the penetration of vegetation roots, widens these cracks over time, causing translational slides, rockfalls, and debris flows. These processes deposit significant sediment loads along the coastline, altering beach dynamics (Delgado et al., 2018; Poulos et al., 2019). Localized high-wave events and marine undercutting further destabilize the base of the coastal slopes, creating overhangs and weakening the upper geological layers. This underscores the necessity for targeted mitigation measures addressing both geological and marine influences (Terzaghi et al., 1996). While prior studies suggest relative stability in some parts of the Kalamaki coastline, high-energy events have repeatedly triggered localized failures, highlighting the importance of assessing these vulnerabilities. For a better understanding of the failures on the coastal slopes of Kalamaki, this paper uses the results of the Coastal Vulnerability Index (CVI) estimation for specific areas (Boumpoulis, 2024; Boumpoulis et al., 2025) in combination with the classical slope stability analysis. Using GIS-based spatial analysis for CVI, and Hoek et al. (1977) two-dimensional slope stability analysis, this study identifies coastal erosion and slope destabilization hotspots, identifying the failure mechanism and providing critical information on areas requiring immediate protection.

ABSTRACT. The urgent need to address climate change has never been more critical, as its impacts are being felt globally, with severe consequences for ecosystems, economy, and human communities. Adapting to a rapidly changing world is equally essential. Climate change poses one of the greatest challenges of our era, making immediate action imperative. Education, including geoeducation, can serve as a key tool in preparing future generations to mitigate and adapt to these challenges. Geoeducation, enriched with geoconservation principles, emphasizes the importance of protecting geological heritage while fostering an understanding of Earth's processes and their relevance to the climate crisis. Therefore, it provides a unique opportunity to equip students with the knowledge and skills to grasp the complexities of climate change and its impact on our planet. This paper underscores the significance of education, particularly environmental education and geoeducation, in addressing the climate crisis, while also exploring obstacles and challenges regarding the implementation of climate change education in Greece. Additionally, it proposes general strategic approaches for systematically integrating climate change education into the compulsory education system, with the objective of fostering both mitigation and adaptation in response to the climate crisis. The study employs a mixed-method approach to explore integrating climate change education (CCE) into Greek compulsory education. A systematic review of national and international studies identifies best practices, challenges, and gaps in implementing CCE. SWOT analysis evaluates internal factors like teacher preparedness and resources, while PEST examines external political, economic, social, and technological influences.

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ABSTRACT. This study aims to highlight Natural History Museums as suitable educational spaces for teaching geosciences to High school students. Specifically, it presents the design and practical use of a museum kit inspired by the geology of Greece. Museum kits are innovative educational tools that combine experiential learning with environmental education. This study examines the design, development, and application of a museum kit that connects the exhibits of the Natural History Museum of Arsakeia Schools with the teaching of Geology-Geography, as outlined in the curriculum for 2nd and 3rd High School grades This educational tool focuses on familiarizing students with the geological history of Greece. It includes geological maps, rocks, minerals, fossils, and activities designed to help students understand the unique geotectonic structure of the region. The museum kit was piloted with 90 students, yielding highly positive results.

ABSTRACT. Research Highlights The present work includes a summary of the main materials used and initiatives undertaken by Psiloritis UNESCO Global Geopark and the Center for Environmental Education and Sustainability of Anogia for the education of children and adults on Geology and Geology- related topics in the area of Psiloritis UNESCO Global Geopark, (Crete) Greece. Introduction / Background UNESCO Global Geoparks (UGGps) are single, unified geographical areas with exceptional geological features of international significance. They are managed with a holistic approach towards the protection, education and sustainable development of their territories, adopting a bottom-up approach through the active involvement of their local communities in their efforts (UNESCO, 2024). For any UGGp, education at all levels is one of the main focus areas of its operation (UNESCO, 2015). It is essential for a UGGp to develop and perform educational activities to disseminate knowledge and raise awareness on geodiversity and its connections to biodiversity and other traits of the tangible and intangible cultural heritage, with the purpose to educate and inspire on the significance of the territory and to increase local involvement and engage the audiences into more effective conservation. Many UGGps form synergies with specialized educational institutions, at the national or local level, to achieve better pedagogical and more widespread results in their initiatives for education. One such example is the cooperation between Psiloritis UGGp and the Center for Environmental Education and Sustainability (CEES) of Anogia. CEESs are an institution of multiple different centers throughout Greece, established by the Greek Ministry of Education, Religious Affairs and Sports as a bridge between the school and society. In the CEESs’ philosophy of operation, emphasis is put on the need to raise interest in all forms of life towards the development of an environmental ethic and by linking the education for the environment and sustainability with the need to also instill a system of values. Objectives Presently, there are 213 UNESCO Global Geoparks in 48 countries and, even though they produce numerous and innovative educational materials, the amount of published works on UGGp- education still remains limited in comparison to research on other topics concerning UGGps and with an availability of resources not much broader than that of local implementation and dissemination through conference participation (Martínez-Martín et al., 2023). The present work aims to present the materials, programs and digital tools developed and used for education by Psiloritis UGGp and its education partner, the CEES of Anogia, as they are currently being implemented in the area. Area Psiloritis Geopark was established in 2001 and since 2015 it has been recognized as a UNESCO Global Geopark. It is located in the central part of the island of Crete (Greece) with the mountain of Psiloritis, or ancient Idi (2456m), being the main point of reference for the territory, thus, also providing the name for the Geopark. It has a total area of 1272 km2, including villages and settlements from 8 different Municipalities and a population of approximately 38.000 residents. The complex topography of the area and the variety of rocks combined with the isolation of the entire island of Crete, make the mountainous mass of the geopark a hotspot for biodiversity and endemism, leading to the inclusion of ~56% of the territory in the European NATURA 2000 Network. The connection of the area with the people has been strong and persistent since the times of antiquity, as can be demonstrated by the numerous findings and monuments spanning from the Minoan era to the Roman times and the many religious and cultural monuments of our days. The intangible cultural heritage of Psiloritis is also worldwide famous with the traditional handicrafts, cuisine, and music being only some of the examples. Concerning the geodiversity of Psiloritis Geopark, it spans over a period of about 360 million years, with a variety of rocks attributed in 7 different tectonic nappes and ranging from the most common limestones and dolomites to the more rare stromatolites and ophiolites. The fossils of Psiloritis Geopark also bear witness to its history and evolution of life, including findings such as the rare Fodele fossils (corals, brachiopods and bivalves of about 360-300 million years ago) or the most recent fossils from terrestrial vertebrates (dwarf elephants and deer, giant mice from the Pleistocene) as evidence of a special adaptation mechanism to island life. The geodiversity of the Geopark bear witness to the geological history of the area that has been (and is still being) dominated by tectonism, uplift of the mountains and karstic erosion. Large- and small-scale folds and faults and all kinds of karstic features (surface and subterranean) appear throughout the area of Psiloritis, providing the opportunity for the visitor to find all the evidence that explain the formation of the high mountains and their continuous transformation through the creation of impressive gorges, mystical caves and fertile plateaus, as well as fascinating landscapes. Results and Discussion Psiloritis UGGp and Anogia CEES are both institutions with a long history of operation in the area (Psiloritis Geopark was established in 2001 and Anogia CEES in 2006), offering formal and non- formal educational activities in the wider area of Psiloritis. Both organizations have so far informed and trained thousands of students, teachers and also local professionals, residents and visitors. It is characteristically mentioned that for the year 2024, Psiloritis UGGp and Anogia CEES received a total of approximately 1035 children aged 5-18 (students, scouts), with whom educational activities were implemented either indoors or in the field. Most of the developed materials and tools used within this context, could be broadly categorized in the following general thematic categories: Geodiversity, Biodiversity, Human History/ Traditions and Arts, Sustainable way of life. These are briefly presented in the table below (Table) according to the typology of each material that is currently being implemented, its title and a brief description, the thematic category it falls into, whether it’s being implemented by the staff of Psiloritis UGGp, Anogia CEES or by the two in cooperation and finally, the age of the audiences each material is addressed to.

Based on the quantity and multidisciplinarity of the materials provided for geo- education and geology- related topics in Psiloritis UGGp (Table), it becomes once again evident that these territories are important loci for the interpretation and education on themes and phenomena related to the formation and conservation of the natural world. In Psiloritis UGGp, educational activities are implemented by the staff of the organization as well as by the Anogia CEES, one of the geopark’ s partners for education within the territory. Interestingly, even though the educators in the CEES of Anogia are not trained geologists, they have exhibited a consistent passion for geo- education since the early years of their operation, recognizing the importance of the local geodiversity and promoting it through the numerous education programs and initiatives they implement (Table). The excellent cooperation between Anogia CEES and Psiloritis UGGp has provided high- quality (scientifically and pedagogically) education materials and initiatives, educating an overall of approximately 10.000 students and 5.000 teachers on relevant topics (Fig. 1) in the territory so far (data from Anogia CEES). Both organizations have developed and are implementing activities in the form of complete and structured educational programs or individual materials (activity books, short experiments etc.) for students of different levels, but also adults that may be university students, teachers or professionals of the area, receiving training on Geopark- related subjects in the form of workshops. Other forms of education initiatives may include field trips, textbooks and other activities performed during special occasions (i.e., celebration of International Days, special visits etc.) (Catana & Brilha, 2020; Rossi et al., 2022) also potentially aiming at locals or visitors, within the context of communication/ public outreach- that share some goals and principles with education- on what concerns the interpretation of the natural world of a territory (Crofts et al., 2020). A wide range of pedagogical techniques is embedded in these educational activities: step-based education, familiarization and empowerment games, field studies, observation and orientation games, experiments that visualize natural processes, inquiry-based learning and many more, while at the same time they enhance critical thinking, cooperation between students/ student groups, and empirical knowledge. The multidisciplinary approach and the promotion of links between themes is obvious in most materials while the successful communication between the organizations itself can be seen in the complementarity of some of the materials/ initiatives e.g., the CEES of Anogia has a greater experience in organizing training seminars for teachers and educators and Psiloritis UGGp has a larger set of options of digital tools (Tab. #11; Fig.2; Fassoulas et al., 2022). All the above observations (quantitatively, qualitatively) generally agree with findings and conclusions from Catana & Brilha (2020) and Rossi et al., (2022) on the mode of how educational tools and activities are designed and executed in most geopark territories. Furthermore, with reference to the seventeen United Nations Sustainable Development Goals (SDGs), the potential of the tools presented here can easily be grasped within the context of SDG 4 “Quality Education” and SDG 17 “Partnership for the Goals”. Additional SDGs can also be observed in, for example, materials #4b- 5b (Table) that are clearly linked to SDG 15 “Life on Land” and material #10 (Table) that is linked to SDG 13 “Climate Action”. Furthermore, other stand- alone activities and individual actions from initiatives #13, 14, 15 (Table)- that are not mentioned here in detail for reasons of space availability and overall relevance- are directly related to SDGs focusing on the triplet People- Prosperity- Planet. This further underlines the role of UGGps as areas for the promotion of the natural sciences but, also, sustainability (Catana & Brilha, 2020; da Silva, 2020).

Conclusions Geology is all around us through the rocks and minerals that we use, the processes that shape our surroundings and the very substrate we walk on! However, as a scientific field, it unfortunately still remains rather unpopular and non- understandable by most of the public. UGGps as organizations and as territories are, indeed, playing a significant role addressing this issue, since they have the background and experience to “translate” this often-inaccessible knowledge for the local communities (students and adults) in a way that is scientifically and pedagogically appropriate. Thus, educational tools developed and implemented in UGGp territories, especially in cooperation with local educational partners, are numerous, innovative and extremely useful if one considers the overall limited and very much needed interpretive and teaching resources on geology for the more effective protection of this aspect of the natural heritage of our territories. Extending the conversation to other relevant issues of sustainability such as the climate crisis, natural hazards, water availability and many more, we could find ourselves in the position to also inform, sensitize, engage, and prepare members of local communities on matters that are extremely pressing nowadays. The impact of this effort increases significantly if we, as organizations, share all these tools and practices within our networks and more broadly into the scientific community and other conservation organizations and protected areas, with whom we share the same goals.

ABSTRACT. Abstract This paper examines the integration of drama and science as an innovative approach to teaching scientific concepts, focusing on the educational theatrical production Pluto is Lost!, created and performed by students at the 3rd Junior High School of Glyfada, Athens, Greece. The initiative aimed to introduce students to the Solar System and environmental science—subjects often overlooked in the Greek compulsory school curriculum—while fostering creativity, teamwork, and critical thinking. The project was implemented within the framework of the "Learning Science Through Theatre" program, which promotes interdisciplinary learning by merging science education with artistic expression. Through a project-based learning model, students engaged in five phases: defining goals, designing, executing tasks, presenting results, and evaluating outcomes. They humanized astronomical and environmental concepts by creating a storyline where celestial bodies and Earth's ecosystems were personified, and the dynamics of the Solar System and environmental sustainability were explored through imaginative narratives. The embodied learning process enabled students to express scientific ideas through gestures, movements, and emotional engagement, enhancing comprehension and retention. The production also addressed contemporary challenges, such as climate change, environmental conservation, and societal issues, connecting science to real-world contexts. Dissemination efforts included performances in collaboration with local institutions and recognition through multiple awards, including the "Learning Science Through Theatre" award for best theatrical and musical performance, the EPI2 award from the Athens Science Festival, and presentations at COSPAR 2022 (Athens, Greece) with the latter receiving a full grant. The study concludes that combining science and theatre effectively engages students, promotes scientific literacy, and encourages creative exploration of complex topics. This initiative highlights the potential of arts-based methods in science education, offering a replicable model for fostering interdisciplinary learning and inspiring passion for STEAM fields.

Figure 1. Asteroids Dancing Acknowledgements The authors would like to express their gratitude to Mr. Menelaos Sotiriou, Dr. Zacharoula Smyrnaiou, and Science View for their invaluable support and guidance throughout this project. References Aikenhead G. (2006) Science education for everyday life: Evidence-based practice (New York and London, Teachers’ College Press). Alexopoulos I., Sotiriou S., Smyrnaiou Z., Sotiriou M., Bogner F (2016) Developing an Engaging Science Classroom Available online at https://www.researchgate.net/publication/312176004_Developing_an_Engaging_Science_Classroom (accessed 11 July 2022). Braund M. (2010) Talk in science: Forgotten corner of the constructivist classroom?, in: D. Mogari, A. Mji, F. Mundalamo, U. Ogbonnaya (Eds) Proceedings of the ISTE international conference on mathematics, science and technology education: towards effective teaching and meaningful learning in mathematics, science and technology education. Mopani Camp, Kruger National Park, South Africa, 18–21 October 2010 (Pretoria, University of South Africa (UNISA) Press), 287–301. Braund, M. (2013) Drama and learning science: An empty space? Available online at https://www.researchgate.net/publication/260410840_Drama_and_learning_science_An_empty_space (accessed 11 July 2022) Brinder, K., Anuj, S.(2004) S & T Communication through pupperty – A case study (India) Available online at https://www.academia.edu/48647908/S_and_T_Communication_Through_Puppetry_a_Case_Study_India_(accessed 11 July 2022) Musacchio, G, Lanza, T, D’Addezio(2015) An Experience of Science Theatre to Introduce Earth Interior and Natural Hazards to Children Available online at https://www.ccsenet.org/journal/index.php/jel/article/view/43677 (accessed 11 July 2022) Ødegaard, M. (2003) Dramatic science. A critical review of drama in science education, Studies inScience Education, 39(1), 75–101. Smyrnaiou, Z., Georgakopoulou, E., Sotiriou, M., Sotiriou, S. (2018). Constructing Scientific Notions: Students’ Conceptual Change through a Re-sponsible Research and Innovation Initiative. Co-Create ! - Co-creation of curricula, tools and educational scenarios for building softcompetences for personal development and employability (Multi-conference on Responsible Research and Innovation in Science, Innovation and Society m-rrisis 2018). Tartu, Estonia, 17-19 Septembre Smyrnaiou Z., Georgakopoulou E., Sotiriou M., Sotiriou S. (2017). The Learning Science Through Theatre initiative in the context of Responsible Research and Innovation. Proceedings of The 10th International Multi-Conference on Society, Cybernetics and Informatics: IMSCI 2017 Toonders, W., Verhoeff, R.P., Zwart, H.A.E.(2016) Performing the future: on the use of drama in philosophy courses for science students Available online at https://repository.ubn.ru.nl/handle/2066/161707 (accessed 11 July 2022)

ABSTRACT. This paper aims to help teachers who intend to organize educational trips to the region of Thessaly and for this reason these characteristic landforms have been selected, which have the potential to impress students and attract their interest. The geotopes selected are Mt. Olympus, Tempi valley, Mikrothives volcano, Meteora, Elassona basin and Tyrnavos fault. The Worksheets and Evaluation Sheets, which correspond to each geotope, include activities and tasks that can be done independently of the educational trip, but can be part of the teaching of the course of "Geology – Geography" of the first and second grade of High School, in order to understand geological concepts, such as weathering and erosion, deposition, faults and earthquakes, volcanos, fossilization, etc. that are phenomena that take place daily in areas of the planet and affect people's lives.

ABSTRACT. This study investigates the relationship between sense of place, geoethical awareness, and participation in a place-based educational program. Thirty-three educators participating in the 4th Summer School at the Sitia UNESCO Global Geopark (UGGp) in Greece completed pre- and post-program questionnaires assessing place attachment, place meaning, and geoethical awareness. Non-parametric statistical analyses revealed significant increases in all three variables following the program. Findings suggest that stronger emotional connections to place and deeper personal meanings associated with the Sitia UGGp are correlated with increased geoethical awareness. This highlights the importance of fostering both emotional and cognitive connections to place in promoting geoethical thinking. Furthermore, this study underscores the potential of UNESCO Global Geoparks as platforms for advancing sustainable development, geoeducation, and community engagement through the conservation and appreciation of geoheritage.

ABSTRACT. Lemnos island located in the north eastern Aegean sea, represents an area rich with numerous geological and geomorphological features, especially fossiliferous sites, volcanic geosites and impressive erosional landforms in sedimentary formations which are excellent representatives of this area’s geodiversity. Geosites are protected elements according to Green environmental legislation (Law 1650/1986, Law 3937/2011) as they consist the main witnesses of the history of the earth. However these geosites and their geotourism potential still remains fully unrevealed. In this paper we present the work carried out aiming to identify, map and asses the various geosites of Lemnos Island in order to select the most representative ones based mainly on their aesthetic value as well as their geotourism potential. Τhe research team on geological heritage and geodiversity of the Department of Geography of the Aegean University and the Natural History Museum of the Lesvos Petrified Forest started the a research effort to identify and map the fossiliferous locations of fossil plants on Lemnos island in 2012. As a result the Lemnos petrified forest declared a protected natural monument in 2013. The research effort continued to identify and map the variety of Lemnos geosites. Following an emerging global trend for geotourism our main goal was to link the individual geosites along thematic geotrails with other elements and sites of ecological and cultural value. This strategy has the potential to involve wider community interest, engagement, support and involvement in its management. This is supported by the North Aegean 2014-2020 Regional Operational Program - Action "Creation-operation of digital applications for the promotion of geo-monuments of Lemnos" implemented by the Museum of Natural History of the Petrified Forest of Lesvos in collaboration with the Municipality of Lemnos, which concerns the promotion of geological monuments, landscapes and places of ecological interest, with the aim of utilizing them for the development of alternative forms of tourism.

ABSTRACT. For the purposes of the present announcement, we briefly outline some of the findings, recently outlined in detail by Koutsovitis et al. (2025), concerning some of the St. martin granitoids that encompass relatively high modal amounts of mafic minerals.

