ABSTRACT. We investigate the seasonal variability of the κ0 parameter, which describes the near-surface high-frequency attenuation of seismic waves. We analyze data from the ARGONET vertical array of accelerometers in Cephalonia, Greece, focusing on comparisons of high-frequency spectral decay between the surface station CK0 and the borehole bedrock station CK83. The study uses the ARGONET database records from July 2015 to October 2022. Results using two different approaches agree on a significant variation of κ0 at CK0, with lower values in summer (dry period for Cephalonia) and higher values in winter (rainy period). This suggests that weather/climate related factors, such as soil moisture and temperature, influence near-surface attenuation, at least as expressed through the value of κ0. This result challenges the assumption of a static value for κ0 often made in site characterization for seismic hazard assessment.

ABSTRACT. This study investigates the potential of the Horizontal-to-Vertical (H/V) spectral ratio method, a technique typically used for site characterization, as a complementary tool for detecting underground voids. We leverage ambient noise measurements conducted at the Mycenaean cemetery of Voudeni, Peloponnese, Greece, utilizing the site's numerous underground tombs as test targets. We analyzed the H/V spectral amplitudes above the centers of various sized tombs and the spatial variation of horizontal and vertical spectral amplitudes and of their ratio along trial linear arrays. We verify the suggestion of previous research that over voids the H/V curve shows a characteristic drop below unity at high frequencies (in our test cases, typically >20Hz), which remains below unity for a considerable frequency interval. This phenomenon is attributed to a velocity reversal caused by the void within the surrounding rock. We attempt a first-order comparison of the void size and frequency of initiation of the characteristic drop and conclude that larger subsurface voids tend to affect the H/V curve at lower frequencies compared to smaller voids, exhibiting an exponential relationship. We also observe that the H/V drop over our test voids is primarily driven by the amplification of the vertical component rather than de-amplification of the horizontal component and this suggests that using linear arrays of vertical component geophones alone could be effective for void detection, particularly as a complement to other geophysical methods. We demonstrate this possibility through trial linear arrays of vertical sensors. We conclude that the H/V method and linear arrays of vertical sensors hinder promising advancements as void detection techniques, especially considering their readily deployable and cost-effective character, although theoretical modeling and extensive testing in various geological settings and void characteristics are required to better understand the observed phenomena.

ABSTRACT. Introduction The most recent seismic activities around Lesvos Island and the coastal area of western Turkey show that the potential for earthquake hazards is evident. The shallow soil structure beneath an urban area is more dominant than the source features for earthquake damage.

The western part of the Türkiye and the Greek islands in the east of the Aegean Sea have suffered from destructive earthquakes throughout history. The 1912 Mürefte (Mw 7.3), 1944 Edremit (Ms 6.8), 1953 Yenice-Gönen (Ms 7.2) and 1964 Manyas (Ms 6.9) earthquakes shake the NW Türkiye in the 20th century. There were three significant events in the coastal areas of in the eastern Aegean Sea. In south, the 20 July 2017 Kos (Mw 6.6) earthquakes shake the island and city of Bodrum. In north, the Ayvacık swarm in February and the Lesvos (Midilli) earthquake (Mw 6.3) in June were strongly felt in the region and moderately damaged the villages. Then, the most recent 2020 Samos (Mw 7.0) earthquake affected the Samos Island and city of Izmir. The mainshock, which generated high damage especially in the Bornova Basin (Izmir), showed that the importance of the effect of deep basin structure and building quality in urban areas. The effect of the recent earthquakes broadly in the eastern Mediterranean region indicate that the knowledge of earthquake sources, seismic wave propagations and characteristics of ground motions is critical for urban hazard mitigation and planning in active seismic zones.

In this study, the earthquake hazard of Lesvos Island and the western coast of Türkiye where contain high populated cities, historic heritage and important touristic destinations were investigated considering (1) faulting and rupture features of the 12.06.2017 Lesvos mainshock, (2) numerical waveform simulations with regional 1D velocity structure and shallow soil amplification, (3) relocated earthquakes and (4) cumulative crustal Coulomb stress change due to the destructive earthquakes in the region. The inversion algorithm by Kikuchi and Kanamori (1991) for the teleseismic body waveforms is used to obtain the mainshock's focal mechanism parameters and the rupture propagation. Different from the routine approach in seismological studies, we compared the rupture models of the mainshock using numerical waveform simulations (Karagoz et al., 2018). For this aim, the synthetic seismograms were generated utilizing the discrete wavenumber method with a characterized source model, 1D velocity model between event and stations and amplification of shallow soil beneath stations. The simulation let us not only validate the source model and 1D regional velocity structures but also understand the high damage in the region. We also relocated the earthquakes in the study area with the double-difference inversion method (Waldhauser and Ellsworth, 2000) to understand the seismicity with reliable horizontal and vertical uncertainties. Finally, Coulomb stress change analyses (Lin and Stein, 2004) are performed to calculate the static stress loading areas where the next destructive earthquake may occur.

Results and Conclusions We invert teleseismic waveforms to determine fault plane solution and rupture propagation of the mainshock. The fault plane parameters are 127°, 47° and -97° for the strike, dip and rake angles, respectively. The finite fault slip model indicates that the rupture propagates circularly from the focal in the first 2-3 s with maximum energy release. Then, it moves to the surface in the next 7-8 s. The maximum slip is 1.8 m, and the average stress drop is 3.6 MPa. The aftershock activity (Papadimitriou et al., 2018) is low in the high-slip patch on the rupture area and vice versa, as observed in the recent 2020 Samos and 2023 Kahramanmaraş destructive earthquakes.

The numerical waveform simulation considering the local soil information is applied to the Lesvos stations to understand the reason for the structural damage on the island. The frequency of the synthetic waveforms with the highest horizontal amplitude (PGV, PGA) is around 3 Hz in Vrissa, which agrees with the fundamental frequency determined from the reported shallow soil Vs model for the region (Figure 1). This frequency match may generate a resonance phenomenon in the soil-covered western part of Vrissa. Thus, we can conclude that the damage in Vrissa is caused mainly by site effects of soil structure, not rupture propagation of the mainshock.

The relocated earthquakes with the double-difference inversion method show the detail of the seismic activity in the region (Figure 2). The 2019 (ML 5.0) and 2024 (ML 4.9) earthquakes in Ayvacık are on the southwest of the right-lateral Evciler Fault, and their oblique focal mechanism solutions indicate that the strike-slip motion extends to Ayvacık. However, the 2017 Ayvacık swarm has a NW-SE normal faulting mechanism. Different characteristics of these earthquakes indicate a complex tectonic structure in a small area on the Biga Peninsula (NW Türkiye). One of the important observations in this study is that the two notable clusters in 2021 and 2023 are at the two ends of the Agia-Paraskevi Fault. Each cluster has more than 300 events appearing in a limited period and has a right-lateral strike-slip mechanism. The spatio-temporal characteristics of seismicity show that there are several earthquake clusters in the region, and they show a high activation rate in a short period, like in different regions in western Türkiye. We consider that the Psara-Lesvos and Agia-Paraskevi faults are the principal displacement zone of a SW-NE right-lateral strike-slip shear zone (SW continuation of the southern branch of the North Anatolian Fault Zone), and the 2021 and 2023 earthquake clusters are on its right-lateral synthetic shears (R).

The Coulomb stress change analyses utilizing the well-known destructive earthquakes in the last 150 years argue that the final stress loading stage on the faults infers continuity of earthquake hazard possibility for Lesvos Island and its surroundings. The cumulative stress change calculations for the events on optimal normal and strike-slip faults are shown in Figure 3. In general, positive and negative stress lobs for both fault types are similar; there is no important difference. The stress load in the region and the most recent 22.01.2025 earthquake are evidence of the future earthquake hazard for the study area.

ABSTRACT. Earthquakes are natural phenomena, often with significant impacts on the human infrastructure. Understanding the factors that influence seismic motion at a specific location is crucial for reducing earthquake risk. These factors include the earthquake source (e.g., magnitude and rupture mechanism), the propagation path (e.g., geometrical spreading and anelastic attenuation), as well as local site effects. The later factor, local site effects, can play a critical role, as they can amplify seismic motion and significantly influence the level of ground shaking. One of the most common approaches to assess local site effects involves calculating the time-averaged shear wave velocity down to 30 meters, VS30, (e.g., EN1998-1, NEHRP97, etc.). However, reliably estimating VS30 is not always straightforward. Traditional methods such as borehole drilling, or geophysical measurements, including refraction, MASW (Multichannel Analysis of Surface Waves), and microtremor measurements (e.g., Chatzis et al., 2018, Chatzis et al., 2022), require significant time, human resources, and funding. Meanwhile, proxy methods, like those based on slope or terrain (e.g., Wald and Allen, 1997) often introduce significant errors. This highlights the need for simple, cost-effective, and reliable methodologies. Ni et al. (2014) proposed a promising approach, the P-wave seismogram method, to estimate the time-averaged shear wave velocity down to a depth z (VSZ) at a station’s location using seismic records. This methodology has been extensively validated using small to moderate magnitude earthquakes (M2–4) across various regions, including Central and Eastern North America (Kim et al., 2016), Texas, Oklahoma, and Kansas (Zalachoris et al., 2017), California (Li and Rathje, 2023), Japan (Miao et al., 2018), and Korea (Kim et al., 2020). It has also been applied to larger earthquakes (M4.0–5.5) near the Anchorage Basin in Alaska (Skarlatoudis et al., 2022) and microearthquakes (-1.1 ≤ ML ≤ 1.7) in the Pohang Basin, South Korea (Lee et al., 2022). In all cases, the method demonstrated a good correlation between estimated and reference (in situ) VS30 values, verifying its potential as a reliable tool. Greece, one of Europe’s most seismically active countries, has a dense seismic network covering both inhabited and remote areas. However, reliable VS30 data is unavailable for many of the stations’ locations, making it a critical area of study. Pappa et al. (2025) applied the P-wave seismogram method to two accelerometric arrays in Greece and found a strong correlation with reference values, after employing a standard bandpass filter (0.2–40 Hz) and making appropriate corrections for the effect of the ray parameter and earthquake magnitude on VSZ. In this study, we applied the same methodology to test its applicability at seven stations, those with the most extensive datasets, from the arrays already used by Pappa et al. (2025). However, we deliberately chose not to apply the bandpass filter to assess whether the method performs reliably without it. Our findings revealed that the results were not satisfactory, with all stations showing a bias with respect to reference values, typically exceeding 50%, especially in basin areas (low VS30 sites). To address this issue, we explored an alternative approach, by considering the same data in the frequency domain instead of the time domain. This modification significantly reduced the method errors, offering a potential pathway to improve the reliability of the P-wave seismogram method in estimating VS30 values for noisy sites, especially for stations located in basin sites.

ABSTRACT. During the last decade, a number of machine learning techniques have been developed for seismology, and equally importantly, became available as open software. This, combined with the wide availability of open seismological data and open tools for their manipulation, sets the stage for significant improvements in both routine earthquake monitoring and seismological research. In the present study, we use the sequence of the November 3, 2024 MW 5.3 Kassandra earthquake as a case study. With the application of deep-neural-network-based seismic arrival picks we locate the sequence, in order to obtain a dataset of sufficient quality and sufficient size to describe the spatial and temporal distribution of the events.

ABSTRACT. This paper presents an effort to assess the liquefaction potential across the Thessaloniki metropolitan area by calculating the Soil Vulnerability Index (SVI or Kg) for the surface geological formations and comparing the results with those of previous research. The SVI is associated with shear strain (γ) imposed on surface geological layers and has been effectively correlated with building damage and soil failures, such as liquefaction. To determine the dynamic properties of surface formations, including fundamental frequency (fo) and corresponding amplitude (Ao), the Horizontal-to-Vertical Spectral Ratio (HVSR) method of microtremor measurements was used. A total of 190 microtremor measurements were analyzed, revealing a good correlation between the SVI and liquefaction potential based on previous studies. High SVI values, indicative of increased liquefaction potential, are linked to low fundamental frequencies, high amplitudes, and are predominantly found in areas near the coast, where thick coastal soft deposits and riverbeds are prevalent. Additionally, strain (γ) values, which are related to SVI, were calculated for various peak ground acceleration scenarios and seismic basement velocities (Vb) specific to Thessaloniki. The results, represented in spatially interpolated maps generated via Geographic Information System (QGIS), align quite well with previous liquefaction potential studies conducted throughout the city using different estimation methods. This agreement encourages the use of microtremor measurements, directly linking them to liquefaction potential by employing the methodology utilized in the current study, in other regions as well.

ABSTRACT. Good quality seismic data is of great importance in a wide range of seismological studies, whether focusing on the source, path or site effect. Errors related to the sensors (calibration, orientation, or installation issues) or metadata may produce unreliable data that do not reflect true ground motion, either in all or in part of the frequency range of interest. In this study, we focus our attention on selected stations of the Hellenic Unified Seismic Network (HUSN), and in particular on the HP network (University of Patras) which with the HL (National Observatory of Athens) are the main networks that possess co-located broadband and strong motion sensors, with a view to scrutinizing their data over their frequency band and time period of common operation. To perform a detailed analysis, we developed a targeted in-house code for data processing. We compiled a dataset of more than 1000 recordings from a total of 11 collocated sensors. Our records are of events with magnitudes M4 or larger, at distances depending on magnitude. After inspecting the raw waveforms and identifying clipped data, we manually process them in the time and frequency domain, considering both horizontal components per event. By examining cases where differences and deviations occurred, we were first able to identify and amend certain underlying errors in sensor response. We then meticulously determined the usable frequency range on a waveform-specific basis and compared this range between the respective channels. Taking into account the noise regime per station, we assessed the reliability and usability of data at the low and high end of the usable frequency range of the acceleration spectrum.

ABSTRACT. We apply the method of seismic interferometry by deconvolution to analyze vertical accelerometer array data from the CORSSA site in Greece and determine P-wave velocities (VP) at shallow depths. We show that in the case of the CORSSA site, the method is able to overcome the challenges of resolving the much faster P-wave travel times and provide statistically robust mean velocity values for different depth ranges. Thus, we propose a VP velocity model for the studied site to complement the previously proposed VS models. We also compare the interferometry inferred VPVS values with independent results and find them to be realistic and consistent with empirical relationships based on rich data sets from different parts of the world. Within the nearly 10 years that the studied dataset spans, we observe a significant temporal variation of VP, mostly in the shallower depth ranges studied, which appears to be longer in duration than the seasonal variation previously reported for VS at this site. However, the lack of temporal continuity in our dataset does not allow a detailed analysis of this variation.

ABSTRACT. The Geopark concept was introduced at late 90’s aiming to protect and promote Earth heritage sites through the sustainable local development of territories containing abiotic nature of significant value. In June 2000 the first Geoparks Network was formed in Europe by four territories hosting geological heritage sites of international significance. The first four Geoparks in Europe were the Reserve Geologique Haute Provence - France, the VulkanEifer Geopark - Germany, the Petrified Forest of Lesvos - Greece and the Maestrazgo Cultural Park - Spain. The European Geoparks Network (ΕGN) developed quickly including new territories from from the founding countries as well as from UK, Italy, Ireland and Austria offering a new model for the protection and sustainable management of the geological heritage monuments through the sustainable development of the local communities. Geoparks activities gain support of the United Nations Educational, Scientific and Cultural Organization (UNESCO) as part of it’s official programme. UNESCO’s Division of Earth Sciences supported the EGN development and signed a collaboration agreement in 2001. In 2004 the EGN included 17 members from 8 European countries. Taking into account the success of the EGN as well as Geopark initiatives in China, UNESCO’s Division of Earth Sciences started efforts for the creation of the Global Geoparks Network as a platform of cooperation between areas hosting and managing geological heritage of international significance. The Global Geoparks Network (GGN) was established in 2004, under the umbrella of UNESCO, including 25 Global Geoparks from Europe and China. The GGN operated as an international voluntary network, bringing together protected geological heritage sites management bodies, government agencies, non-governmental organizations, scientists and experts from all countries around the world in a unique worldwide partnership. Global Geoparks as members of GGN operate to share best practice and exchange know how on various aspects in order to protect, conserve and enhance the value of geological heritage sites, including landscapes and geological formations, which are key witnesses to the evolution of our planet and to promote the sustainable development of their territories through geo-tourism and education activities. In 2014 after one decade of successful operation as a volunteer network the GGN gained legal personality in order to achieve a major goal, the recognition of the Geopark label, the officialization of it’s relationship with UNESCO and the establishment of the third UNESCO site designation. The GGN General Assembly during the 6th International Geoparks Conference in Stonehammer Global Geopark, Canada agreed to the new GGN Statutes and the GGN became an international non-profit international association, subject to French legislation (the 1901 law on associations). Thus the GGN became an International Association following the ICOM model, including institutional members - Global Geoparks and individual members - Global Geopark professionals. The GGN includes Regional Geopark Networks which foster international co-operation and promotion of the Geopark concept and activities at the regional level. The 38th UNESCO General Conference on November 17th 2015, ratified the statutes of the new International Geoscience and Geoparks Programme and the UNESCO Global Geoparks Operational Guidelines, introducing the brand UNESCO Global Geopark as a label of excellence for areas that meet certain criteria. The GGN is maintaining formal relations with UNESCO and became the official partner for the operation of the UNESCO Global Geoparks programme under the umbrella of the International Geosciences and Geoparks Programme (IGGP). 21 years after its establishment the GGN includes 213 UNESCO Global Geoparks in 48 countries and during 2025 will add 16 new members, reaching 229 UNESCO Global Geoparks in 50 countries.