ABSTRACT. Research Highlights In this study we argue about the biogenicity of biomorphous structures related with As-mineralization from the Kolumbo diffuser chimneys based on their syngenicity and indigenousness, geological context, morphology and composition. Introduction Modern seafloor hydrothermal vents present a hostile environment for life which consists of high acidity, discharge of high-temperature magmatic gases and potentially toxic metal(loids) such as As, Sb, Pb, Tl. Arsenic is widely recognized as a major pollutant for marine ecosystems and a potentially toxic element harmful to most living organisms (Hu et al., 2023). It is established that hydrothermal vent fields are a vast microbial habitat, hosting a significant population of microorganisms (Runge et al., 2023, Kilias et al., 2013) Furthermore, this kind of environment is regarded as analogue for the emergence of primordial life while As-enriched oceans are considered a potential cradle for the origin of life (Russel et al., 2005, Hu et al., 2020). To endure direct exposure to such extreme environments, various microbial species have evolved resistance mechanisms involving detoxification, biotransformation and even generating energy by oxidizing arsenite. (Hu et al., 2020). It is well known that microorganisms in the hydrothermal vents can contribute significantly to the formation of mineral deposits rich in metal(loid)s (Southam and Saunders, 2005, Kilias et al., 2013). However, little is known about the microbial processes associated with the precipitation of arsenic sulfides. (Hu et al., 2020). Here we present morphological, mineralogical and geochemical evidence for the biogenicity of arsenic sulfides on the active hydrothermal diffusers at Kolumbo arc volcano. Geological Background The submarine volcano of Kolumbo located in the Anhydros Basin, Aegean Sea as part of the Christiana-Santorini-Kolumbo volcanic field that lies in the center of the Hellenic Volcanic Arc (HVA). Kolumbo crater has a basal diameter of 3 km with NE-SW orientation. (Hector et al., 2024). On top of the crater lies an active hydrothermal vent field with diffuser chimneys emitting shimmering water to ~265°C pure gaseous CO2 fluid forming, a polymetallic Au-rich Seafloor Massive Sulfides (SMS) deposit. The studied samples present four distinct mineralogical zones. The thick porous Inner Sulfide-Sulfate Core (ISSC) is composed of barite, pyrite, marcasite, sphalerite, galena, Pb-Sb sulfosalts, minor anglesite, and minor chalcopyrite. Surrounding the ISSC is the Outer Arsenic Layer (OAsL), which contains barite, pyrite, sphalerite, Pb-Sb sulfosalts, stibnite, As-Pb-Sb sulfosalts, and amorphous arsenic-rich sulfides resembling realgar and orpiment. Encasing the OAsL is a gelatinous orange to brown Surface of Fe-rich Microbial Crust (SFeMC), primarily composed of amorphous Fe-(hydrated)-oxyhydroxides. In this study we focus on the OAsL where the As-related biomorphous structures are observed on that layer (Kilias et al., 2013). Materials and methods Sampling The samples studied were collected during two oceanographic expeditions collected from the northern part of the Kolumbo crater floor using the Remotely Operated Vehicles (ROV) Hercules and Max Rover. Optical microscopy and Scanning electron microscopy All samples were petrographically examined via transmitted and reflected light microscopy at the Department of Geology and Geoenvironment, National and Kapodistrian University of Athens (NKUA). The biomorphous structures were further observed under a Scanning Electron Microscope (SEM) in order to a) examine the morphologies and textural relationships under high magnification, b) obtain semi-quantitative X-ray elemental maps. For that purpose, a Nova NanoSEM Field Emission-SEM (FE-SEM) was utilized, equipped with, a BacksSattered Electron (BSE) detector, a Secondary Electron (SE) detector, and a Bruker X Flash EDS detector. Samples were carbon-coated with an average thickness of 15 nm, to achieve surface conductivity, and the instrument was operated at a 30-kV accelerating voltage, while electron beam stability was calibrated using a copper standard. Raman spectroscopy Raman spectroscopy analyses were performed using a Renishaw inVia Raman confocal microscope, equipped with two lasers, emitting at 532 (green) and 785 nm (red). The green and red lasers are coupled with gratings of 1800 and 1200 groves per mm2, respectively. Spectra were obtained using the 785 nm laser with a power range between 0.5 and 0.05 mW, due to the varying stability and fluorescence of the analysis spots. Samples were exposed to the laser through a long-focal distance, 50X objective lens with 0.55 numerical aperture, and with the measured spectral range extended from 100 to 3200 cm-1. The obtained spectra were then processed by the WiRE software for Windows. Background noise was reduced by the subtraction of a polynomial baseline, and cosmic ray removal corrections were performed for all spectra. Results Optical Microscopy To provide a detailed description, the biomorphous structures are classified in three types based on morphology as well as differences in chemistry. Type 1 structures are identified as diatoms species. Type 2 are filamentous biomorphs. Type 3 are globular biomorphs. Diatom morphology is very evident in Fig. 2. After thorough observation and due to morphology and spectroscopic data (see below) we conclude that it belongs to Chaetoseros sp., one of the most diverse planktonic diatom species (De Luca et al., 2019). The main characteristic of family is the existence of setae that appear to come out from the valve of the cells. Setae help diatoms create chains of cells that a expand for tens of micrometers. To prevent the chains from extending too far, terminal setae are produced from several cells. Each cell exhibits an outer layer known as frustule. It is crucial to mention that diatoms in this study demonstrate different levels of As-mineralization. Diatoms are mostly observed in open spaces and in close association with barite. The type 2 biomorphous structures are filamentous and extend up to several tens of micrometers. Depending on their width, a stibnite core is visible which appears black or gray depending on parallel or crossed polaroids under reflected light, while arsenic is mostly in the form of orpiment. The filaments exhibit a plethora of different characteristics. (Fig. 3) Some of them appear more lineal and demonstrate terminal swelling while others exhibit twisting and branching or even septated structures (Qu et al., 2023). Sometimes those can co-exist. The thinner filaments tend to form net-like structures and exhibit pinching (Hu et al., 2020). Furthermore, in some cases filaments appear to grow on diatoms (Fig 2. c). It is important to note that even the thinner filaments exhibit a stibnite core, but it is not always visible due to scale. The filaments are usually found as intergrowths with stibnite and Pb-Sb sulphosalts on a barite substrate as they also develop in open space. It is important to note that in most cases the filaments seem to penetrate the mineral surface of primary abiogenic orpiment and other As-rich minerals like arsenian pyrite and Pb-Sb sulfosalts. (Fig. 6). Type 3 biomorphous orpiment like structures are quite different in morphology. They appear as globules either observed on diatoms (mostly on setae) or forming grape-like structures in open spaces. Their diameter is not bigger than 3 micrometers. They can be found in association with filaments as well. (Fig. 4). It is interesting that when a lineal substrate appears (like a diatom seta or a needle-like stibnite) these globular biomorphs can display a string of beads (Qu et al., 2023). Mineral Chemistry-SEM EDS Further detailed geochemical analyses on biomorphous structures were performed by SEM-EDS to evaluate their chemical composition. The results showed the presence of As-sulfide in all the examined biomorphs. Regarding type 1 biomorphs, SEM-EDS confirmed the presence of silica which further proves they are diatoms. As it has been established, diatoms are known to form silica cell walls (Hildebrand, 2008). It is evident (Fig. 5) that silica is distributed on the frustule as well as on setae. When it comes to filamentous biomorphs, SEM-EDS confirms the stibnite core as well as the As-sulfide shell and absence of silica. As for the globular biomorphs, arsenic, antimony and sulfur seem to be equally dispersed. Spectral characterization of biomorphous structures The contribution of Raman spectroscopy for this study was crucial. Point analyses revealed the presence of carbonaceous matter (CM) in all the biomorphs under investigation. Raman mapping was used to better understand the pattern of mineral phases on the studied biomorphs. Spectroscopic data showed the presence of amorphous hydrated silica and orpiment (As2S3) and realgar (As4S4) mineralization on biomorphous structures (Papoutsa et al., 2024). The occurrence of CM as a structural component was verified by the occurrence of first order (1000-1650cm-1) and second-order (2500-3200 cm-1) bands (Papoutsa et al., 2024). The notable features consist of a prominent G-band at 1583 cm⁻¹, distinct from the D2 band at approximately 1608 cm⁻¹, along with clearly defined D1 and D4 peaks at 1347 cm⁻¹ and 1245 cm⁻¹, respectively. G/D2 band ratio was used to better interpret the distribution of CM. For the type 1 biomorphs, Raman peaks at ~490, 602, 812, 980 and 1000 cm-1 are indicative of Si-OH (hydrated silica) that compose the diatomaceous cell wall (Papoutsa et al.,2024). The hydrated silica seems to be concentrated mainly on the frustule. Regarding the filamentous biomoprhs, Raman spectroscopy confirmed the presence of stibnite core and orpiment-realgar shell. CM was also identified within the structure. As for the globular structures, CM and orpiment were identified as well. However, it is important to note that their small diameter approaches the limit of spatial resolution of Raman mapping with the available objective lens. Regardless that, Raman maps of CM distribution in the type 3 structures, were successfully constructed. Criteria for biogenicity To examine the biogenic origin of the aforementioned biomorphs, 4 criteria were tested. (Ivarsson et al., 2015) Geological context Modern hydrothermal vent fields associated with Seafloor Massive Sulfides (SMS) deposition are widely regarded as significant microbial habitats (Hu et al., 2020). They sustain extraordinary biological communities, featuring rare and endemic species uniquely adapted to the conditions of hydrothermal vents (Georgieva et al., 2021). SMS being the closest modern analogue of ancient Volcanogenic Massive Sulfides (VMS) deposits, which are proven to be one the earliest known habitats for microbial life (Hu et al., 2020). Therefore, these types of environments are closely associated with the history of life and its origination (Hu et al., 2020, Georgieva et al., 2021). The fossil record of hydrothermal vents possibly represents the earliest direct evidence of life on Earth, highlighting their significance as biological habitats throughout Earth's history. Hydrothermal vent microbial communities consist of relatively high concentrations of a few species that rely on chemosynthesis for survival such as Proteobacteria and Campylobacterota (Georgieva et al., 2021). Syngenicity and indigenousness All the observed biomorphs, and especially the filaments and the globules, originate from the surface of the minerals present at the chimneys and/or the surface of diatoms. The transition from the mineral surface to the filaments are smooth and undisturbed (Fig. 6) indicating that the filaments grow out of the surface of minerals. In cases, the open pore space has been colonized from a biofilm which filamentous net-like and from globular grape-like structures grow (Fig. 6). The existence of the biomorphs on the outer layer of the chimneys and their close association with the primary sulfide minerals indicates that microbial activity was synchronous with the arsenic mineralization. These observations coupled with high counts of genes associated with arsenic oxidation (Papoutsa et al., 2024) suggest that the filamentous and globular biomorphs are indigenous of the chimneys and syngenetic with the As-sulfide deposition. Diatoms are not usually inhabiting hydrothermal vents, rather they accidentally sink from the upper levels of the water column onto the diffuser chimneys. Morphology The occurrence of filaments and globules as whole clusters resemble the culture media precipitates of As-respiring bacterial strain (Hu et al., 2020). The growth of clusters over diatoms, orpiment and other As-rich phases, achieved by penetrating and dissolving the mineral surface, mirrors microbial strategies for colonizing mineral surfaces to extract nutrients. Composition Despite the filamentous and globular biomorphs being embedded in epoxy resin, Raman spectroscopy revealed distinct CM within their structures. Comparisons with the spectra of the epoxy rule out contamination and confirm that the carbonaceous matter is indigenous to the structures. Raman mapping (Fig. 7) revealed that CM is localized in specific areas such as the As-rich shell of the filaments rather than the stibnite core. This suggests that indigenous CM is preserved in the late stages of the mineral paragenesis. The presence of CM in the shell of the structures agrees with other studies arguing about biogenic origin of As-sulfides (Hu et al., 2020) and it suggests that microbial activity was synchronous to As-sulfide deposition. Synchrotron X-ray absorption near edge structure analysis has shown that the As-sulfides in diffusers contain a mixture of As (II) and As (III). These heterogeneities in the valence of As can be credited to microbial activity. Metagenomic libraries constructed from the Kolumbo vents, which revealed high counts of functional genes involved in microbial oxidation of As (II) to As (III) (Papoutsa et al., 2024) further prove this point. Conclusions In this study we report observations of different biomorphous structures associated with As-sulfides mineralization. Three types of biomorphs have been identified; Type 1) Diatoms, Type 2) Filaments and Type 3) Globules. The morphological features of the studied biomorphs, combined with their distinct spectroscopic characteristics and their geochemical composition along with the metagenomic data suggest that As mineralization was contemporaneous with microbial activity. The lack of diatom related gene counts in the metagenomic libraries shows that diatoms are not directly involved in the mineralization of As, rather they exist as the substrate for microorganisms to develop, providing CM and nutrient from the swallow waters to the deep sea. This theory is further supported by the fact that filamentous and globular structures seem to grow over the diatoms resembling microbial strategies for colonizing mineral surfaces. Acknowledgments We are thankful to NKUA for granting us access to Raman Spectroscopy at Core Facility of the School of Science. We are grateful to the Electron Microscopy Facility of the Materials Treatment Centre in VITO (Mol, Belgium) for the use of FE-SEM and the citizen science Horizon funded project nexus-monARC for fully supporting the analyses that took place in VITO. Also, to Maria-Despoina Chrysafeni for her FE-SEM images. References De Luca, D., Sarno, D., Piredda, R., and Kooistra, W.H.C.F., 2019. A multigene phylogeny to infer the evolutionary history of Chaetocerotaceae (Bacillariophyta). Molecular Phylogenetics and Evolution 140, 106575. Georgieva, M.N., Little C.T., Maslennikov, V.V., Glover, A.G., Ayupova, N.R., & Herrington, R.J. (2021). The history of life at hydrothermal vents. Earth-Science Reviews 217, 103602. Hector, S., Patten, C.G.C., Beranoaguirre, A., Lanari, P., Kilias, S., Nomikou, P., Peillod, A., Eiche, E., and Kolb, J., 2024. Magmatic evolution of the Kolumbo submarine volcano and its implication to seafloor massive sulfide formation. Mineralium Deposita 59, 1229–1248. Hildebrand, M., 2008. Diatoms, biomineralization processes, and genomics. Chemical Reviews 108, 4855–4874. Hu, S.Y., Barnes, S.J., Pagès, A., Parr, J., Binns, R., Verrall, M., Quadir, Z., Rickard, W.D.A., Liu, W., Fougerouse, D., Grice, K., Schoneveld, L., Ryan, C., and Paterson, D., 2020. Life on the edge: Microbial biomineralization in an arsenic- and lead-rich deep-sea hydrothermal vent. Chemical Geology 533, 119438. Ivarsson, M., Peckmann, J., Tehler, A., Broman, C., Bach, W., Behrens, K., Reitner, J., Böttcher, M.E., and Ivarsson, L.N., 2015. Zygomycetes in vesicular basanites from vesteris seamount, Greenland Basin - A new type of cryptoendolithic fungi. PLoS ONE 10, e0133368. Kilias, S.P., Nomikou, P., Papanikolaou, D., Polymenakou, P.N., Godelitsas, A., Argyraki, A., Carey, S., Gamaletsos, P., Mertzimekis, T.J., Stathopoulou, E., Goettlicher, J., Steininger, R., Betzelou, K., Livanos, I., Christakis, C., Bell, K.C., Skoullos, M., 2013. New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece. Scientific Reports 3, 2421. Papoutsa, A., Pletsas, V., Kilias, S., Dimou, E., Polymenakou, P., Nomikou, P., Papadimitriou, V., Maak, J., Ivarsson, M., Kyrpides, N.C., 2024. Raman spectroscopy evidence for arsenic-sulfide mineralized diatom-like structures in deep-sea hydrothermal vents at Kolumbo: contribution to arsenic biomineralization. 16th International GeoRAMAN Conference, Rhodes, Greece, p.49-50. Qu, Y., Yin, Z., Kustatscher, E., Nützel, A., Peckmann, J., Vajda, V., and Ivarsson, M., 2023. Traces of Ancient Life in Oceanic Basalt Preserved as Iron-Mineralized Ultrastructures: Implications for Detecting Extraterrestrial Biosignatures. Astrobiology 23, 769–785. Runge, E.A., Mansor, M., Kappler, A., and Duda, J.P., 2023. Microbial biosignatures in ancient deep-sea hydrothermal sulfides. Geobiology 21, 355–377. Russell, M.J., Hall, A.J., Boyce A.J., Fallick A.E., 2005. On hydrothermal convection systems and the emergence of life. 100th anniversary special paper, Economic Geology 100, 259–270. Southam, G., and Saunders, J.A., 2005. The Geomicrobiology of Ore Deposits. Economic Geology 100, 1067–1084.

ABSTRACT. Vast amounts of raw materials from minerals will be needed to meet the demand for a global economy free of hydrocarbons. Some are categorised as Critical and Strategic Minerals (CSMs) due to their high economic significance and supply risk. Of the 34 minerals and metals on the current EU list of CSMs, established in 2023, 16—such as copper, nickel, and aluminium—are strategically significant (Grohol et al., 2023). The CSMs are the foundation on which modern technology is built. From photovoltaics to semiconductors, wind turbines, and lithium batteries, to transport and store the produced renewable energy. In addition to lithium, battery value chains need cobalt, graphite, nickel, and manganese (Rachovides, et al., 2024). The electrification of cars requires permanent magnets, whose value chains use rare earth elements (REE) such as neodymium, dysprosium, and praseodymium, but also increase the use of nickel, copper, zinc, and lead. The CSMs are also essential in digital technology. Without CSMs, there cannot be an energy and digital shift. As a result, the resilience and sustainability of the CSM value chains that deal with technology facilitating the energy transition are highly valued by the EU. The EU would need up to 18 times more lithium and 5 times more cobalt by 2030 and almost 60 times more lithium and 15 times more cobalt by 2050 to cope with the increase in the production of electric vehicle batteries. By 2030, the demand for graphite is expected to reach 4 million tons per year, with 75% going to lithium battery anodes (Rachovides, et al., 2024). A shortfall of around 780,000 tonnes per year is estimated by 2030. Given that several of the Green Deal's goals, such as reducing greenhouse gas emissions by at least 55%, must be addressed and achieved by 2030, the growing need for CSMs becomes even more urgent. The above forecasts seem "scary" considering that the EU depends on 75 to 100% of imports for most CSMs. It also happens that the production and processing of many CSMs are geographically controlled, making their geopolitical access and disposal vulnerable, accompanied by a series of social, economic, environmental, and other risks. So, some CSMs, but also their related value chains, tend to a large extent to be productively monopolized by specific regions of the planet, sometimes by essentially one country. For example, about 60% of the world's cobalt comes from the Democratic Republic of Congo (Fig. 1). China mines around 60% of the world's REE production, produces 85% of associated processed and metallurgical products, and consumes 70% (Arvanitidis, 2024). The urgent need for a global hydrocarbon-free economy will require therefore increasing quantities of raw materials. Therefore, it is important to know which and how many raw materials are needed to understand and assess the implications of their scarce access or scarcity for the European, and hence the Greek, economy. This article views why and how strategic and criticality in mineral resources arises, the geopolitical dominance of China, the European Regulation on Strategic and Critical Mineral Resources Act(CRMA), the key deposit of strategic and critical mineral raw materials resources, the need for increased investment in mineral exploration, new methodological approaches to mineral exploration, dynamic CRM systems in Europe and Greece and proposals for projects in mineral bearing areas of Greece.

ABSTRACT. Introduction Antimony (Sb) is consistently included in the European Union’s (EU) list of Critical Raw Materials (CRM) since its establishment in 2011, due to its economic importance and the EU’s supply reliance on imports from third countries (European Commission, 2023). Greece is one of the EU member states that host a significant number of antimony mineralization (both occurrences and deposits that were exploited in the past), located in central-eastern Macedonia, western Thrace, the eastern Aegean Sea, and the Pelion peninsula (Stergiou et al., 2022,2023; Kanellopoulos et al., 2024). Antimony mineralization at Pelion has never been the subject of systematic research, especially compared to other Greek antimony mineralization. The aim of this study is to determine the mineralogical and geochemical characteristics of the antimony mineralization at the Mantemia and Moni Panagias sites, North Pelion, in an attempt to determine the conditions of ore deposition.

Regional Geology The Pelion peninsula consists of a HP-LT metasedimentary sequence (e.g., mica schists) of Permian-Cretaceous age, which can be subdivided into two units (i.e. the North Pelion unit and the South Pelion unit) based on dissimilarities regarding their lithology, stratigraphy and provenance (Hinshaw et al., 2024). The metamorphic rocks of North Pelion are deposited on the Permo-Carboniferous and Neoproterozoic Pelagonian basement and exhibit similar provenance history to the Cycladic Blueschist Unit (CBU) (Hinshaw et al., 2024). Magmatic intrusions of Tertiary age and porphyritic texture occur throughout the North Pelion unit, crosscutting the metamorphic rocks (IGME, 1987). Antimony mineralization occurs in the “Alikopetra” area of N. Pelion, in proximity to the contact of the HP-LT metamorphic rocks of the North Pelion unit and the marbles of the Pelagonian basement.

Methods Sixteen (16) samples were collected from two Sb-mineralization sites, namely the “Mantemia” and “Moni Panagias”, in the broad “Alikopetra” area. The mineralogical content of the samples was determined using optical microscopy, X-ray Diffraction analysis (XRD), and Scanning Electron Microscopy combined with Energy-dispersive X-ray Spectroscopy (SEM-EDS). Geochemical analyses included X-ray Fluorescence Spectroscopy (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analyses were conducted at the laboratories of the Hellenic Survey of Geology and Mineral Exploration (HSGME).

Results and Discussion The antimony mineralization at the “Mantemia” site occurs in the form of stibnite lenses within the marble, ranging in size between 2-15 cm (Fig. 2A). The ore assemblage consists of stibnite, pyrite, sphalerite and Sb-Pb sulfosalts, accompanied by the secondary Sb minerals valentinite, a mineral of the roméite group, stibiconite and senarmontite (Fig. 2B, C). Five different species of Sb-Pb sulfosalts were identified, namely zinkenite, fülöppite, plagionite, robinsonite and boulangerite (Fig. 3). Sphalerite exhibits low Fe concentrations (up to 1.65 wt.%). Pyrite has a high As content, reaching up to 10 wt% and being mostly incorporated in the rims of the crystals. Geochemical analysis yielded concentrations up to 29 wt.% Sb, 6.13 wt.% Fe, 6100 ppm Zn, 3550 ppm As, 2400 ppm Pb, 300 ppm Cu, 40 ppm Sn, 167 ppm Ga, 67 ppm Ta, 3 ppm Te and 2 ppm Ag in the ore. The hydrothermal alteration of the host-rock consists of quartz, carbonate minerals (calcite, dolomite), and muscovite. The antimony ore at “Moni Panagias” occurs in thin and discontinuous quartz veins (Fig. 2D). The ore assemblage at this site appears more diverse, consisting of stibnite, pyrite, sphalerite, arsenopyrite, cinnabar, Bi-Pb-Cu±Ag sulfosalts, (Bi-tennantite, coloradoite and tetradymite, accompanied by the same secondary Sb minerals as in “Mantemia” (Fig. 2E, F). Iron content in sphalerite reaches 2.32 wt.%, while As content in arsenic pyrite reaches 4.98 wt.%. The geochemical composition of the “Moni Panagias” ore consists of 9.10 wt.% Sb, 2.41 wt.% Fe, 7200 ppm Zn, 2240 ppm As, 160 ppm Cu, 2 ppm Ag and 2 ppm Te. The “Moni Panagias” mineralization exhibits a depletion in Pb (up to 210 ppm), Sn (up to 10 ppm), Ga (up to 7 ppm) and Ta (up to 6 ppm), and an enrichment in Bi (up to 30 ppm) compared to the “Mantemia ore”. The mineral composition of the hydrothermal alteration remains similar to “Mantemia”; however, the quartz participation is significantly higher in this location.

Fig. 2. (A) In-situ antimony mineralization at the “Mantemia” site, (B) Backscattered electron image (BSE) of pyrite and stibnite crystals from the “Mantemia” ore, (C) BSE of sphalerite, zinkenite and stibnite crystals from the “Mantemia” ore, (D) In-situ antimony mineralization at the “Moni Panagias” site, (E) BSE of stibnite, sphalerite, pyrite and quartz from the “Moni Panagias” ore (F) BSE of mineral inclusions inside a pyrite crystal, consisting of Bi-Pb-Cu±Ag sulfosalts, (Bi-)tennantite, arsenopyrite, coloradoite and tetradymite. Abbreviations (according to IMA–CNMNC 2021): Py=pyrite, Sbn=stibnite, Sp=sphalerite, Zkn=zinkenite, Qz=quartz, Tnt=tennantite, Apy=arsenopyrite, Clr=coloradoite, Ttd=tetradymite.

Fig. 3. Composition of Sb-Pb sulfosalts from “Mantemia” plotted on a Sb-Pb-As ternary diagram.

Conclusions The antimony mineralization in Pelion exhibits characteristics of an epithermal mineralization, formed due to hydrothermal activity, under relatively low temperatures and intermediate to low-sulfidation fluid states. The differences identified between the two mineralization sites can be attributed to variations of physicochemical conditions during the precipitation of the ore, such as lower fluid sulfidation states and temperatures during the precipitation of the “Moni Panagias” ore (probably due to increased neutralization and/or sulfur consumption), compared to those at “Mantemia” ores.

Acknowledgements Part of this work was funded by the European Union under the Horizon Europe grant No. 101091374 of MultiMiner project - Multi-source and Multi-scale Earth observation and Novel Machine Learning Methods for Mineral Exploration and Mine Site Monitoring.

References European Commission, Study on the Critical Raw Materials for the EU 2023 – Final Report. https://data.europa.eu/doi/10.2873/725585 Hinshaw, E.R., Stockli, D.F., and Soukis, K., 2024. Coherent underplating of HP-LT blueschist packages and basement during the Hellenic subduction recorded by zircon U-Pb data, Pelion, Greece. Journal of the Geological Society, vol. 181 (2). IGME, 1987. Geological Map of Greece, Scale 1.50,000, “Zagora‐Syki” Sheet. Institute of Geology and Mineral Exploration in Athens. Kanellopoulos, C., Sboras, S., Voudouris, P., Soukis, K., Moritz, R., 2024. Antimony's significance as a Critical Metal: The global perspective and the Greek Deposits. Minerals, 14, 121, https://doi.org/10.3390/min14020121 Stergiou, C.L., Melfos, V., Voudouris, P., Papadopoulou, L., Spry, P.G., Peytcheva, I., Dimitrova, D., Stefanova, E. 2022. A Fluid Inclusion and Critical/Rare Metal Study of epithermal Quartz-Stibnite Veins associated with the Gerakario Porphyry Deposit, northern Greece. Applied Sciences 12, 909, https://doi.org/10.3390/app12020909 Stergiou, C.L., Sakellaris, G-A., Melfos, V., Voudouris, P., Papadopoulou, L., Kantiranis, N., Skoupras, E., 2023. Mineralogy, Geochemistry and Fluid Inclusion Study of the Stibnite Vein-Type Mineralization at Rizana, Northern Greece. Geosciences, 13, 61. https://doi.org/10.3390/geosciences13020061

ABSTRACT. Highlights Coupled to magmatic degassing of metal (loid)‐ and volatile‐rich fluids, boiling, and fluid-seawater mixing mechanisms are responsible for Sb hyper-enrichment in the Kolumbo SMS mineralization. Our results raise the possibility of (sub)seafloor Sb-rich mineralization at Kolumbo and other submarine volcanoes along the 500 km of the Hellenic Volcanic Arc. Introduction / Background Antimony (Sb) is a metalloid of Critical Raw Materials (CRMs) that are both of great economic importance for the EU and of high supply risk (European Commission, 2023). Therefore, its sustainable supply greatly depends on understanding the Sb-ore precipitation mechanisms, especially stibnite (Sb2S3), the worldwide major source of Sb. A target setting to secure sustainable access to CRMs, including Sb and related metal(loid)s (Au, Ag, Ga, Ge, Te), is sea-floor massive sulfide (SMS) deposits worldwide. Recent advances in understanding Sb solubility and transportation in hydrothermal ore-fluids on land, showed mainly aqueous species of thioantimonite (H2Sb2S4) and hydroxothioantimonite [Sb2S2(OH)2], while vein-type stibnite precipitation was controlled by: boiling-related solubility reduction of H2Sb2S4, and subsequent cooling-induced solubility decrease of Sb2S2(OH)2 (Yu et al., 2023). Recently, Kodera et al. (2024), and Kaufmann et al. (2024), have suggested that hydrothermal fluid temperature decrease has been the main mechanism for stibnite precipitation in vein-type epithermal deposits on land (Slovakia). However, whether these phenomena can cause Sb mineralization (i.e., stibnite and Sb-bearing sulfosalts) in submarine hydrothermal systems, remains incompletely known. To our knowledge only Dekov et al. (2022) have dealt with the physicochemical conditions of stibnite precipitation at the Daiyon-Yonaguni Knoll (Okinawa Trough) hydrothermal barite deposits, and suggested that precipitation at ~80◦C, low log10a of Sb2S42- and Eh<0), from sub-seafloor phase separated fluids. Driven by the scarce knowledge on Sb enrichment (i.e., stibnite, Sb-sulfosalts) processes at seafloor hydrothermal conditions, we investigated the Sb-rich, polymetallic, SMS mineralization of modern CO2-degassing, SMS diffuser vents, of Kolumbo submarine volcano, Hellenic volcanic arc [hereafter “Kolumbo CO2 diffusers” (“KCO2Ds”)]. These rare actively forming Sb- and Au-rich polymetallic (As, Ag, Tl, Pb, Zn, Hg) SMS SMS deposits comprising pyrite, marcasite, sphalerite, chalcopyrite, galena, Pb-Sb sulfosalts, stibnite, orpiment/realgar and barite (Kilias et al., 2013). The KCO2Ds display a distinct mineral zonation, grading from a pyrite-dominated, barite-polymetallic sulfide inner part (ISSC), through a thin sphalerite-dominated sulfide zone, to a barite-sulfide outer layer, and finally to an orpiment-dominated exterior (OAsL) locally covered by Fe3+-(hydrated)-oxyhydroxides (SFeC) (Kilias et al. 2013). Importantly, pyrite occurs erratically within, and throughout, the KCO2Ds, and occurs as compositionally zoned colloform pyrite 1 (Py1) that is overgrown by aggregated anhedral pyrite 2 (Py2), and coarse-grained euhedral pyrite 3 (Py3) (see Fig. 1 and Kilias et al., 2022). Samples came from KCO2Ds that vent nearly pure CO2 boiling fluids at 265oC (Kilias et al., 2013; Zegkinoglou et al., 2023). Hence, the Kolumbo system represents an optimum natural laboratory to decipher the effect of boiling and cooling due to fluid-seawater mixing, on stibnite composition, and Sb hyper-enrichment associated with SMS mineralization. Materials and Methods • Sampling Sulfide samples were retrieved with Remotely Operated Vehicles (ROVs) from the northern part of the Kolumbo crater. Detailed descriptions on sampling and preparation methods are presented in Kilias et al. (2013) and in HCMR’s “SeaBioTech Report 2013”. • Optical microscopy and Mineral Analyses All samples were petrographically examined via transmitted and reflected light microscopy. The quantitative analyses of the main sulfide-sulfosalt phases were conducted by Energy Dispersive Spectroscopy (EPMA-EDS) using a JEOL JXA-8600 Superprobe. The S contents were determined by EPMA analysis. Trace element analysis was performed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) using a New Wave Research-ESI 213 nm laser unit attached to a ThermoScientific ICAP-Q quadrupole ICP-MS. Analytical precision and accuracy were monitored by the repeated analysis of FeS-1 and MASS-1 (United States Geological Survey-USGS). Trace element concentrations were processed by the Iolite software package (https://iolite-software.com). • Raman spectroscopy Raman spectroscopy was performed using a Renishaw inVia Raman confocal microscope. Spectra were obtained using the 785 nm laser and a grating of 1200 groves per mm, with a power range between 0.5 and 0.05 mW, due to the varying stability and fluorescence of the analysis spots. Samples were exposed to the laser through a long-focal distance, 50X objective lens with 0.55 numerical aperture, and with the measured spectral range extended from 100 to 3200 cm-1. The obtained spectra were then processed by the WiRE software for Windows. Background noise was reduced by the subtraction of a polynomial baseline, and cosmic ray removal corrections were performed for all spectra. • Synchrotron X‐ray fluorescence (μ‐XRF) Polished thin sections of selected representative samples were analyzed using scanning μ-XRF at the Nanoscopium hard X-ray CX3-scanning spectromicroscopy beamline of Synchrotron Soleil (France). A monochromatic X-ray beam, with an energy range of 11.8–20 keV, was focused on the sample area using a Kirkpatrick–Baez nano-focusing mirror. To achieve micrometer resolution in elemental mapping of mm²-sized sample areas, the fast-continuous scanning (FLYSCAN) technique was employed. Results • Mineralogy, textures and paragenesis of stibnite (Sb2S3) and Sb-sulfosalts Antimony phases include thin, needle-like stibnite crystals mainly in the OBL and OAsL and individual Sb-bearing sulfosalt phases, such as semseyite and meneghinite, throughout the KCO2Ds (see below and Kilias et al., 2022). Sb-bearing sulfosalts, relatively abundant in the ISSC, mostly occur as dendritic fishbone-like crystals, as intergrowths with barite rimming pyrite successions, and as overgrowths on Py1. Sb-bearing sulfosalts may also occur as colloform-like phases rimming As-sulfides, such as orpiment. Replacement of Sb-bearing sulfosalts by orpiment has also been observed, resulting in a porous and inclusion-rich (Pb-Sb sus) As-sulfide. The As-sulfide overgrowth precipitates from hydrothermal solution, indicating boiling-induced Coupled Dissolution Reprecipitation (CDR) processes. Moreover, a progressive transition of Pb-Sb sulfosalts to orpiment-like As-sulfides resembling frutexites-like microstomatolites with branching and outgrowths formed by cyclic growth has also been detected. The alternating banding consists of Pb-Sb sulfosalts progressively transitioning to orpiment-like As-sulfides. Rare stibnite occurs as independent needle-like crystals in open space, as inclusions in prismatic barite, or as intergrowths with Pb-Sb sulfosalts and orpiment of the OAsL. Stibnite has also been found as a tube-like core in orpiment filamentous structures. • Spectral characterization of Sb-bearing phases The majority of the obtained Raman spectra indicate that the dominant Sb-bearing phases in the KCO2Ds are stibnite (Sb2S3) and semseyite (Pb9Sb8S21). Stibnite exhibits sharp, characteristic Raman peaks, with decreasing intensity, at 312, 283, 240, 192, 156 and 129 cm-1. Semseyite, presents a dominant Raman peak at 217 cm-1, with a broad shoulder at 176 cm-1. Raman peaks of lesser intensity are present at 335, and 120 cm-1. A less abundant, Sb-bearing sulfosalt that has been identified through Raman spectroscopy is meneghinite (Pb13CuSb7S24), presenting a dominant Raman peak at 212 cm-1 with a shouldering peak at 248 cm-1, and a secondary but intense peak at 328 cm-1. • Mineral chemistry and Sb enrichment (LA-ICP-MS) LA-ICP-MS spot analyses show a unique enrichment in Sb in all the mineral phases present at the KCO2Ds. Galena exhibits a strong Sb enrichment with maximum concentration of 98000 ppm. Py1 is the most common sulfide mineral in the system and displays high Sb concentrations, up to 111192 ppm. The concentration of Sb in Py2 reaches up to 36100 ppm, whereas Py3 is the most depleted generation of pyrite, with maximum concentration of 79000. Sphalerite is also highly enriched in Sb concentration, reaching up to 98000 ppm. Marcasite and chalcopyrite are moderately enriched in Sb ranging up to 7730 ppm, and 16100 ppm, respectively. Lastly, the Sb concentration in orpiment is measured up to 16100 ppm. To better understand the sequestration of trace metals and especially Sb, in the main mineral phases, LA-ICP-MS depth profiles were thoroughly examined. The smooth parts of LA-ICP-MS time resolved spectra indicate structurally bound metal(loid)s while the irregular and spiky parts of the profiles signify the presence of micro/nanoparticles in the structure (George et al., 2019). The LA-ICP-MS depth profiles in stibnite display irregular parts for most trace elements (Zn, Ag, Au, Tl) implying that these elements are incorporated as nanoparticles in the structure of stibnite. The depth profiles for Sb in pyrite exhibit both smooth and spiky parts indicating that Sb precipitates both as nanoparticles along with other metal(loid)s and as lattice bounded in the structure of pyrite. Pb-Sb sulfosalts depth profiles appear spiky with respect to As, Cu, Ag, Zn and Au suggesting the incorporation of those metal(loid)s as inclusions. • Synchrotron X‐ray fluorescence (μ‐XRF) Multi-scale length elemental maps on Py1 demonstrate that metal(loids) do not exhibit a homogeneous distribution, but rather a concentric chemical zoning. Elements such as Fe and Pb exhibit oscillatory chemical zoning at the inner part of the pyrite, whereas Zn, Cu, and As tend to enrich the outer zones of the crystal. Antimony, on the other hand demonstrates oscillatory zoning rimwards. Core-to-rim traverse on Py1 indicates that the Sb, Pb and Tl concentrations have been affected predominately by boiling processes. The spatial distribution of Sb/Pb ratios with values less than 0.5, which are characteristic of boiling-induced precipitation (Falkenberg et al., 2021) demonstrate an alternation of boiling-dominated, and likely seawater mixing-dominated regions, that coincide with the oscillatory chemical zoning of Sb. Discussion and Conclusions Kolumbo is a submarine arc volcano that hosts a complex and dynamic magmatic-hydrothermal system with constantly evolving fluid chemistry through space and time (Zegkinoglou et al., 2023; Patten et al., 2024; Hector et al., 2024. Geochemical and micro-textural evidence shows that the Kolumbo SMS mineralization has been formed by fluids undergoing multiple recurrent intense boiling and/or flashing or gentle and/or non-boiling events; moreover, the high contents of Sb, along with As, Hg, and Tl in the KCO2 Ds support boiling and zone refining processes, as these metal(loid)s are easily mobilized in the vapor phase (see Zegkinoglou et al., 2023). The Kolumbo pyrite has recorded critical information related to boiling vs. non-boiling: The features displayed by Py1(±Py2) that occurs erratically distributed within the KCO2Ds, reflect multiple episodes of vigorous boiling to flashing, whereas Py2 that occurs mostly in the inner KCO2D parts, it is spatially concurrent with chalcopyrite lining narrow channels, has features that suggest precipitation from hot (>250°C) gently boiling to non-boiling fluids (Zegkinoglou et al., 2023). Thus, pyrite can provide key information for the interpretation of associated Sb mineralization (stibnite, semseyite and meneghinite) forming conditions, and conditions of Sb incorporation in pyrite, during the 3-stage KCO2Ds growth model (Berkenbosch et al., 2012; Zegkinoglou et al., 2023; Roman et al., 2019; Falkenberg et al., 2021). Vigorous boiling events have coincided with periods of intense magmatic degassing of volatiles and metal(loid)s (i.e., Cu, Au, Sb), and increase of the proportion of magmatic fluids into the Kolumbo hydrothermal system. In addition, the evolving Kolumbo magmatic-hydrothermal system could include periods of magmatic quiescence that results in a seawater-dominated hydrothermal fluid (Zegkinoglou et al., 2023; Hector et al., 2024). At Kolumbo, textural and chemical variations of multiple pyrite (colloform, microcrystalline, crustiform banding, euhedral), chalcopyrite (linings), Pb-Sb sulfosalt (semseyite, meneghinite) (dendrites, colloform and subhedral crystals) generations, are indicative for sulfide-sulfosalt precipitation during repeated cycles of progression from a young low-temperature <150–200oC) seawater-dominated, to a more “refined” system with a higher temperature (up to 300-350oC) upwelling of phase separated liquid-, or vapor-, dominated fluid flux and less seawater mixing (Falkenberg et al., 2021). The close association of dendritic semseyite (Pb9Sb8S21), with adjacent concentrically layered colloform Py1, and anhedral sphalerite, occupying pore space of the Stage 1 barite substrate, suggests an early semseyite formation due to rapid precipitation and undercooling at temperatures <150–200oC, due to mixing of upwelling boiling, liquid- or vapor-dominated fluids, with seawater, in seawater-dominated inner KCO2Ds (ISSC) zones (Berkenbosch et al., 2012; Falkenberg et al., 2021). In addition, semseyite that is interbanded with barite layers associated with colloform-crustiform banded Py1, suggests that semseyite was synchronous with the development of barite and Py banding, and resulted from rapid precipitation due to boiled off hydrothermal fluid-seawater mixing-cooling cycles (Berkenbosch et al., 2012; Roman et al., 2019). Similarly, semseyite associated with orpiment [highly enriched in Sb (≤1.23 wt%)-unpublished data)], on the outer chimney wall (OBL, OAsL), indicates a genetic linkage to low-temperature (≤100 °C) As and Sb-rich boiled off vapor input and vapor-seawater mixing (Dekov et al., 2013). The replacement and recrystallization of massive, or stromatolite-like, semseyite to colloform As-sulfides (i.e., orpiment) probably represent a low-temperature (100 to 150oC) overprint and coupled dissolution and reprecipitation (CDR) processes based on zone refining (Berkenbosch et al., 2012; Falkenberg et al., 2021). The trace element incorporation mechanisms in the Kolumbo stibnite, semseyite, and pyrite, also depends on variable degrees of fluid-seawater mixing and fluid boiling precipitation. For example, intensity spikes in time-integrated LA-ICP-MS spectra are likely related to microscale polymetallic inclusions in stibnite and semseyite. Such inclusions may well reflect hydrothermal fluid supersaturation in Cu, Ag, Sb, and Pb, caused either by abrupt cooling because of abundant fluid-seawater mixing, or boiling that caused destabilization of metal(loid) complexes (Falkenberg et al., 2021). These notions are supported by chemically zoned Py1 spheroids that exhibit low Sb/Pb and Tl/Pb ratios, and decoupled zoning between trace metal(loids), indicating boiling-induced precipitation. In this paper, we have documented that additional to magmatic volatile degassing, boiling- and seawater mixing-induced processes, may be responsible for hyper-enrichment of Sb in the Kolumbo SMS mineralization. Acknowledgements We thank Daniel Smith (University of Leicester) and Manuel Keith (Friedrich-Alexander-Universitat) for their assistance in the LA-ICP-MS analyses. References Berkenbosch H. A., de Ronde C. E. J., Gemmell J. B., McNeill A. W., Goemann K., 2012. Mineralogy and Formation of Black Smoker Chimneys from Brothers Submarine Volcano, Kermadec Arc. Economic Geology 107, 1613–1633. Falkenberg, J.J., Keith, M., Haase, K.M., Bach, W., Klemd, R., Strauss, H., Yeo, I.A., Rubin, K.H., Storch, B., Anderson, M.O., 2021. Effects of fluid boiling on Au and volatile element enrichment in submarine arc-related hydrothermal systems. Geochimica et Cosmochimica Acta 307, 105-132. Hector, S., Patten, C.G., Beranoaguirre, A., Lanari, P., Kilias, S., Nomikou, P., Peillod, A., Eiche, E., Kolb, J., 2024. Magmatic evolution of the Kolumbo submarine volcano and its implication to seafloor massive sulfide formation. Mineralium Deposita 59, 1229-1248. George, L.L., Biagioni, C., Lepore, G.O., Lacalamita, M., Agrosi, G., Capitani, G.C., Bonaccorsi, E., d’Acapito, F., 2019 The speciation of thallium on (Tl,Sb,As)-rich pyrite. Ore Geology Reviews 107, 364-380. Kaufmann, A.B., Lazarov, M., Weyer, S., Števko, M., Kiefer, S., Majzlan, J., 2024. Changes in antimony isotopic composition as a tracer of hydrothermal fluid evolution at the Sb deposits in Pezinok (Slovakia). Mineralium Deposita 59(3), 559-575. Koděra, P., Mathur, R., Zhai, D., Milovský, R., Bačo, P. and Majzlan, J., 2024. Coupled antimony and sulfur isotopic composition of stibnite as a window to the origin of Sb mineralization in epithermal systems (examples from the Kremnica and Zlatá Baňa deposits, Slovakia). Mineralium Deposita, pp.1-17. Patten, C.G.C., Hector, S., Kilias, S., Ulrich, M., Peillod, A., Beranoaguirre, A., Nomikou, P., Eiche, E., Kolb, J., 2024. Transfer of sulfur and chalcophile metals via sulfide-volatile compound drops in the Christiana-Santorini-Kolumbo volcanic field. Nature Communications, 15(1), 4968. Roman N., Reich M., Leisen M., Morata D., Barra F., Deditius A. P., 2019. Geochemical and micro-textural fingerprints of boiling in pyrite. Geochimica et Cosmochimica Acta 246, 60–85. Yu, H.C., Qiu, K.F., Simon, A.C., Wang, D., Mathur, R., Wan, R.Q., Jiang, X.Y., Deng, J., 2023. Telescoped boiling and cooling mechanisms triggered hydrothermal stibnite precipitation: Insights from the world’s largest antimony deposit in Xikuangshan China. American Mineralogist, 108(7), 1213-1223. Zegkinoglou, N.N., Ryan, M., Kilias, S.P., Godfrey, L., Pletsas, V., Nomikou, P., Zaronikola, N., 2023, Boiling-induced extreme Cu isotope fractionation in sulfide minerals forming by active hydrothermal diffusers at the Aegean Kolumbo volcano: Evidence from in situ isotope analysis. Geology 51,1072–1076.

ABSTRACT. Evaluation of PAHs sorption behavior in coals and cokes

Georgaki M. 1, Karapanagioti H.K.2, Wojtaszek-Kalaitzidi M.3, Kalaitzidis S.1*

(1) Department of Geology, University of Patras, Rio-Patras, GR 265 04, Greece, skalait@upatras.gr (2) Department of Chemistry, University of Patras, Rio-Patras, GR 265 04, Greece (3) Institute of Energy and Fuel Processing Technology, 1 Zamkowa Street, Zabrze, Poland

Research Highlights This study investigates the sorption behavior of phenanthrene in coals and cokes, highlighting the influence of coal rank and maceral composition on phenanthrene sorption capacity. Introduction / Background Organic petrography has become an important tool in environmental research, particularly in studying the sorption capacities of polycyclic aromatic hydrocarbons (PAHs) in various types of coal (e.g., Ligouis et al., 2005; Kalaitzidis et al., 2006; Yan et al., 2011). This is important as it provides insights into the interactions between PAHs and organic matter, which are critical for predicting the behavior and environmental fate of these pollutants in natural systems. PAHs refer to a broader category of harmful and toxic organic pollutants widely distributed in nature (Van der Oost et al., 2003; White et al., 2016; Patel et al., 2020). Some of these compounds can be mutagenic or carcinogenic in living organisms, leading to their classification as priority pollutants (ATSDR, 1995). Phenanthrene (C14Η10) belongs to PAHs and is a hydrophobic organic pollutant, due to its potential toxicity to humans and other living organisms, as well as its prevalence and persistence in the environment (Hussar et al., 2012). It is commonly used in sorption studies as a model organic chemical and is also used in this study. Previous studies showed that the sorption of phenanthrene in low-rank coals is controlled, among others, through the inertinite content (e.g. Kalaitzidis et al., 2006). Objectives In the current study, the sorption behavior of phenanthrene in a series of various rank coals such as lignite, bituminous coals, semi-anthracite and anthracite, as well as naturally coked coals and industrial cokes, is examined (Figure 1). The rank series represents a wide range of coal basins and coal-forming periods, ranging from Gondwana coals from Australia and South Africa, Laurasian coals from China and Poland, and Neogene lignite from the Czech Republic, thus demonstrating variable physical and chemical characteristics and most importantly, maceral contents (Table 1). The main purpose of this study is to evaluate the impact of coal rank upon sorption attributes, but also to test the hypothesis that sorption will increase proportionally to carbonized material (e.g. inertinite content) in higher-rank coals, as it was observed for low-rank coals (Kalaitzidis et al., 2006). Methods In total twenty-two samples were analyzed, comprising lignite (ERT_3,_4), bituminous coal (ERT_5,_6,_7,_10,_11, _12,_13,_14,_15,_16), anthracite (ERT_1,_2,_8,_9), naturally coked coals (ERT_18,_19) and industrial cokes (ERT_17,_20,_21,_22). On the representative samples proximate, ultimate and petrographical analyses were conducted. Proximate analysis was performed according to ASTM (D3174; D3175; D3302, 2004). Ultimate analysis was carried out using a Carlo Erba EAGER 200 Automatic Analyzer according to ASTM D5373, 2004. Maceral analysis was performed according to ISO 7404-3 (2009) using a Leica DMRX coal-petrography microscope (ICCP, 1998, 2001; Sýkorová et al., 2005; ASTM D5061, 2007; Pickel et al., 2017). Vitrinite reflectance (Ro%) and bireflectance (Rbi%) were measured according to ISO 7404-5 (2009) using Leica MPV/SP spectral photometer and AxioImager M1m/Zeiss+MSP 400 Spectrophotometer. Additionally, all samples were tested for their sorption capacity in batch triplicate reactors at the same initial phenanthrene concentration (Co) of 250 μg/L. Based on the sorption and petrographical analysis results, nine samples were selected for further sorption experiments of phenanthrene at concentrations (Co), ranging from 20 to 200 μg/L (Kleineidam et al., 1999; Karapanagioti and Sabatini, 2000; Karapanagioti et al., 2001), as well as for BET analysis. The surface area, pore volume and pore size distribution of selected samples were determined by nitrogen gas (N2) adsorption-desorption with the Tristar 3000 Analyzer (Micrometrics® GA, USA) using the Brunauer, Emmett, and Teller (BET) equation, at the Laboratory of Heterogeneous Catalysis, Department of Chemistry of the University of Patras. Results and Discussion Proximate analysis determines that the moisture varies from 0.7 to 10.0 wt% (on an as-received basis). The ash yield shows a high variability with values ranging from 2.5 to 64.8 wt% (db). The volatile matter yields vary from 2.9 to 58.8 wt% (daf). The carbon content of the samples ranges from 59 to 95 wt% (daf). Hydrogen and nitrogen fluctuate from 0.3 to 6.2 wt% and 1.1 to 2.3 wt% (daf), respectively. Sulfur content varies from 0.1 to 3.9 wt% (daf). Table 1. Samples characteristic, rank, results of proximate and ultimate analyses, vitrinite reflectance and bireflectance. Sample Location Ash VM Ro% Rank (wt.%, db) (wt.%, daf) ERT_1 South Africa 14.2 11.3 2.31 Anthracite C ERT_2 China 12.8 10.6 3.37 Anthracite B ERT_3 Germany 2.5 58.8 0.32 Lignite B ERT_4 Czech 2.6 54.4 0.30 Lignite B ERT_5 Australia 22.2 31.5 0.73 Bituminous C ERT_6 Australia 11.6 21.7 1.28 Bituminous B ERT_7 Australia 16.6 20.5 1.52 Bituminous A ERT_8 Australia 10.1 8.6 4.38 Anthracite A ERT_9 Australia 12.1 10.9 4.63 Anthracite A ERT_10 Australia 5.3 24.0 1.20 Bituminous B ERT_11 Australia 7.0 18.2 1.61 Bituminous A ERT_12 Australia 47.4 17.4 1.90 Bituminous A ERT_13 Australia 5.4 19.8 1.20 Bituminous B ERT_14 Poland 9.6 29.4 1.11 Bituminous B ERT_15 Poland 6.0 36.8 0.87 Bituminous C ERT_16 Poland 7.8 25.5 1.25 Bituminous B Rbi% ERT_17 Australia 12.0 6.3 5.52 Coke ERT_18 Australia 64.8 18.6 4.75 Coked coal ERT_19 Australia 64.6 15.8 3.70 Coked coal ERT_20 Poland 11.0 2.9 4.72 Coke ERT_21 Poland 13.0 4.1 1.43 Coke ERT_22 Poland 12.1 3.0 4.89 Coke VM: volatile matter; Ro%: vitrinite reflectance; Rbi%: bireflectance; ar: as-received basis; db: dry basis; daf: dry, ash-free basis. The petrographical analysis indicates that huminite is the dominant maceral group in the lignite samples ranging from 85.6 to 92.6 vol%, on an organic matter basis. Vitrinite is the dominant maceral in the bituminous coal and anthracite samples, ranging from 56.9 to 100 vol%, where two of them (ERT_8,9) were anthracite A with 100 vol% vitrinite. Inertinite content in lignite samples is generally low (<9 vol%), while in bituminous coal and anthracite, it ranges from 3.3 to 40.7 vol%. Liptinite content is up to 10.6 in lignite and bituminous coal samples. Naturally coked and coke samples were dominated by binder phase (69.6-95.0 vol%) and less filler phase (5.0-30.0 vol%). The phenanthrene sorption distribution coefficient (Kd, Kd = qe × Ce-1) at the same initial phenanthrene concentration (Co) of 250 μg/L ranges from 1,024 to 37,329 L/Kg, with samples ERT_14 and ERT_1 displaying the lowest and the highest values, respectively. Of the 9 samples selected for further sorption experiments, samples ERT_3, ERT_18, and ERT_19 show the highest sorption capacity at both high (Co=180 μg/L) and low concentrations (Co=15 μg/L). Anthracite (ERT_1) exhibited nonlinear sorption behavior (Freundlich exponent N > 1), while bituminous coals (ERT_6, _11, _14 _15, _16), showed a correlation between inertinite content and sorption nonlinearity (N < 1). Coke samples (ERT_18, _19) displayed the highest organic carbon-normalized sorption capacity (Koc, Koc = Kd × foc−1) at low phenanthrene concentrations. The BET analysis reveals that the surface areas vary from 1.0 to 41.2 m2/g. Pore volume ranges from 0.0056 to 0.062 cm3/g. Samples ERT_18 and ERT_19 with high surface area also exhibit high pore volume. The pore size ranges from 62 to 303 Å. Considering the above, the sorption behavior seems to be affected by the coal rank, except for the lignite (ERT_3) sample. However, if the organic carbon content is considered, it follows the same pattern observed in a previous study (Kalaitzidis et al., 2006), which found a positive correlation between inertinite content and Koc, indicating that as inertinite content increases, sorption capacity also increases.