ABSTRACT. Introduction The “Rio do Peixe Dinosaur Valley” comprises four sedimentary basins: Sousa, Triunfo (also called the Uiraúna-Brejo das Freiras basin), Pombal, and Vertentes. Located in the western part of the Brazilian Paraíba State, these areas are intracratonic basins that developed along preexisting structural trends of the basement during the origin of the South Atlantic Ocean. The age of these basins, based on microfossils, is characteristic of the Rio da Serra (Berriasian to Hauterivian) and Aratu (early Barremian) local stages (Lima and Coelho, 1987; Regali, 1990; Sousa et al., 2019). Deposition is the result of tectonic activity, and it is represented by alluvial fans at the faulted borders, changing to an anastomosing fluvial system more distally, and by meandering fluvial system with a wide floodplain, where perennial and temporary lakes developed, in the central region of the basins (Carvalho, 2000; Fig. 1). Especially in the Sousa Basin footprints and trackways, mainly of large theropods, sauropods, and ornithopods are common, as well as invertebrate ichnofossils, such as traces and burrows (Fernandes and Carvalho 2001). Body fossils are represented by ostracods, conchostracans, plant fragments, paly¬nomorphs, fish scales, and bones of crocodylomorph and dinosaurs. The abundance of dinosaurian ichnofaunas represents an extensive Lower Cretaceous megatracksite (Viana et al., 1993; Carvalho, 2000; Leonardi and Carvalho, 2000, 2002) established during the early stages of the South Atlantic opening. In this area, 42 sites and approximately 96 individual stratigraphic levels preserve occurrences of more than 636 individual dinosaur trackways and isolated footprints, as well as rare tracks and traces of the vertebrate mesofauna (Leonardi and Carvalho, 2021). To date, the four basins of “Rio do Peixe Dinosaur Valley” show together the following dinosaur trackmakers for the corresponding trackways or isolated footprints: 38 graviportal ornithopods (Fig. 2A); one ankylosaur; one small quadrupedal thyreophoran; two small ornithopods (altogether, 42 ornithischians). Then, 447 individual theropods (Fig. 2B-C); 90 sauropods (altogether, 537 saurischians). In total, the number of classifiable dinosaur individual tracks is 579; and the total number of dinosaur footprints and trackways, including the indeterminate tracks, is 636. This last number includes also four possible dinosaur tail impressions. The meso-ichnofauna, very rare in these basins, is represented by just one set of batrachopodid prints; some crocodilian traces and tracks; one lacertoid footprint; perhaps a poor specimen of mammal tracks; and a very large number of small chelonian swimming tracks (Leonardi, 1989, 2021; Leonardi and Carvalho, 2021, 2024). It is noteworthy that the large number of theropods represented is impressive, compared to the number of herbivores, which is quite common in the whole world. This phenomenon seems to be contrary to the biomass pyramid theory. It can be explained, however, considering that carnivores probably had a higher level of mobility and therefore printed more tracks and footprints daily. It is also quite remarkable that the ankylosaur hand-foot set (specimen SOES 7, from the Serrote do Pimenta, Sousa), discovered in 1979 (Leonardi, 1984, 1989, 1994) represents the first record of the presence of this clade of Thyreophora in the South American continent.

The diversity of dinosaur tracks: an insight to the Early Cretaceous ecosystems The dinosaur footprints in the Sousa Basin occur in at least 42 localities, in clastic deposits within all the formations of the Rio do Peixe Group (Antenor Navarro, Sousa and Rio Piranhas formations). At least 636 individual trackmakers are recorded in the Rio do Peixe basins (Carvalho and Leonardi 1992; Leonardi, 1984, 1994; Leonardi and Carvalho, 2021, 2024), and many others in a widely distributed set of track localities named the Borborema Megatracksite (Viana et al., 1993). This megatracksite expands to the neighboring basins of Icó, Iguatu, Malhada Vermelha, Lima Campos (Leonardi, 1989; Leonardi and Spezzamonte, 1994), Cedro (Carvalho et al., 1993), Araripe (Carvalho et al., 1994, 2019, 2024; Carvalho and Leonardi, 2021, 2024) and can also be extended to encompass the region of the Cameroon Basin (Africa) as suggested by Jacobs et al. (2024).

Figure 1. Geological context of Sousa Basin, northeastern Brazil during the Barremian-Hauterivian. The dinosaur footprints from the Sousa Basin were formed in the environments established during the first stages of South America – Africa drifting (modified from Popoff, 1988).

The set of footprints is indicative of the high diversity of dinosaurs in the terrestrial ecosystems, despite the few osteological remains. Footprints are rare in the Antenor Navarro and Rio Piranhas formations as they are preserved only in fine sediments that accumulated as subaerial sandy bars in alluvial fans and anastomosing rivers close to the basin margins. In the Sousa Formation, the sediments’ generally finer grain sizes are more suitable for track preservation. This last unit is interpreted as the deposition in lacustrine, swampy, and meandering braided fluvial environments (Leonardi and Carvalho, 2024; Fig. 2).

The Dinosaur Valley and its Influence in the Sousa Community The town of Sousa is undeniably the “capital” of the “valley of the dinosaurs” of western Paraíba. The Sousa municipality has a territory of 842 km² located in the region of the Alto Sertão da Paraíba, in the semi-arid belt of Paraíba State. The municipality of Sousa has 67,259 inhabitants (IBGE, 2022). The influence of the scientific studies concerning dinosaur tracks in the region allowed new economical perspectives. After one hundred years of research (beginning with Moraes, 1924), dinosaur footprints became a popular aspect of the local culture. The main occurrence and most accessible ichnosite is located at Passagem das Pedras (Ilha Farm) in the Sousa municipality. In December 1992 (Diário Oficial do Estado da Paraíba, Decree no 14.833, December 20th, 1992), through a state act, the area was defined as a natural monument and named “Dinosaur Valley Natural Monument” (Monumento Natural Vale dos Dinossauros). Since then, the influence of the dinosaur theme on a variety of community activities has been incontestable, reflecting the improvement of science knowledge in the municipality. Over the last fifty years, the region, previously known mainly for its cotton agriculture, acquires a new identity as a result of the regular presence of researchers, undergraduate and graduate students, and the media’s diffusion about the dinosaur tracks in the Sousa County. In the downtown of Sousa city references to dinosaurs progressively invaded different aspects of community life, from sports to commercial and social activities, which shows the value that the people of Sousa connect to the dinosaur tracks recorded in their municipality, considered to be a heritage that deserves to be preserved (Fig. 3). It is possible to preserve any geological heritage through public polices, but the main way to preserve it is the reconnaissance by the community about their importance and economic relevance. The tourism in the Sousa region, the local museum, a national identity based on the soccer team (Green Dinosaurs from Sertão, Sousa Futebol Clube), and the continuous support of scientific research allowed the engagement of the local population to the preservation of their ichnofossils. They are recognized as important objects to the economy and social development (Carvalho and Leonardi, 2007; Fernandes and Carvalho, 2007; Santos et al., 2015, 2019), a fundamental condition for safeguarding their physical integrity. But the ichnofossils of Sousa are exposed to risks of non-anthropic origin that call for new approaches to the issue of in-situ preservation of this type of heritage. Although the best way for educational and economic purposes is the preservation of the footprints in the natural outcrops, the environmental conditions to which they are currently subject can destroy them. Many of the track-bearing surfaces will be worn out by natural erosion, especially where the tracks occur in surfaces nearside the temporary rivers. Besides the traditional methodology of documentation, it is also necessary to digitally reconstruct the ichnosites and their footprints (Falkingham et al., 2014, 2018) as they are subject to destruction by erosion and in some rare cases to vandalism. In these cases, the removal to house in museums, universities and research centers is the best solution to an ex-situ preservation of the paleontological heritage. Given the relevance of these ichnofossils to the population of Sousa, it would be necessary to consider replacing the original footprints with replicas, as happened within prehistoric cave paintings like Lascaux and Chauvet in France, or Altamira in Spain, a non-consensual management strategy but generally well accepted by tourists (Hughes et al., 2021).

Figure 2. The great diversity of dinosaur tracks in the region of the Sousa Basin allows the reconstruction of terrestrial Cretaceous ecosystems. A. Iguanodontid footprints, the longest trackway (57 m) found in Sousa Basin, Passagem das Pedras ichnosite; B. Theropod footprints after excavation on mudstones with mudcracks, Passagem das Pedras ichnosite; C. Theropod footprint on coarse sandstones from Serrote do Letreiro ichnosite.

Figure 3. The references to dinosaurs and their tracks in the emergence of a new identity for the region: A. Sousa Radio (Progresso AM); B. Sousa Sport Club, the main soccer game from the Sousa city, Paraíba State; C. A small inn located in the downtown; D. A market and bakery; E. A veterinary drugstore.

Acknowledgements The authors acknowledge the support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (303596/2016-3) and Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (E-26/200.998/2024). This study was supported by Portuguese funds of Fundação para a Ciência e a Tecnologia in the frame of the UIDB/00073/2020 Project (Portugal).

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ABSTRACT. The Vikos-Aoos Geopark serves as a unique example of the interaction between geological formations, the natural environment, and culture, highlighting the enduring relationship between geological heritage and human activity. The region’s geodiversity, characterized by designated geosites and a wide variety of geological formations, provides evidence of long-term geodynamic processes that have significantly shaped local ecosystems and biodiversity. At the same time, these geological features have been utilized by local communities, contributing to the development of a biocultural heritage, where the geoenvironment and human activity have jointly shaped the landscape and cultural identity of the area. The integration of the geological environment into the daily lives of local communities extends beyond the mere exploitation of natural resources, such as the use of rocks in traditional architecture. Instead, it is deeply embedded in the toponymic tradition, the process by which geographical features are named, allowing communities to attribute distinct characteristics and meaning to the landscape. Toponyms are not merely linguistic data; rather, they function as carriers of valuable information across multiple disciplines, including history, archaeology, geology, and folklore. Geology, by examining the gradual transformations of the Earth's surface, contributes to the understanding of geographic and cultural migrations of populations, as well as the selection of specific sites for human settlement. Meanwhile, folklore studies investigate how toponyms encapsulate religious beliefs, local traditions, and ritual practices, establishing a profound connection between inhabitants and their natural surroundings, transforming the landscape from a natural into a humanized space. Research Methodology and Objectives The present research aims to identify and highlight examples that demonstrate the dynamic relationship between geological formations and human activity, illustrating the connection between geological heritage and cultural identity. Additionally, it seeks to enhance the participation of local communities in the management and promotion of the Vikos-Aoos Geopark, recognizing the significance of local knowledge in preserving both natural and cultural heritage. A qualitative research methodology was applied to collect, analyze, and interpret data, aiming at an in-depth investigation of experiences and social processes related to the region’s geological heritage. Data collection techniques included: • Literature review and content analysis of scientific and historical sources. • Interviews with residents of the Geopark to document local perceptions and oral traditions. • Participant observation through field research in locations of particular geological and cultural interest. As part of the field research, studies were conducted in the community of Pyrgos in Konitsa, where an on-site visit was carried out with its President, Mr. Christos Papadimitriou, and in the village of Laista in Zagori, where data was collected in collaboration with the President of the Laista Mountaineering Association, Ms. Toula Poala. Findings and Conclusions Preliminary research findings indicate that the Vikos-Aoos Geopark hosts numerous locations of significant geological interest and designated geosites that have been incorporated into the collective memory of local communities through toponymic tradition. Notable examples include “Nterti”, “Vrachos tou Chodza” (“Hodja’s Rock”), “Kokkino Lithari” (“Red Rock”), as well as the well-known Dragon Lakes of Smolikas and Tymfi. These findings suggest that diverse geological formations—ranging from steep cliffs to crystalline springs—have acquired profound significance for local populations, becoming an integral part of their cultural heritage. This exploration of the interplay between geology and culture underscores that geology is not merely a science that interprets the Earth's past but also a bridge to sustainable development and cultural empowerment. The Vikos-Aoos Geopark serves as a living example of the intricate relationship between the natural environment and human activity, emphasizing the need for holistic approaches in the management and promotion of geological heritage. Prospects and Management of Geocultural Heritage The management of the region’s geocultural heritage aligns with the principles of UNESCO, fostering the systematic interpretation of geological and cultural heritage while promoting sustainable development. Strengthening the connection between humans, nature, and culture through managing the Vikos-Aoos Geopark is a priority, ensuring the preservation of the geological and cultural elements that make the area unique. Thus, understanding the relationship between geological structures and cultural practices not only contributes to scientific knowledge but also plays a crucial role in reinforcing local identity and ensuring the sustainable development of the region.

References 1.Toponymy of Zagori, Konstantinos Ev. Oikonomou, Ph.D. Dissertation, University of Ioannina, 1986 2.Toponymics, N.G. Politis, P.D. Sakellariou Publications, Athens, 1914 and 1916 3.Our Toponyms: Their Value and Their Problems, Thomopoulos I., Thessaloniki, 1958 4.Toponyms & Oikonyms of the Mason Villages of Konitsa: Documentation, Interpretation, Etymology, Comments, Ziogas Th., Athens, 2013 5.A Tree Spreads Its Branches, G. Poala, Laista Zagori Mountaineering Club, Ioannina, 2006 6.The Echoing Rock of Sellio and Stratiani, Soureli-Galani Eleni, Kaktos Publications, Athens, 2023 7.Miscellaneous Folklore Studies, Nitsiakos V., Odysseas Publications, 1997 8.Building Space and Time, Nitsiakos V., Odysseas Publications, 2003 9."The Kantsiotika", Informational and Cultural Publication of the Drosopigi Brotherhood, Issue No. 22, August 2015 10.Technical Report on the Geological Formations of the Vikos-Aoos UNESCO Global Geopark, EPIRUS S.A., Ioannina, 2023 11.Vikos-Aoos Geopark: Nature Narrates Its History, Papaioannou Ch. & Kitsaki G. (eds.), IPIROS S.A., Region of Epirus, 2014

ABSTRACT. Introduction / Background The Lesvos Petrified Forest stands as the hallmark of the Lesvos Island UNESCO Global Geopark, representing a unique natural monument celebrated for its remarkable fossilized trees. These fossils provide invaluable insight into the region’s geological history. Preserving and interpreting these fossil-rich sites is essential for advancing scientific research, promoting public education, and fostering sustainable tourism. This paper examines key strategies for conserving and interpreting the newly excavated sites within the Geopark framework. Formed approximately 20 million years ago due to intense volcanic activity in the northeastern Aegean, the Lesvos Petrified Forest is a geological treasure of international significance. It played a crucial role in Lesvos Island's recognition as a UNESCO Global Geopark. Covering an area of 15,000 hectares in the island’s western region, the protected area of the Lesvos Petrified Forest offers a rich window into past ecosystems and geological processes. The Natural History Museum of the Lesvos Petrified Forest serves as the public institution dedicated to the protection and sustainable management of this extraordinary heritage. The Museum also conducts rescue excavations within the protected area when fossils are discovered during public or private construction projects, ensuring their preservation and proper study.

Challenges in Fossiliferous Site Conservation

While fossils may appear robust and enduring, they are, in reality, highly susceptible to various environmental factors that can lead to significant mechanical and chemical deterioration. Elements such as humidity, temperature fluctuations, and exposure to biological agents, including plant roots, lichens and fungi, contribute to their gradual decay. Additionally, human activities such as vandalism and unauthorized fossil collection pose substantial threats to their preservation. Fossiliferous sites face multiple threats that jeopardize their preservation. Natural processes such as erosion and weathering progressively degrade these sites over time. Human activities exacerbate these risks, including uncontrolled tourism, which can physically damage delicate fossils, illegal excavations that disrupt the geological context, and infrastructure development that may permanently destroy valuable paleontological resources. Furthermore, climate change compounds these challenges, as increasing temperatures and the rising frequency of extreme weather events accelerate the deterioration of fossils and their surrounding environments. Consequently, conservation efforts must extend beyond the fossils themselves to include the broader geological and ecological contexts in which they are embedded. Protective measures such as erosion control, vegetation management, and site stabilization are essential to ensuring the long-term integrity of fossiliferous sites. By maintaining these sites, researchers and educators can continue to derive scientific and educational value from them, benefiting future generations. Efforts to protect and sustainably manage Earth’s heritage and geodiversity are being advanced in UNESCO Global Geoparks. These initiatives align with international frameworks, including Agenda 21 and the Agenda of Science for Environment and Development, which were adopted at the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro (1992) and reaffirmed at the World Summit on Sustainable Development in Johannesburg (2002). Geology, geomorphology, and landscapes have profoundly shaped human societies, civilizations, and cultural diversity. The Lesvos Island UNESCO Global Geopark initiative enhances the objectives of the 1972 Convention on the Protection of the World Cultural and Natural Heritage by emphasizing the interconnectedness of socio-economic development, cultural heritage, and the conservation of natural environments. Conservation Strategies Effective site protection involves the establishment and enforcement of protected areas around fossiliferous sites, the implementation of erosion control measures such as soil stabilization and drainage systems, and continuous monitoring and surveillance to deter illegal activities. Scientific research is indispensable, requiring ongoing paleontological and geological investigations to deepen our understanding of a site's significance. This includes systematic data collection and analysis on site conditions, microclimate variations, and visitor impact to inform conservation strategies. Geoconservation techniques play a vital role in preserving these valuable resources. Wherever feasible, in situ preservation should be prioritized to maintain the original context of fossils. The construction of protective structures, such as shelters, helps shield fossils from weathering, while fences and designated safe pathways limit human impact without compromising fossil integrity. These paths should be strategically designed with materials that blend with the natural landscape, ensuring accessibility while safeguarding the site's geological and paleontological features. Additionally, visitor education and guided tours serve as essential tools in fostering public awareness and reducing inadvertent damage to fossil sites.

Controlled excavations, accompanied by meticulous documentation and secure storage of recovered fossils, are critical for scientific research and the preservation of paleontological heritage. Advanced digital documentation methods, including 3D scanning and photogrammetry, can aid in creating precise and non-invasive records of fossil sites. Moreover, fostering collaboration with local communities, policymakers, and conservation organizations strengthens long-term protection efforts by integrating traditional knowledge with sustainable conservation practices. By adopting a comprehensive approach that integrates scientific research, infrastructure development, community engagement, and stringent policy enforcement, fossiliferous sites can be effectively conserved for future generations. These measures ensure that these invaluable scientific and natural resources remain accessible for research, education, and public appreciation while maintaining their geological and ecological integrity.

Protection measures A series of protection and enhancement works have been implemented to improve the accessibility, interpretation, and promotion of the fossiliferous sites within the Geopark. These interventions include: • Protective measures for the preservation and promotion of fossiliferous sites including shelters and protective stone constructions for the control of the erosion. • Infrastructure improvements to facilitate safe visitor access, ensuring accessibility for all, including individuals with disabilities. • Signage and interpretative projects that provide information on the fossils that appear in the fossiliferous sites, along with awareness campaigns and educational programs for schools and universities. • Initiatives to promote alternative forms of tourism, particularly environmental and cultural tourism, through targeted promotional and publicity campaigns.

By integrating scientific research with innovative interpretation strategies, the Lesvos Island UNESCO Global Geopark serves as a model for fossiliferous site conservation worldwide. Its comprehensive approach highlights the balance between conservation, education, and sustainable development, ensuring that the paleontological heritage of the region is preserved and appreciated by future generations.