Figure 1. Photomicrographs of selected samples; a) ERT_14 bituminous B coal, V: vitrinite, Sf: semifusinite, L: liptinite, I: inertinite; b) optical texture of coke sample ERT_20; c) view of inertinite in naturally coked coal ERT_19; d) view of naturally coked coal sample ERT_18.

Conclusions The anthracite (ERT_1) exhibited the highest sorption capacity (Kd) from all samples, but also its behavior was totally different from the rest samples. Anthracite had a nonlinear Freundlich exponent (N) higher than 1, which suggests that the more the sorbed phenanthrene the higher the affinity of the sorbent for phenanthrene. Bituminous coals (ERT_6, _11, _14 _15, _16) sorption behavior seemed to be affected by the inertinite content in terms of their nonlinearity (N<1); nonlinearity increases (N decreases) with increasing inertinite amount. The two coke samples (ERT_18, _19) demonstrated the highest sorption affinity (Koc); which is the sorption capacity normalized for the fraction of organic carbon content for phenanthrene at low concentrations. Acknowledgments The authors would like to thank Ms. Vasiliki Kostopoulou and Mr. Dimitrios Bampagenes for conducting laboratory experiments. Dr. Dimitrios Vachliotis, Laboratory of Instrumental Analysis, Faculty of Sciences, University of Patras, is also acknowledged for performing the Carlo Erba analysis. References Agency for Toxic Substances and Disease Registry (ATSDR), 1995. Toxicological profile for Polycyclic Aromatic Hydrocarbons (PAHs). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. American Society for Testing and Materials (ASTM) D3174, 2004. Standard Method for Ash in the Analysis Sample of Coal and Coke from Coal. 2004 Annual Book of ASTM Standards, Gaseous Fuels; Coal and Coke, vol. 05. ASTM, Philadelphia, PA, pp. 322–326 06. American Society for Testing and Materials (ASTM) D3175, 2004. Standard Method for Volatile Matter in the Analysis Sample of Coal and Coke. 2004 Annual Book of ASTM Standards, Gaseous Fuels; Coal and Coke, vol. 05. ASTM, Philadelphia, PA, pp. 327–330 06. American Society for Testing and Materials (ASTM) D3302, 2004. 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Journal of hazardous materials, 192(1), 86-92. .

ABSTRACT. This study investigates the tephrochronology of the Nisyros volcano within the South Aegean Active Volcanic Arc (SAAVA), emphasizing its potential volcanic hazard to surrounding regions, including southwestern Türkiye. The six newly identified outcrops of medial Nisyros tephra on Datça Peninsula, specifically the Kyra unit, have been dated to 133.5 ± 3.4 ka, refining the Nisyros tephrostratigraphy. These findings highlight the importance of identifying and dating pre-caldera medial tephra deposits to better assess eruption frequency and volcanic risk associated with Kos-Nisyros-Yali volcanic system.

ABSTRACT. The Aegean Sea (Greece), in its present configuration, was formed as a response to the retreat of the Hellenic subduction zone, a retreat that was accelerated since the Middle Miocene, leading to the exhumation of lower and middle crustal rocks that were previously subducted to great depths. Active faulting is restricted along narrow zones with strike-slip and oblique-normal sense of motion, where shallow-intermediate depth seismicity also manifests. The Attic Cycladic Crystalline Complex is one such area where the central part is generally aseismic, and major active faults and earthquake activity are located along the north and especially the southern margin, where the modern volcanic arc has been established since the Pliocene. At the southeastern margin, the Santorini – Amorgos basin is characterized by NE-SW faults creating a complex horst and graben pattern with sediments exceeding 1000m in thickness. From January to March 2025, swarm-type earthquakes of magnitudes in the range 1≤M≤5.2 were recorded, having epicenters at depths mainly from 15 km up to 4 km concentrated along a narrow zone extending offshore Santorini near the Columbo volcanic center towards NE, south of Amorgos Island. Whether this sequence could result just from tectonic forces or the combined effect of tectonic forces and magmatic activity is debated. In this paper, we investigate the structural evolution of the region by virtue of a numerical model, starting from a pure continuum brittle crust due to combined tectonic forces and magmatism. Given that the studied region of the south Cyclades plateau is a major volcanic center and driven from knowledge of hydraulic fracturing processes in deep reservoirs, we examine the hypothesis that the swarm-type of earthquakes is that of magma injections in chambers or dykes lying along this narrow zone. 

ABSTRACT. Recent seismic activity in the Santorini region has attracted global attention and raised concerns about ongoing volcanic hazards. Santorini, a large volcanic caldera featuring the central islets of Nea Kameni and Palea Kameni, has a complex eruptive history spanning approximately 650,000 years, including the catastrophic eruption (~1560 B.C.) linked to the decline of the Minoan civilization. Since 27 January 2025, the region has experienced a major seismic crisis, with over 2,000 earthquakes recorded, including 14 events with magnitudes ≥5.0 and a maximum magnitude of 5.3. Seismicity has been concentrated approximately 25 km northeast of Santorini and 25 km southwest of Amorgos. We present the results of two geochemical surveys conducted between March and April 2025, involving water sampling from 10 wells, measurements of soil CO₂ fluxes and ¹³C-CO₂ values in Santorini and Nea Kameni, as well as sampling of fumarolic gases at Nea Kameni and bubbling gases at Palea Kameni. These data provide a preliminary assessment of the current degassing dynamics of the area. Comparison and integration with existing literature indicate that the post-seismic volcanic phase following the January–February 2025 seismic crisis is marked by an increased degassing rate in the Nea Kameni region. However, the chemical and isotopic compositions of the gases (³He/4He and ¹³C values) exhibit only minor variations relative to pre-crisis measurements reported in previous studies. Although preliminary, these findings underscore the critical need for continuous monitoring of the Santorini volcanic system, in order to deliver timely and reliable information to the local community and to support effective volcanic risk mitigation strategies.

ABSTRACT. Foreshocks, aftershocks and swarms are the most common types of space-time seismicity clusters (Mogi, 1963). The real-time discrimination between foreshocks and other types of clusters is of great importance for the short-term hazard assessment but it is a challenging issue. Therefore, only a posteriori solutions have been proposed. During January-March 2025 a space-time seismicity cluster was recorded between Santorini and Amorgos islands, South Aegean, with the largest earthquake (ML=5.3) occurring on 10 February 2025. This case offered a good opportunity to decipher the type of the ongoing seismic cluster based on the daily re-evaluation of the seismicity state. We utilized tools from the earthquake statistics and the complex networks theory and were able to discriminate beforehand the foreshock-aftershock nature of the ongoing cluster. Our findings were documented on time with internal reports as well as with public reports and statements.

ABSTRACT. Highlights The seismic swarm that stroke northeast of Santorini Island (Greece) in February 2025 highlights the critical need to assess tsunami hazards in this historically vulnerable region. Using Okada's model for seafloor displacement and subsequent tsunami simulations, we discuss hypothetical tsunamis from shallow normal faults identified in the area of the recent swarm. Our simulations suggest that a potential tsunami could impact the eastern coast of Santorini in as little as 6 minutes and reach the surrounding islands within 25 minutes. For a magnitude 6.3 earthquake, heights along nearby coastlines could range from 0.1 to 0.3 meters, with localized amplification possible in closed bays. Based on these scenarios, we propose a strategic placing of tide gauges at Agios Nikolaos Port (Anafi) and Agios Andreas (Astypalaia) to enhance tsunami detection and improve regional early warning capabilities.

Context A volcano-tectonic unrest has been active since late 2024 in the surrounding area of the Santorini volcano, in the Aegean Sea (Greece), peaking with a significant seismic swarm during the first half of February 2025, along a fault zone that ranges between the Santorini and Amorgos islands. This region is characterized by both significant volcanic and seismic hazards, as it lies along the volcanic arc associated with the Hellenic subduction zone and an active rift likely related to the Anatolian extrusion. Historically, the area has experienced destructive tsunamis, notably a volcanic-induced event after the Minoan eruption at Santorini around 1600 BC (McCoy and Heiken, 2000; Friedrich et al., 2006; Manning et al., 2006; Goodman-Tchernov et al., 2009) and an earthquake-triggered tsunami after the 9 July 1956 earthquake along the eastern coast of Amorgos (Galanopoulos, 1957; Ambraseys, 1960; Okal et al., 2009; Leclerc et al., 2024). The 2025 seismic crisis has been occurring in the southwestern continuity of the 1956 earthquake zone, underlining the need for a reevaluation of the seismic and tsunamigenic hazards in the area.

Potential for seismic rupture The seismic crisis initially began in September 2024 within the Santorini caldera, then migrated northeast of the island from 27 January 2025. Throughout February 2025, approximately 200 earthquakes with magnitudes Mω ≥ 4.0 and 13 events with Mω ≥ 5.0 were recorded. At the time of writing (March 2025), the seismic activity has been slowing down, with yet recurrent earthquakes exceeding magnitude Mω ≥ 4.0. With geodetic calculations indicating lower crustal aseismic slip of an equivalent seismic moment of 2×1019 N·m, i.e., over an order of magnitude greater than the cumulated seismic moment, the possibility of a stronger earthquake triggered by aseismic loading of the upper crust cannot be ruled out. Should such an event occur on a shallow fault, it would likely generate a tsunami. This study investigates such a scenario, assuming a shallow earthquake on a ~14 km long, 9 km wide fault inclined at 60°, with 0.8 m of slip, corresponding to a typical earthquake of magnitude Mω = 6.3. We consider two candidate faults from the NOAfaults1 database (Table 1). The focal mechanism of a hypothetical rupture on the Anhydros Fault (GR3219) is illustrated in Figure 1 (MODEL1).

Table 1. Characteristics of the two candidate faults considered. Fault Code Name Length Width Centroid (°E, °N, Depth) Azimuth Dip Slip Type GR3219 Anhydros Fault 14.6 km 9 km 25.71, 36.52, 7 km N045° 60° NW Pure normal GR3222 SAF-SW Branch 13.5 km 9 km 25.55, 36.58, 7 km N222° 60° SE Pure normal

Figure 1. Focal mechanism of a hypothetical rupture on the Anhydros Fault (GR3219): N045°, 60°NW, pure normal slip. Surface traces of faults GR3219 (NW) and GR3222 (SE) are represented in grey.

Tsunami simulations We use Okada’s equations (Okada, 1985) to calculate the seafloor displacement induced by potential ruptures on these faults. The Glimsdal transfer equation (Glimsdal et al., 2013) is then applied to evaluate the initial water surface deformation. Finally, tsunami propagation is modelled using the Taitoko code, developed by the Commissariat à l’Énergie Atomique (CEA, France), based on shallow-water wave equations (Heinrich et al., 2021; Heinrich et al., 2024). These calculations use bathymetric data from the European Marine Observation and Data Network (EMODnet), with a grid resolution of 110 meters. Figure 2 illustrates the initial water surface displacement for an instantaneous and homogeneous normal slip of 80 cm on fault GR3222, with its upper edge located at 3 km depth (MODEL1).

Figure 2. Initial water displacement for 80 cm homogenous normal slip stopping at 3 km depth on fault GR3222. Surface projection of the rupture patch is represented with a rectangle. A potential rupture area on fault GR3219 is also drawn (to the NW).

Figure 3 shows the wave position after 10 minutes of propagation for the same model. One of the key results of our simulations is that, if an earthquake were to occur in the zone of unrest, the first wave would reach: the eastern coast of Santorini in 6 to 15 minutes, depending on the fault location and dip direction; Agios Nikolaos Port (Anafi Island) in 11 to 16 minutes; Katapola Port (Amorgos Island) in 20 to 25 minutes; Chora Port (Ios Island) in 22 to 27 minutes.

Figure 3. Location of the wave after 10 minutes for the scenario of a rupture with an 80 cm normal slip stopping at 3 km depth on fault GR3222 (MODEL1). The locations of the main harbors are indicated.

Figure 4 presents these arrival times for key ports and coastal areas for the rupture of MODEL1. These short arrival times emphasize the critical need for early anticipation to ensure an effective response for at-risk populations. According to our simulations, a tsunami generated by ruptures like MODEL1 would produce wave heights between 0.1 and 0.3 m along the coastlines of nearby islands. The precise wave height depends on the depth and location of the rupture. While these heights may seem moderate, they represent a significant volume of displaced water and high wave energy upon coastal impact, as observed in Samos in 2020 (Kalligeris et al., 2022), with potential risks to people and infrastructure. Due to their geomorphological configuration, bays and inlets are particularly vulnerable to wave amplification, making coastal flooding highly likely in the most pessimistic scenarios. Figure 4. Arrival times at nearby harbors relative to the earthquake origin time for MODEL1 (fault GR3222).

As illustrated in Figure 5, water movement in Chora Bay (Ios Island) varies significantly under different rupture depth, fault position, and dip direction scenarios: GR3219: Northwest dip, fault southwest of Anhydros Island. GR3222: Southeast dip, fault south of Anhydros Island. The upper edge of the rupture is tested at 1 km, 3 km, and 5 km depth. Figure 5: 1-hour water oscillations in Chora Bay (Ios) for two faults and three upper rupture depths.

Our simulations indicate that, in this case, the rupture location is the primary factor influencing both wave arrival times and wave attenuation or amplification, depending on interactions with headlands, islands, or underwater obstacles. For instance, shifting the hypocenter 15 km north significantly reduces the wave amplitude reaching Chora Bay (Figure 5). Unlike lower-magnitude earthquakes, whose effects are quickly dampened by upper-crustal layers, the depth of the upper fault edge appears to play a secondary role, provided it remains within realistic values for the region. As shown in Figure 5, variations in depth have a negligible impact on tsunami amplitude, with a maximum discrepancy of only a few centimeters. The azimuth and dip angle of the fault also have limited influence on tsunami morphology, as any normal fault generates an initial water surface depression with a relatively consistent shape. This is confirmed by tests made using the same fault location but opposite fault dips. In response to recent tsunami events, studies that used local high-resolution bathymetric data digitized from nautical charts demonstrated that incorporating finer (e.g., ~10 m pixel resolution) bathymetric grids into models significantly modifies tsunami waveforms, potentially doubling temporary wave amplitudes at the coastline (Zahradník et al., 2022; Alfonsi et al., 2024). It is therefore highly problematic that, despite the existence of numerous high-resolution bathymetric datasets in the Aegean Sea, none are freely accessible. This situation introduces significant reliability issues for tsunami modelling and poses a critical risk to civil safety, as emergency preparedness scenarios may be underestimated, leading to inadequate hazard assessment. It should also be noted that environmental factors, such as tidal conditions and atmospheric pressure, can intensify the impact of tsunamis. These key parameters call for continuous monitoring of sea level heights and coastal subsidence in the region. In this framework, as part of the ongoing GNSS deployment to monitor, among others, the Santorini magma chamber inflation, a priority should be given to co-located GNSS and tide gauge stations.

Comparison with the 1956 Amorgos Tsunami On 9 July 1956, a magnitude Mω = 7.1–7.8 earthquake struck south of Amorgos Island, just a few dozen kilometers north of the current seismic swarm (Lee and Engdahl, 2015). This event generated an exceptionally large tsunami, with waves reaching up to 20 meters in height in Astypalaia, causing 3 direct fatalities on Kalimnos Island and several injuries and severe coastal damage in the nearby islands (Ambraseys, 1960). For a long time, the unusual size of this tsunami was attributed to a submarine landslide (Galanopoulos, 1957; Okal et al., 2009), which was believed to have displaced a large volume of water, producing a wave of exceptional intensity. However, recent studies have failed to find clear evidence of such a landslide, shifting the focus to the hypothesis of a co-seismic displacement of approximately 10 meters as the primary cause (Leclerc et al., 2024). Given the steep submarine slopes in the region, which show evidence of past landslides, a similar scenario cannot be ruled out for the ongoing seismic crisis, potentially leading to a much stronger tsunami. This study does not specifically address this less likely hypothesis. Recommended tide gauge locations for a useful monitoring of future tsunamis Based on our simulations, closed bays such as the Santorini Caldera, where sub-meter amplitude waves either do not arrive or arrive with a significant delay, should be avoided. Instead, we recommend the maintenance and continuity of instruments on the east coast of Santorini (e.g., NOA-99), where waves arrive quickly with minimal interference or attenuation. Our results highlight the need for more tide gauges in the region, to monitor water movements in the event of a tsunami, to better constrain climate-change-induced sea level rise, and, ideally, to provide early warning if the gauges are positioned at strategic locations along possible wave paths. High-frequency sampling (~1 Hz) is advised to ensure a rapid and accurate tsunami alert. In the framework of the current instrumentation of the Santorini region, we suggest two more locations for additional tide gauge installation: Port of Agios Nikolaos, on the island of Anafi. This harbor appears to be a strategic location for early warning. Simulations show that waves always reach it quickly due to the deep waters offshore. It is not located in an enclosed bay, and the coastline is relatively smooth, minimizing the effects of wave interference. From a broader regional perspective, southern Anafi is an optimal monitoring site as it would be among the first coasts to be hit by a tsunami arriving from the south, particularly likely given the seismic hazard in Crete, which hosts both the Hellenic subduction zone and active normal faults. Port of Agios Andreas, on the north coast of the island of Astypalaia. Given the high amplitude of the waves that reached this coast after the 1956 earthquake (Ambraseys, 1960), the harbor of Agios Andreas, on the north coast of Astypalaia, appears as a suitable location for studying large-scale wave propagation in the region.

Conclusions The possibility of a tsunami triggered by volcanic or seismic events in the highly active southern Aegean Sea is significant and must be taken into account. Local populations and tourists should be adequately prepared, particularly by being informed about potential wave propagation scenarios resulting from such events. Civil protection authorities should also be ready to issue tsunami alerts rapidly. Accurate knowledge of wave trajectories and arrival times is crucial for enhancing preparedness and improving tsunami early warning protocols. Tsunami wave modelling allows for identifying the most suitable observation sites, whether for post-event analysis to understand tsunami processes or for real-time monitoring to support early warning systems. It also helps distinguish less strategic locations, such as enclosed harbors, where waves tend to be delayed and are less representative of regional tsunami impacts. Tide gauges are valuable instruments for monitoring other phenomena like climate change-induced sea-level rise, thus necessitating long-term installations capable of generating reliable time series with minimal influence from local effects such as coastal subsidence. The critical lack of publicly available coastal bathymetric data introduces significant uncertainties into tsunami modelling, putting people’s lives at risk. Addressing this urgent issue by ensuring the existence of comprehensive and accessible coastal bathymetric datasets is, therefore, of paramount importance.

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ABSTRACT. The southern part of the Aegean Sea was affected by an earthquake swarm generated in the Santorini–Amorgos area between late January and late March 2025. This seismic sequence raised several critical questions and concerns regarding its evolution, duration, and cessation, its comparison with previous seismic events in the region, and its potential association with magmatic and volcanic activity. The significance and rarity of this sequence stem not only from these scientific uncertainties and the triggered secondary effects, but also from the challenges it posed for emergency response and impact management. The Santorini–Amorgos seismic crisis represents a rare case where increased preparedness measures were proactively implemented in anticipation of a geophysical disaster. This study examines the measures undertaken by the authorities and the operational structures of the Civil Protection system in Greece in response to the sequence. Particular emphasis is placed on protecting both residents and visitors, while actively mitigating potential risks associated with the occurrence of stronger seismic events, in terms of magnitude, intensity and impact on the natural and built environments and the population. This comprehensive approach adapted to the specific geological conditions of the southern part of the Aegean Sea, can be considered a model practice in managing seismic emergencies and offers valuable lessons for other areas facing similar hazards and risks.

ABSTRACT. The preliminary results of high-resolution microgravity monitoring during the 2025 Santorini unrest indicate renewed volcanic activity beneath the Santorini volcanic complex. Conducted between February 7 and 13, 2025, the gravity survey encompassed 865 measurements at 137 stations distributed across Santorini and adjacent islands. Analysis of these recent observations, compared with earlier surveys (2012, 2014), detected significant subsurface mass redistribution, particularly under Nea Kameni and extending northwest towards Kolumbo. These findings emphasize the importance of integrated gravity, GNSS, and InSAR analyses in volcanic monitoring, recommending continued interdisciplinary approaches for refined hazard assessments and timely updates on volcanic risks.

ABSTRACT. Thira/Santorini is a very significant volcanic island in the Aegean Sea that was formed into present day morphology by a catastrophic eruption about 3500 years ago. The volcano is still active, as demonstrated by numerous lava eruptions during the last two centuries, with the last lava flow in 1950. Very recent volcanic unrest took place in 2011-2012 with increased seismicity, gas emissions and surface inflation/deflation process. Gravity monitoring presented in this paper started in 2013. After all corrections, the gravity difference between 2013 and 2021 showed relative calm evolution in the formerly active central lava island of Nea Kameni. On the other hand, in the NE part of the island a significant decrease of gravity was observed. It was not caused by surface uplift, rather by rock massif volume density decrease, probably due to an extensional proces within the Kolumbo fault zone, which gave origin to the Kolumbo underwater volcano about 6 km to NE of the coast.