Interpretation and Public Engagement The Lesvos Island UNESCO Global Geopark plays a crucial role in conserving and interpreting fossiliferous sites. As a designated UNESCO site, it has a responsibility to balance the needs of conservation with the socio-economic development of the region, support scientific research and promote public education about the geological and paleontological significance of the area, engage local communities in the management and interpretation of heritage sites, and share best practices and lessons learned with other geoparks worldwide. The Lesvos Petrified Forest is an outstanding example of a fossiliferous site that combines conservation, education, and sustainable tourism. The interpretation of fossiliferous sites within the Geopark is a crucial aspect of its management, aiming to enhance public understanding of the geological heritage and promote geotourism. Interpretation efforts include well-designed information panels, and guided tours that provide insight into the region’s paleontological significance. Interactive exhibits, 3D models, and digital reconstructions allow visitors to visualize the past ecosystems that existed 20 million years ago. Moreover, on-site interpretation through signage and designated trails ensures that visitors can explore the fossiliferous sites without causing damage to the delicate specimens.

The Natural History Museum of the Lesvos Petrified Forest employs modern technology, such as augmented reality (AR) applications and virtual reality (VR) experiences, to engage visitors and present scientific information in an accessible and compelling manner. Additionally, educational and outreach programs involving schools, universities, the local communities and visitors foster a deeper appreciation for the importance of geoconservation and the need to protect fossiliferous sites.

Conclusions The conservation and interpretation of fossiliferous sites in the Lesvos Petrified Forest UNESCO Global Geopark demonstrate the significance of integrating scientific research, infrastructure development, community engagement, and policy enforcement to ensure the long-term preservation of this invaluable natural heritage. The Geopark serves as a model for sustainable management, balancing the protection of fossiliferous sites with public education and regional socio-economic development. Effective conservation strategies have been implemented to mitigate environmental and human-induced threats, including erosion control, site stabilization, and protective infrastructure. In situ preservation remains a priority, ensuring that fossils retain their original geological context while minimizing damage from external factors. The application of geoconservation techniques, such as the construction of shelters, designated visitor pathways, and fencing, has proven effective in reducing human impact while maintaining site accessibility and visitor engagement. Public interpretation and engagement play a crucial role in fostering awareness and appreciation of fossiliferous sites. The Geopark has invested in comprehensive educational programs, guided tours, interpretative signage, and innovative digital tools, such as augmented and virtual reality applications, to enhance visitor experiences and scientific outreach. These efforts not only improve public understanding of geological heritage but also promote geotourism as a sustainable economic activity for the region. The series of enhancement projects within the Geopark—ranging from improving accessibility for all visitors, including individuals with disabilities, to promoting alternative tourism models—illustrates a holistic approach to conservation and interpretation. By integrating cutting-edge scientific documentation methods like 3D scanning and photogrammetry with traditional conservation practices, the Geopark ensures the meticulous recording and preservation of fossiliferous sites for future research and educational initiatives. Moreover, the collaborative efforts between the Natural History Museum of the Lesvos Petrified Forest, the University of the Aegean, local communities, and policymakers highlight the importance of interdisciplinary cooperation in geoconservation. The involvement of local stakeholders strengthens conservation efforts, fosters a sense of ownership, and enhances the sustainable development of the region. Ultimately, the Lesvos Petrified Forest UNESCO Global Geopark exemplifies best practices in fossiliferous site conservation by maintaining a delicate balance between scientific study, heritage protection, and responsible tourism. Its comprehensive approach ensures that these paleontological treasures continue to contribute to global scientific knowledge, public education, and sustainable economic growth while preserving their ecological and geological integrity for future generations.

References Kyriazi, E., & Zouros, N. (2008). Conserving the Lesvos Petrified Forest. Studies in Conservation, 53(sup1), 141–145. https://doi.org/10.1179/sic.2008.53.Supplement-1.141 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, pp. 395–396. 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), pp. 29–33. Pe-Piper, G. & Piper, D.J.W. (1993) Revised stratigraphy of the Miocene volcanic rocks of Lesbos, Greece. Neues Jahrbuch für Geologie und Palaeontologie Monatshefte, 1993 (2),97–110. 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. Pe-Piper, G., Imperial, A.M., Piper, D.J.W., Zouros, N.C. & Anastasakis, G. 2019. Nature of the hydrothermal alteration of the Miocene Sigri Petrified Forest and host pyroclastic rocks, western Lesbos, Greece. Journal of Volcanology and Geothermal Research, 369,172–187. 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, pp. 398–399. 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. Velitzelos, E., Zouros, N., 1998. New results on the petrified forest of Lesvos. Bulletin of the Geological Society of Greece, 32(2), 133–142. Zouros,N., I. Valiakos, G. Gribilakos, A. Plougarlis, K. Mpentana, V. Rozakis, M. Agiasoti, O. Tsalkitzi, 2015. New fossil findings in the Petrified Forest of Lesvos along the new Kaloni-Sigri road. The forest under the road a new tarveling exhibition of the Lesvos Geopark. 13th European Geoparks Conference, Rokua, Finland. 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. and Lamprakopoulos,A. 2022: 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.

ABSTRACT. Nisyros Geopark, a candidate for inclusion in the UNESCO Global Geoparks Network, is distinguished by its remarkable geological, natural, and cultural features. Situated in the Southeastern Aegean, it spans 481 km² and includes the active Nisyros volcano along with nearby islands (Fig. 1). Positioned at the southeastern edge of the South Aegean Volcanic Arc—one of the world's most significant active volcanic systems—the geopark offers a unique terrestrial and submarine landscape shaped by its volcanic origins. The geopark encompasses 24 geosites (Fig. 2), showcasing its rich geological history. Visitors can explore the impressive collapse caldera, hydrothermal craters and lava domes on the western side, stratified layers of lava, ash, and pyroclastics, which chronicle its extensive geological evolution (Parcharidis et al., 2018). Active hydrothermal craters and numerous coastal hot springs highlight ongoing hydrothermal activity, while the submarine aspects of the geopark are key to its formation and development. These features attract international scientific research, positioning Nisyros Geopark as a prominent natural geological laboratory in the Eastern Mediterranean. As part of the South Aegean Volcanic Arc, the geopark features a striking landscape shaped by five eruptive cycles over the past 160,000 years (Dietrich & Lagios, 2018). These cycles have left their mark on both the land and the seabed (Nomikou & Papanikolaou, 2011). The offshore region continues this volcanic landscape beneath the sea, hosting basins, underwater volcanic structures like craters and lava domes, fractures, and even a prehistoric caldera, Avyssos, located northeast of Strongyli islet (Tibaldi et al., 2008; Nomikou et al., 2021).

Beyond its geological wonders, the geopark is steeped in cultural heritage. Despite its modest size, the region has been continuously inhabited for millennia and is linked to the myth of Gigantomachy. The region's cultural heritage has stood steadfast through the ages, showcasing the brilliance of art and civilization through its prehistoric and historic sites and monuments. It is home to remarkable archaeological and cultural landmarks, including fortresses such as Paleokastro and the Mandraki castle, remnants of ancient settlements, numerous Byzantine-era churches and monasteries like the famous Panagia Spliani Monastery (Fig. 3), as well as thermal springs tied to its long-standing tradition of thermal baths. Together, these elements have shaped the region's history, fostering the traditions and preserving the tangible and intangible heritage cherished by its local communities today. Moreover, the Geopark features rich biodiversity protected by the two internationally designated Natura 2000 areas including its entire surface, as well as three wildlife refuge areas recognized at a national level. A great number of species of flora, avifauna and reptiles thrive within the geopark’s area (Antoniou et al., 2019).

To enhance visitor engagement and educational opportunities, Nisyros Geopark is upgrading its services. Current initiatives include the development of two free mobile applications, Nisyros Geopark App and Nisyros Volcano App, an informative website (www.nisyrosgeopark.gr) and a variety of educational materials. The geopark actively promotes awareness through talks, workshops, summer schools, and media campaigns, fostering an appreciation of its unique geological and cultural significance among residents and visitors alike.

Acknowledgements We extend our heartfelt gratitude to the management body of Nisyros Geopark (DIKEN) and the Mayor of Nisyros, Mr. Koroneos Christofis, for their invaluable contribution, unwavering support, and dedication to the vision of the geopark. Their efforts have been instrumental in promoting the sustainable development of the region, preserving its unique geological and cultural heritage, and advancing its candidacy as a UNESCO Global Geopark.

References Antoniou, V., Nomikou, P., Zafeirakopoulou E., Bardouli P., Ioannou T., 2019. Geo-biodiversity and cultural environment of Nisyros volcano, 15th International Congress of the Geological Society of Greece, Athens, 22-24 May, 2019 | Harokopio University of Athens, Greece. Bulletin of the Geological Society of Greece, Sp. Pub. 7 Ext. Abs. GSG2019-195. Dietrich, V. and Lagios, E., 2018. Nisyros Volcano, The Kos - Yali - Nisyros Volcanic Field. 1st ed. Springer, Cham. Nomikou P., Papanikolaou D. (2011). Extension of active fault zones on Nisyros volcano across the Yali-Nisyros Channel based on onshore and offshore data. Marine Geophysical Research 32 (1), pp.181. DOI 10.1007/s11001-011-9119-z. Nomikou, P., Krassakis, P., Kazana, S., Papanikolaou, D. and Koukouzas, N., 2021. The Volcanic Relief within the Kos-Nisyros-Tilos Tectonic Graben at the Eastern Edge of the Aegean Volcanic Arc, Greece and Geohazard Implications. Geosciences, 11(6), p.231. Parcharidis, I., Lagios, E. and Sakkas, V., 2018. Differential interferometry as a tool of an early warning system in reducing the volcano risk: the case of Nisyros volcano. Bulletin of the Geological Society of Greece, 36(2), p.913. Tibaldi A., Pasquarè F.A., Papanikolaou D., Nomikou P. (2008). Tectonics of Nisyros Island, Greece, by field and offshore data, and analogue modeling. Journal of Structural Geology 30 (12), pp.1489.

ABSTRACT. Geoheritage and geotourism help to promote inclusive and sustainable economic growth, full and productive employment and decent work for all, in line with the Sustainable Development Goals of the 2030 Agenda. This is a particularly important issue for peri-Mediterranean countries, whose economy is heavily dependent on tourism, mostly seasonal and concentrated on beaches.The current conditions of the Portuguese Natural Monuments of national rank are a long way from such goals and the communities that occupy the territories are completely oblivious to the geological heritage that surrounds them. This top-down nature conservation strategy has proved to be totally inappropriate and has not contributed to harmonious integration between communities and nature.

ABSTRACT. This study investigates the volcanic formations and fossil record preservation within the Akrocheiras hill area of the Lesvos Petrified Forest, the geological heritage treasure with international significance of the Lesvos Island UNESCO Global Geopark. Detailed geological mapping was conducted to identify petrified tree trunks and pyroclastic formations that contributing to the recognition of successive fossiliferous horizons linked to distinct Miocene volcanic eruptions. The area, dominated by the Sigri pyroclastic formation, exhibits numerous preserved silicified tree trunks and complex volcanic sequences containing vitric and lithic tuffs. The research highlights various pyroclastic horizons and suggests the existence of numerous petrified forests. Findings provide key insights into the geomorphological evolution, eruptive history, and paleoclimate of the region.

ABSTRACT. Both Lesvos UNESCO Global Geopark, (Greece) and Ida Madra Geopark (Türkiye) include a variety of geological heritage sites of international significance and are characterized by rich geodiversity. The majority of the geological heritage sites present in the respective territories are related to volcanism, with the 72% of the geosites in Lesvos Geopark and 62% of the geosites in Ida Madra Geopark found on igneous rocks. Highlighting the shared and complementary geohistorical context of neighboring geoparks can enhance the interpretation, conservation, and promotion of geoheritage in a holistic manner and cooperation between territories. The Aegean region is among the most tectonically active regions on Earth due to the subduction of the African plate beneath the Eurasian plate and the westward extension of the Anatolian microplate. Consequently, the region saw extensive extrusive and intrusive volcanism during the Miocene period (Bozkurt et al. 2005, Innocenti et al. 2009). The vigorous volcanic activity created complex volcanic formations. The geosites of Lesvos Geopark (Greece) and Ida Madra Geopark (Türkiye) are closely associated with Miocene volcanism and tectonics. A Geopark might be likened to a chapter in a novel; it may be coherent independently but remains incomplete without the additional chapters that contribute to the overarching narrative. In this regard, the coinciding and complementary geosites of the Lesvos Geopark and Ida Madra Geopark may offer a more comprehensive perspective for both. Both Geoparks belong geologically to the Sakarya - Pelagonia massif.

ABSTRACT. Introduction The Corinth Canal is an artificial waterway in Greece that connects the Corinth and Saronic Gulfs. It crosses the narrow Isthmus of Corinth, a 79 m high ridge which once linked the Peloponnese peninsula to the Greek mainland, creating a natural barrier between the Ionian and Aegean Seas. The Canal extends in a straight line for 6,343 m. It is 24.60 m wide at the sea surface narrowing to 21.30 m at its bottom, while the water height in it ranges from 7.50 to 8 m (CorinthCanal). In this paper, we present an overview of the technical aspects of this admirable engineering work tracking the historical route of its opening from antiquity until the late 19th century and briefly describe the accompanying infrastructure works and the ongoing interventions, mainly driven by the geotectonic setting of the area. We argue for the monumentality of the Corinth Canal that mandate its future preservation and we propose a framework of actions to protect this prominent heritage. Thoughts on the future of the Corinth Canal Nowadays navigation through the canal appears to be limited to mainly tourist vessels, as large ships prefer other easier sea routes in the open sea than a restricted canal to get from the Ionian to the Aegean Sea, thus downgrading its economic importance. The Corinth Canal is mainly a tourist attraction, thus its widening to accommodate ships larger than its current capacity seems to have no effect in conjunction with the exorbitant construction costs and the loss of its monumentality. After all, this proposal was rejected during the design of the new bridges in the 1990s. Although it seems that the Greek state is moving in this direction ['the Canal should not only be a project that facilitates navigation, but also in itself be a visitable destination in order to highlight the overall tourism product of the region' (Hellenic Republic, 2022)], at the same time the Ministry of Infrastructure and Transportation approves large-scale interventions for slope stabilisation on the Peloponnese side, without any environmental restrictions under the guise of urgent user safety, sadly causing significant alterations in the physiognomy of this unique monument. Immediate restoration of the canal’s slope to its original form by a reinforced earth wall is required, while any future interventions of this scale will invalidate its monumentality. Unfortunately, political decisions appear to be driven by development policies, yet they lack a clear strategy for ensuring the long-term viability of the canal. However, it seems that only an alternative management of the Corinth Canal, while maintaining its existing function, creates a development perspective. The production and promotion of a new tourism product is suggested, which will offer an immersive experience and tour of the canal through its historic path. Though it be focused on the Corinth Canal highlighting its monumental qualities and geological features, will also include accompanying monuments (e.g. ancient diolkos, bunkers, new bridges, submersible bridges, etc.). This tourism product would be flexible, catering to different types of tourism (both conventional and alternative), visitor demand, and available time, while ensuring accessibility and safety to visitors of all ages. The Corinth Canal, a prominent engineering project of the time with an outstanding universal value, is a monumental infrastructure, highlighting how certain structures, while fulfilling necessary functions, transcend their utility and become symbols of cultural identity, history, and human achievement. It should have long since been classified as a recent monument of Greek cultural heritage, fully protected and subject to sustainable interventions under the provisions of Law No. 3028/2002, as in force. In addition, coordinated efforts ought to make the competent bodies so that the area of the Corinth Canal could be designated UNESCO World Heritage Site, recognizing its global significance both historically and culturally, as well as for its geological features. Thinking that 'monuments have shaped and are still shaping contemporary views on the past' (Bußmann, 2019), we marvel at how this monumental, man-made 'mega-trench' shapes perceptions of the geotectonic processes reflected on its slopes. It is our duty to preserve engineering achievements and historical memory for present and future generations, thereby substantially enhancing our social and cultural identity.

ABSTRACT. Introduction The Chelmos-Vouraikos UNESCO Global Geopark has continued to demonstrate its unwavering commitment to conservation, education, and community engagement through a series of impactful actions during 2024. These initiatives highlight the Geopark’s dedication to preserving natural and cultural heritage, while fostering sustainable development in close collaboration with local communities, national organizations, and international stakeholders. Engaging with Society Throughout the year, the Geopark got actively engaged with society through various events and initiatives that bridged cultural, environmental, and recreational themes. The organization of the 5th UNESCO Global Geoparks Conference of Greece and Cyprus, in Kalavryta, by Chelmos-Vouraikos Geopark, provided an international platform to showcase the Geopark’s efforts in conservation and sustainable tourism. Publications such as the new geodiversity and plant guides and leaflets about freshwater fish fauna and the endemic plants of the geopark have been produced and distributed to educate visitors about the region’s unique biodiversity (fig.1). Additionally, the new Geopark’s Information Center (fig.2), which serves as a hub for visitor orientation and education, commenced its operation last year, offering an enhanced experience for visitors to learn about the area’s natural and cultural heritage. Promoting Sustainable Tourism and Regional Identity Events like Oinoxeneia highlighted local gastronomy and traditions, fostering a deeper connection between the Geopark and its communities. Digital and physical tools, including info kiosks and a dedicated Geopark mobile application, enhanced visitor experiences and accessibility. Recreational activities such as the 44th Annual Vouraikos Gorge Crossing, the 1st Helmos Enduro 2024, and the 2nd Helmos Mountain Festival (fig.3), which took place in the past year, were organized by local entities within the Geopark, such as the Kalavryta Mountaineering Club and the Kalavryta Ski Center. These events were always accompanied by collaboration and parallel actions from the Chelmos-Vouraikos Geopark, emphasizing the strong partnership in promoting sustainable tourism and outdoor recreation within the region. Cultural collaborations, including the Ziria Festival and TEDx Patras, which were organized outside the Geopark, further underscored the Geopark’s role in promoting regional identity. Despite being external events, these initiatives involved collaboration with the Chelmos-Vouraikos Geopark, highlighting its active role in supporting and enhancing regional cultural efforts. Additionally, the annual meeting of Trekking Hellas Achaia emphasized sustainable trekking practices and eco-tourism, while the participation of handball federation athletes in the Vouraikos Gorge connected sports with natural heritage under the organization of Chelmos- Vouraikos Geopark. The Aigio Mountaineering Club hosted a symposium entitled “On the Mountain’s Paths,” featuring a presentation on “Biodiversity Conservation: Linking with Mountaineering,” which was delivered by staff members of the Chelmos-Vouraikos Geopark. This presentation highlighted the Geopark's efforts in promoting the connection between mountaineering and biodiversity conservation. Historical significance was also honored through the event commemorating the 20-year anniversary of the Holocaust Museum. This two-day event, organized by the Kalavryta Holocaust Museum, featured a presentation on the protected area, and participants of the seminar were given a guided tour of the Geopark's Information Center. These activities further highlighted the importance of conservation and the Geopark's role in preserving the region's natural and cultural heritage, reinforcing the ongoing collaboration between the Geopark and the Museum. This partnership has been strengthened through joint initiatives, such as the seminar on climate change co-organized the previous year as part of the International Museum Day celebrations. Environment Day this year was celebrated in three distinct ways: with a hike on Mount Panachaiko, a volunteer cleanup of Kastria stream, and a planting initiative with students from the Special School of Kalavryta. These activities highlighted the community's commitment to environmental stewardship and provided an opportunity for collaboration with local schools and organizations. Inspiring Education and Academic Research Educational activities with schools and universities played a pivotal role in inspiring the next generation and supporting academic research. Collaborative efforts with the Special School of Kalavryta under the GRECABAT program integrated hands-on activities that connected biodiversity with education. On International Mountain Day, a presentation and interactive games at Diakopto Primary School raised awareness about mountain ecosystems. At Arsakeio School of Patras, a presentation titled “Natural Disasters and UNESCO Global Geoparks” emphasized the role of Geoparks in disaster risk reduction. Activities at Rodea Camp included an informational session and guided hike, fostering environmental awareness among participants. The European Bird Day celebration at Lake Doxa highlighted the importance of avian biodiversity and was celebrated in collaboration with the Primary, Secondary, and High School of Kleitoria. The event featured birdwatching activities and games, providing students with a hands-on learning experience about local wildlife and the significance of bird conservation. Field trips with Harokopio University provided students with the opportunity to conduct research in Vouraikos Gorge, focusing on topics such as fluvial geomorphology, ecosystem services and environmental cartography. The Geopark also welcomed annual visits from international researchers studying glacial formations, showcasing its global scientific relevance. Advancing Research and Conservation Management Research and management activities within the Geopark have been equally robust, aiming to enhance conservation and sustainable development. Efforts to protect rare and endemic species were supported through the establishment of micro-reserves. Biodiversity studies focusing on otters, dormice, and ichthyofauna enriched the understanding of local ecosystems. A monitoring station in Vouraikos River provides essential data for conservation strategies by measuring parameters such as water temperature, water level, conductivity, pH, dissolved oxygen, and turbidity. This data plays a crucial role in the proper management of the Vouraikos River, ensuring the health of the ecosystem and supporting sustainable tourism development through informed decision-making. The renowned Cave of the Lakes was the subject of a comprehensive management study to protect its geological and ecological features. Additionally, the development of a quality label study aligned local products and services with sustainable practices. The conservation program for Silene conglomeratica, a critically endangered endemic species within the Chelmos-Vouraikos UNESCO Global Geopark, highlights the essential link between geodiversity and biodiversity. Moreover, a carrying capacity study for Mount Helmos is currently underway, emphasizing the importance of regulating visitor numbers to balance tourism promotion with the preservation of the area’s natural environment. Conclusions Through these comprehensive actions, the Chelmos-Vouraikos UNESCO Global Geopark continues to exemplify its role as a leading stakeholder in conservation, education, and community collaboration. These efforts contribute significantly to the global mission of UNESCO Global Geoparks, ensuring a sustainable future for the region’s natural and cultural heritage.

ABSTRACT. Research Highlights Sediments of Trichonis Lake are dominated by quartz and calcite, reflecting the lithological influence of surrounding limestone and flysch formations. Reduced nutrient levels in lake water since the late 1990s highlight the positive ecological impact of decreased agricultural pressures, providing a foundation for sustainable lake management strategies.

Introduction / Background European Union countries have evaluated all freshwater habitats larger than 50 hectares to comply with the Water Framework Directive 2000 (European Commission, 2000). To support biological, hydromorphological, and physico-chemical monitoring, a range of indicators and multimetric indices has been developed. These include factors such as morphology, hydrology, nutrient levels, thermal conditions, salinity, pollutants, and priority substances. Geochemical indicators such as pH, sediment mineralogy, and the concentrations of ions, nutrients, and potential pollutants in soil and water, are normally used to assess habitat quality and quantify the environmental stress affecting ecosystems (ecological status) (e.g. Vasilatos et al., 2019). Trichonis Lake, located in western Greece, is the largest and one of the deepest natural freshwater lakes in Greece, with a maximum depth of 58 m and a surface area of approximately 98 km² (Figure 1). On the northeastern side of the lake the steep slope of Panaitoliko Mountain is visible, while the southwestern side is bounded by the ridge of Arakinthos Mountain. The wider “Trichonis basin” is a neo-tectonic graben approximately 30 km in length and 10 km in width (Doutsos et al., 1987); its hydrological basin extends to an area of 402 km2 (Koutsoyiannis et al., 2008) and its southern boundary is defined by a prominent WNW-ESE trending normal fault. Geologically, the area belongs to the External Hellenides, specifically the Pindos and Gavrovo geotectonic units (Figure 2). Trichonis Lake occupies the eastern margin of a fractured tectonic trough at a semi-circular shape. This trough was formed primarily due to the intense tectonic activity of the region and partially by the collapse of limestone masses into existing underground caverns, which constitute an extensive karstic network. These karsts are continually enlarged by the erosive and solvent action of water, leading to the collapse of overlying layers and contributing to ongoing changes in the morphology of the region (Evangelidis et al., 2008; Kiratzi et al., 2008, Benekos et al., 2013). Trichonis Lake main geomorphological characteristics are summarized in Table 1.

The water level of the lake is artificially controlled by a dam being constructed to regulate its discharge at an average altitude of 15.5 m with a fluctuation of ±1 m. This dam communicates by means of a 2.8 km long Trichonis-Lysimachia Unifying Trench with Lysimachia Lake, to which its excess water potential is channeled. The lake is recognized for its rich biodiversity, including endemic fish (e.g. Vardakas et al. 2022), freshwater hydrobiids (e.g. Radea et al. 2017), and algae species (Economou-Amilli 1979, 1982); and generally, for the presence of unique aquatic plants, as well as its role in local hydrology and as a water source for nearby communities. However, like many freshwater ecosystems globally, Trichonis faces environmental pressures due to agricultural activities, urban runoff, and sedimentation processes, potentially threatening the health of its ecosystem. In previous studies (e.g., Kehayias & Doulka, 2014; Overbeck et al., 1982; Tafas et al., 1997) due to its limnological and biological characteristics Trichonis was classified as a carbonate-type, low-conductivity lake ("class II, low salinity" warm lake) with an oligotrophic to mesotrophic ecosystem. Furthermore, Kehayias & Doulka (2014), using zooplankton as a biotic indicator, suggested that Trichonis Lake is undergoing a transitional shift toward a eutrophic state, emphasizing the need for continuous monitoring and inspection of the ecosystem.

Objectives The objective of this study is to assess the geo-environmental status of Trichonis Lake by analyzing the mineralogical and sedimentological characteristics of its sediments along with the physicochemical parameters of lake water. This analysis aims to identify changes in sediment composition, assess nutrients concentrations, and evaluate the impact of anthropogenic activities, offering a comprehensive assessment of current environmental condition of the lake and helping guide future management efforts.

Methods Study Area and Sampling Sites Bottom sediment and water samples were collected from various sites throughout Trichonis Lake in September 27-28, 2024, to capture a representative profile of the lake's sedimentary environment (Figure 2). Sampling sites were selected to encompass areas near potential pollution sources, such as agricultural runoff zones and areas adjacent to urban settlements, as well as deeper, central lake locations to account for natural sediment deposition.

Sediment Sampling, Preparation and Analysis Sediment was retrieved from each site using a stainless-steel dredge bottom sludge sediment grab sampler (Figure 3). Sediment samples were collected in 2 L plastic bags. Before the experimental procedure, the coarse organic matter was removed from the samples. In the laboratory they were air-dried, homogenized, and sieved to remove particles larger than 2 mm. Fine fractions were preserved for further mineralogical, sedimentological, and chemical analyses. The granulometric characterization was conducted according to Folk’s methodology and classification (Folk, 1974). Mineralogical analysis was carried out by using an X-Ray Siemens D 5005 Diffractometer, equipped with a Cu tube and a graphite monochromator, in combination with the DIFFRACplus software package at NKUA, Department of Geology and Geoenvironment. The organic matter (OM) content was determined using dry combustion, involving drying at 105°C for 24 hours and combustion at 380°C for 6 hours in a muffle furnace (Vasilatos et al., 2019). The CaCO3 (%) content was estimated by combusting the above samples at 950°C for 1 hour.

Water Sampling, Preparation and Analysis pH, redox potential (Eh), conductivity, total dissolved solids (TDS) and dissolved oxygen (DO) measurements were performed in situ, using a portable Multiparameter Analyzer (CyberScan Series 600, EUTECH). Water samples (Figure 3) were filtered through 0.45 μm membrane filters, collected and stored in polyethylaine containers. They were divided into two groups; the first group was persevered for the measurements of anions while the second was acidified by addition of concentrated HNO3 for the measurements of cations. Then they were all stored at cooling conditions (~ 4oC) into a portable refrigerator. Chemical analyses for NO2-, NO3-, NH4+, PO43- and SO42- were performed using a HACH DR/2400 spectrometer. The detection limits of the methods were 0.007 mg∙L-1, 0.05 mg∙L-1, 0.013 mg∙L-1, 0.01 mg∙L-1, and 3 mg∙L-1, respectively.

Results and Discussion Sedimentology Particle size data (Figure 4) can reveal sediment transport patterns and indicate environmental conditions impacting sedimentation, such as changes in water flow or anthropogenic disturbances. Sedimentological analysis indicated that sites near limestone formations are classified as sand while samples nearby flysch formations are silty sand, dominated by finer sediment fractions (Figure 4). This distribution suggests that sedimentation processes in the lake are controlled by the mineralogical composition of the adjacent lithologies and rock erosion.

Sediments Mineralogy and Chemistry Quartz and calcite were confirmed in all samples originated from the surrounding flysch and limestone formations (Table 2). Clay minerals (chlorite and muscovite) and feldspars have been identified in samples adjacent to the flysch and related Quaternary deposits (Figure 2). These findings align with typical mineral assemblages expected in freshwater lake sediments within flysch and limestone-rich areas. The organic matter content in the bottom sediments ranged from 0.1% to 6.2% (Table 3). The maximum value (6.2%) was observed at sampling site TR9, located near the opening of the Trichonis-Lysimachia Unifying Trench, pointing out the ecological importance of this trench. The high value of organic matter content at that site is a strong indicator of ecological processes like increased biological productivity or enhanced sediment accumulation. Samples with the lowest organic matter content showed the highest quartz content based on their X-ray diffraction (XRD) patterns

Water Chemistry Physicochemical parameters, concentration and chemical composition of the major anions of water samples from Trichonis Lake are presented in Table 4. All measured water parameters comply with the standards for water intended for human consumption (European Commission, 2000). The measured pH values range from 6.52 to 7.90, falling within the typical range for lake water associated with limestone or flysch lithologies. The observed high concentrations of NH4-, NO3-, and PO42- in the sample TR8, as well as of NO3-, NO2-, and PO42- in the sample TR4 suggest a tangible impact of agricultural and urban runoff on Trichonis Lake. The consistent SO₄²⁻ levels (27.1–28.4 mg/L) across sampling sites indicate minimal influence from human activities, which would cause greater variability near potential sources. Instead, these concentrations may stem from natural processes, such as the presence of evaporitic formations in the wider area. Nutrient levels are much lower than in 1980–1997 (Koutsoyiannis et al., 2008) but similar to 2000–2002 (Koutsoyiannis et al., 2008) presumably due to the late-1990s abandonment of extensive tobacco cultivation around the lake, which had caused ecological strain.

Comparison with Other Mediterranean Lakes Even though Trichonis Lake has been classified as a typical warm lake, it resembles more closely to temperate lakes than tropical ones (Tafas et al., 1997) exhibiting shallow metalimnia that characterize lakes of higher latitudes. The bottom sediments of Trichonis Lake are primarily composed of quartz, calcite, and clay minerals such as chlorite and muscovite, reflecting the geological influence of surrounding flysch and limestone formations. This composition is characteristic of carbonate-type lakes in limestone-dominated regions (Tafas et al., 1997; Kehayias & Doulka, 2014). In contrast, many Mediterranean lakes exhibit more diverse sediment compositions depending on local geology, including higher proportions of volcanic materials (e.g., in volcanic lake basins) or organic-rich sediments in eutrophic systems (Karathanasis & Hajek, 1993; Gkenas et al., 2012; Michaloudi et al., 2013; Köprücü & Polat, 2017). The relatively low organic matter content (ranging from 0.1% to 6.2%) in Trichonis sediments aligns with its oligotrophic to mesotrophic status, whereas highly eutrophic Mediterranean lakes often exhibit significantly higher organic matter concentrations due to increased biological productivity and nutrient input (Overbeck et al., 1982; Tafas et al., 1997; Kehayias & Doulka, 2014). The high CaCO3 content (up to 69.4%) further distinguishes Trichonis as a carbonate-rich system, a feature not universally observed in Mediterranean lakes, where sediment composition varies widely. Nutrient levels (e.g., NH4-, NO3-, and PO43-) in Trichonis Lake water are relatively low compared to heavily impacted Mediterranean lakes, although localized agricultural and urban runoff has resulted in elevated nutrient concentrations in specific sites, indicating ongoing anthropogenic pressure (Petaloti et al., 2004). When compared to other Mediterranean lakes, Trichonis exhibits nutrient levels and chemical parameters indicative of a transitional ecosystem, less impacted by eutrophication than many lakes in the region.

Conclusions Comprehensive assessment of the geo-environmental status in Trichonis Lake revealed insights into its sedimentological, mineralogical, and chemical characteristics, as well as into the impact of natural and anthropogenic factors. Key conclusions include: • The sediments are predominantly composed of quartz and calcite, reflecting a lithological influence of the surrounding flysch and limestone formations. Variations in sediment texture, ranging from sand to silty sand, highlight localized sediment transport and deposition processes. • Organic matter content ranged from 0.1% to 6.2%, with higher values near areas of enhanced biological productivity, such as at the Trichonis-Lysimachia trench. This differentiation signifies the ecological importance of sedimentary organic matter accumulation in assessing ecosystem “health”. • Physicochemical parameters, including pH, Eh, and TDS, are consistent with those expected in freshwater systems influenced by limestone and flysch. Elevated nutrient levels at specific sites point to agricultural runoff and urban influences, although the overall nutrient concentrations declined since the late 1990s, likely due to reduced agricultural pressures, including the cessation of tobacco cultivation. • While some localized contamination is evident, such as elevated NH4-, NO3-, and PO43- levels near agricultural areas, the consistent SO₄²⁻ levels across sites suggest limited anthropogenic influence on this parameter. The mineralogical composition of the lake sediments also emphasizes the dominance of natural geochemical processes in shaping its chemistry. • Overall, Trichonis Lake shares some commonalities with other Mediterranean lakes in terms of its sensitivity to anthropogenic impacts and nutrient dynamics. However, its distinct carbonate-rich sediment composition and relatively stable water chemistry highlight its unique geological and ecological context. This underscores the importance of tailored conservation efforts to preserve the lake’s ecological balance amidst regional anthropogenic pressures. This study provides a baseline for understanding the geo-environmental dynamics of Trichonis Lake and offers valuable guidance for future conservation and management strategies aimed at maintaining the health of this vital freshwater ecosystem. Findings underscore the need for continued monitoring and sustainable land-use practices to mitigate anthropogenic pressures and preserve the ecological integrity of the lake.

Acknowledgements This work was supported by the EU frame of HORIZON-MISS-2023-OCEAN-01 “Integrated emerging approaches for joint protection and restoration of Natural Lakes in the spirit of European life heritage support (ProCleanLakes)”. The presentation of this work was funded by the Special Account for Research Grants, National and Kapodistrian University of Athens.

ABSTRACT. Geochemical mapping is commonly applied by geoscientists to document the spatial distribution of elemental concentration levels in materials occurring at the Earth’s surface, such as soil. Here, we present the soil geochemical characteristics in the unique island of Lesvos that exhibits a complex geological structure with different rocks occurring on island surface. A total of 74 surface (0-20 cm depth) soil samples were collected from 66 locations on a 5 km x 5 km grid extending across the whole island. Preliminary results in terms of distribution of major and trace element concentrations and interpretations based on geology and mineralization are presented.