ABSTRACT. Introduction The Ammonitico Rosso (AR) Formation (Fm) is one of the best-known lithofacies of the Tethys Ocean’s history due to its peculiar lithological features (Cecca et al. 1992). During the Early Jurassic, the opening of the Tethys Ocean begun, influenced by intense faulting which led to the development of both shallow marine platforms and deep-sea basins (Bernoulli and Renz, 1970). Extensional stress led to the development of the Ionian Basin (Bernoulli and Renz, 1970; Zelilidis et al., 2015). Intrabasinal differentiations resulted in submarine highs with minimal sediment deposition and continuous deposition in local depressions (Bernoulli and Renz, 1970). Benthic foraminifera and ostracods are valuable tools for palaeoenvironmental reconstructions (Ansari et al., 2022 and reference therein;). Especially for the Jurassic, they could be useful for the age determinations of the studied formations as well. Thus, a variety of studies on Lower – Middle Jurassic ostracods and benthic foraminifera have been conducted in the Neo-Tethys region. Despite extensive research on Jurassic foraminifera and ostracods in the Tethys Ocean, there is a notable absence of such studies in Greece, except for a few studies on Jurassic benthic foraminifera using thin sections. Nevertheless, the systematic study of ostracods through the study of thin sections is not possible. Landslides that produce mass-transport deposits occur in loosely consolidated soft sediments in both subaerial and submarine environments (Ferrill et al. 2023). Synsedimentary deformation structures (synsedimentary faults, folds, slide planes, dewatering structures, etc.) are widely distributed in the syn-rift formations of the Ionian Basin of Greece (Golfinopoulos et al. 2025 and reference therein). The study area is located in the region of Western Greece, in the regional district of Aitoloakarnania, approximately 8 km northwest of Astakos town and 10 km southeast of Mytikas village. In this area, Jurassic and Cretaceous formations of the External Ionian Basin are exposed in coastal sections, road cuts, and sparsely vegetated mountain slopes. Objectives The main objectives of this study are: i) to document the first stereoscopic record of Jurassic benthic foraminifera and ostracods in Greece, ii) to reconstruct the palaeoenvironment and determine the age of the AR and Posidonia beds Fms in the Ionian Basin, iii) to unravel the internal structure of AR Fm, which includes several horizons of synsedimentary deformation and iv) to present the revised geological map of the studied area as part of this project. Methods In the field, detailed bed-by-bed logs were measured, and then the corresponding lithostratigraphic columns were produced. Fieldwork also included measurements, descriptions, and reconstruction of the studied stratigraphy, bearing in mind the local tectonic activity. A total of 52 rock samples and 8 sediment samples were collected from eight sequences. Thirty of the most characteristic rock samples were thin sectioned for microfacies analysis. Microfacies analysis was conducted using Folk’s (Folk, 1959) and Dunham’s (Dunham, 1962) classifications. Additionally, the revised Wilson model (Wilson, 1975), which defines 26 standard microfacies (SMF) types that are associated with 10 standard facies zones (FZ), was employed. For all sediments samples, micropalaeontological analysis was carried out. The strongly deformed horizons were recorded in detail, including their thickness, deformation axis, their relation to the underlying and overlying horizons, and the bedding planes’ dip and direction. Additionally, the characteristics and kinematics of the faults were recorded and analyzed in relation to the depositional processes. Results The Jurassic to Cretaceous formations of the External Ionian sub-basin were studied, focusing on the AR Fm, as it appears fully developed in the study area. Specifically, in this area, the following formations are exposed (from the base to the top): Pantokrator limestones, Sinies limestones, Lower Posidonia beds, AR, limestones with filaments, and Vigla limestones Fms. The base of the succession consists of massive- to thick-bedded white limestones (Pantokrator Fm, Sequence 1). These are overlain by thin- to medium-bedded siliceous limestones (Sinies Fm) which locally contain ichnofossils, stylolites, and occasional chert nodules (Sequences 2-5). Conformably, on the latter, alternations of laminated green-brown pelites with laminated marly limestones were recognized (possible Posidonia beds, Sequence 6, the beginning of Sequence 7). Above them, alternations of red pelites and calcilutites with grey and red nodular limestones were observed (AR Fm, Sequence 7). In the red pelites, grey nodular limestones, and red nodular limestones, ammonites and ichnofossils were observed. The upper stratigraphic part of this formation consists of pink-beige limestones (Limestones with filaments Fm, the beginning of Sequence 8). These strata are laminated to medium-bedded. In the upper part of the studied section, thin- to thick-bedded beige siliceous limestones with chert nodules and chert bands (Vigla limestone Fm, Sequence 8) are present. Notably, within this upper formation, brown shales containing very small polymetallic nodules were recorded (Golfinopoulos et al. 2025, Figure 1).

Figure 1: A) Simplified geological map of the External Hellenides in NW Greece, modified from (Zelilidis et al. 2015), where the red box indicates the study area. B) Geological map of the study area. Codes with letter “S” represent the locations of the sequences referred to in the text (modified from Golfinopoulos et al. 2025). The microfacies analysis of 30 studied thin sections from Sequences 1 - 8 showed two different depositional environments, toe of slope (FZ 3) and platform-margin reefs (FZ 5), corresponding to two different standard microfacies types. Each MF corresponds to a different SMF type. Specifically, MF 1 is classified as biosparite/boundstone (SMF 7), while MF 2 includes micrites, fossiliferous micrites, and both sparse and packed biomicrites/wackestones and packstones (SMF 3, SMF 3-RAD, SMF 3-CALP, SMF 3-FIL). The biofacies analysis revealed among others (radiolaria, filaments, benthic and planktonic foraminifera), the existence of planktonic foraminifera of the genus Globuligerina in Sequences 5, 6, 7 and 8. The samples of Sequence 5 belong to the upper part of Sinies limestone Fm, based on their lithological features and their relationship to the overlying formations, they appear to have been deposited during the Late Pliensbachian. If verified, this claim would shift the first appearance of planktonic foraminifera from the Toarcian to the Pliensbachian (Golfinopoulos et al. 2025). In total 8 sediment samples from Sequences 6-7 were micropalaeontologically studied as well. Two of the samples were barren, while all the other samples contained sufficient numbers of benthic foraminifera tests and ostracod valves. A few fish teeth and sea urchin spines were recorded as well. In total, 15 benthic foraminifera species belonging to 7 families, namely Ichthyolariidae, Vaginulinidae, Lagenidae, Nodosariidae, Polymorphinidae, Spirillinidae and Saccamminidae, were determined. Regarding the ostracod assemblages, at least 10 species belonging to 3 families (Polycopidae, Healdiidae and Bairdiidae), were determined as well. Most of the studied material is moderately to very badly preserved, thus making some of the determinations difficult. Ostracod molds of oval to ellipsoidal shape have been retrieved. Their shape points to a suborder other than Metacopina and Podocopina, whose shape is more sub-triangular. A significant number of the determined in this study benthic foraminifera (Ichthyolariidae, Vaginulinidae, Polymorphinidae and Saccamminidae) and ostracods (Polycopidae and Healdiidae) are characteristic for the Lower Jurassic (Pliensbachian – Toarcian) assemblages of the Tethys Ocean. In Sequence 7 synsedimentary deformation structures have been developed. The succession of this Sequence begins with greenish-grey shales, quite distinct from the overlying red and white limestones and shales of the AR Fm. The base of the unit is not exposed, whereas at beach level, the top is marked by a few centimetres of greenish deformed fissile shale, conformably overlain by AR-type limestone. Along the strike, in the cliff face, the contact appears rather irregular. As the internal details of this unit are not well exposed, it is simply termed the Lower Unit. It is probably either a complex slide or a debris-flow deposit with rafted blocks of bedded limestone, but the possibility that the unit is in situ and suffered some internal deformation from the overlying slide cannot be excluded. The base of the AR Fm shows considerable synsedimentary deformation. The lowest shale unit has a recumbent fold closure. It is overlain by discontinuous decimeter-scale boudins of micritic limestone enclosed in rubbly AR limestones and shale, with a ghost stratigraphy about 1 m thick. This is overlain by 30 cm of apparently undeformed reddish marl and several meters of alternating nodular limestones and reddish shales with discontinuities between packets of limestone beds, thus creating a series of oblique, bedding-parallel slabs of alternating limestone and shale. In places, limestone beds terminate or are boudinaged, and shales are deformed. The proportion of limestone increases upward. This limestone is overlain by a 2 m thick, polymictic limestone, matrix-supported conglomerate interpreted as a debris-flow deposit, termed debrite 1. Debrite 1 is overlain by about 1 m of reddish shales with discontinuous thin limestone beds. Overlying bedded limestones show brittle deformation into metre-scale tilted blocks, apparently as part of the slide mass. Interbedded with the AR limestones is at least one graded calcirudite to calcarenite turbidite. Debrite 2 overlies the tilted blocks and is about 1 m thick. It is redder in colour than debrites 1 and 3 and is also matrix-supported. Debrite 3 is poorly sorted, with large subangular blocks, supported by a matrix of sand-sized limestone clasts and red mud. The top of debrite 3 is overlain by 30 cm of seemingly undeformed red shale and then an AR limestone section that in its upper part is deformed into a large open fold (Figure 2). The fold is unconformably overlain by about 1 m of bedded limestones with rapid lateral thinning, suggesting that it is also a block within the overall slide. These bedded limestones are overlain by an 1 m bed of sorted conglomerate with an erosional contact with the underlying limestones. The conglomerate consists of rounded limestone pebbles, with the upper part of the bed comprising fine pebbles and granules. Above this conglomerate is a succession of red-grey bedded calcarenites (Golfinopoulos et al. 2025).

Figure 2: Representative view of sequence 7, where the three debrites (1-3) are developing. Conclusions During this study, 8 sedimentary sequences in the Astakos area have been studied. Detailed sedimentological, tectonic, and biostratigraphic analyses of both carbonate and clastic sediments have been conducted. Therefore, the following findings have been reported: • This work presents the first stereoscopic record of Jurassic ostracods and benthic foraminifera in Greece. • There are indications that some Globuligerina tests occurred earlier than previously known; their first appearance probably occurred during the Pliensbachian. • Lower Posidonia Beds and Ammonitico Rosso Formations were deposited in the shelf and transported in deeper environments during the Pliensbachian to Toarcian. • The studied sedimentary sequence, though, comprises an allochthonous submarine slide deposit, consisting of four imbricate slices capped by debrites (except the upper one) rather than four discrete slides. Upwards, a conglomerate with reworked limestone clasts has been deposited as a result of a single turbidite. The sequence closes with sediments of the limestone with filaments and Lower Posidonia bed Fms. • The autochthonous AR Fm depositional setting fits well with a carbonate ramp, on which turbidity currents with a transport distance of several kilometres would have developed from a watery debris flow formed by headwall collapse • The discovery of the AR Fm slide has a profound effect on the reported sedimentation rates for the area, which until now have not taken under consideration the duplication of the layers, and which thus must be significantly lower.

ABSTRACT. This study presents a comprehensive palaeoenvironmental reconstruction of the Mesolongi Lagoon, utilizing a 21-meter sediment core to analyze Holocene depositional and ecological changes. A multiproxy approach, integrating micropaleontological, sedimentological, and geotechnical analysis, was employed to investigate shifts in environmental conditions over time. The findings reveal distinct transitions from freshwater-influenced brackish phases to marine-dominated conditions, highlighting the influence of climatic and hydrodynamic processes.Foraminiferal and ostracod assemblages, combined with geotechnical properties such as plasticity index and moisture content, provide critical insights into the lagoon's palaeoenvironmental evolution and depositional changes.These results contribute to a deeper understanding of coastal lagoon dynamics and their response to natural and anthropogenic influences.

ABSTRACT. International Ocean Discovery Program Expedition 398 ‘Hellenic-Arc-Volcanic-Field’ took place in the Christiana-Santorini-Kolumbo Volcanic-Field (CSKVF) in the central Hellenic Volcanic Arc. The CSKVF is one of the most hazardous volcano-tectonic regions in the world, as the volcano has produced many and highly explosive eruptions in the past and could be of a threat for at least eastern Mediterranean (Druitt et al., 1999; Nomikou et al., 2013, 2019). This volcanic field produced the notorious Late Bronze age Minoan eruption that is considered to have contributed to the fall of an entire civilization (Bruins et al., 2008). The overall objectives of the expedition were to investigate the links and feedbacks between volcanism/magmatism, crustal tectonics and sea level, as well as to groundtruth the seismic stratigraphy of the Santorini caldera, to reconstruct the subsidence history of the southern Aegean Sea and search for deep life inside and outside of Santorini caldera (Druitt et al., 2022). IODP Expedition 398 was conducted with the R/V JOIDES Resolution, from 11 December 2022 to 10 February 2023. During the expedition despite the very challenging drilling conditions, twelve sites were drilled, for a total of 7345 meter in 28 holes, retrieving 780 cores with a total recovery of 3356 meters (Druitt et al., 2024b; Figure 1). Outside of Santorini caldera, drilling penetrated the thick basin fills of the crustal rift system hosting the CSKVF, and identified more than 1000 tephra layers, some known from onland and others formerly unknown, the seismic stratigraphy was groundtruthed (Preine et al., 2024), detailed age-depth constraints were provided mainly by biostratigraphy, drilling penetrated the Alpine basement and ancient life DNA was recovered, proving that most of the volcano-tectonic history of the CSK field, as the volcano-sedimentary sequences, lies under the sea. One of the first results, constrained by a multidisciplinary approach and highlighting the hazards of submarine explosive eruptions, includes the discovery of a giant rhyolitic pumice, the Archaeos Tuff, as the result of a shallow marine eruption of ancestral Santorini Volcano (Druitt et al., 2024a). The Archaeos Tuff was emplaced during the Middle Pleistocene at water depths of 200 to 1000 m, as suggested by foraminiferal and calcareous nannoplankton biostratigraphic markers. It formed a 90 km3 volcaniclastic megaturbidite up to 150m thick in the marine basins (Druitt et al., 2024a), six times bigger than the pyroclastic current deposit from the Minoan eruption (~15 km3; Karstens et al., 2023).These kind of large explosive volcanic eruptions from island arcs pour pyroclastic currents into marine basins, causing high plumes of ash, earthquakes and associated tsunamis and severely affecting coastal communities and infrastructures. Marine ecosystems are particularly vulnerable to eruptions and their consequences (ocean acidification, fertilization, debris flows, increased temperatures, ash falls) leading to diversity changes and even biodiversity loss (e.g., Finger and Lipps, 1981; Hart et al., 2022). The effects in foraminiferal microfauna of such extreme events, as volcanic eruptions, were investigated in the sediments deposited prior and after the emplacement of Archaeos Tuff. The exact intervals before, during and after this pyroclastic flow (for interval details on the Archaeos Tuff see Druitt et al., 2024a) were studied in six cores along the different basins, and here we present our preliminary results on its impacts on foraminiferal community structure. During deposition of the submarine pumice, benthic foraminifera species were severely affected both in terms of density and diversity, with survivor infaunal species, shelf species and damaged specimens likely representing downslope reworking. Some samples were barren even from accompanying ostracods, molluscs and pteropods, while planktonic foraminifera were also rarely present. Following deposition of the pumice, the foraminiferal repopulation took place, with high numbers and diversity values, suggesting the recovery of the stressed environment and the restoration of the oligotrophic and well-oxygenated conditions. Our findings highlight the foraminiferal fauna ability to tolerate major catastrophic events in their environment and to recover and recolonize, which is both admirable and extremely useful as a tool to interpret biostratigraphic correlations and paleoenvironmental conditions. Acknowledgements We are thankful to the International Ocean Discovery Program (IODP), the technical staff of the JOIDES Resolution, and all of the shipboard personnel for a great expedition. We also thank the member organizations of IODP for financial aid, and the Municipality of Thera for help in preparing for the expedition. References Bruins, H.J., MacGillivray, J.A., Synolakis, C.E., Benjamini, C., Keller, J., Kisch, H.J., Klügel, A., van der Plicht, J., 2008. Geoarchaeological tsunami deposits at Palaikastro (Crete) and the late Minoan IA eruption of Santorini. Journal of Archaeological Science 35(1), 191-212. Druitt, T.H., Edwards, L., Mellors, R.M., Pyle, D.M., Sparks, R.S.J., Lanphere, M., Davies, M., Barreirio, B., 1999. Santorini Volcano. Memoir - Geological Society of London 19, 165pp. Druitt, T., Kutterolf, S., Höfig, T.W., 2022. Expedition 398 Scientific Prospectus: Hellenic Arc Volcanic Field. International Ocean Discovery Program. https://doi.org/10.14379/iodp.sp.398.2022 Druitt, T., Kutterolf, S., Ronge, T.A., Hübscher, C., Nomikou, P., Preine, J., Gertisser, R., Karstens, J., Keller, J., Koukousioura, O., Manga, M., Metcalfe, A., McCanta, M., McIntosh, I., Pank, K., Woodhouse, A., Beethe, S., Berthod, C., Chiyonobu, S., Chen, H., Clark, A., DeBari, S., Johnston, R., Peccia, A., Yamamoto, Y., Bernard, A., Fernandez Perez, T., Jones, C., Joshi, K.B., Kletetschka, G., Li, X., Morris, A., Polymenakou, P., Tominaga, M., Papanikolaou, D., Wang, K.-L., Lee, H.-Y., 2024a. Giant offshore pumice deposit records a shallow submarine explosive eruption of ancestral Santorini. Communications Earth and Environment 5, 24. Druitt, T.H., Kutterolf, S., Ronge, T.A., Beethe, S., Bernard, A., Berthod, C., Chen, H., Chiyonobu, S., Clark, A., DeBari, S., Fernandez Perez, T.I., Gertisser, R., Hübscher, C., Johnston, R.M., Jones, C., Joshi, K.B., Kletetschka, G., Koukousioura, O., Li, X., Manga, M., McCanta, M., McIntosh, I., Morris, A., Nomikou, P., Pank, K., Peccia, A., Polymenakou, P.N., Preine, J., Tominaga, M., Woodhouse, A., and Yamamoto, Y., 2024b. Expedition 398 summary, in: Druitt, T.H., Kutterolf, S., Ronge, T.A., and the Expedition 398 Scientists, Hellenic Arc Volcanic Field. Proceedings of the International Ocean Discovery Program, 398: College Station, TX (International Ocean Discovery Program). https://doi.org/10.14379/iodp.proc.398.101.2024 Finger, K.L., Lipps, J.H., 1981. Foraminiferal decimation and repopulation in an active volcanic caldera, Deception Island, Antarctica. Micropaleontology 27, 111-139. Hart, M.B., Fisher, J.K., Smart, C.W., Speers, R., Wall-Palmer, D., 2022. Re-colonization of hostile environments by benthic foraminifera: an example from Montserrat, Lesser Antilles Volcanic Arc. Micropaleontology 68(1), 1-27. Karstens, J., Preine, J., Crutchley, G.J., Kutterolf, S., van der Bilt, W.G.M., Hooft, E.E.E., Druitt, T.H., Schmid, F., Cederstrøm, J.M., Hübscher, C., Nomikou, P., Carey, S., Kühn, M., Elger, J., Berndt, C., 2023. Revised Minoan eruption volume as benchmark for large volcanic eruptions. Nature Communications 14, 2497. Nomikou, P., Papanikolaou, D., Alexandri, M., Sakellariou, D., Rousakis, G., 2013. Submarine volcanoes along the Aegean volcanic arc. Tectonophysics 597-598, 123-146. Nomikou, P., Hübscher, C., Carey, S., 2019. The Christiana-Santorini-Kolumbo Volcanic Field. Elements 15(3), 171-176. Preine, J., Karstens, J., Hübscher, C., Druitt, T., Kutterolf, S., Nomikou, P., Manga, M., Gertisser, R., Pank, K., Beethe, S., Berthod, C., Crutchley, G., McIntosh, I., Ronge, T., Tominaga, M., Clark, A., DeBari, S., Johnston, R., Mateo, Z., Peccia, A., Jones, C., Kletetschka, G., Metcalfe, A., Bernard, A., Chen, H., Chiyonobu, S., Fernandez-Perez, T., Joshi, K.B., Koukousioura, O., McCanta, M., Morris, A., Polymenakou, P., Woodhouse, A., Yamamoto, Y., Wang, K.-L., Lee, H.-Y., Li, X., Papanikolaou, D., 2024. Hazardous explosive eruptions of a recharging multi-cyclic island arc caldera. Nature Geoscience 17, 323-331.

ABSTRACT. This study explores the palaeoecology of sediments from the Cave of the Lakes in Northern Peloponnese, Greece, highlighting the discovery of a new species of ostracod, Trapezicandona n. sp. The analysis of seven surface sediment samples revealed low diversity and varying frequency assemblages, dominated by Neglecandona vernalis and accompanied by Schellencandona sp. and the newly identified species. The findings suggest a depositional environment characterized by low energy, with certain samples indicating higher energy conditions or mass death events. The study also identified significant anthropogenic impacts, including microplastics. This research marks a pioneering step in Greek cave ostracod studies and underscores the need for further investigations into the cave’s biodiversity, its subterranean assemblages, and palaeoenvironmental evolution in response to climatic and human influences.

ABSTRACT. Research highlights New insights into the plant palaeoassemblages from the Petrified Forest of Lesvos Island are revealed through the documentation and taxonomic determination of the leaf macro-remains from Vrisaki fossiliferous locality. Background The Petrified Forest, located at the western peninsula of the Lesvos Island, Greece, and recognized as a UNESCO Global Geopark, plays a pivotal role in preserving and showcasing the natural heritage of the Lesvos Island through efforts in scientific research, geo-conservation, geo-education and geo-tourism. The recent construction of the new Kalloni-Sigri road, crossing the protected area of the Lesvos Petrified Forest in Western Lesvos, has exposed a remarkable wealth of plant fossil sites (Fig. 1, 1B). Especially, twelve fossiliferous localities were identified and excavated along the road, carefully protected, and studied to ensure their preservation and to advance knowledge. The findings include a wide variety of fallen and in situ fossilized tree trunks along with mass occurrences of leaf macro-remains revealing the great palaeobotanical richness of the region (Zouros, 2021). The unearthed fossil material surpasses all prior expectations establishing the Lesvos Petrified Forest as one of the most significant areas for scientific investigations worldwide. Recent studies on both wood anatomy and leaf macro-morphology have provided new insights into the preserved volcanic flora of the broader protected area of the Petrified Forest (Velitzelos et al., 2019; Iamandei et al., 2022, 2024; Kafetzidou et al., 2022; Tsitsou et al., 2022; Liapi et al., 2022, 2023, 2024; Zhu et al. 2024). Objectives The primary objective of this work is to enhance the study of the palaeobotanical record of the Petrified Forest through the documentation and taxonomic determination of leaf macro-remains from the new fossil sites along the Kalloni-Sigri road which traverses the Akrocheiras hill range (Fig. 1, 1B). In this context, several leaf macro-remains from Vrisaki fossiliferous locality have been examined, described and determined. Additionally, the palaeoecological signals of the plant taxa have been assessed to reconstruct the environmental conditions that prevailed during the early Miocene. Material and Methods The studied material consists 500 fossiliferous slabs comprising over 6930 leaves and a small number of reproductive organs. These remains have been preserved within different fine- to coarse-grained tuff layers, occurring both as leaf litter accumulated in the fine tuff layers, and as scattered leaves intermixed with pyroclastic material. The slabs were collected, conserved and cataloged by the research and technical team of the Natural History Museum of the Lesvos Petrified Forest (Zouros et al., 2022). The fossils were evaluated, with the majority of the material examined under an OPTIKA SLX-5 stereomicroscope. The taxonomic determination was conducted following the manual of leaf architecture with a focus on the key macro-morphological features of the fossils, including margin type, apex and base shapes, as well as venation architecture (Ellis et al., 2009). Preliminary Results To date, the palaeoflora of Vrisaki consists of at least one bryophyte, two ferns and more than 50 different angiosperm taxa. From the latter 50 angiosperm taxa, it has so far been possible to determine only 21 to a more specific taxonomic category. The determined taxa based on foliage include Bryophyta gen. et sp. indet., aff. Pronephrium stiriacum (Unger) Erw.Knobloch & Kvaček, aff. Rumohra recentior (Unger) Barthel, Daphnogene polymorpha (A. Braun) Ettingshausen, Laurophyllum sp. 1, Laurophyllum sp. 2, Smilax weberi P.Wessel, Phoenicites sp., Calamus sp., Zingiberaceae gen. et sp. indet., aff. Zingiberales, Fagaceae gen. et sp. indet. 1, Fagaceae gen. et sp. indet. 2, Juglandaceae gen. et sp. indet., Alnus vel Rubus, Rubus sp., aff. Celtis japeti Unger, Populus sp., Nerium sp., Myrtophyllum sp., and Pungiphyllum cruciatum (A. Braun) Frankenhäuser & V. Wilde. Additionally, the leaf material has been grouped into several distinct morphotypes, each requiring further investigation for a more detailed classification (Fig. 4, 4.4–4.7). Based on reproductive organs, the flora includes a solely infructescence of Alnus ?kefersteinii (Göppert) Unger, winged fruits of Acer sp. and cf. Acer sp., and a few buds probably of lauraceous affinity. Different representative plant taxa of the studied area are illustrated in Figures 2–4, underscoring the floral diversity of Vrisaki. Discussion The enormous quantities of leaf macro-remains and the numerous petrified tree trunks preserved in various fossiliferous localities within the pyroclastic rocks of the Lesvos Petrified Forest provides a great opportunity to decipher the early Miocene subtropical history of the Island. This ongoing research focuses on the documentation and systematic taxonomy of the abundant leaf material from the fossiliferous locality of Vrisaki. The studied leaf macro-remains and fruits represent a diverse palaeoflora that requires meticulous examination to fully delineate the floristic composition of the area. So far, more than 53 plant taxa have been documented and analyzed based on their macro-morphological characteristics. The palaeoflora of the Vrisaki fossiliferous locality represents a diverse array of vegetation types, ranging from riparian habitats to lowland and upland mesophytic forest regions. The determined taxa are linked to one or more vegetation units, reflecting the ecological diversity and complexity of the palaeoenvironment. Evidence of a riparian plant association is suggested by taxa such as aff. Pronephrium stiriacum, aff. Rumohra recentior, Daphnogene polymorpha, Phoenicites sp., Alnus ?kefersteini, Alnus vel Rubus, Populus sp. and possibly Pungiphyllum cruciatum. The occurrence of members of the Lauraceae and Fagaceae families, Juglandaceae gen. et sp. indet., aff. Celtis japeti and Nerium sp. is indicative of well-drained forests. Herbaceous monocots, including members of Zingiberales, were likely adapted to the shaded understory beneath the forest canopy of the riparian or well-drained forests. In addition, lianas such as Smilax weberi and Calamus sp. may have been part of riparian or well-drained forests, suggesting a forest structure with multiple layers. The preliminary results from the systematic taxonomy of the Vrisaki fossiliferous locality reveal sufficient floristic similarities with the West Akrocheiras fossiliferous locality from the Akrocheiras hill (Kafetzidou et al., 2022; Tsitsou et al., 2022; Liapi et al., 2022, 2023). Both palaeofloras share plant taxa such as aff. Pronephrium stiriacum, Daphnogene polymorpha, Laurophyllum sp. 1, Smilax weberi, Phoenicites, Calamus, Zingiberaceae gen. et sp. indet., Fagaceae gen. et sp. indet. 1, Rubus, Populus, Acer, Nerium, Myrtophyllum, and Pungiphyllum cruciatum. Notably, the Vrisaki palaeoflora appears to exhibit a greater diversity based on fruit remains, including Alnus ?kefersteinii, Acer sp. and cf. Acer. However, several angiosperm foliage have not yet been identified to a particular genus and species in both Vrisaki and West Akrocheiras. Despite the progress that has been made in recent years, further investigation is required as several morphotypes still remain under study. The systematic taxonomy of the plant macro-remains from Akrocheiras hill poses challenges due to the extensive abundance of collected specimens and the overlapping morphological features exhibited by certain leaf types. Completing the systematic classification in the future will provide a more comprehensive floristic knowledge and offer valuable insights into the palaeoenvironmental history of the early Miocene of Lesvos.