ABSTRACT. Introduction Travertine, also known as Lapis Tiburtinus by ancient Romans, is a type of "chemically precipitated continental limestone" which consists of calcite or aragonite minerals. (Pentecost, 2005). The precipitation of carbonate minerals occurs primarily through the degassing of carbon dioxide from a groundwater source, resulting in calcium carbonate supersaturation (Pentecost, 2005). The occurrence of travertine deposits has been observed around both cold springs (i.e. tufa or meteogene travertine) and warm-hot springs (i.e. travertine or thermogene travertine), suggesting two distinct origins of travertine. The distinction between these two types of deposit can be determined based on features of parent waters and on the source of CO2 (e.g. Pentecost and Viles, 1994; Ford and Pedley, 1996). Meteogene travertines are formed from parent waters that are characterized by lower temperature and neutral pH values (7-8). CO2 has a meteoric and/or biogenic origin and shows carbon isotope compositions that range mostly from about -11 to 0 ‰, reflecting the depleted 13C of soil CO2 (Deines, 1980). On the other hand, thermogene travertines form from parent waters with high temperatures and lower pH values. The CO2 in this case has mostly a geogenic source, with a δ13C range of -4 to +8 ‰ (Pentecost and Viles, 1994), resulting from the interaction between host rocks and deep CO2-rich fluids, such as mantle fluids or metamorphic decarbonation reactions (Ohmoto and Rye, 1979). In addition, while meteogene travertines display low deposition rates (<10 mmol cm−2 a−1), thermogene travertine show very high deposition rate of hundreds of mmol cm−2 a−1 (D’Alessandro et al., 2007). An increased interest in studying travertine deposits is driven by their potential applications in paleoclimatic and paleoenvironmental studies, as well as in hydrogeological studies, rock and oil exploitation. Thermogenic travertine deposits also allow for the evaluation of any endogenic processes. Additionally, travertine deposits facilitate the estimation of paleo CO2 fluxes associated with their deposition (Mancini et al., 2019). Travertine deposits are widespread in Greece, with the most studied being found in Northern Euboea and Eastern Central Greece. These areas are characterised by a high geothermal gradient, which leads to the presence of sev-eral thermal springs. In some of these thermal springs are depositing thermogene travertine, as a result of the cooling and degassing of thermal waters, leading to the rapid precipitation of calcium carbonate (Kanellopoulos et al., 2017 and references therein). In this research, we present data about the mineralogical and geochemical compositions of 39 travertine samples collected along the whole Hellenic territory from thermal, cold–gas-rich, acidic and hyperalkaline springs, in order to better investigate the possible differences between different type of parent waters.  Methods Thirty-nine travertine samples were collected along the whole Hellenic territory (Fig.1 and Table 1) from a variety of springs, including thermal, cold–gas-rich, acidic and hyperalkaline springs. Samples were analysed for their mineralogical and geochemical composition. Information on the physico-chemical parameters and the chemical composition of the parent waters were taken from (Li Vigni et al., 2022, 2023). Samples were, firstly, pulverised in an agate mortar and then, subdivided in two aliquots. The first aliquot was used for the investigation of mineralogical composition by X-ray powder diffraction (XRPD). The XRPD analysis was being carried out at the laboratories of the Department of Earth and Marine Sciences of the University of Palermo, using a PANanalytical X’PERT PRO diffractometer. The second aliquot was mineralized to obtain the chemical composition of the samples. About 100 mg of dried sample were dissolved in a polypropylene bottle with a solution of 1 mL of ultrapure HCl (37%), 0.5 mL of ultrapure HNO3 (65%) and 50 mL of milliQ water. The obtained solutions were analysed for major cations (Ca, K, Mg, Na, P, S, Si) by Inductively Coupled Plasma Opti-cal Emission Spectrometry (ICP-OES; Jobin Yvon Ultima 2), whilst 26 trace elements (Li, Be, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Sn, Sb, Cs, Ba, Tl, Pb, and U) were analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS; Agilent 7800). Results are expressed as µg g-1 of solid. Pre-treatment procedures were carried out at the laboratories of the Department of Earth and Marine Sciences of the University of Palermo, and analysis were carried out at laboratories of the Istituto Nazionale di Geofisica e Vulcanologia (INGV-Palermo). Results X-ray diffraction analyses were carried out on 13 travertine samples. The analysis revealed that the main mineral phases show close similarities. The samples are predominantly composed of calcite (Fig. 2), with a very low percentage of aragonite in few samples. Traces of halite and hydromagnesite were also found. Further investigations are underway to verify their presence. Moreover, traces of hematite were found in travertine samples of Meso-chori (GR01) and Giotrisi (GR02), whereas traces of clay minerals were found in Archani (GR20). The results of the geochemical analyses are summarised in the boxplot in figure 3, which shows a wide range of concentration, generally, exceeding three orders of magnitude. Calcium is the dominant cation in all the samples, with concentrations ranging from 94,800 µg g-1 to 462,000 µg g-1. The elements can be categorized, based on their median concentrations, into minor elements (Mg, S, Na, Fe, Sr, Si), which show a median values between 1% and 0.1%, and into trace elements (Mn, Ba, P, B, Zn, As, Li, Ti, Ni, Cr, Cu, V, Pb, Rb, Co, Be, U, Cs, Sb, Mo, Se, Cd, Sn, Tl) with median concentrations below to 0.1%. Thermogene travertine samples of Thermopyles (GR23, GR24, GR25), Ilion (GR26, GR27) and Edipsos (GR37, GR38) have been compared with literature data (Kanellopoulous et al., 2017), showing a similar composition. Elements such as Fe (Thermopyles up to 265 µg g-1, Ilion up to 285,800 µg g-1, Edipsos up to 9280 µg g-1) and As (Thermopyles up to 156 µg g-1, Ilion up to 15,360 µg g-1, Edipsos up to 90.6 µg g-1) displayed concentrations within the range reported by the same authors. According to them, the lithogeochemistry of these ore-bearing travertines reflects the geochemical composition of the parent hydrothermal fluids, which are enriched in Fe and As, particularly in the case of Ilion. The presence of metal(loid)s in thermogenic travertine can be attributed to a primary magmatic source and to reduced and low-sulfidation state of the hydrothermal fluids (Kanellopoulous et al., 2017). However, other travertine samples exhibit enrichment in some metal(loid)s, including Mesochori (GR01), Giotrisi (GR02, GR12) and Skra (GR04). All these trace elements may be incorporated in the mineral structure of the carbonates substituting for Ca or precipitate as constituents of secondary minerals or be adsorbed onto the surface of the forming crystals or amorphous phases. Therefore, further studies are required to ascertain both the origin and water-rock interaction processes, such as the precipitation of secondary minerals, that took place. Conclusions Despite the widespread presence of travertine in Greece, few studies can be found in the scientific literature. Their geochemical and mineralogical characterization may provide important information on water-rock interaction processes, dissolution and precipitation patterns, the origin of CO2 and the genesis of travertines themselves. These preliminary data show both their mineralogical phases associated dominantly with calcite although traces of aragonite, hydromagnesite, hematite and clay minerals are sometimes found. From a geochemical perspective, calcium is the predominant element. Nonetheless, their chemical composition comprises a large number of trace metals, including some potentially toxic elements (e.g. As, Ba, Cu, Cr, Ni, Pb, V) and some strategical industrial elements like Li and B. Further steps of this preliminary study will be to investigate the relationship between travertine samples and their parent waters in order to better understand water-rock interaction processes.

ABSTRACT. This study investigates the impact of field sampling density on the quality and reliability of regional geochemical maps using chromium (Cr) and lead (Pb) as case studies due to their contrasting geochemical behavior within the mapped area. Two datasets, comprising 117 and 24, evenly distributed, sampling locations within the same study area of 2500 km2, were analyzed to produce geochemical maps for each element. The statistical characteristics of the datasets were compared, highlighting differences in data representation at varying densities. The IDW interpolation method was then applied to generate maps, enabling visualization of spatial variability.

ABSTRACT. The aim of this study was to investigate the geochemical distribution of uranium (U) and thorium (Th) in the soils of the Sarigkiol Basin, Kozani, as well as to evaluate their potential environmental impact. Additionally, an important environmental question addressed in this study is whether the origin of these two trace elements is lithogenic or anthropogenic. These questions were examined through mineralogical, chemical, and statistical analyses, supported by geochemical maps and prediction models. The results obtained provide a clearer picture of the pollution levels of these two radioactive elements and the monitoring they may require in the future

ABSTRACT. This study explores the geological landscape of the western Navarino Bay through time, with a focus on mapping the relationship between the area's geology and human presence. Through field surveys, Geographic Information Systems (GIS), and optical microscopy, detailed maps were created to highlight the geological features and archaeological data of the region. The findings reveal that archaeological artifacts, primarily ceramics and occasionally walls or large limestone rocks, were predominantly located in three elevated areas on the Coryphasium Peninsula—namely the hills of Prophitis Ilias and Koukouras, which are largely composed of limestone. In contrast, fewer archaeological remains were found in the surrounding lagoon and cultivated areas. This distribution suggests that human settlement was likely influenced by the geological landscape, and the study investigates how these factors may have interacted over time. The research provides an initial understanding of the long-term relationship between human habitation and the geological environment, with the conclusion that further studies are required to confirm these findings and gain a deeper understanding of the region’s history.

ABSTRACT. This study presents a methodology for rapidly estimating construction and demolition waste (C&DW) quantities following natural disasters, focusing on geospatial data analysis. Using empirical data from 182 buildings in Vrisa, Lesvos, affected by the 2017 earthquake, a mathematical model based on multiple linear regression is developed to calculate C&DW quantities in weight and volume. The model incorporates variables such as building height, floor area, and the number of floors, which are efficiently derived using geoinformatics systems. Detailed 3D visualizations and GIS data enabled accurate estimates at area, street, and building scales, with findings showing significant discrepancies from previous estimation models. The study underscores the importance of pre-disaster data collection and the development of context-specific methodologies for effective debris management and disaster recovery planning, particularly in traditional settlements with unique architectural features.

ABSTRACT. This study presents the development of a cartographic web application designed for monitoring the Corinth Canal, leveraging UAV (Unmanned Aerial Vehicle) technologies. The Corinth Canal, a significant historical and engineering landmark, is subject to geological risks such as erosion and landslides, necessitating continuous monitoring. UAVs equipped with RGB cameras, thermal sensors, and GNSS receivers were deployed to capture high-resolution geospatial data, producing 3D models, orthomosaics, digital elevation models (DEMs), and thermal imagery. These datasets were integrated into a user-friendly web platform, enabling stakeholders to visualize and monitor the canal’s structural health in real time. The platform supports multitemporal analysis, allowing for the detection of changes over time, such as slope instabilities or material stress. It includes tools for measurement and annotation, facilitating efficient decision-making for maintenance and preservation. This research highlights the transformative potential of UAV-based data collection combined with GIS technology in managing and preserving cultural and industrial heritage sites. The web-based platform provides a scalable model for similar infrastructure monitoring, offering valuable insights for long-term conservation efforts and risk management strategies.

ABSTRACT. A detailed presentation of the Argo-Beachrock Project, its objectives and survey areas. Web mapping and geovisualisation of beachrocks using UAS along the littoral zone of the Argolic Gulf: a methodological approach to surveying the nearshore zone, with advantages and constraints for bathymetric reconstruction.

ABSTRACT. Both the modern human-made and natural environment face numerous challenges and risks that have direct and indirect consequences on their sustainability and security. Climate change combined with the accumulated pressures, ageing infrastructure, and the impact of natural hazards, contribute to the rising frequency of phenomena and events that demand effective and intelligent responses (Kyriou et al., 2023). In this context, the need for a modern, multiparametric framework to monitor and provide up-to-date information on the pressures affecting both the environment and critical infrastructure led to the proposal and successful implementation of the research project, “PROION”. The project was based on innovative technologies and methodologies that make use of the latest available infrastructure and development tools. From the perspective of optimal observation of critical infrastructure and the surrounding physical environment, the PROION project aimed to acquire, process, organise and make available measurement data both through the use of in-situ sensors and free satellite products that provide valuable information on the ground deformation, as well as the stability of critical infrastructure. Receiving co-funding from the European Union and the Greek Government, PROION (T2EDK-02396) was invited to implement its vision in the region of Achaia (Fig. 1), part of the Enceladus Hellenic Supersite (EHS).

ABSTRACT. The rapid growth in Earth Observation (EO) data availability necessitates advanced tools for visualizing and analyzing complex datasets, particularly for applications involving Persistent Scatterer Interferometry (PSI). This study introduces a multiscale geo-visualization dashboard optimized for effective exploration and interpretation of PSI data, with a focus on spatiotemporal ground displacement analysis. A novel generalization algorithm was developed to adapt PSI datasets to eight predefined cartographic scales, ensuring appropriate visualization for each scale while mitigating data overlap. The interactive dashboard integrates original and generalized PSI datasets with auxiliary geospatial layers, providing functionalities for visualizing attributes such as mean velocity, temporal coherence, cumulative deformation and time-series graphs. The interaction and synchronization of each dashboard component, enable a cohesive exploration experience. Results demonstrate the dashboard's capability to visualize PSI datasets of varying resolutions across multiple scales, revealing insights about the prevailing conditions of ground deformation. Despite limitations in advanced customization and generalized dataset analysis, the dashboard represents a cost-effective, standalone tool for visualizing and analyzing PSI data, with significant potential applications in geosciences, urban planning, and environmental studies.

ABSTRACT. In this paper, we use 3D animation technologies to visualize, interpret and communicate geological heritage in Lesvos UNESCO Global Geopark. Our objective is to make geological heritage more accessible to the general public. 3D animations have been utilized as a means to periodically monitor and document changes in geological sites over time, supporting conservation initiatives. Additionally, they can replicate geological events, describe the formation and evolution of landscapes, simulate how we believe paleoenvironments looked for a holistic learning experience. Their interactive and dynamic nature can boost engagement and facilitate learning in an educational context, while it can also engage tourists by offering previews, virtual tours of inaccessible or fragile sites. In this paper, we select 21 case studies of geosites or monuments of geological heritage to 3D geo-visualize. The selection method is based on three criteria: accessibility, supervision and relief of the geosite out of the total number of 151 designated geosites of the Geopark. The results were verified with a pilot study to participants of environment educational programs in the Natural History Museum of Lesvos Petrified Forest in 2024. . Overall, the approach promotes visitor democracy, as all groups have access to the visualized geosites and can be used to further improve the visibility of the geosites and that of the Geopark.

ABSTRACT. A coastal collapse at Mylos Gialtron in Northern Evia was triggered by the Mw:4.9 magnitude earthquake of June 8th 2023, 10 km southwest of Atalanti. Airborne orthophotomosaic, digital terrain and surface models (DTM, DSM) of the coastal zone combined with swath bathymetry mapping of Gialtra and Aidipsos Bays provide detailed documentation of the coastal collapse and show that it evolved as submarine landslide. A 20 m long by up to 10 m wide part of the sandy beach at Mylos Gialtron collapsed and slid toward the 35-40 m deep flat seafloor of Gialtra Bay, leaving behind an amphitheatric scar. The sliding mass created a 15 m wide by 3-4 m deep gully on the slope down to roughly 15-20 m depth and created a 50 to 60 m in diameter depositional lobe that extends up to the 30 m depth contour. The estimated total volume of the slide is calculated to >7,000 m3. One more, older, two times larger depositional lobe is found on the seafloor beyond the 35 m depth contour, at roughly 150-200 m distance from the shoreline. Its shape and orientation suggests that it is the result of a coastal slide that was triggered by the 9th July 1980, M:6.3 Almyros earthquake, 43 years before the recent coastal collapse. Many segments of Greece’s coastal zone display structural and morphological characteristics similar to the ones of Mylos Gialtron coastal zone. They need to be systematically surveyed with the aim to understand their vulnerability to coastal landslides and design measures for the mitigation of their impact on the coastal societies.

ABSTRACT. New sedimentological and geochemical evidence derived from two gravity cores collected south of Amorgos and Anafi Islands, respectively, confirm the occurrence of submarine landslide deposits linked to the 1956 earthquake(s). The 1956 Mass Transport Deposits (MTDs) vary in thickness from 55 to 100 cm. They are characterized by a gray color, calcite dilution, higher gamma density values, a terrestrial origin, sharp boundaries, and a mixture of cohesive and non-cohesive flows. Additionally, they contain lower amounts of phosphorus (P), calcium (Ca), magnesium (Mg), cobalt (Co), chromium (Cr), iodine (I), manganese (Mn), nickel (Ni), and strontium (Sr). The differences in sedimentological characteristics of the MTDs are attributed to their proximity to the seismic event. The rapid deposition during the seismic shaking preserved the old seafloor, maintaining its physical and chemical characteristics. The predominant fraction of the sediments is clay, followed by sand, while silt is negligible.

ABSTRACT. Research Highlights Discovery of small depressions in the North Aegean Trough that probably contribute to the Limnos oil seep cluster Introduction Pockmarks are crater-like depressions of the seafloor where underlying fluids in the sediment pores escape to the water column. They have been discovered in numerous environments all around the world: in shallow areas, along continental margins, and in deep environments (Judd and Hovland, 2007), even in lakes (i.e., Toker and Tur, 2021). The records of pockmarks in Greece are numerous as well (Papatheodorou et al., 1993), mostly found in shallow areas, like the pockmark fields in Patra and Corinth gulfs (Christodoulou et al., 2003). During a marine survey for the laying of a power cable between Thrace and Limnos Island, numerous small depressions resembling pockmarks were discovered along a narrow corridor in the North Aegean Trough (NAT) (Figure 1a,b). NAT is a main geotectonic and morphological feature in the North Aegean Sea. It has a complex bathymetry containing three main basins (Limnos, Athos and Sporades). The tipping point of the most important fault system that characterizes the region, the dextral strike-slip fault known as the North Anatolian Fault (NAF), is differentiating the SW part of the NAT (Sporades and Athos basins) from the NE part of the NAT (Limnos basin) (Sakellariou et al., 2016). The basins have small dimensions and steep slopes, and they are isolated and separated from each other by bathymetric highs (Roussakis et al., 2004). The bathymetric high between Athos and Limnos Basins is the area under consideration for this study. Recently, Jatiault et al. (2024) discovered numerous oil seeps in the wider NAT region probably related to leakage from the broader fault system (Figure 1b). The western part of NAT (to the west of north Limnos), including the survey area, was mapped by Papanikolaou et al. (2002), however, pockmarks were not discerned. Thus, the objective of this study is to describe the distribution, morphology, size and density of the observed depressions and examine their potential relation with the oil seeps reported by Jatiault et al. (2024).

Figure 1. (a) Location of the broader study area (in green), (b) general bathymetric map of the Νorth Aegean and location of the surveyed area (brown line) and of the Limnos seep cluster (blue box) studied by Jatiault et al. (2024), (c) bathymetry of the surveyed area overlaid by slope (selected layer transparency: 40%), clipped to 3 subregions for better visualization.

Methods The survey was conducted during June 2024, along a corridor that was pre-selected by the Independent Power Transmission Operator (IPTO) of Greece, to pass along a bathymetric high in-between Limnos and Athos basins, so as to limit the depth of cable laying and burial. The distance between the survey lines was approximately 250 m. For bathymetry an R2Sonic 2026 (170-450 kHz) multibeam echosounder (MBES) was used. A Valeport Midas profiler was utilized for sound velocity profiles. Data acquisition was performed using the NaviScan and R2Sonic controller software packages. For the morphological survey, an EdgeTech 2050 Side Scan Sonar (SSS) was deployed, able to scan simultaneously the seafloor with a lower (230 kHz) and a higher frequency (540 kHz). A Sonardyne Ranger-2 USBL system was used for the towfish position. Survey speed was maintained at approximately 3-4 knots. Subbottom profiler records and sediment cores were also collected but are not presented in this study. MBES processing was performed utilizing EIVA, whilst for the SSS data processing and analysis and the production of high-resolution georeferenced sonar mosaics (pixel size of 0.25 m), the Chesapeake Technology SonarWiz software was used. QGIS was used for (i) mapping purposes (bathymetry cell size of 1 m), (ii) the descriptive measurements of the depressions, (iii) slope extraction and (iv) the creation of shaded relief imagery. Results Water depths in the study area range between 194 and 373 m. The northernmost part of the surveyed area is relatively shallow but gradually towards the south, the depth increases, reaching its maximum value (Figure 1c) with the deepest region occupying only a small part of the corridor. After this area and towards the southernmost part of the surveyed area, the depth is maintained at approximately 260 m. Slopes gradients are mild, not exceeding ~4.5. Throughout the surveyed area, numerous depressions were easily observed. Most of the pockmarks appear in the northern and southern parts of the surveyed zone, whilst along the deepest part depressions rarely occur. A total of 136 depressions were recognized and mapped (Table 1). Although relatively small (average spatial extent of ~1830 m2) and shallow (1-3 m deep) they appear in a variety of shapes, and they were categorized following the definitions of Judd and Hovland, (2007) for pockmark morphologies. 90 resemble “asymmetrical pockmarks”, lacking a well-defined rim, something that made their recognition difficult in the bathymetric maps. 40 were categorized as “well-defined circular”, and 6 appeared as “composite pockmarks”, implying merging of two or more smaller depressions. Table 1. Summary of pockmarks’ main characteristics. Minimum Maximum Average Occurrence water depth (m) 197 370 282.4 Pockmark depth (m) 1 3 1.3 Perimeter (m) 15.8 675.8 149.9 Area (m2) 16.6 21414.9 1831.2

The SSS records revealed a uniformly low reflectivity seabed, which indicates the presence of fine-grained sediments. Abundant crossing longitudinal marks suggest intense trawling fishing creating sharp scars on the soft seabed. Upon comparing the pockmarks detected in the bathymetric data with the SSS observations, it was evident that numerous depressions observed in the bathymetrical survey were not observed in the morphological survey, and SSS navigation errors produced discrepancies in the pockmark positions. Thus, unlike the bathymetric data, the SSS images discerned only 104 pockmarks, 28 in both SSS frequencies, 53 only in the low frequency, 11 only in the high frequency, whilst for 12 only low-frequency data were available, thus they could not be compared with the higher frequency information that was missing. Also, along specific areas towards the southern part of the surveyed area, anomalous reflections were recognized in the water column of the SSS records, probably due to fluid seepage (Figure 1c). Jatiault et al., (2024) studying Sentinel-1 data, reported oil seepage on topographic highs located west of Limnos trough and close to the NAF that coincides with the area under consideration. Fluid leakage was attributed to upward fluid migration through the local fault zone that displaces the shallow sedimentary structure. Discussion and Conclusions The study area is located within a topographic high of NAT, separating Limnos and Athos basins and has depths that do not exceed 370 m. The observed pockmarks are so far the deepest observed in the Greek maritime region, even if they have small dimensions. It must be mentioned that since the surveyed corridor spreads only for 1.1-1.2 km, pockmarks are obviously expected to occur in the wider area. This is also supported by the fact that the Limnos oil seep cluster (Jatiault et al., 2024) extends over ~40 km, in water depths ranging from 140 to 1200 m. Leakage in the water column is fueled through faults from deeper sedimentary strata, however, fluid seepage may also take place through pockmarks, and this process might have likewise contributed to their formation. Yet, the fact that leaking fluids in the water column, as observed in the SSS images, were not detected over the entirety of the pockmark field, possibly indicates that seeping activity through pockmarks is sporadic, and that probably only some of the observed pockmarks contribute to the fluid leakage in lower concentrations. Although the wider area is characterized by relatively high sedimentation rates (Roussakis et al., 2004) the topographic high where pockmarks occur probably corresponds to an area of lower sediment accumulation rates, thus ensuring the more stable conditions also needed for pockmark formation (Judd and Hovland, 2007). Finally, at least the surficial sediments are fine-grained, as observed in SSS images, a fact that contributes to the variety of pockmark morphologies that can be found in certain fields (Judd and Hovland, 2007). References Christodoulou, D., Papatheodorou, G., Ferentinos, G., Masson, M., 2003. Active seepage in two contrasting pockmark fields in the Patras and Corinth gulfs, Greece. Geo-Mar Letters 23, 194-199. Jatiault, R., Henry, P., Loncke, L., Sadaoui, M., Sakellariou, D., 2024. Natural oil seep systems in the Aegean Sea. Marine and Petroleum Geology 163, 106754. Judd, A., Hovland, M., 2007. Seabed Fluid Flow: The Impact on Geology, Biology, and the Marine Environment, 1st ed. Cambridge University Press. Papanikolaou, D., Alexandri, M., Nomikou, P., Ballas, D., 2002. Morphotectonic structure of the western part of the North Aegean Basin based on swath bathymetry. Marine Geology 190, 465-492. Papatheodorou, G., Hasiotis, T., Ferentinos, G., 1993. Gas charged sediments in the Aegean and Ionian Seas, Greece. Marine Geology 112, 171-184. Roussakis, G., Karageorgis, A.P., Conispoliatis, N., Lykousis, V., 2004. Last glacial–Holocene sediment sequences in N. Aegean basins: structure, accumulation rates and clay mineral distribution. Geo-Mar Letters 24, 97-111. Sakellariou, D., Rousakis, G., Vougioukalakis, G., Ioakim, C., Panagiotopoulos, I., Morfis, I., Zimianitis, E., Athanasoulis, K., Tsampouraki-Kraounaki, K., Mpardis, D., Karageorgis, A.P., 2016. Deformation pattern in the western North Aegean trough: preliminary results. Bulletin of the Geological Society of Greece 50 (1), 124-133. Toker, M., Tur, H., 2021. Shallow seismic characteristics and distribution of gas in lacustrine sediments at Lake Erçek, Eastern Anatolia, Turkey, from high-resolution seismic data. Environmental Earth Sciences 80, 727.

ABSTRACT. Introduction Assessing the state and dynamics of sandy shorelines (beaches) is vital for developing efficient management strategies (e.g. Karditsa et al., 2024; Chalazas et al., 2024), with the approaches used depending on their spatio-temporal scales and the available information and resources. In regional (island) scales, the extensive scope of studies and the high potential costs of adaptation (Narayan et al., 2016) may require prioritization of responses and efficient allocation of the (mostly) limited resources. This requires, among others, information of the geospatial characteristics and their interrelationships which may provide much needed information and identify potential controls of beach dynamics. Therefore, the objective of this short contribution is to present an approach that could acquire such information at a regional (island) scale on the basis of widely available geospatial data; the approach is demonstrated for the island of Kos, South Aegean Sea, Greece (Fig.1). Study area Kos has an area of about 295 km2, a coastline length of 112 km and a resident population of about 37,100. Kos is a highly touristic island: in 2023, 1.3 million passengers arrived at the island of Kos. There are > 57,000 hotel beds in Kos, tourism density and intensity being very high (28,917 tourist nights/km2). Most of this infrastructure and the tourist activities are associated with the island’s beaches, as Kos is a global tourist destination for Sea-Sand-Sun - 3S tourism (SETE, 2024). Kos coast is microtidal (0.1 m astronomical tidal range). In the north NNW waves dominate with the largest waves showing heights Hs of 3.8 m and periods Tp of 7.5 s. Energetic waves occasionally impinge on western and southern coasts, with the largest waves having heights of 4–5 m and periods of 9–10 s (Monioudi et al., 2025). Kos is a part of the easternmost South Aegean volcanic arc. Its northeastern part is mostly formed on Plio-Quaternary sediments, whereas its southeastern highlands are made mostly of alpine and pre-alpine metamorphics and some Miocene volcanics (Pe-Piper et al., 2024). Following a hiatus, volcanism, resumed 3 million years ago (mostly) in the island’s west; the large eruption of the Kos Plateau Tuff volcano (161 ka BP) deposited pyroclastics up to 15 m thick that covered most of the western Kos and the adjacent islands (Piper and Pe-Piper, 2020). Most large/wide beaches are found in the low-relief, sedimentary northeastern Kos (Fig. 1), indicating a potential geological control.

Figure 1. Kos: Beach maximum width (BMW) and long-term beach erosion trends. Numbers refer to the ID of the 78 beaches of Kos (after Monioudi et al., 2025).

Methods The compiled inventory of the Kos beaches provides information on the dimensions, sediment types and the presence of outflowing streams, coastal defenses or artificial and natural features. Using satellite images available in the Google Earth Pro application, subaerial (dry) beaches were digitized as polygons based on clearly visible boundaries: natural features like vegetated dunes or cliffs and permanent artificial structures such as embankments, seawalls, or buildings and the shoreline define the landward and seaward limits, respectively. To ensure consistency, all digitization was conducted by a single analyst adhering to strict delimitation rules. The database was constructed through the digitization of beach polygons from selected images obtained in the period 2003–2021, which allowed an estimation of the recent historical changes. The beach (CNES/Airbus and Maxar) imagery has a spatial resolution about 0.5 m, but its results are constrained by the image accuracy; comparison of satellite images with concurrent RTK-DGPS ground observations showed an RMSE of about 2 m. Moreover, although tidal effects on the shoreline position are very small care was taken to analyze satellite images from the same season and under low hydrodynamic conditions; however as the available images along the islands’ coasts have been collected at different times and under different preceding hydrodynamic conditions, recorded beach dimensions may not represent synoptic conditions at the island scale. Such limitations, however, cannot be avoided in the analysis of (historical) satellite imagery at large spatial scales (Monioudi et al., 2023). Following these procedures, the characteristics of 78 (Kos) beaches (Fig. 1) were identified, recorded and compared. Results The majority of beaches (53%) were found to have maximum widths (BMWs) of 20-50 m, 35% had widths < 20 m and 10 beaches had widths > 50 m (Fig. 1); the average maximum width was found to be 31 m. Despite the higher wave energy of the north- and west-facing beaches, a clear trend was observed in the development of northwest-facing beaches (303.75°- 348.75°). Fewer beaches were found to develop with southeast (16%) and south (12%) orientations, with the remaining beaches exhibiting other orientations (Fig. 2). This supports the hypothesis that the development of the Kos beaches is not controlled by the hydrodynamics, but is mainly subject to geological controls.

Figure 2. (a) Distribution of the Kos beach orientation. (b) Rose diagram of the beach maximum widths.

The relationship between orientation and the BMWs was further investigated using Angular-Linear correlation (Mardia, 1976; Zar, 2014) was used. This statistical test assesses the null hypothesis H0 of no correlation between the two variables against the alternative hypothesis H₁ of a significant correlation. The results showed an R2 = 0.0327 and p = 0.279, suggesting rejection of the H0 hypothesis as p > 0.05; thus, there is no statistically significant correlation between the two variables. There are outflowing streams in many Kos beaches (49%), indicating (potential) terrestrial sediment supply. Comparison of the BMWs with the occurrence of streams, shows that stream presence affects the beach size. In 2021, beaches with streams were found to have an average maximum width of 40.4 m which was almost double the width of beaches without streams (22.8 m). In order to examine the potential correlation between stream presence and BMWs it was checked whether the BMWs follow a normal distribution. Using the Shapiro-Wilk regularity test (Shapino and Wilk, 1965), it was found that the BMWs do not show 'normality' in terms of distribution (the Shapiro-Wilk regularity control gave W = 0.772, p <0.001); thus, the non-parametric Mann-Whitney test was used. Its result showed that these two types of beaches differ (U = 307.5, p <0.001), i.e., there is a correlation between beaches without streams and smaller BMWs with a median width of 22 m (Fig. 3a). Regarding beach sediments, the majority of Kos beaches (53%) form on sandy sediments, whereas 32 % of the beaches on mixed sediments (gravels/sands) and 15% on pebbles. Comparison of the BMWs with the different sediment types showed good correlations; sandy beaches had an average BMW of 40.8 m (standard deviation 20), i.e. they are significantly wider than mixed sediment beaches and pebble beaches which showed average BMWs of 23.4 m (10.8 standard deviation) and 16 m (7.3 standard deviation), respectively. Even when the mixed sediment and pebble beaches were grouped together, their comparison with the sandy beaches showed a clear difference. Sandy beaches were found to have significantly greater BMWs (40.8 m) compared to the grouped mixed sediment/pebble beaches (21 m). It appears that the coarse sediment beaches attain BMWs 10-25 m, whereas the sand beach BMWs 30-50 m and 50-80 m (Fig. 3b). In addition, it appears that about 60% of sandy beaches are also associated with outflowing streams, compared with those beaches forming on mixed sediments (45%) and pebbles (17%). To check this hypothesis the non-parametric Kruskal-Wallis test was used (the BMWs do not follow a normal distribution). The test checked the hypotheses: H0, no correlation between the BMWs and the local sediment; and H1, correlation between BMWs and the local sediments. The test showed that there is a clear difference between the maximum widths of beaches forming on sand and those forming on mixed/coarse sediments (H1 = 25.911, p < 0.001). Beaches forming on pebbles have a median BMW of 14.9 m, whereas those formed on mixed sediments and sands 22.6 m and 40.5 m, respectively. A Kruskal-Wallis test (Kruskal and Wallis, 1952) was also applied in the case that beaches divided into two classes: those with sand sediments and those with mixed sediments and pebbles. The test showed a clear difference between these beach classes (H1 = 25.090, p <0.001).

Figure 3. (a) Beach maximum widths (BMW) and the presence of beach streams (5 m steps), (b) BMWs and sediment texture (2 categories), (c) BMWs with the presence of backshore cliffs (10 m steps) excluding beaches with backshore infrastructure, and (d) Histogram of frequencies of areal changes.

A total of 50% of the island's beaches are characterized by the presence of backshore coastal cliffs. An initial investigation of the potential correlation with the BMWs did not reveal a significant relationship. However, as the presence of infrastructure/assets along the immediate backshore might affect the BMWs and other beach dimensions due to e.g., reduction/interruption of the land sediment supply and, thus, the correlation. Excluding beaches where there are backshore infrastructure/assets (about 50% of the total), a significant relationship is apparent (Fig. 3c). Many beaches with cliffs show BMWs of 10-20 m (and up to 30-50 m), whereas the beaches without cliffs attain obviously greater BMWs. The relationship was tested using the Mann-Whitney method excluding beaches with backshore infrastructure/assets. It appears that there is a statistically significant relationship (U = 34, p <0.001). Those beaches without a backshore cliff are larger (a median BMW of 46 m) than those with a backshore cliff (median of 22 m). It seems that the coastal topography controls beach formation and size. To assess the impact and effectiveness of coastal protection schemes, the areal changes between the beach polygons obtained from older imagery (2004-2009) and 2021 were considered which was preferred over more recent ones, as images were taken in spring/summer months (Fig. 3d). The Shapiro-Wilk regularity test for the variable 'beach area change' yielded results W = 0.889 and p <0.001 showing that the data do not follow a normal distribution. Thus, the non-parametric Mann-Whitney control was also applied by controlling the following assumptions: H0, the distribution of the continuous variable "percentage of change of beach area" is similar between beaches with coastal protection works and beaches without protection works; and H1, the distribution of the continuous variable "percentage of change of beach area" differs between beaches with protection works and beaches without works. The test results show there is a significant areal difference (U= 260, p=0.050) between beaches with and without coastal works. Discussion and Conclusions The analysis of the geo-spatial data using both basic statistical metrics and more complex parametric and non-parametric tests, led to interesting findings regarding the Kos beaches. Comparison of the digitized polygons of the beaches showed erosion trends (Fig. 1) with the average BMW having decreased in 76% of the beaches compared to the period 2004-2009 (average decrease of 3 m). In addition, the area was reduced in 61 beaches out of the 78 beaches of the island, with an average decrease of 15% per beach. As the maximum dry width is considered a relatively conservative indicator of beach erosion (Monioudi and Velegrakis, 2022), the estimation of the areal reduction offers a more comprehensive picture. The analysis also showed that the detection of long-term erosive trends requires availability of time series of data with spatio-temporal resolution better than that currently available in open source imagery. In the near future, when it is expected that the availability of such data will increase significantly (Velegrakis et al., 2024), the approach developed/applied in the present study can be used more for the detection (and management) of coastal morphodynamics (erosion). In Kos, the orientation of the beaches does appear to affect the size of the beach, which on the contrary is related to stream presence and sediment texture size. In addition, the presence of backshore cliffs is correlated with small BMWs. Generally, it appears the Kos beach dimensions are primarily controlled by the geology rather the hydrodynamics. Acknowledgements This research was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the ‘2nd Call for H.F.R.I. Research Projects to Support Post-Doctoral Researchers’ (MARICC, Project Number: 211). References Chalazas, T., Bove, G., Chatzistratis, D., Monioudi, I.N., Velegrakis, A.F., 2024. A system for the management of sandy shorelines under climate change: United States Virgin Islands (USVI). Ambio 53, 406 - 420. https://doi.org/10.1007/s13280-023-01946-w Karditsa, A., Niavis, S., Paramana, T., Monioudi, I, et al., 2024. Is the insular coastal tourism of western Greece at risk due to climate induced sea level rise? Ocean & Coastal Management 251, 107088. https://doi.org/10.1016/j.ocecoaman.2024.107088. Kruskal, W.H., Wallis, W.A., 1952. Use of ranks in one-criterion variance analysis. Journal of the American statistical Association 47(260), 583-621. https://doi.org/10.1080/01621459.1952.10483441 Monioudi I.N., Velegrakis, A.F., 2022. Beach Carrying Capacity at Touristic 3S Destinations: Its Significance, Projected Decreases and Adaptation Options under Climate Change. Journal Of Tourism and Hospitality 11, 500. Monioudi, I.N., Velegrakis, A.F., Chatzistratis, D. et al., 2023. Climate change—induced hazards on touristic island beaches: Cyprus, Eastern Mediterranean. Front. Mar. Sci. 10, 1188896. https://doi.org/10.3389/fmars.2023.1188896 Monioudi, I.N., Chatzistratis, D., Chalazas, T. et al. 2025. A prioritization framework for adaptation responses for climate change-induced erosion in island beaches—Cases from the Aegean islands, Greece. J. Mar. Sci. Eng. 13, 491. https://doi.org/10.3390/jmse13030491 Mardia, K., 1976. Linear-Circular Correlation Coefficients and Rhythmometry. Biometrika 63 (2), 403–405, https://doi.org/10.2307/2335637 Narayan, S., Beck, M.W., Reguero, B.G. et al., 2016. The effectiveness, costs and coastal protection benefits of natural and nature-based defences. PLoS ONE 2016, 11, e0154735. https://doi.org/10.1371/journal.pone.0154735 Pe-Piper, G., Piper, D.J., Tsoukalas, N., 2024. Mineralogy and Geochemistry of Upper Miocene Igneous Rocks, Kos Island, Greece: Extension during Strike-Slip Faulting and Subduction Rollback. Minerals 14(10), 989. https://doi.org/10.3390/min14100989 Piper, D.J.W., Pe-Piper, G., 2020. A reworked isolated deposit of the Kos Plateau Tuff and its significance for dating raised marine terraces, Kos, Greece. Geol. Mag. 157, 2021–2032. https://doi.org/10.1017/S0016756820000254 SETE, 2024. Annual Report of Competitiveness and Structural Adjustment in the Touristic Sector for 2023: South Aegean. https://insete.gr/wp-content/uploads/2024/12/24-12_South_Aegean-1.pdf (in Greek) Shapiro, S.S., Wilk, M.B., 1965. An analysis of variance test for normality (complete samples). Biometrika 52(3–4), 591–611. https://doi.org/10.1093/biomet/52.3-4.591 Velegrakis, A.F, Chatzistratis, D., Chalazas, T., et al., 2024. Earth observation technologies, policies and legislation for the coastal flood risk assessment and management: a European perspective. Anthropocene Coasts 7, 3. https://doi.org/10.1007/s44218-024-00037-x Zar, J.H., 2014. Biostatistical Analysis. Pearson Education Limited

ABSTRACT. The assumption of reference station conditions is an important one, yet is often taken for granted, especially at seismological stations or those presumably lying on rock. Stations are not always installed on true bedrock or in ideal free-field conditions, and –what is more– rock formations do not always exhibit negligible amplification, as assumed. In Greece, few site effects studies or field surveys have been conducted to characterise seismic networks in their entirety. Here, we first investigate broadband and accelerometric stations from the HL network, run by the National Observatory of Athens (NOA) throughout mainland and island Greece. There are 60 such stations with publicly available data streams in the period 2012-2024 which are thought to lie on rock. We address the reference station question compiling a wide variety of parameters: waveform-derived (site-specific amplification characteristics), operator-derived (on-site observations from station visits and walk-overs), and external sources (geological maps and literature). We co-evaluate all these factors to propose a transparent scheme for assessing reference stations for the HL network. Finally, we propose the extension of this pilot study to include other networks in the region of Macedonia and Thrace, as they can be of use in studying seismicity and seismic hazard in the Kavala-Prinos area, in the framework of EU project COREu.