Acknowledgments The authors would like to express appreciation to the research and technical team of the Natural History Museum of the Lesvos Petrified Forest for their contribution and support to the current palaeobotanical research.

References Ellis, B., Daly, D.C., Hickey, L.J., Johnson, K.R., Mitchell, J.D., Wilf, P., Wing, S.L., 2009. Manual of Leaf Architecture. Cornell University Press, New York. Iamandei, S., Iamandei, E., Velitzelos, D., Velitzelos, E., 2022. Palaeoxylotomical studies in the Cenozoic petrified forests of Greece. Part two – conifers. Acta Palaeontologica Romaniae 18 (1), 65–111. Iamandei, S., Iamandei, E., Velitzelos, D., Velitzelos, E., 2024. Palaeoxylotomical studies in the Cenozoic petrified forests of Greece. Part three – dicots. Acta Palaeontologica Romaniae 20 (2), 61–96. Kafetzidou, A., Kouli, K., Zidianakis, G., Kostopoulos, D., Zouros, N., 2022. The early Miocene angiosperm flora of Akrocheiras in Lesvos Petrified Forest (North Aegean, Greece) – Preliminary results. Review of Palaeobotany and Palynology 296, 104559. Liapi, E., Zidianakis, G., Tsitsou, E., Iliopoulos, G., Zouros, N., 2022. New floristic data of the Early Miocene Lesvos Petrified Forest − Part A: Non-vascular plants, ferns and monocots from the West Akrocheiras outcrop. Bulletin of Geological Society of Greece Sp. Publ. 10, 64–65. Liapi, E., Tsitsou, E., Iliopoulos, G., Zouros, N., 2023. Taxonomic investigations of the West Akrocheiras plant assemblage of the Lesvos Petrified Forest. 8th Agora Paleobotanica Meeting, abstracts volume, Belver de Cerdanya, pp. 39–40. Liapi, E., Iliopoulos, G., Zouros, N., 2024. Documenting the leaf flora of a new fossiliferous locality from the Lesvos Petrified Forest. Folia Musei Rerum Naturalium Bohemiae Occidentalis - Geologica et Paleobiologica 58 (1), 29–33. Tsitsou, E., Zidianakis, G., Liapi, E., Iliopoulos, G., Zouros, N., 2022. New floristic data of the Early Miocene Lesvos Petrified Forest − Part B: Dicotyledon taxa from the West Akrocheiras outcrop. Bulletin of Geological Society of Greece Sp. Publ. 10, 66–67. Velitzelos, D., Iamandei, S., Iamandei, E., Velitzelos, E., 2019. Palaeoxylotomical studies in the Cenozoic petrified forests of Greece. Part one – palms. Acta Palaeobotanica 59 (2), 289–350. Zhu, Y.B., Li, Y., Zhang, J.P., Wang, Y.D., Zouros, N., 2024. A new species of Pseudotsuga (Pinaceae) from the lower Miocene of Lesvos, Greece, and its palaeogeographical and palaeoclimatic implications, Palaeoworld. doi.org/10.1016/j.palwor.2024.06.001. Zouros, N.C., 2021. The Miocene petrified forest of Lesvos, Greece: Research and geoconservation activities. Geoconservation Research. 4 (2), 635–649. Zouros, N., Soulakellis, N., Valiakos, I., Bentana, K., Theodorou, E., Zgournios, E., Antonakis, E., Lamprakopoulos, A., 2022. Enhancement and promotion of the new fossiliferous sites along the new Kalloni Sigri road–An example of good practice of geoconservation in Lesvos Island UNESCO Global Geopark Greece. Bulletin of Geological Society of Greece Sp. Publ. 10, 849–850.

ABSTRACT. Introduction / Background The Lesvos Petrified Forest is a geological heritage site of global significance, featuring silicified tree trunks, fossil leaves and volcanic deposits dated back to the lower Miocene. Initially brought to scientific attention in 1844, it gained broader recognition in late 19th and early 20th centuries, with pivotal research in the 1990s elucidating its formation processes (e.g. Velitzelos & Zouros, 1997). Designated as one of the first European Geoparks in 2000, and Global Geoaprk in 2004, the Lesvos Petrified Forest is the main geological heritage area of international significance for the recognition of Lesvos island as an UNESCO Global Geopark in 2015 (https://www.lesvosmuseum.gr/en/node). Recognized as one of the first 100 IUGS geological heritage sites in 2022, the Lesvos Petrified Forest is a hub for research, education, and sustainable tourism. Recent construction works of the Kalloni-Sigri road brought to the light new fossiliferous localities hosting thousands of fossils including fossilized trees and leaves (Zouros et al., 2022). The road cuts at the new fossiliferous sites enable detailed stratigraphic analysis of the Sigri pyroclastic rocks and a reevaluation of the area’s stratigraphy and palaeoenvironmental evolution. This study focuses on the analysis of West Akroheiras section (39.230107°, 25.905465°, 320 m section length, Fig. 1) following a pilot multi-proxy approach and aiming in the inquiry of the most effective methods for palaeoenvironmental reconstruction of the Lesvos Petrified Forest monument. Geological setting The volcanic rocks of Lesvos have been extensively studied and mapped, with notable contributions from researchers such as Hecht (1972, 1974a,b), Pe-Piper (1978, 1980) and Pe-Piper et al. (2019), who established the stratigraphic framework and identified key volcanic structures. These formations lie at the top of Permian schists (Katsikatsos et al., 1982) and marbles, and include the Sigri Pyroclastic Formation, which features pyroclastic and volcaniclastic deposits rich in silicified tree trunks and fossilized leaves (Velitzelos & Zouros, 1997, Zouros, 2021). The Sigri pyroclastics derived from an earlyMiocene stratovolcano chain (Hecht, 1972; 1974a, b; Pe‐Piper, 1980), dating between 21.5 and 18.4 Ma ago (Piper et al., 2019), with stratigraphic divisions inferred from adjacent geological formations. The volcanic chain follows a NNE-SSW orientation influenced by the dextral strike-slip tectonic regime of the Aegean-Anatolian microplate (Yilmaz et al., 2000). Over geological time, this regime evolved, giving rise to various fault systems, including dextral, sinistral and normal faults during Neogene and Quaternary times. These findings highlight the complex tectonic and volcanic history of the island, contributing to a deeper understanding of its geological evolution.

Material and Methods Stratigraphic logging was performed in several places of the studied section as the lateral continuity of the layers was interrupted by faults, in addition to the many lateral changes in the nature of the pyroclastic material. The lithological characterisation of the pyroclastic rocks followed Fisher & Schmincke (1984) and Francis & Oppenheimer (2003). The most prominent fallen or standing tree trunks and fossil leaf horizons were noted along with basic sedimentological characteristics. Taphonomic observations of the fossil leaves were made in situ. Bed by bed sampling was also conducted. Rough stratigraphic cross sections containing the most important features (characteristic horizons, major faults etc.) were compiled and photos were taken. The sections were digitised later on (using CorelDRAW Graphics Suite), and the respective stratigraphic columns were drawn (using Strater 5 software) (Figs 2 and 3) and correlated. Moreover, very High-Resolution Images acquired through Unmanned Aerial Vehicles were used to generate: i. a 2D orthophotomap and ii. 3D textured model both used for digital stratigraphic measurements (e.g. layer thickness). A number of rock samples were picked up for selected pilot analysis methods (XRD, organic petrography, micropalaeontologic analyses, and organic geochemistry, as well as systematics and taphonomy of fossil leaves). Powder XRD analysis was conducted on three palaeosoil samples (B6, B13, B23; Fig. 2) in the Department of Geology, University of Patras. Organic petrography analysis was conducted on five samples (B3, B6 and B12; Fig. 2) also at the Department of Geology, University of Patras. Micropalaeontologic analysis for aquatic organism remains (e.g. ostracods, diatoms) was conducted in fifteen samples (A1, A2, A3, A4, A5, B1, B2, B9, B10, B12, B13, D1, D2, Fig. 2) (Department of Geology, University of Patras). Samples B1, B6, B9, B12, B13, B19, B20 and D1 (Fig. 2) were subjected to organic geochemistry analysis at the Birmingham University. The systematic classification of the fossil leaves was based on their macro-morphological characteristics and was performed at the Natural History Museum of the Lesvos Petrified Forest.

Results West Akrocheiras section consists mainly of coarse tuffs, lapilli tuffs and less of tuff breccia layers intercalated with palaeosoil horizons, with a total thickness of 22 m (Figs 2 and 3, columns C8.1-C8.13). Volcaniclastic layers are also included. Several strike slip faults exist with vertical displacements < 2 m, uplifting the western parts of the section. After correlating the stratigraphic data from the combined study of several sections along the Akrocheiras Hill roadcuts, seven palaeosoil horizons have been recorded in this section (Figs. 2 and 3, PS8.1-PS8.7), separating it in eight units (Units 8.1-8.8, Figs 2 and 3). Standing fossil trunks were recorded in three palaeosoil horizons (Figs. 2 and 4 - PS8.3, Fig. 3 - PS8.5 and PS8.6). Fossil leaves were recorded in great numbers in many horizons throughout this section (units U8.1, U8.3 and U8.4), both as leaf litter between different layers and also oriented in different directions, mixed with the pyroclastic materials. The lower part of the section (units U8.1-U8.4) exhibits intense volcaniclastic characteristics (conglomerate lenses mostly at the western part). Unit U8.2 possibly represents deposition of volcaniclastic material in a water body, as implied by the massive unconsolidated pyroclastic coarse ash layer with thickness around 1 m (column C8.1, Fig. 2). In this unit transported coal were found (column C8.2). Unit U8.4 bears a series of avalanche layers with leaf litter in at least five horizons (columns C8.2 and C8.3). XRD analysis in the soil samples revealed that they consist mostly of crystalline intermediate feldspars and clay minerals or/and zeolites. Amorphous inorganic or/and organic material is also included. Maceral analysis of sample B3 (unit 8.2) obtained from the 1-m-thick coarse pyroclastic ash layer at the bottom of the sequence, proved containing partially charred biomass derived from fresh and/or slightly peatified organic matter, probably of arboreal origin. Several organic fragments display a gelified texture and are heat-affected, as the relatively high mean random vitrinite reflectance values (0.47-2.0%) and the cracks indicate. These partially or totally-carbonised peaty, and woody fragments may be air-borne transported from the surroundings and deposited there. Sample B6 (unit 8.2) represents a thin black layer, which contains charred particles (semifusinite and degradofusinite) with plasticized edges and displays a mean reflectance of 0.85%. In the same strata, charred particles with thin cell walls (pyrofusinite) are also common, with reflectance values ranging up to 1.4%. Interestingly, several particles display a pre-charring gelification, whereas the in-situ growth of the precursor plants is evident by the included charred corpohuminite particles. Sample B12 (unit 8.3) is characterized as a carbonaceous or sapropelic coaly layer (i.e. elevated liptinite content), with limited thermal affection and VR of 0.5%; the mode of deposition seems to be in a short-lasted water-logged limnic/limnotelmatic environment; an epigenetic thermal influence is evident only by some cracks. All the samples that were micropalaeontologically examined, were barren. This implies either a non-aquatic environment, unfavorable life conditions (e.g. anoxic) or/and unfavorable preservation conditions (e.g. low pH values). Pilot biomarker analyses of the eight samples revealed that the majority of them have plant wax n-alkanes in with only one showing an absence of these compounds. Some samples show some signs of thermal/diagenetic impact (B1), but overall the samples show high potential for organic geochemical work, including sufficient concentrations for compound specific isotope analyses. Some samples appear exquisitely well preserved, comparable with extract leaf matter of modern or very recent age (Holocene). Alkane response varies from 0-91% (samples D1 and B1/B20, respectively). Total Lipid content (TLE) varies from 0.6 mg (sample B19) to 5.8 mg (sample B9). No correlation was found between TLE and the abundance of n-alkanes in the samples. Sample B20 shows a very distinctive pattern where alkanes are persistent but a cluster of broad peaks is observed around C26-C29 alkane response time. To date, the systematic taxonomy of the fossil leaves has revealed more than 55 plant taxa from West Akrocheiras. The palaeoflora consist of bryophytes, ferns and several angiosperms (including herbaceous and woody monocots, dicots). Among the identified plant taxa, Daphnogene polymorpha (A. Braun) Ettingshausen, Laurophyllum sp., Phoenicites sp., Rosa sp., Nerium sp., Myrtophyllum sp., Pungiphyllum cruciatum (A.Braun) Frankenhäuser & V.Wilde and members of Fagaceae family are abundant floristic elements. Discussion Palaeosoil horizons were examined in order to distinguish the different eruption events. In West Acroheiras section at least 8 different eruption events have been recognized corresponding to units U8.1- U8.8 (Figs 2 and 3). The pilot studies on the palaeoenvironmental evolution of West Acroheiras section gave encouraging results. The lithology of some layers of the lower part (units 8.1 and 8.2) provides evidence of a water body (layer of samples B1-B2), nevertheless, the micropalaeontological analysis gave no results implying unfavorable life or preservation conditions. The organic geochemical analysis of sample B1 revealed high content of thermally matured organic matter, possibly rapidly deposited under anoxic conditions. Thus, if there was a water body there, then a hot pyroclastic flow must have entered it. This is in agreement with the results of the organic petrography analysis for sample B3, which reveals organic matter charred in various degrees, representing roots and arboreal plants, possibly deriving from a nearby peat-forming environment. The combined analysis of sample B6 from palaeosoil horizon PS8.2 (which marks the end of unit 8.2) reveals a palaeoenvironment with high organic matter content, partially affected by thermal alteration and buried rapidly under anoxic conditions. The very good preservation conditions of alkanes can be also attributed to clay minerals as was shown by the XRD analysis of the same sample. Unit 8.3 shows volcaniclastic lithological characteristics. The fossil leaves scattered in the layer, reveal the deposition of transported material. Both organic petrography and organic geochemistry analyses of palaeosoil horizon PS8.3 show preservation of organic material (samples B12/B23). The palaeoenvironment is characterized as water-logged with limited thermal affection. On this palaeosoil horizon a remarkable fossilized standing tree trunk has been preserved (possibly a giant Sequoia tree, typically thriving on soils with good moisture retention). It is worth mentioning that the layers of units 1-3 show limited lateral continuity. Unit 8.4 bears a lot of fossiliferous layers. Fossilized leaf litter (fossil leaves laid on fine-grained horizons) were found at various levels along with transported fossilized leaves and trunks scattered in the pyroclastic material. Organic geochemical analysis of sample B19 deriving from a lapilli tuff layer with scattered fossilized leaves and trunks, gave low values of alkane response and TLE relatively to samples from palaeosoil horizons such as sample B20 but still the presence of organic remains is noted. According to Retallack (1984), the preservation of leaves and wood in non-calcareous environments is only possible in water-logged environments with 0<Eh<200 mV and pH 2-5. Thus, the pyroclastic flow that generated this specific layer, contained sufficient amount of acidic water for the preservation of fossilized plant material and thus, the depositional environment was anoxic. Sample B20 from a small palaeosoil horizon gave evidence for a dry climate and a terrestrial environment (where waxy coatings on plants were more prominent) possibly consisted of vascular plants, trees, shrubs and herbaceous elements. The systematic taxonomy of fossil leaves indicates a rich flora dominating different habitats such as riparian and mesophytic forests in the lowlands and adjacent surroundings. Several plant taxa including ferns, diverse palms (e.g, Phoenicites sp.), Daphnogene polymorpha suggest proximity to a water source, while others such as Laurophyllum sp., Nerium sp. and Fagaceae spp. are indicative of well-drained soils. Units 8.5 to 8.8 present more thick and coarse-grained, organic matter-lean layers.

Conclusions • The stratigraphic analysis of West Akroheiras section allowed the identification of at least eight different eruption events recorded in the layers of this section (units 8.1-8.8). Based on standing fossil trunks at least three forests had developed on some of the palaeosoil horizons of this section. Detailed stratigraphic analysis of the volcaniclastic sequence serves as a basis for the synthesis of the results from all methods and for palaeoenvironmental reconstruction. • The taxonomy of the fossil leaves so far has revealed a mosaic of habitats such as riparian and mesophytic forests occurring in the broader area. The high alkane response and/or TLE implies decomposition and chemical transformation of organic matter (plants, algae or/and microrganisms) and favourable conditions for organic matter preservation (e.g. anoxic conditions, rapid burial and presence of clay minerals). • The preservation of leaves and wood in non-calcareous environments is only possible in water-logged environments with 0<Eh<200 mV and pH 2-5 (acidic environments). Thus, evidence for the physicochemical conditions of the water-saturated layers is provided. • Organic petrography on palaeosoil horizons gave evidence for water-logged environments amongst others. The diverse methods revealed that there is a great potential in clarifying the Miocene palaeoclimatic and palaeoenvironmental conditions of the Lesvos Petrified Forest and this potential is multiplied when these methods are applied combinatorically. In the future more systematic and detailed analyses are needed in order to fully unravel the history of the area, its palaeoclimatic and palaeoenvironmental evolution.

Acknowledgements We would like to sincerely thank Ass. Prof. Lambropoulou Paraskevi for the XRD analysis.

References Fischer, R., Schmincke, H.U., 1984. Pyroclastic Rocks, Springer-Verlag Berlin Heidelberg. [Book] Francis, P., Oppenheimer, C., 2003. Volcanoes. Oxford University Press. [Book] Hecht, J.,1972: Geological map Plomari-Mytilene sheet. 1:50000. IGME, Athens. Hecht, J., 1974a: Geological map Mithimna sheet. 1:50000. IGME, Athens Hecht, J., 1974b: Geological map Polychnitos sheet. 1:50000. IGME, Athens. Katsikatsos, G., Mataragas, D., Migiros, G., Triandafillou, E., 1982. Geological study of Lesbos island, Special Report, IGME, Athens. Pe-Piper, G., 1978. The Cenozoic volcanic rocks of Lesbos (Greece), unpublished readership thesis, University of Patras. [Dissertation] Pe- Piper, G., 1980. The Cenozoic Volcanic Sequence of Lesvos, Greece. Z. dt. geol. Ges., 131, 889- 901. [Journal Article] Pe-Piper, G., Piper, J.W.D., Zouros, N., Anastasakis, G., 2019. Age, stratigraphy, sedimentology and tectonic setting of the Sigri Pyroclastic Formation and its fossil forests, Early Miocene, Lesbos, Greece. Basin Research 2019, DOI: 10.1111/bre.12365. [Journal Article] Retallack, G., 1984. Completeness of the rock and fossil record: some estimates using fossil soils. Paleobiology, 10(1), pp.59-78. [Journal Article] Velitzelos, E., Zouros, N., 1997. The petrified forest of Lesvos–Protected natural monument. Proc. Internat. Sympos. On Engineering Geology and the Environment, Athens, 3037-304. [Conference Proceedings] Yılmaz, Y., Genç, Ş. C., Gürer, F., Bozcu, M., Yılmaz, K., Karacik, Z., … Elmas, A., 2000. When did the western Anatolian grabens begin to develop? Geological Society, London, Special Publication, 173, 353–384. https://doi.org/10.1144/GSL.SP.2000.173.01.17. [Journal Article] Zouros, N.C., 2021. The Miocene petrified forest of Lesvos, Greece: Research and geoconservation activities. Geoconservation Research. 4(2), 635–649.[Journal Article] Zouros,N., Soulakellis,N.,Valiakos,I., Bentana,K., Theodorou,E., Zgournios,E., Antonakis,E. and Lamprakopoulos,A.: Enhancement and promotion of the new fossiliferous sites along the new Kalloni Sigri road.-An example of good practice in geoconservation in Lesvos Isl. UNESCO Global Geopark Greece. Bulletin of Geological Society of Greece Sp. Publ. 10, pp. 849-850.[Conference Proceedings]

ABSTRACT. This study concerns the geobiological dimension of the influence of microorganisms on skeletal elements in relation to the fossilization/conservation environment. Our first aim is the identification of microstructures and their correlation with specific microorganisms (bacteria, cyanobacteria, fungi, etc.). The second aim is to correlate the presence of micro-organisms to specific geochemical conditions and to specific environment of activity (terrestrial or aquatic). However, it is also important to determine the exogenous or endogenous origin of microorganisms.

ABSTRACT. This study investigates the impact of Cyclone Daniel, which struck Greece in September 2023, leading to significant geohazard occurrences in the Meteora municipality, Trikala Prefecture. Focusing on the Municipal Units of Kleinovos, Kastania, and Aspropotamos, this paper examines the relationship between extreme weather events and the increase in geohazard phenomena such as landslides, erosion, and flood-induced deposition of materials. The research aims to understand the triggering mechanisms of these events and assess the effectiveness of existing landslide susceptibility maps in predicting landslide locations. By analyzing 114 recorded geohazard events, the study identifies key meteorological factors influencing slope stability and provides recommendations for improved risk mitigation strategies. These strategies include enhanced water management, tailored landslide prevention measures, and ongoing infrastructure maintenance. The findings contribute valuable insights for refining susceptibility mapping and developing more robust geohazard risk management frameworks for the region.