ABSTRACT. Introduction The seismic hazard analysis aims to minimize the damage by determining local site conditions and peak ground acceleration before an earthquake as much as possible. Engineering geophysical methods are one of the fast and economical ways to determine the strength of the soil that will carry engineering structures, the thickness of the layers, water content, behavior under dynamic load, etc. The surface wave analyses allow to S-wave velocity model of the soil layers from the shallow surface to the engineering/seismic bedrock at a site.

In the last 25 years, seismic hazard studies have become important for seismological and earthquake engineering applications in the world. Turkey is one of the countries that have suffered from destructive earthquakes, especially since the 1999 Kocaeli earthquake. The latest 6 February 2023 Kahramanmaraş earthquakes defined as catastrophe earthquakes show that we have not made enough progress in reducing earthquake risk since 1999.

The Western Türkiye covers rapidly growing areas and encompasses the main financial and industrial centers Especially Istanbul, which is one of the most populated cities in the world, and the other cities in the Marmara Region such as Tekirdag, Çanakkale, and Balıkesir are the part of the Marmara Supersite that are a high priority to the geohazard community (Figure 1). Additionally, Izmir, the third biggest city, is also located in western Türkiye and affected by earthquakes.

Historical records show that destructive earthquakes frequently visit the region. In the last century, the 9 August 1912 Mürefte (Mw 7.3) earthquake hit the western part while the 17 August 1999 Kocaeli (Mw 7.4) earthquake destroyed the eastern part of the Marmara Region. The Gokceada earthquake (24 May 2014, Mw 6.9) also affected the west of the region. The last destructive earthquake occurred on 30 October 2020, in the north of Samos Island. Even the Bornova Basin, where the city of İzmir is mainly settled, is 70 km away from the earthquake epicenter, significant damage occurred in the city center because of the tick sediment basin. The number of collapsed, heavily damaged and moderately damaged buildings in İzmir is 54, 676 and 789, respectively. A total of 7,683 buildings were labeled as slightly damaged. Totally 117 people died during the mainshock.

One of the important points for local seismic hazard studies is to define 1D S-wave velocity (Vs) structures from the surface to the seismic or engineering bedrock. This is necessary to know site responses to estimate the ground motion impact on the buildings. The local geology significantly modifies ground motion characteristics and controls the irregular distribution of damage during large earthquakes. Therefore, shallow low-velocity layers are responsible for the variation of earthquake ground motion amplification at a site. Heterogeneity of the soil structures, velocity impedance differences between layers, resonant effects, irregular topography of the layers beneath a basin, the effect of the surface topography, nonlinear soil behavior, fault geometry and lateral variation of Vs causes variation of earthquake ground motion amplifications. It is important to estimate the Vs structure in near-surface layers for estimating strong motion characteristics during an earthquake. Furthermore, investigating the amplification of shallow soil structures is essential as accurately as possible to close the real ones. It is the first step to reduce casualties and collapse buildings before an earthquake for damage assessment. The amplitude, frequency content, and duration of strong ground motions are generally controlled by the local soil structures and have the main role for building damage during an earthquake.

To reduce to earthquake local site effect, a 1D soil profile can be obtained by different geophysical methods, using earthquake data or ambient noise recording to retrieve the vertical soil structure as well as borehole logging. The 1D assumption of the soil structure is widely accepted and easy to implement. Array explorations of microtremors (i.e. SPAC) and MASW methods have been gaining much popularity in the world to obtain 1D Vs profiles. Because they are one of the economic methods and easily applicable for the estimation of Vs structure by a simple circular array with a few seismometers (Figure 2). The Rayleigh waves are considered when vertical sensors are used for microtremor records. Surface wave phase velocity dispersion curves from microtremor records can be utilized to investigate 1D S-wave velocity structures for shallow soil structures.

In this study, the results of array microtremor studies in western Türkiye are presented. The data are collected by the international and national projects from 2013 October to 2024 August. The projects were focused on different methods and practices for disaster mitigation for western Türkiye. One of the main research fields of the projects is the determination of the deep and shallow velocity structure for “seismic characterization and damage prediction” that aims to improve the prediction accuracy of estimating the damages induced by strong ground motions.

Results and Conclusions 1D Vs structures of shallow sedimentary layers down to the engineering bedrock were explored by applying short-period microtremor Spatial Autocorrelation (SPAC) array measurements (Aki, 1957; Okada, 2003) on the different geological units in Istanbul (Zeytinburnu), Tekirdağ, Edirne, Çanakkale, Balıkesir and İzmir in western Türkiye (Figure 1, 2).

The microtremor array data was gathered with temporarily installed seismic sensors, which were set by using the small and large array circles measurements (Figure 2). Phase velocities of Rayleigh waves were estimated from vertical components of microtremors using the SPAC method proposed by Okada (2003). The SPAC method computes cross-correlations between station pairs in the array with the SPAC coefficients for the calculation of phase velocity at different frequencies. Each vertical-component record was divided into 81.92 s time segments. Then, the transient and artificial noises generated by local conditions such as pedestrians and cars near the sensors during the measurements were removed. The Parzen window with a bandwidth of 0.2 Hz was chosen for smoothing in the data processing. We used the 6-14 segments (average 10) for averaging to get the phase velocity at each frequency (Karagoz et al., 2015).

The observed phase velocities were used for the estimation of 1D S-wave velocity structure profiles using the hybrid heuristic method (Yamanaka 2007) as an inversion method to find an optimal S-wave velocity model. This method searches a 1D soil profile by minimizing the misfit function that is defined as a sum of squared differences between the observed and calculated phase velocities. The method used for theoretical dispersion curves of the fundamental mode of Rayleigh waves is based on Haskell (1953). We assumed a horizontally layered, isotropic and homogenous model. The layer model is characterized by four parameters; thickness (h), density (), P-wave velocity (Vp) and S-wave velocity (Vs) for each layer. Thicknesses and shear-wave velocities are the unknown parameters in the inversion. The density was assumed to increase with increasing S-wave velocity. P-wave velocity is not inverted but derived from S-wave velocity by using the empirical relation by Kitsunezaki et al. (1990), defined as Vp = 1.29+1.11*Vs where the units of Vp and Vs are expressed in km/s (Karagoz et al., 2015).

The observed Rayleigh wave phase velocities from field studies were between ~200 and 1000 m/s, ~90 and 930 m/s, ~120 and 850 m/s, ~200 and 1000 m/s in a frequency range from 2 to 30 Hz respectively for Zeytinburnu, Tekirdag, Çanakkale and İzmir, respectively. Most of the sites in Tekirdag had predominant frequencies higher than 2 Hz., 0.5 Hz for Zeytinburnu, 0.8 Hz Çannakale, 0.5 Hz for Izmir (Figure 3). The high amplifications at low frequencies are related to the thick sedimentary layers beneath the cities. Therefore, the reality of the seismic risk of the cities where close to the potential seismic sources (faults) and are on sedimentary basins must be considered for a sustainable future.

References Aki, K., 1957. Space and time spectra of stationary stochastic waves, with special reference to microtremors. BERI, 35, 415-456. Haskell NA (1953) The dispersion of surface waves on multilayered media. Bull Seism Soc Am 43:17–34 Karagoz, O., Chimoto, K., Citak, S., Ozel, O., Yamanaka, H., Hatayama, K., 2015. Estimation of shallow S-wave velocity structure and site response characteristics by microtremor array measurements in Tekirdag region, NW Turkey. Earth, Planets and Space, 67(1), 1-17. Kitsunezaki C, Goto N, Kobayashi Y, Ikawa T, Horike M, Saito T, Kurota T, Yamabe K, Okuzumi K (1990) Estimation of P- and S-wave velocities in deep soil deposits for evaluating ground vibrations in earthquake. J Japan Soc for Natural Disaster Scie 9:1–17 Okada H., 2003. The microtremor survey method. Geoph. Monog. Series. SEG, 12. Yamanaka H (2007) Inversion of surface-wave phase velocity using hybrid heuristic search method. Butsuri Tansa 60:265–275. doi:10.3124/segj.60.265 (in Japanese)

ABSTRACT. Earthquake source duration plays an important role in earthquake engineering, seismic hazard assessment and the design and safety of structures. We explore two global datasets: centroid time-delays from the Global Centroid Moment Tensor inversion and source time functions from the SCARDEC database. We derive empirical scaling relations that connect earthquake source duration with earthquake magnitude with a clear dependence on earthquake depth. Shallow earthquakes exhibit longer source durations compared to deeper events (depth>=60 km), in accordance with theoretical models. We present a catalogue of source durations for the Greek region based on the derived relationships and discuss further applications such as earthquake early warning feasibility assessments and improved seismic hazard estimates.

ABSTRACT. Moment tensors (MTs) are an essential tool for understanding earthquake source processes, improving seismic hazard assessment at various scales, and mitigating earthquake disaster risk. The Aegean Sea and its environs have the highest seismic activity in Europe and the Eastern Mediterranean, providing a wealth of earthquake data that can be used for moment tensor computations. In this work, we summarize moment tensor solutions published by the Global Centroid Moment Tensor Group (GCMT) and compare a subset of them with corresponding moment tensors from the Institute of Geodynamics of the National Observatory of Athens (NOA). We statistically examine the two datasets, primarily from the point of view of the style of faulting implied by the moment tensors in the study area and the associated Mw reporting. We also analyze the metrics of this comparison with respect to various factors, such as the location and magnitude of the associated earthquakes, their hypocentral depth, etc. Overall, we find a good agreement between the moment tensors of GCMT and NOA for 85% of the cases studied. Poor comparisons are mostly restricted to moderate magnitude events along the Hellenic Arc.

ABSTRACT. Seismic swarms are characterized by intense seismic activity strongly clustered in time and space and without the occurrence of a major event that can be considered as the mainshock. Such intense seismic activity is most commonly associated with external aseismic factors, as pore-fluid pressure diffusion, aseismic creep, or magmatic intrusion that can perturb the regional stresses locally triggering the observed seismicity. These factors can control the spatiotemporal evolution of seismic swarms, frequently exhibiting spatial expansion and migration of event hypocenters with time. This phenomenon, termed as earthquake diffusion, can be highly anisotropic and complex, with earthquakes occurring preferentially along fractures and zones of weakness within the heterogeneous crust, presenting anisotropic diffusivities that may locally vary over several orders of magnitude. The efficient modelling of the complex spatiotemporal evolution of seismic swarms, thus, represents a major challenge. Herein, we develop a stochastic framework based on the well-established Continuous Time Random Walk (CTRW) model, to map the spatiotemporal evolution of seismic swarms. Within this context, earthquake occurrence is considered as a point- process in space and time, with jump lengths and waiting times between successive earthquakes drawn from a joint probability density function. The spatiotemporal evolution of seismicity is then described with an appropriate master equation and the time-fractional diffusion equation (TFDE). The applicability of the model is demonstrated for the 2014 Long Valley Caldera (California) seismic swarm, which has been associated with a pore-fluid pressure triggering mechanism, and the results are compared with other seismic swarms in the Corinth Rift, as well as injection-induced seismicity, including the 2025 seismic crisis in the Santorini-Amorgos zone. Statistical analysis of the seismic swarm in the light of the CTRW model shows that the mean squared distance of event hypocenters grows slowly with time, with a diffusion exponent much lower than unity, as well as a broad waiting times distribution with asymptotic power law behavior. Such properties are intrinsic characteristics of anomalous earthquake diffusion and particularly subdiffusion. Furthermore, the asymptotic solution of the TFDE can successfully capture the main features of earthquake progression in time and space, showing a peak of event concentration close to the initial source of the stress perturbation and a stretched relaxation of seismicity with distance. Overall, the results demonstrate that the CTRW model and the TFDE can efficiently be used to decipher the complex spatiotemporal evolution of seismic swarms.

ABSTRACT. The Hellenic Macroseismic Database for historical earthquakes (HMDB.UoA, Kouskouna and Sakkas 2013) was developed at the Laboratory of Seismology of the University of Athens in 2013 within the framework of NERIES and SHARE projects, as a contributor to the Archive of Historical Earthquake Data inventory of Europe. Since then, new studies presenting additional macroseismic intensities from historical earthquakes have been published. Our aim is to update this database with the new Macroseismic Data Points (MDPs) and present its latest version. In addition, amendments regarding the parameters PlaceID, PlaceName and coordinates were introduced in order to better constrain the identity of localities and their multiple names within the centuries. Thus, a separate column containing the latest name of the locality is added, as well as one for comments related to the amendments. We anticipate to add earthquakes from the early 20th century in the near future.

ABSTRACT. The history of the Proto-Atlantic and the opening up of the Atlantic are particularly well expressed on the Western Iberian Margin (WIM) and are of interest to many geosciences’ experts and curiosity to many citizens. The expressiveness of the last 600 million years of the WIM's geological history is particularly eloquent in a territory that covers an east-west strip of the Beira Litoral (Central Portugal), comprising the municipalities of Figueira da Foz, Mira, Cantanhede, Mealhada, Montemor-o-Velho and Penacova (Fig. 1). The “Atlantic Geopark” Project consists of inventorying and evaluating the geological heritage of those six municipalities, with a view to its conservation, valuation and monitoring for a future application to the Global Geoparks Network (GGN). The results obtained will provide technical support for the application dossier, that has to also include a sustainable management plan for the territory aiming at fostering socio-economic development, conserving the geological heritage and inspirating its replication in similar transatlantic territories.

ABSTRACT. The Lavreotiki Geopark occupies the area where both hypogene and supergene processes created an amazing underground world, decorated with an exquisite variety of minerals of international recognition and value. Its mineralization is unique and of high geodiversity, as the territory contains 748 naturally occurring mineral species(Rieck, 2024). From about 10 to 7 million years ago, massive tectonic movements along the so-called “Western Cycladic Detachment System”, accommodated magma emplacement, and facilitated hydrothermal fluid circulation and ore deposition within permeable lithologies. These processes in combination with subsequent supergene oxidation of the ores, gave birth to one of the most important, historically and economically, polymetallic deposits in the world exploited by the Ancient Greeks and during the modern times.

ABSTRACT. The variety of microfossils identified allowed to reconstruct the original ecosystem of the lake areas of the Pululahua Volcano after its destructive volcanic events. Based on the characterization and timing of charcoal pebbles encountered within a distant but prominent ash-layer, it has been possible to identify how an ancient culture has been destroyed in coastal Ecuador, some 3,5 ka ago.

ABSTRACT. Nisyros Geopark, located in the Southeastern Aegean, is a candidate for inclusion in the UNESCO Global Geoparks Network, recognized for its exceptional volcanic heritage and its integration of geological, natural, and cultural elements. Covering 481 km², the geopark is centered on the active Nisyros volcano and nearby islands, forming a dynamic landscape shaped by the South Aegean Volcanic Arc. Among its 24 geosites are active hydrothermal craters, a collapse caldera, volcanic domes, and numerous coastal hot springs, all of which serve as key focal points for educational activities. Education is a cornerstone of the Geopark’s mission, with a range of ongoing programs designed to share its unique geological story with diverse audiences. Workshops, guided tours, summer schools and educational programs are regularly organized to connect participants—ranging from local students to international visitors—with the island's volcanic and cultural history (Fig. 1,2). These activities aim to foster an understanding of the dynamic processes that shaped the island and their relevance to contemporary environmental issues.

Modern communication tools further enhance the educational experience. The Geopark’s official website (www.nisyrosgeopark.gr), along with dedicated mobile applications, provides accessible and engaging resources, enabling visitors to explore the region’s geoheritage independently or as part of structured activities. Partnerships with schools, universities, and cultural institutions ensure that educational outreach is deeply integrated into the community, encouraging active participation and fostering a long-term appreciation of the island's natural and cultural heritage. By combining hands-on experiences, innovative communication techniques, and collaborations with educational organizations, Nisyros Geopark is establishing itself as a hub for learning and discovery. These efforts position the Geopark as a model for integrating education with the preservation and celebration of volcanic heritage, ensuring its significance is understood and valued by future generations.

ABSTRACT. Recent research within the Vikos-Aoos UNESCO Global Geopark and neighboring Albania has highlighted the significance of sulfuric acid speleogenesis (SAS) caves, drawing the attention of explorers and researchers alike. Collaborative efforts by the Geopark and the School of Geology at Aristotle University of Thessaloniki focus on mapping these caves and investigating their unique processes. Their presence in a Greek Geopark underscores their scientific importance and potential for fostering awareness and sustainable tourism. However, the challenges posed by toxic atmospheres and fragile ecosystems necessitate strict protection measures, advocating for innovative approaches such as Information and Communication Technologies (ICT) to ensure responsible geosite development.

ABSTRACT. The Noravank geosite displays an upper Farsnian - lower Famennian sedimentary sequence that crops out just below the legendary Noravank monastery, one of the most touristic destinations in Armenia. The monastery was built by the powerful Orbelian dynasty in medieval Armenia. Hermann Abich, knwon as "the Father of Caucasian Geology" found in the middle of teh 19th century a new brachiopod species, which he dedicated to the Orbelian dynasty by naming it Spirifer orbelianus. The leading author of this study revised the generic name of this species and he dedicated it to Aramazd, the chief god in pre-Christian Armenian mythology. He also established the biostratigraphic significance of this species, as a lwoer Famennian marker species. Finally recent palynological results obtained from the neigbouring Ertych section allow to make a link of the Frasnian-Famennian outcrop at Noravank with the global change sthat took place during the Kelwasser mass extinction event. All these elemnts provide ground for teh geotouristic dvelopment of teh Noravank geosite.