ABSTRACT. Engineering geological and geotechnical design for slope stability to ensure the long-term protection of the overlying buildings and footpath along a coastal slope in the traditional settlement of Chora, in Andros Island (Cyclades), including design implementation, rehabilitation works, and aesthetic interventions. The failure occurred along a weakness zone in the schist rock mass, resulting in a wide caving and smaller-scale slides. In order to ensure the stability of the slope, to eliminate the unsafe conditions for the overlying buildings along the slope crest and the risk of accidents in case of additional rockfalls along the footpath running close to the slope toe, to provide long-term protection of the rock mass against wedge and planar failure, erosion induced from water runoff, coastal erosion due to the slope’s proximity to the sea, and its continuous exposure to wind and waves, as well as to rehabilitate the caving and overall geometry of the slope from both recent and older failures, a rehabilitation scheme comprising the combination of rock bolts, shotcrete, and wire mesh across the entire slope surface was proposed, as the most efficient and aesthetically acceptable support system. Moreover, special attention was given to shaping the final slope surface to closely resemble its condition prior to the rehabilitation works, with aesthetic interventions made in consideration of the features of the traditional settlement.

ABSTRACT. In recent years, the Acoustic Emission (AE) method has seen significant advancement and usage in the field of rock mechanics for monitoring the gradual fracturing process and stress induced damage due to crystal or grain sliding, crack growth and coalescence. The AE technique has been used both in laboratory and in-situ applications especially in tunnels for studying the elastic wave propagation characteristics and acquiring parameters that can reflect the rock fabric and damage evolution process before the macroscopic rock failure. Acoustic Emissions consist of elastic sound waves that are transmitted from the interior of a localized source (etc. rock sample) during crack development. These elastic waves are the result of stored accumulated energy that suddenly releases during external loading. The resulting AE waves propagate through the rock and then captured from specialized surface piezoelectric sensors. The sensors convert the mechanical waves into electrical signals and record them as AE events (Hits) in specialized acquisition programs. Several parameters can be extracted from the raw data such as hits, time of arrival, amplitude, frequency and energy of the AE signals.

According to literature, the AE method has been used in the laboratory for the determination of various values and factors such as (1) the AE activity regions (Boyce et al., 1981) and their connection with the main cracking stages, namely the crack coalescence (σcc), the crack initiation (σci) and the crack damage (σcd) stages in the stress-strain diagram (Martin C.D., 1993), (2) the B-value factor whose reduction during the loading process provides insight on the gradual failure and the stability of the rock (C. H. Scholz, 1968) and has been used as a risk assessment tool in various civil projects (Gerd Manthei et al., 2018) and (3) the Felicity ratio (FR) after several loading cycles. FR less than unity depicts the transition from the Kaiser effect (absence of AE events until the previously experienced stress on the material is exceeded (Lavrov, 2002)) to the Felicity effect ( presence of AE events before the previous cycle’s peak stress) from which point, the damage that has been accumulated is irreversible. As such the FR value can be used as a rock’s quality index (Kallimogiannis, 2023). Outside the laboratory scale and into the deep tunnel construction, the already complex in-situ stress environment is redistributed during excavation causing microcrack and later macrocrack generation if the crack initiation load is exceeded. These microcracks gradually cause changes in the rockmass integrity, stability and physical characteristics that if not suitably predicted and supported, lead to brittle rock failure. As such, AΕ monitoring has been utilized together with numerical simulations and laboratory AE tests in several underground mining and tunneling projects to examine the size of the excavation-disturbed zone (EDZ) (Stephen D. et. al., 1996) and predict hazards such as rockbursts (X. Chang et. al., 2015), thermal induced dilation (J Hesser et. al., 2015) and ruptures of not-persistent joints (Shuting Miao et. al., 2024).

In this study, the AE method was implemented during Uniaxial Compressive and Cyclic loading laboratory tests* in several rock types such as a Limestone both in intact and karst form from Revithousa island, a tectonized Slate from South Crete and a Trachyandesite from Poros island. The scope of this study is to examine if the determination of the above factors with the Acoustic Emission method can be utilized as basic monitoring tool both inside the laboratory and in underground construction projects, providing greater insight into the rockmass behavior from the standard rock mechanic tests.

ABSTRACT. The analysis of rockfall hazard on rocky slopes is of vital importance for the safety of engineering works and the protection of human lives, being the subject of numerous scientific studies. Advances in technology, with the use of unmanned aerial vehicles (UAVs) combined with photogrammetric techniques, allow the creation of high accuracy 3D models for rockfall mapping, even in inaccessible areas. Although internationally these methods are widely applied, in Greece the relevant studies are limited. In the area of the Vrachon Theatre in the Municipality of Byron, UAV was used to collect 500 aerial photographs, which were processed with Pix4DMapper. Using AutoCAD and ArcGISPro, a topographic map and cross-sections were created, while RocFall was used for falling simulations. The objective was to assess the hazard, suggest mitigation measures and generate a hazard map.

ABSTRACT. Landslides pose a significant risk to communities, infrastructures, and the natural environment throughout Europe and worldwide. Driven by complex geological settings, increasing urban development, and infrastructure expansion, as well as the occurrence of extreme climatic events, landslides are becoming more frequent and severe. This presents a growing hazard for both human activities and economic assets. The presented in this work Landslide Inventory Platform named as He.L.P. (Hellenic Landslide Platform) is a first attempt to publish a web-based GIS platform that provides information on landslide phenomena which have been recorded over time in the geographic territory of Western Greece, as defined by the administrative regions of Western Greece, Epirus, and Ionian Islands

ABSTRACT. Rock slope instabilities pose a significant problem to cultural heritage sites in Greece. The paper presents the assessment of rock slope stability of the volcanic rock cliff in the village of Petra in Lesvos Island, on which the Church of the Koimisi of Theotokos is founded. The rock cliff has almost vertical slopes with height up to 40 m and is formed by an andesitic rockmass, fractured by four discontinuity sets. The predominant kinematic instability is wedge or toppling failures of medium-sized rock blocks. The problem of potential rock instability of the volcanic slope in Petra has been investigated in the past and rock fall episodes have occurred mainly triggered by intense rainfall. Due to the weathering and deterioration of the andesitic rockmass, the risk of rock instability has increased in the last two decades and it was deemed necessary to protect the foundation of the monument as well as the surrounding settlement and visitors from potential rockfalls. Stabilisation measures were proposed to minimize the risk of rockfalls and protect the foundation of the Church

ABSTRACT. Lunar pits are distinct geological features scattered across the Moon's surface that offer insights to the subsurface structure of the Moon, potentially indicating the existence of ancient lava tubes formed by volcanic activity. This study conducts a statistical analysis of 278 documented pits, utilising morphometric and geophysical datasets derived from the Planetary Data System Archive (PDS) of the Lunar Reconnaissance Orbiter Camera (LROC) and the Lunar QuickMap platform accordingly.The examination of the morphometric and geophysical properties of lunar pits showed that they often have undefined or elliptical shape, varying geometry and are often present in several clusters, near depressions located within crater impact melts. Mineralogy and chemistry are consistent with the geological context of their locations. Although the spatial resolution of the current available data is often a limiting factor, the examination of their properties are indicative of the Moon’s geological history, surface processes and stability. Furthermore, lunar pits are potentially linked to subsurface lava tubes or caves which could be promising sites for future human exploration, human habitats and infrastructures. Their unique structure potentially offers natural protection from extreme temperatures, cosmic radiation, and meteorite impacts, making them prime candidates for sustainable lunar bases, landing site selection and long-term lunar sustainability research.This study is part of Mr. Klimis’ BSc thesis. Future continuation of this work includes the study of the each pit cluster, comparison of different pit clusters within different geological contexts, thermal properties (outside and within pits), and the detection of new pits potentially linked to subsurface lava tubes or caves.

ABSTRACT. Pheneos polje, located in northern Peloponnese (Greece) is strongly linked to the homonymous mythical lake. Throughout the past millennia, flooding events in the southern part of this polje have given rise to a lake. The myths associated with the lake revolve mostly around its drainage periods, with local populations suggesting that Hercules himself excavated openings to the ground with his bare hands to rescue the villagers from flooding (Jones, 1988). In reality, the water drains through sinkholes that are part of the region’s karstic system (Tsoflias, 1973). In the southernmost part of the polje, distinct step-like scarps on the landscape serve as indicators of past lake levels (Figure 1). These scarps, representing notable geomorphological features, have been documented by Pausanias and other historical travelers (Groumpou, 2024). The primary objective of this study was to verify these features as relict shorelines of the ancient Pheneos lake. Two distinct datasets, consisting of orthophoto maps and digital surface models (DSMs) were used to identify and map the step-like landforms across the landscape. The first dataset consists of a 50 cm spatial resolution orthophoto map and a 5 m pixel size DSM, whereas the second dataset consists of an orthophoto and a DSM of 4 cm spatial resolution. ArcMap 10.8 was used to display and analyze the two datasets. Subsequently, fieldwork was conducted to examine the characteristic features of the stepped landforms, and 35 surface sediment samples were collected from the different step-like scarps across the southern margins of the polje and processed for micropalaeontological analysis. The results reveal that the step-like scarps in the landscape consist of alternating coarse-grained gravel material and fine-grained material rich in gravel containing lacustrine taxa, which were deposited in a nearshore environment (Groumpou et al., 2024). A pattern of at least four such alternating sediment deposits has been mapped from the orthophoto maps, corresponding to distinct palaeoshorelines (Figure 2). These deposits contain a micropalaeontological assemblage comprising charophyte remains (gyrogonites and oospores), ostracods and gastropods. The most representative taxa of the identified micropalaeontological assemblage are Nitellopsis obtusa (Desvaux) Groves, 1919, Sphaerochara prolifera (Ziz. Ex. A. Braun) emend. Soulié-Märsche, 1989, Chara vulgaris Linnaeus, 1753, Ilyocypris bradyi Sars, 1890, Ilyocypris inermis Kaufmann, 1900, and Candona neglecta Sars, 1887 (Figure 3). Based on the ecological preferences of these taxa and their geographical distribution along the southern margins of the polje, three distinct lacustrine palaeoenvironments are identified: i) ephemeral lake (possibly annual) dominated by S. prolifera which is present up to an altitude of 710 m ii) cold and oligotrophic lake environment characterized by the presence of N. obtusa and I. inermis, observed up to an altitude of 729 m and iii) warmer and mesotrophic lake, extending to altitudes of up to 744 m. The analysis of the stepped landscape in the southern margins of Pheneos polje revealed a sequence of at least four alternating sedimentary deposits, enriched with lacustrine taxa and which are indicative of near-shore depositional environments. The possible boundaries of Pheneos palaeolake are mapped and three distinct lacustrine palaeoenvironments were recognized based on the ecological preferences of the respective taxa (Groumpou et al., 2024). These findings provide insights into the Holocene dynamics and depositional history of the Pheneos polje.

ABSTRACT. This paper introduces a newly developed 55-hour educational program designed for higher education graduates to bridge knowledge gaps in speleology. The multidisciplinary course covered geosciences, biology, and archaeology, combining theoretical learning with practical fieldwork and advanced technologies. Emphasizing safety, data collection, and interdisciplinary methodologies, the program prepared participants for comprehensive cave research. Offering 4 ECTS credits and a specialized certificate, it significantly advanced speleological education while promoting sustainable research practices.

ABSTRACT. The Laconic Peninsula (SE Peloponnese), located in the tectonically active forearc of the Hellenic Subduction Zone, is a first order example for the investigation of the long-term tectonic activity and landscape evolution through the study of uplifted marine terraces. This research aims to map and analyze the distribution of marine terraces in three sectors located at the western and eastern coasts of the peninsula, employing GIS techniques on high resolution topography and field survey. In Sector A, eight well-preserved marine terraces were identified at elevations ranging from 5 to 460 m, shaped by tectonic processes associated with the subduction zone and local faulting. Sector B revealed seven terraces at lower elevations (9 to 200 m), reflecting tectonic displacement driven by fault activity. Sector C displayed five terraces at lower elevations (5 to 118 m), suggesting reduced tectonic influence compared to the other sectors. The findings indicate differential uplift rates and tectonic deformation across the peninsula, driven by the interplay between the subduction zone and local faults. Future geochronological studies are recommended to refine terrace dating and deepen understanding of regional tectonic dynamics.

ABSTRACT. Shell middens are anthropogenic deposits containing significant amounts of shell material. They form in areas where human communities - whether hunter-gatherers, horticulturalists, agriculturalists or industrial societies - intensively harvest shellfish, extract and process the meat for consumption, or repurpose the shells as raw materials. In this study, we present the results of Optically Stimulated Luminescence (OSL) dating of five sediment samples collected from sand layers developed below and above a coastal shell midden outcrop approximately 80 m from the shore at Umhlanga Rocks on the Natal north coast. OSL ages obtained for the sedimentary layers of the stratigraphic section range from 4.55±0.14 ka to 1.08±0.04 ka. These ages are generally in stratigraphic order (with the exception of one sample) and align with independent age controls derived from radiocarbon dating of samples from the Emberton Way site. Findings from the archaeological excavation of the Emberton Way midden, located near the stratigraphic section studied here, suggest a connection between large beachfront shell midden deposits and substantial inland village sites during the Msuluzi-Ntshekane period. The limited range of resources exploited from the middens, as documented by previous researchers along with the distinctive Early Iron Age ceramics, strongly supports an agriculturist attribution for these sites. This evidence contradicts the earlier hypothesis of residual hunter-gatherer origin.

ABSTRACT. Here we investigate microplastic contamination in remote karst aquifers of Crete, Greece. We sampled water from three caves within the Lefka Ori mountain range, analyzing the samples for microplastics using stereoscopy and μ-Raman spectroscopy. We found a significant number of microplastic fibers and fragments, predominantly blue and transparent. Also, low electrical conductivity of the water samples suggests rapid water percolation hence we suggest that aeolian transport via westerly winds is the likely source of microplastic contamination. Our highlight the pervasive nature of microplastic pollution, even in seemingly pristine environments.

ABSTRACT. The lower bauxite strata (b1), hosted within the Mesozoic carbonate sequence of Parnassos-Giona Unit, hasn’t been studied extensively, since it occurs sporadically, with limited quantities and low grade in terms of Al. In this study, seven sampling sites were examined in order to assess the main mineralogical, geochemical and mineral-chemical characteristics of the bauxite profiles, with emphasis on the REE distribution. The aim of this study is to investigate the REE mode of occurrence in the bauxite samples in the lower bauxite strata of the Parnassos-Giona Unit. The lower bauxitic strata b1 shows a relative enrichment in rare earth elements, which seem to concentrate at the pure bauxite samples in comparison to the transitional lithologies. Additionally, for the first time REE-bearing minerals within b1 are reported. The overall geochemical signatures point to variable depositional conditions in terms of alkalinity, as well as redox conditions.

ABSTRACT. The use of clay in the ceramics industry is significant, because the properties influence greatly the final product's quality and performance. Greece has clay deposits that remain underexploited for artisanal and handicraft applications and imported clays are predominantly used. This study aims to evaluate the suitability of specific clayey raw materials for ceramic applications such as pottery, through characterization and mechanical testing. The research involves granulometric analysis, particle size analysis, and determination of Atterberg limits to assess plasticity. Experimental clay specimens are manufactured and subjected to mechanical strength tests, including flexural, tensile and compression testing, at two different firing temperatures. Additionally, mineralogical characterization is performed on both clayey raw materials and sintered specimens to investigate phase transformations. Particle size analysis and other complementary techniques are employed to further understand the material’s behavior. Raw material prospection and sampling were undertaken, in accordance with the data provided from Mineral & Aggregate Resources Division of Greek Ministry of Environment, Energy and Climate Change. The clay samples are sourced from active quarries in Greece, specifically from Central Euboea, Central and Western Macedonia, and Central Greece, as potential material sources for pottery applications. The results will provide critical insights into the clay’s applicability in ceramic production, highlighting its structural integrity and performance under different conditions. Additionally, these findings will promote the use of Greek clays in pottery applications.

ABSTRACT. The Philadelphio Sb-mineralization features complex mineralogical and geochemical characteristics, with stibnite as the primary mineral alongside native antimony, sphalerite, pyrite, and accessory phases such as chalcostibite, tetrahedrite, wolframite, and berthierite. Microscopically, stibnite exhibits bireflectance, pressure lamellae, and intergrowths with quartz, forming massive or disseminated textures. Supergene oxidation has produced secondary minerals like stibiconite, chapmanite, and kermesite. SEM-EDS analysis reveals trace element variability in stibnite, with Ag, As, Cu, and Fe showing moderate incorporation influenced by geochemical conditions. Sphalerite forms intergrowths with stibnite and contains trace elements like As, Cd, and Mn, reflecting heterogeneous fluid conditions. Compared to stibnite from Rizana and Gerakario, Philadelphio displays greater trace element enrichment, indicating dynamic mineralizing fluids and varied formation conditions. Ongoing EPMA and LA-ICP-MS analyses aim to refine the genetic model and enhance understanding of the mineralization processes, contributing to regional metallogenic studies.

ABSTRACT. The capture and storage of carbon dioxide is an important process, as it helps to prevent the negative impacts of CO2 emissions in the atmosphere, such as the greenhouse effect and ocean acidification, among others. On the other hand, the storage of hydrogen is an environmentally friendly process, as it allows for large-scale controlled and flexible energy conversion. Storage of both hydrogen and carbon dioxide in salt caverns has emerged recently as a favourable option due to its numerous benefits, such as the high withdrawal capacity, favourable mechanical properties, and enhanced safety. Triassic evaporites diapirism, which involves the buoyant uprise of large masses of evaporites through piercing and displacing, either reaching the surface or halting at depth, has mainly occurred in Western Greece along the Ionian zone, as in the areas of Aitolo-Akarnania, Hepirus, the Ionian islands, as well as in the Western Peloponnese. Salt caverns provide significantly higher storage volumes compared to traditional surface fuel tanks, making them ideal for large-scale energy storage. The geological suitability for geo-energy storage in salt caverns is determined by certain fundamental geological criteria, such as i) the depth of development of the storage cavities, ii) the minimum thickness of the salt formation, (iii) the mineralogical composition of the evaporite formations, and (iv) the petrophysical properties of the host rock (i.e., low porosity and permeability, pore structure, etc.), in order to ensure that the supercritical gas remains in the cavity and to prevent the potential risk of leakage. The above criteria for geological suitability for subsurface storage were examined and evaluated in some representative areas in Western Greece, where evaporitic rock samples were collected and analysed, by applying several laboratory techniques (e.g., XRD, MICP, BET-analysis) in the areas of Katouna (Aitolo-Akarnania), Pagos (Corfu), and various sites in proximity to Preveza (Kanalaki-Aidonia-Chimadio sites). Based on the interpretation of these preliminary results and the required geological criteria for underground energy storage, the prospects of storage in artificial cavities in evaporite rock formations are discussed, and the adverse factors that require further study in the future research stages are presented.

ABSTRACT. Indium and tellurium are critical metals for renewable energy and advanced technologies. Tellurium is essential for cadmium telluride (CdTe) solar cells, while indium is vital for indium tin oxide (ITO) coatings used in displays and solar panels (Werner et al. 2017). Both elements are primarily obtained as by-products of base-metal mining (e.g., zinc and copper refining), making their production highly dependent on these industries. Understanding their geological occurrences is crucial for enabling more targeted exploration and efficient extraction, thereby reducing reliance on imports. This is of particularly significance, as China dominates global production, creating supply chain vulnerabilities (Werner et al. 2017). The Pefka high- to intermediate-sulfidation deposit hosts the highest indium and tellurium grades in Greece (1160 ppm In and >1000 ppm Te), making it an ideal case to study the enrichment processes of these metals in an epithermal environment (Voudouris et al. 2022; Melfou et al. 2023). The objective of this study is to investigate the capacity of minerals to incorporate indium and tellurium at various stages of mineralization and the processes that control their enrichment. These particularly include roquesite for indium and tellurides/goldfieldite for tellurium, but also in minor proportions galena, luzonite, chalcopyrite, and Cu-rich varieties of tennantite-tetrahedrite. Furthermore, the study aims to assess the potential of pyrite to provide insights into ore-forming conditions within a deposit characterized by a complex paragenetic sequence with numerous mineral phases.

ABSTRACT. Hydrothermal alteration of peridotites or serpentinites from ophiolite complexes, remnants of the Neotethys oceanic lithosphere has formed listvenites either mineralized or non-mineralized in many places, including Kosovo, Greece, Turkey, Oman, and Iran. In Greece, listvenites have been reported in Tinos Island, Mount Oeta in Central Greece, Gerakini and Vavdos at Chalkidiki, and in Vyrsini at Komotini. The term listvenitization is used to describe the range of carbonization processes, from carbonate-rich to silica-rich phases, caused by hydrothermal fluids enriched in CO2. These rocks are typically composed of quartz, Ca-Fe-Mg carbonates, fuchsite, serpentine, talc, chlorite, relics of chromite, magnetite, sulfides, and arsenides. They commonly occur in shear or fault zones that serve as pathways for hydrothermal fluids, facilitating CO2 infiltration and subsequent metasomatism. Listvenites are important since they are commonly associated with lode gold mineralization, as well as enrichment in other precious and critical metals, such as Ag, Hg, Co, Ni, As, and Sb that have been formed under low temperature conditions. The transformation of peridotite to listvenite involves multiple stages, beginning with hydration to form serpentinite, followed by carbonation and metasomatism through the influx of CO2 rich fluids. This transition is gradual, evolving with increasing CO₂, and involves intermediate stages characterized by the progressive replacement of serpentine or talc, leading to quartz-carbonate assemblages. Based on the modal proportions of quartz and carbonate, three types of listvenite lithologies can be classified: carbonate listvenites, silica-carbonate listvenites, and silica listvenites. The objective of this study is to present preliminary data on the mineral composition of the listvenite occurrences in the Kato Vyrsini region in the Rhodope massif, and to document the mineralization they host, which has not been studied in detail so far.

ABSTRACT. This study focuses on the analysis of crustal deformation the period before and after the strong Mw6.8, 2018 Zakynthos earthquake, utilizing Interferometric Synthetic Aperture Radar (InSAR) data detecting ground surface changes over a period of six years. The earthquake took place southwest of the island on October 25, 2018, with an estimated magnitude of Mw6.8 (Papadimitriou et al., 2021). This seismic event was one of the most significant events in recent years in the broad region, producing noticeable ground displacement (~40 mm in the southern part of Zakynthos), reflecting the dynamic tectonic processes on the South Ionian Islands. Analysing pre- and post- seismic InSAR datasets, patterns of ground motion were identified and quantified aiming to assess the deformation processes before and after the earthquake based on the estimated velocity changes and its spatial distribution across Zakynthos.

ABSTRACT. The main objectives of the current study include the determination of the mean recurrence time, Tr, of large (M6.0) earthquakes associated with the major fault segments of the Corinth Rift, Greece, and the estimation of the conditional occurrence probabilities of an impending M6.0 earthquake on each major fault segment. The recurrence behavior of large earthquakes (e.g. M6.0) on specific fault segments is one of the primary input parameters for developing long–term Earthquake Rupture Forecast (ERF) models. These models integrate a series of parameters (maximum observed magnitude, fault dimensions, long–term slip rates, available recurrence times) to estimate the occurrence likelihood of nearly characteristic magnitude earthquakes in a specific time span. The primary output of such models is the mean recurrence time, which can later be used for the application of statistical models, which, in turn, return the likelihood of the occurrence of near characteristic magnitude earthquakes over specific time intervals and can be based on either a time–independent or an elastic rebound motivated renewal assumption. A precise and robust estimation of Tr requires the inclusion of as many large earthquakes associated with individual fault segments as possible, including both historical and instrumental data along with the selection of the appropriate statistical model. However, large earthquakes associated with specific fault segments are often limited, with only a few cases having about 3 to 10 observations due to the long duration required for stress accumulation and the short time span of available large earthquake records. To address these challenges and limitations, an alternative approach is the estimation of Tr through the application of the seismic moment rate conservation method (Field et al., 1999). This method defines the mean recurrence time as the ratio of the maximum expected seismic moment corresponding to a large earthquake with the maximum observed magnitude (Mmax) occurring on a given fault segment, to the seismic moment that might be released by the respective fault segment due to the tectonic loading, assuming a nearly characteristic earthquake model. This approach can provide more precise Tr estimates because the overall rate and size distribution of earthquakes should reflect the tectonic loading in the brittle part of the crust, and this function is typically constrained by the principle of seismic moment rate conservation.

ABSTRACT. The Kefalonia Transform Fault Zone (KTFZ) is the most seismically active area in the Mediterranean and consists of two major branches, the Lefkada fault segment to the north and the Kefalonia fault segment to the south. KTFZ acts as an active boundary between the subduction zone of the remnants of the oceanic lithosphere of the Eastern Mediterranean that subducts under the Aegean microplate to the south and the continental collision between the Eurasian plate and the Adriatic Microplate to the north. The tectonic activity in the region is reflected in the rapid crustal deformation rates of the region and subsequently the frequent occurrence of strong earthquakes (Mw>6.0) that occurred during both the historical and instrumental era of seismology. Those strong earthquakes and their temporal distribution can be explained due to stress transfer between closely located fault segments (Papadimitriou, 2002) and as such, studying those stress interactions is an integral part of understanding the long-term tectonic loading in the region. For better understanding of the kinematics and the distribution of continental deformation that is occurring within the brittle crustal layer in the study area, we assess the regional stress field by inverting focal mechanisms. Contemporary stress field in an area is a result of processes that operate at significantly different spatial scales (Zoback, 1992). Forces that are linked to major tectonic movements such as ridge push and slab pull affect the stress field at large wavelengths, beyond 2000 km and are considered first–order sources of stress field perturbation. At intermediate wavelengths (between 2000 and 500 km) the crustal stress field is affected by processes such as orogenic lithospheric flexure (Zoback, 1992) with those processes representing second order sources of stress field disturbances. Third order patterns of crustal stress field are linked to small–scale variations (<100km) that are produced by processes such as active faulting and at times these variations may lead to the nucleation of potentially destructive earthquakes (Hergert and Heidbach, 2011). Detailed knowledge of the contemporary stress field characteristics of high–risk areas, such the central Ionian Islands region is valuable for possible investigations of stress triggering sensitivity due to the coseismic slip of strong earthquakes.

ABSTRACT. Introduction Western Greece, a tectonically active region, is marking a North to South shift between collision to subduction, driven by the interaction between the Apulian platform, the oceanic subduction beneath the central and south Ionian Sea, and surrounding micro-blocks on the overriding plate. This region exhibits complex fault interactions and significant seismicity due to broader active faulting and the convergence of the Nubian and Eurasian plates. The area’s tectonics are dominated by the Cephalonia Transform Fault Zone (CTF), a series of right-lateral fault segments, which mediates the transition from continental collision in the north to oceanic subduction in the south. This study leverages geodetic data (GNSS observations) to develop an elastic block model that elucidates fault geometries, block rotations, and slip rates, improving understanding of seismic hazards and regional deformation.

Study Area and Tectonic Setting Western Greece encompasses the Ionian Islands, the western Peloponnese, and mainland areas such as Epirus and Aitoloakarnania. The CTF delineates a significant tectonic boundary between the Apulian-Ionian block and northwestern Greece. In addition, extensional grabens, including the Gulf of Amvrakikos (GoA), Gulf of Patras (GoP), and Gulf of Corinth (GoC), mark Plio-Quaternary active fault systems linked to slab retreat. Strike-slip faulting along two major continental faults is taking place along the Katouna-Stamna Fault (KSF) and the Movri Fault Zone (MFZ) which is located in the northwestern Peloponnese.

Methodology Using geodetic data from 92 published GNSS stations spanning Greece and southern Italy, this study applies an elastic block model to analyze horizontal velocity fields (Hollenstein et al., 2008, Briole et al., 2021, Serpelloni et al., 2022). The model estimates block rotations, fault slip rates, and strain accumulation, integrating seismic, geological, and geodetic data. Euler poles and velocity residuals were employed to validate fault activity and block boundaries. Key fault segments and their kinematics were characterized based on observed velocity gradients and published geological and seismological data.

Model Results and Block Kinematics The best-fitting model identifies five major tectonic blocks in Western Greece: 1. Apulian Block (APUL): Encompasses the central Ionian Sea and parts of the Italian peninsula. 2. Ionian-Akarnania Block (IAB): Bounded by the CTF, GoA graben, and Katouna-Stamna Fault (KSF). 3. Central Greece Block (CGRE): Defined by faults along the GoC and GoP. 4. Peloponnese Block (PELOP): Southern boundary influenced by the Movri Fault Zone (MFZ) and offshore structures. 5. South Aitolia Block (SAB): Proposed as a micro-block between the GoT and GoP.

Key Findings: 1. Cephalonia Transform Fault (CTF): The CTF exhibits a right-lateral strike-slip motion (~16 mm/yr) with a reverse component (~5 mm/yr). The fault’s slip rates align with previous studies, confirming its role as a boundary accommodating significant crustal deformation. 2. Extensional Grabens: The GoA shows rapid extension (~10 mm/yr), with indications of left-lateral shear consistent with the KSF’s westward continuation. The GoC and GoP are characterized by northward and southward fault-dipping systems. 3. Katouna-Stamna Fault (KSF): This NW-SE striking fault displays left-lateral slip (~12 mm/yr) with low locking depths, suggesting aseismic creep along segments. 4. Movri Fault Zone (MFZ): The MFZ demonstrates right-lateral motion (~8 mm/yr) with a possible tensional component. It likely contributes to the southern boundary of the IAB. 5. Triple Junctions: Two triple junctions were identified -one near the western GoC (Rio area) and another near the GoA (offshore Preveza)- and define zones of complex deformation and intense seismicity. The GoP is a site of interaction between strike-slip and extensional faults.

Validation and Model Performance The model achieves a high data variance reduction (99.4%) and a weighted root mean square error (wrms) of 0.94 mm/yr. Residual analysis highlights minor localized mismatches in areas with complex secondary faults or diffuse deformation zones. Slip vectors from earthquake focal mechanisms align well with predicted fault motions (see Fig. 1a), validating the model’s accuracy.

Conclusions This study underscores the utility of elastic block modeling in delineating the kinematics of fault systems and tectonic blocks using tectonic velocities from high-quality GNSS data. Western Greece’s tectonics are dominated by crustal block interactions of the overriding Aegean plate along major faults such as the CTF, KSF, and MFZ, as well as active grabens. The findings include new data on fault slip rates and locking depths and highlight critical areas for seismic hazard assessment, such as the GoA and GoP, where significant strain accumulation and potential fault creep are observed. Further integration of subduction processes and secondary faults into models could refine predictions of regional seismic risks.

Acknowledgements This research was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the 3rd Call for HFRI PhD Fellowships (Fellowship Number: 05176). Also, this work is supported in part by funds from the Erasmus+ Internships.

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ABSTRACT. Near Fault Observatories (NFO) are natural laboratories undergoing active, and complex geophysical processes at, or in proximity to, densely populated urban areas. NFOs bound relatively small areas and are ideal sites for in-depth monitoring and advanced research. Six NFOs in Europe, have been identified by the European Plate Observing System as long-term Research Infrastructures; three additional NFOs are in observer status. NFOs target the enhanced understanding of the mechanics of earthquakes to unravel the anatomy of complex seismogenic faults. This can only be achieved by the acquisition of continuous, long-term, high-resolution, high-quality, and high-density multidisciplinary data, and the application of consistent, high quality and state-of-the-art data processing. TRANSFORM² has the ambitious goal of improving and transforming the existing NFOs, by integrating cutting-edge methodological and technological solutions, paving the road for the next generation NFOs across Europe. This will be achieved through the development of four ‘concepts’: I) Innovative sensors - new generation of sensors in basic and applied research related to earthquake processes; II) Elevated detectability - novel automatic workflow for enhanced detectability and characterization of earthquakes; III) Early warning - new platforms for supporting decision-makers during earthquake alerts: IV) Test-bed - next generation of accessibility for testing and development of new cutting-edge sensors and algorithms. A focus will be on bringing transformative concepts such as Machine Learning and fiber optic cable sensing to the NFO community. Breakthrough ideas will be explored and addressed with focus on analytical and feasibility control detecting weaknesses and missing elements that will be resolved within the project. Awareness and engagement of stakeholders as well as societal needs will be a priority. Issues concerning NFO funding and sustainability will be addressed.

ABSTRACT. The large quantities of seismic waveform data available have rendered their manual analysis a challenging task. In recent years, the rise of Machine-Learning (ML) models has revolutionized the automatic processing of seismological data, greatly augmenting the number of detected events and lowering the completeness magnitude of seismic catalogs. At the same time, the results produced are highly accurate and comparable to those derived by manual analysis. In this work, we apply the DiTing-Motion (DTM) machine-learning model to measure the First Motion Polarities (FMPs) and use the HASH code to determine the focal mechanisms of weak-magnitude earthquakes that occurred between December 2020 and December 2022 in the western Gulf of Corinth (WGoC). We employ waveform data from the Corinth Rift Laboratory Network (CRLNET) and the Hellenic Unified Seismic Network (HUSN). The automated workflow yielded 370 focal mechanisms for the WGoC crisis of December 2020 - February 2021, and 65 for the aftermath period, up to December 2022, classified by HASH with a quality grade “A”. A comparison with manually measured FMPs showed a good agreement with the automatically determined ones for about 90% of the measurements. Discrepancies were mainly observed for distant stations (>30 km) and accelerometric stations. The Kagan angles between automatic and manually determined focal mechanisms are below 30 degrees in most cases. As ML models can be improved by re-training, using site-specific data, this method is promising, regarding the generation of large datasets of focal mechanisms of small earthquakes. The latter could be useful for studies of fault geometries, spatial stress patterns, and even temporal stress changes prior to impending large earthquakes.

ABSTRACT. The present study focuses on the stability analysis of a rock slope along the Kleisoura – Kastoria road axis. Its main objective is to assess the rock mass behavior, to predict future failures and propose remedial measures to protect the infrastructure. For this purpose, both traditional and modern data collection and processing methods have been utilized. Specifically, the study focuses on the use of Unmanned Aerial Vehicles (UAVs) combined with the application of the photogrammetry method, to create a 3D point cloud of the studied rock slope. This point cloud was then processed and used to semi-automatically extract the discontinuity sets’ orientations and spacing, using the Discontinuity Set Extractor (DSE) software. Subsequently the mean rock volume was calculated, and trajectory analyses were performed. The studied slope consists of gneiss, which forms part of the bedrock of the Pelagonic geotectonic zone. It is characterized by three main discontinuity sets, while a fourth set was only locally observed. The rock exhibits varying degrees of weathering, from slightly weathered to residual soil. The roughness of the discontinuities’ surfaces also varied, with Joint Roughness Coefficient (JRC) values ranging from 7 to 12. The friction angle used in the kinematic analyses was calculated to be 43 degrees and the most common type of potential failure identified was wedge failure. The formed blocks were found to be small to medium in volume. To protect the infrastructure against potential future rockfalls, the installation of a draped mesh was proposed.

ABSTRACT. This study focuses on the mountainous remote settlement of Klepa, which has been influenced by landslide events in the past years, and employs a GIS-based multicriteria analysis using the Analytical Hierarchy Process (AHP) to evaluate geological suitability. This methodology includes six factors (Geohazards/Landslides, Geomorphology/Slope, Geology/Lithology, Hydrology/Rivers, Ground Seismicity Hazard and Tectonics/Faults) affecting the study area to produce a suitability map and categorize existing settlement conditions into safe or unsafe building zones. The Analytical Hierarchy Process (AHP) assigns certain weights to the chosen criteria and spatial datasets are produced within a GIS environment to create a geological suitability map that identifies optimal areas for development. The final map corresponds to unique geological suitability levels, namely Highly suitable, Moderately suitable, Marginally suitable and Unsuitable.

ABSTRACT. A long term investigation on landslide phenomena in Corfu Island, consumes that the majority of them are strongly connected with rainfall events hit Western Greece and Ionian Sea islands, annually. The last years an increasing number of precipitation events occurred in Greece are characterized by meteorologists as extreme events, with a large amount of rain falls in a short time. Based on the landslide database of the Hellenic Survey and Mineral Exploration (H.S.G.M.E.) from 1959 to 2022, 203 landslides in a 592 km2 area have been officially recorded and mapped into a multi-temporal landslide inventory map. In general, the study area is prone to landslides, but where? Landslide susceptibility assessment is an important tool for identifying areas prone to landsliding. This study discusses the quality of the landslide susceptibility map of Corfu Island using retrospective data from landslides to examine the predictive performance and the acceptance of such maps.

ABSTRACT. This study assesses slope stability at Lake Most, a Czech Republic reclaimed lignite mine, using CPTu data. Spoil heterogeneity posed challenges, necessitating analysis of 24 CPTu tests. The study utilized the Ic index for soil classification and determined undrained shear strength (cu) via empirical correlations. Slide2 software performed limit equilibrium analyses on a two-layer slope model, incorporating a weak zone. The resulting safety factor (FS=1.19) is deemed insufficient for long-term stability, highlighting the need for a minimum FS of 1.4 in reclamation projects.

ABSTRACT. Different types of Engineering Geology research works and studies have already become not only necessary but in fact obligatory steps for the permitting of new construction projects. Furthermore, it is recognized amongst related scientists that Engineering Geology can contribute to the rescuing and enhancing of even small-scale cultural works effectively. This article presents how the major findings of the geological – geotechnical engineering study of the ancient Antaeus Fountain environment can be used for the Fountain’s protection and enhancement. The close co-operation among geologists and the other scientists involved like archaeologists constitutes key component for the successful implementation of the research results.

ABSTRACT. For the monitoring of the climate and assessing the risks related to the coast in port cities, it is important to track the meteorological variability over longer time periods. This research examines the weather patterns of Alexandria in Egypt by using twenty years of observational data (2007-2025) from weather stations located around Alexandria Port. The main variables studied are: temperature, wind speed and direction, humidity, precipitation, and atmospheric pressure. The work has shown that by applying the methods of statistical trend analysis and seasonal decomposition, there are significant changes in the climatic characteristics of Alexandria such as the growth of the mean annual temperature. Of particular concern is the shift in the seasonal wind circulation. The findings also confirm the Eastern Mediterranean climate change projections, which increases the concern about the coast’s climate vulnerability. This study does not analyze the operational data from the ports; however, it's motivated by the need for continuous local meteorological observations in support of port climate adaptation strategies in maritime regions. These observations are essential for urban designers, climate change researchers, and decision-makers to strengthen the policies and frameworks aimed at developing warning networks for coastal infrastructure in the northern coastal region of Egypt.

ABSTRACT. Climate extremes have become more frequent and intense in recent years due to global climate change, leading to an increased risk of geohazard occurrences. Extreme events, such as heavy precipitation, can contribute directly to the occurrence of geohazards, including floods and landslides. Additionally, prolonged heatwaves can directly lead to increased soil erosion and indirectly to more frequent and intense wildfires, which, in turn, can increase landslide hazard, by reducing vegetation cover and destabilizing the soil. This study examines historical climate data and future projections, to identify potential climatic changes, which may induce geohazards in Greece.

ABSTRACT. The year 2023 was a tipping point for the wildfires in Greece (first in EU countries with 42% of the total burnt area), which suffered the largest wildfire ever recorded in Europe as estimated by the European Forest Fire Information System (ESOTC, 2023). The study sites are located in two forest areas in Greece that were among the Protected Areas, which were most affected by the major fires of 2023, namely the National Park of Dadia ("Dadia") and the nature reserve Vounokalathos in Southern Rhodes ("Rhodes"). This research aims to provide local-scale understandings of the climatological characteristics of the kye climate indicators. To evaluate the meteorological dynamics, precipitation patterns and climatic elements shaping the environmental landscapes of the study sites, this research employs trend and statistical analysis methods. Using observed data in the regions of interest from 1981 to 2023, this study characterizes changes observed over the last 43 years for two key climatic parameters (e.g. mean, maximum and minimum air temperature at 2 m and precipitation), at the annual and seasonal scales. The methodology consists of three main parts: the selection of the geographical sites in which the indices would be assessed; the collection of daily meteorological data to calculate averages for each parameter at monthly, seasonal and annual timescales, as well as long term averages for the climatological reference period of 1991-2020 (climatological analysis) and an assessment of the co-existence of positive temperature anomalies and negative precipitation anomalies (warm/dry) during the same fire season for the observed period (1981-2023) at each site. Additionally, 27 climate indices as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI), are calculated on an annual timescale for the observed period (1981-2023) at each site; and finally the performance (existence, magnitude, and statistical significance at 95% level of confidence of potential trends) of the indices is analyzed using Kendall’s Tau correlation coefficient and Theil-Sen slope estimator methods (trend analysis). By examining patterns and changes in the local climate system, the research provides new insights into the climate-induced impacts on wildfire activity, as they put into perspective the underlying combinations of weather and climate conditions that are conducive to wildfires, based on daily climate data for the period 1981–2023. The results of the climatological analysis indicated that 2023 is ranked as the warmest for both sites of interest, according to historical temperature data for the period 1981-2023. Anomalies were detected in climatic conditions in relation to forest fire incidents. Analysis of climate indices revealed a general warming trend in both sites, which is consistent with global warming (Carnicer et al., 2022). In addition, we propose that climate change affects temperature and precipitation patterns, creating drier and extremely warm conditions that are more likely to lead to forest fires. This strengthens the evidence that climate change increases the frequency and/or severity of fire weather, with a high fire risk due to a combination of high temperatures and low rainfall at the sites of interest. However, establishing a direct causal link between a single case and climate change remains challenging as some events would still occur even without climate change. It is therefore important to understand the changes in frequency and intensity at which these events occur. More research is, of course, necessary to fully understand the key role of the climate change in increasing the risk, frequency, total area burned and severity of wildfires.

ABSTRACT. Rising sea levels, increasing frequency of extreme weather events, and transformations in marine ecosystems present significant challenges for the shipping industry. These changes directly affect maritime routes, port infrastructure, and the regulatory frameworks designed to protect the environment. In this context, understanding the relationship between sea surface temperature (SST) fluctuations and their effects on shipping operations has become a matter of increasing importance. This paper focuses on an in-depth analysis of SST trends in the Eastern Mediterranean from 1940 to 2023, examining both annual and monthly scales. By analyzing these temperature trends, the study aims to assess their potential impacts on the shipping sector, considering both operational and environmental perspectives. In addition to SST trends, this research includes a detailed examination of extreme weather phenomena, specifically Mediterranean cyclones, and their connection to rising sea temperatures. A case study of the Mediterranean Cyclone Zorba, which significantly impacted the Eastern Mediterranean in September 2018, is included. The connection between this cyclone and the SST during that period will be explored, as well as how such events are expected to evolve in response to ongoing climate changes. Through this integrated approach, the paper aims to provide valuable insights into the challenges and risks faced by the maritime industry and offer guidance for future strategies in navigating these emerging environmental shifts.

ABSTRACT. Research Highlights Assessing the risk of damage to cultural heritage due to climate change. Future projections using the up-to-date regional climate model (RCM) RegCM4 for two Greek cultural heritage sites.

Introduction Cultural heritage sites have historically been, and will continue to be, affected by environmental factors such as weathering processes. However, climate change presents significant new challenges, accelerating deterioration processes and amplifying the vulnerability of these non-renewable heritages. Changes in temperature, precipitation, air pollution, wind intensity, and the frequency and severity of extreme weather events—such as droughts, floods, and landslides—along with sea level rise (SLR) and the interaction between climate change and air pollution, have significant impacts on cultural heritage (Sesana et al. (2021)). These factors have been recognized by UNESCO as serious threats to cultural heritage (UNESCO World Heritage Centre, (2008)). Climate change can intensify physical, chemical, and biological mechanisms of degradation, affecting the structure and composition of materials. The destructive effects of climate change are particularly evident in regions like the Mediterranean, which include monuments that remain actively used long after their original construction. Outdoor cultural heritage, such as ancient Greek theaters, which form an integral part of Mediterranean culture, provides a prime example of how monuments are impacted by climate change and other contributing factors. These include the natural deterioration of materials over time, the increasing frequency and intensity of extreme weather events, and degradation caused by continued human use of the monuments and their surroundings. Researchers have recognized the risks posed by climate change to cultural heritage sites and have approached the issue in various ways. Ioannidis et al. (2024) studied the impacts of climate change on European cultural heritage sites from 1970 to 2020, highlighting the increased heat stress on elements made from stone and marble, thereby increasing the risk of damage. Kapsomenakis et al. (2023) evaluated the impacts of climate change on multiple UNESCO cultural and natural heritage sites in the Mediterranean, revealing that as global warming progresses, the risks to most of the sites studied intensify. In our previous work (Tringa and Tolika (2023)), we explored the impacts of climate change on Thessaloniki and Delphi, showing that the risk of damage to inorganic materials is expected to increase with temperature fluctuations. Despite the growing body of research on the effects of climate change on cultural heritage, the need for quantitative data and projections remains critical for developing effective adaptation and mitigation strategies, as emphasized by Bonazza and Sardella (2023).

Research aims Awareness of the significant social and economic value of cultural monuments to the country, along with recognition of the potentially negative impacts of climate change on them, served as the motivation for this research. The aim of this work is to assess the future heritage microclimate risk due to climate change and to quantify the predicted risk of damage to the construction materials of monuments at two Greek cultural heritage sites. Future simulations will provide valuable insights into how climate change could affect the monuments of these sites, offering a basis for informed decision-making in the management and conservation of cultural heritage. This work will contribute to the development of adaptive strategies to safeguard cultural monuments, ensuring their resilience in the face of climate-related challenges.   Data and Methods This work examines the impacts of climate change on cultural heritage at two Greek sites: Mycenae and Delos. Using the Heritage Outdoor Microclimate Risk (HMRout) and Predicted Risk of Damage (PRD) indices, this study quantifies potential damage to inorganic materials due to long-term changes in temperature and relative humidity (RH). The analysis was carried out for three different time periods, the period 1980–2000 and the future periods 2039–2059 and 2079–2099. Climate projections are based on the up-to-date regional climate model RCM RegCM4 with the fine spatial resolution of 10x10km, providing detailed simulations of the climate parameters in Greece. The model's output is based on the updated "medium" emission scenario, Representative Concentration Pathway (RCP4.5).

Discussion The results of this study indicate that climate change poses an increasing threat to the preservation of cultural heritage at both Mycenae and Delos. Τhe long-term analysis, which covers both the present and future climate projections, highlights the potential for accelerated material degradation due to the combination of increased heat stress and relative humidity fluctuations. By using indices such as HMRout and PRD, this study provides valuable insights into the potential future threats faced by the case study sites, offering a scientific basis for conservation efforts and the development of adaptive strategies. Furthermore, the high spatial resolution of the RegCM4 model enables more accurate projections of climate conditions at specific heritage sites, which is essential for developing targeted, site-specific conservation strategies. Finally, as climate change continues to affect both environmental and cultural sites, it is essential for decision-makers and heritage conservationists to incorporate climate change projections into their strategies.

References Sesana, E., Gagnon, A.S., Ciantelli, C., Cassar, J., Hughes, J.J., 2021. Climate Change Impacts on Cultural Heritage: A Literature Review. WIREs Clim. Chang. 12, e710. UNESCO World Heritage Centre. Policy Document on the Impacts of Climate Change on World Heritage Properties; London, UK, 2008. Ioannidis, C., Verykokou, S., Soile, S., Istrati, D., Spyrakos, C., Sarris, A., Akritidis, D., Feidas, H., Georgoulias, A.K., Tringa, E., et al., 2004. Safeguarding Our Heritage—The TRIQUETRA Project Approach. Heritage 7, 758–793, doi:10.3390/heritage7020037. Kapsomenakis, J., Douvis, C., Poupkou, A., Zerefos, S., Solomos, S., Stavraka, T., Melis, N.S., Kyriakidis, E., Kremlis, G., Zerefos, C., 2023. Climate Change Threats to Cultural and Natural Heritage UNESCO Sites in the Mediterranean. Environ. Dev. Sustain. 25, 14519–14544, doi:10.1007/s10668-022-02677-w. Tringa, E., Tolika, K., 2023. Analysis of the Outdoor Microclimate and the Effects on Greek Cultural Heritage Using the Heritage Microclimate Risk (HMR) and Predicted Risk of Damage (PRD) Indices: Present and Future Simulations. Atmosphere 14, 663, doi:10.3390/atmos14040663. Bonazza, A., Sardella, A., 2023. Climate Change and Cultural Heritage: Methods and Approaches for Damage and Risk Assessment Addressed to a Practical Application. Heritage 6, 3578–3589, doi:10.3390/heritage6040190.