ABSTRACT. An ERBE Symposium has a strong element in common with the ancient Greek symposia. The International "ERBE" Symposium, exploring the cultural heritage of geology, mining and metallurgy, has a tradition that goes back more than three decades. The main objective of an ERBE Symposium is to exhibit the cultural heritage in Geosciences, Mining and Metallurgy. The idea of applying for one of the next ERBE Symposia, which could be organised by the Lavreotiki Geopark and the Committee of Geological-Geomorphological Heritage of the Greek Geological Society, was strengthened in our minds after the inclusion of the Lavrion area in the UNESCO Geoparks Group. By organising the next ERBE Symposium in Lavrion, we will be able to present the history, incredible monuments and natural beauty of Lavreotiki so broadly, whilst its organisation would help us to gain international supporters for the inclusion of the area in the UNESCO World Heritage List.

ABSTRACT. The research project, entitled: An educational walk in the historical centre of Athens, is an innovative educational proposal that approaches different scientific fields in an interdisciplinary way. Conducted as part of the research work (project) by 14 school girls and 13 school boys of secondary education of the high school, during the second semester of the 2019-2020 school year. In addition to the historical, social and literary approach to the selected sites, this educational process uses the area around the square in Monastiraki in the light of urban geology and can increase children's knowledge and improve their attitude towards geosciences.

ABSTRACT. The climate crisis is one of humanity's most pressing challenges and has visible and widespread impacts on public health. The presentation links the climate crisis to disease distribution, research, and control. From rising temperatures and the increasing frequency of extreme weather events to the emergence of climate-related diseases and nutritional inequalities, the climate crisis seriously threatens the health and well-being of the population. Using the interdisciplinary approach, we report on the challenges emerging, reemerging, and neglected diseases arising and being influenced by the climate crisis and how they affect our health and everyday life.

ABSTRACT. This study aims at the hydrogeochemical evaluation of surface waters and the possible anthropogenic impact affecting the surface water quality in the complex environment of the Megalopolis basin, including over 50 years of lignite mining. The results can guide sustainable restoration strategies and environmental policies in the transition era of mine closure. In March 2024, 24 surface water samples were collected from upstream to downstream locations along the Alfeios River and its tributaries, which flow near the lignite operations. The chemical parameters of NH4+ (maximum 3 mg/L), SO42- (range from 3 to 1010 mg/L), Mn (range from 1 to 338 μg/L), and Mo (range from 0.2 to 1027 μg/L) were identified as the most of environmental concern, exhibiting significant variability among samples. The presence of SO₄²⁻, Mn, and Mo in the water samples indicates a geogenic origin, strongly influenced by the regional lithology, including lignite deposits, post-Alpine sediments, and geological formations within the Pindos zone. The samples were categorized into three clusters (C1, C2, and C3) according to Hierarchical Cluster Analysis (HCA). Samples in Cluster 3, located near the old mining area, showed the highest concentrations of major and trace elements, exceeding the EU limits for Mn (50 μg/l) and SO42- (250 mg/l) and were classified as Ca2+-SO42- type waters. In contrast, C1 and C2 samples had a Ca2+-HCO3- hydrochemical type. The scatter plot of NO3−/Cl− ratios and Cl−, indicated that the dominant source of NO3− was sewage from the town of Megalopolis. The Alfeios River appeared to be minimally affected by lignite activities, with no significant changes in water chemistry observed before and after the mining area, except for slightly elevated Mn and Mo levels, most of which remained below WHO and EU limits.

ABSTRACT. This study presents the results of a systematic inventory of water wells (boreholes) conducted across Water District EL13, encompassing the Island of Crete and the Island of Gavdos. As part of the project “Systematic Inventory of Water Wells for All Uses Throughout the Country of Greece,” extensive fieldwork carried out by the Hellenic Survey of Geology and Mineral Exploration (HSGME) between July 2019 and January 2023 identified and documented 5,349 water wells across 24 municipalities. The findings reveal significant dependencies on groundwater for irrigation, with 79.4% of wells used for agricultural purposes, 10.5% for drinking water, and 7.6% abandoned or unused. Ownership data highlights that 68.6% of wells are privately owned, posing challenges for regulatory oversight and sustainable resource management.

The Messara Basin, a critical agricultural and hydrogeological area, accounts for 46.3% of all wells, underscoring its substantial reliance on groundwater. This inventory integrates geospatial and technical data into a comprehensive geodatabase, providing a foundation for assessing water balances, evaluating groundwater system pressures, and formulating management strategies. The project supports compliance with the European Union's Water Framework Directive and Greece’s River Basin Management Plans, demonstrating the importance of stakeholder collaboration in addressing groundwater challenges. Future efforts should focus on enhancing monitoring, enforcing regulations, and promoting sustainable water use practices to ensure the long-term viability of Crete's groundwater resources.

ABSTRACT. Quantitative rendering of the impact of urban sprawl on Natura 2000 areas, Wild Life Refuges, Small Islands Wetlands, Archeological areas and Monuments and the Petrified Forest in Lemnos island. Interpretation of results based on spatial planning system in Greece.

ABSTRACT. This study provides a comprehensive overview of the geological mapping of Crete, a monumental endeavor spanning decades of systematic surveys. Foundational geological maps, including the General Geological Map of Greece at a scale of 1:200k and the 24 sheets of the Basic Geological Map of Greece at a scale of 1:50k, have documented the island's intricate and diverse geology. However, the use of varying methodologies, technologies, and scientific approaches during different survey periods has introduced heterogeneity into the resulting maps. Recent efforts by the Hellenic Survey of Geology and Mineral Exploration (HSGME) aim to resolve these inconsistencies through the updating, digitization, and homogenization of the maps, employing GIS technology and modern methodologies. Revised sheets, such as Vatolakkos and Kato Chorio, highlight significant advancements in cartographic quality and geological interpretation, resulting in a more cohesive and accurate geological framework. Moving forward, continued efforts to integrate, update, and modernize Crete's geological data are essential. These initiatives build upon the foundational work of earlier surveys and ensure that the resulting geological framework not only advances academic research but also contributes to the sustainable management of the island’s natural resources.

ABSTRACT. RescueME (Resilient Cultural Landscapes) is a Research project funded by the Horizon Europe programme where five Resilience Landscape Laboratories (R-labscapes) are working with 12 consortium research and technology partners to create new approaches of protecting coastal cultural heritage and landscapes, implementing innovative resilience solutions and culture-focused strategies. The project started in February 1st, 2023, lasts for 42 months and focuses on the enhancement of the resilience of coastal cultural landscapes (CLs) in Europe.

The five case studies (Psiloritis UGGp in Greece, the island of Neuwerk in Germany, Portovenere, Cinque Terre & the Islands in Italy, L’Horta in Spain, and the city of Zadar in Croatia) have been selected carefully as complementary representatives of European coastal landscapes. They act as resilience landscape laboratories (R-labscapes) to validate the results and ensure their replicability. For these five target areas, RescueME is going to produce digital tools and innovative solutions for climate change adaptation and natural disaster risk management.

Regarding Psiloritis UGGp located at the island of Crete, Greece, planned actions focus on shielding of its northern coast (parts of the Municipalities of Mylopotamos & Rethymnon) from the impacts of extreme weather phenomena such as heatwaves, droughts, water shortages and, secondarily, floods. Also, Psiloritis UGGp has set as priority to enhance heritage resilience, raise awareness among local stakeholders and make RescueME project results actionable in the local framework.

RescueME is developing, testing and demonstrating the effectiveness of an Actionable Framework based on the Resilient Historical Landscape approach (RHL) complemented by data, models, methods, and tools able to assess risks and opportunities, co-develop inclusive and just resilience strategies and innovative solutions to protect European cultural heritage and cultural landscapes from climate change, disaster risk, as well as other stressors (such as pollution and over-tourism) with special focus on European coastal landscapes (FUNDACION TECNALIA RESEARCH & INNOVATION, 2023).

ABSTRACT. This work presents the results from six (6) years of GNSS campaign observations on the Methana volcano, central Greece. The observations were collected by occupying five (5) benchmarks using dual frequency geodetic receivers during the period 2018 – 2024. The Methana data set was processed to obtain 24-h position solutions using the GIPSY-X software. For the first time, the displacement velocities of the NOA campaign GNSS stations have been estimated to provide additional geodynamic information in an active volcano area with two permanent stations.

ABSTRACT. Mafic sulfide deposits in Cyprus were studied by Hannington et al. (1998) and Adamides et al. (2010). They are composed mostly of pyrite (Parvaz, 2014). The acid mine drainage (AMD) is the result of sulfide minerals and waste oxidation due to exposure to water and oxygen conditions affecting large areas. The case study is the Memi inactive pyrite mine in Nicosia, Cyprus. Herein, we applied Remote Sensing (RS) techniques for the monitoring of the mine area. To this purpose, the Visible Near Infrared and Shortwave Infrared (VNIR-SWIR) spectral bands of multispectral (MSI) and hyperspectral satellite imagery (HSI) were used. More specifically, a combination of Sentinel-2, WorldView-3 (WV3), both VNIR and SWIR, and Environmental Mapping and Analysis Program (EnMap) data were employed. Two different spectral libraries, namely the United States Geological Survey (USGS) and Jet Propulsion Laboratory (JPL) spectral libraries, and three spectral processing methods were selected to analyze the data in the frame of the m4mining project. The detection of the specific minerals (using USGS or JPL endmembers) at different wavelengths using EnMap, Sentinel-2, and WV3 data seems to be influenced by each sensors’ specifications (e.g. band wavelength position, spectral range, spectral band, spatial resolution, acquisition date etc.) and the inherent physical properties of the samples the spectral signatures of which are retrieved from the spectral library and used as endmembers (e.g. particle size, specific chemistry, environmental context). The SI, BD, and SAM indicate the presence of AMD-related minerals in the study area revealing higher values within the mine area. This is an ongoing work. The verification of the obtained results using in-situ samplings, chemical and mineral laboratory analyses, and in-situ spectral measurements is currently under study.

ABSTRACT. Understanding and monitoring shoreline changes is critical for effective coastal zone management, particularly in regions experiencing dynamic erosion and accretion. This study evaluates the effectiveness of airborne LiDAR and RGB imagery acquired via Unmanned Aerial Systems (UAS) for accurate shoreline detection, focusing on Gavathas Beach, Lesvos Island, Greece. Both technologies were utilized to generate high-resolution Digital Elevation Models (DEMs) and orthophotographs, enabling precise delineation of the shoreline. The LiDAR data, collected using the YellowScan VX-15 system mounted on a DJI Matrice 600 Pro, provided dense 3D point clouds with centimeter-level accuracy. Simultaneously, RGB imagery was captured using a Sony Alpha 6000 camera synchronized with the LiDAR system. The RGB-derived orthophotographs facilitated visual interpretation and supported the identification of shoreline features under varying environmental conditions. Digital Shoreline Analysis System (DSAS) was employed to quantify shoreline changes by comparing the extracted shorelines with reference data collected using a Differential GPS (DGPS) system. The results demonstrated that LiDAR-derived shorelines exhibited superior accuracy, with mean deviations of less than 0.5 meters from the reference data. RGB-derived shorelines showed slightly higher deviations due to challenges in image contrast and environmental lighting conditions but remained within acceptable thresholds for practical applications. This comparative analysis highlights the potential of integrating airborne LiDAR and RGB imagery for efficient and reliable shoreline mapping. The findings emphasize the advantages of LiDAR for its high spatial resolution and robust performance in complex coastal environments, while RGB imagery offers a cost-effective and operationally flexible alternative for areas with clear land-water boundaries. These insights contribute to the optimization of coastal monitoring practices and inform future applications of remote sensing technologies in shoreline management.

ABSTRACT. The southeastern part of the Hellenic Volcanic Arc (HVA), including Kos, Yali and Nisyros islands, is geodynamically very active. Intense seismic activity occurred on Nisyros Island during 1996-1998, accompanied with strong ground deformation and temperature increase of the fumaroles. Ground-deformation studies based on GPS and differential Interferometry for the period 1996-2000 revealed an “opening” of the island along the main faulting zones together with intense uplift of up to 90mm that gradually reduced the following two years (2000-2002). Remeasurement of the Nisyros-Yali GPS network in the following years combined with interferometric data provided the spatial and temporal ground-deformation pattern after the period of the seismic crisis. The GPS results indicated intense subsidence in the northern and central parts of Nisyros that caused the western and eastern flanks of the island to “collapse” towards its center, as is evident from the horizontal component of the GPS vectors. The interferometric analysis based on SqueeSAR and European Ground Motion Service calibrated and decomposed products shown a similar deformational pattern as the GPS one; subsidence is observed along the northern and central parts of Nisyros, while the western part of Nisyros shows eastward motion, and the eastern part, westward. Motions along the main faulting zones that cross-cut the island are also clearly identified. Both analyses have shown that the ground deformation on Yali may be associated with a more regional subsidence that takes place to the south and offshore of the islet, as is clearly indicated from the horizontal component of the GPS vectors. The overall pattern of subsidence in the broader area of Nisyros and Yali after 2000 is consistent with two modelled Mogi sources, and indicates that the pressure inside the two associated magma chambers and hydrothermal system has likely decreased.

ABSTRACT. Introduction In this study, we employed advanced interferometric time series analysis to explore the relationship between water level variability, seismicity, and induced surface motion over the Gardanne coalfield (Figure 1), while also accounting for potential long-term contributions. A spatio-temporal investigation of surface motion measurements was therefore conducted using data from the Copernicus Sentinel-1 mission, ultimately aiming to attribute the observed motion to a deformation mechanism. The Gardanne coalfield, located in southern France between Marseille and Aix-en-Provence, was mined from the 17th century until 2003. Different techniques were employed along the basin with the deepest exploitation reaching up to 1300 m depth to the west of the basin (Dominique et al., 2022). The gradual progression of the mine workings to the west of the basin was affected by groundwater flow and pumping was considered essential to lower the water level and allow access to deeper levels. After mining ceased in 2003, the ending of pumping led to the flooding of the mine, with groundwater levels stabilizing around 2010. Since then, water level is relatively stable by pumping, with annual fluctuations of about twenty meters (Dominique, 2016). With the gradual rise of the underground water level microseismicity was felt by the population in 2010 and a strong seismic swarm occurred in November 2012. Since then, swarming seismic activity lasting a few days has been re-appearing periodically in the same area, especially in November 2012, December 2014, November 2016 - March 2017 and August 2017. Prior analysis of seismic data revealed apparent connection of seismic activity with seasonal changes of underground water level in the mine, as well as with pumping rates (Dominique, 2016). Further analysis showed that swarming activity is related to the reactivation of minor fault segments being favorably oriented with respect to the local tectonic stress field (Dominique et al., 2022). However, no impact on the surface has been observed in post mining period that would indicate collapses of underground mining works (Namjesnik et al. 2022).

Methods / Results Post-mining surface deformation detected from multi-temporal interferometric processing for the period from April 2015 to December 2022 via the SNAPPING service (Foumelis et al., 2022) revealed deformation patterns spatially correlated with the epicentral area of the 2016-2017 Gardanne micro-seismic activity (Figure 2). The temporal evolution of surface motion shows a signal attributed to induced seismicity, evidenced by a clear change in the displacement time series during this specific period. Geometric decomposition of the ascending and descending LoS measurements confirms the above observation, showing prevailing vertical motion with a negligible E-W component. This is also consistent with the focal mechanisms of major recorded events, which indicate normal faulting, typical of post-mining sites. To investigate the relationship between seismicity locations and observed surface motion, we performed spatial clustering of micro-seismicity using the k-means algorithm. This process resulted in 5 distinct clusters (Figure 2), which accounted for ~80% of the total number of events in the catalogue within the epicentral area. It is apparent that seismic activity increased after each pumping phase, with a notable correlation between the magnitude of water table lowering and the frequency of seismic events. The consecutive drops in the water table during 2015 and 2016 contributed to the largest seismic swarm of late 2016 - early 2017, also coincided with the largest surface motion signal. An overall consistency was observed between the timing of micro-seismic events and the occurrence of surface displacements across the various seismic clusters. Although the interpretation of the measurements until early 2017 is straightforward, it becomes more complex when examining the seismic activity and related surface motion for the August 2017 swarm. This signal seems to extend well beyond the main epicentral region, representing a seasonal subsidence component observed in the inter-annual displacement time series from 2015 to 2022. This seasonal signal might mask the maximum motion, potentially impacting the assessment of deformation caused by post-mining seismic activity during this period.

Conclusions Our findings suggest that the observed surface motion is likely a result of energy released by both seismicity and aseismic motion caused by fluctuations of the mine's water table. The onset and variability of surface motion may also be controlled by the heterogeneity of the mine workings, such as differences in the gallery dimensions and the lithological composition of the overlying lithology.

ABSTRACT. In Greece, like worldwide, arid and semi-arid regions face the alternating challenge of water scarcity and erratic rainfall patterns (Kourgialas, 2021; Nabinejad et al., 2023; El-Hamid et al., 2024). Hence, they are highly vulnerable to both droughts and floods. Unfortunately, the frequency and intensity of such extreme weather events are increasing, making traditional management methods obsolete. As a result, both the scientific community and society are now looking for more dynamic and adaptive approaches. This paper studies a novel approach to integrated flood and drought management using Multi-Agent Systems (MAS), an Artificial Intelligence technology. The proposed MAS framework consists of a network of intelligent agents, each responsible for a specific aspect of water resource management, including real-time data collection, flood prediction, drought monitoring, water allocation, and infrastructure control. This distributed and adaptive approach enables autonomous agents to have common goals, allowing them to interact and cooperate to achieve them. As a result, they will contribute to effective responses in case of extreme weather events, promoting sustainable water resource management. More specifically, Intelligent Agents in the context of a water resource management system, can integrate diverse data sources, support real-time decision-making, and enable responses to floods and droughts. The rest paper presents the architecture of the proposed MAS, including the types of agents, their interactions, and the data they utilize. A case study for a representative arid region presents the added value of the proposed approach.

ABSTRACT. Droughts are temporary but impactful natural phenomena that significantly affect water resources, ecosystems, and human activities. This study investigates drought dynamics in Greece using the Standardized Relative Humidity Index (SRHI) to analyze climate variability and drought severity. Relative humidity (RH) data from 42 Hellenic National Meteorological Service (HNMS) stations (1971–2004) were processed to calculate SRHI at multiple time scales (1, 3, 6, 9, and 12 months). Spatial and temporal trends were assessed through statistical analysis and geospatial mapping using Inverse Distance Weighting (IDW). The findings highlight 1989–1990 as the most severe drought period, followed by 2000–2001, revealing significant climate variability patterns. This study contributes to understanding the extent of climate change impacts on Greece, by examining long-term humidity trends and their implications for drought monitoring and especially for the proper water resource management.

ABSTRACT. Water scarcity has emerged as a critical challenge in Greece, particularly following the extreme drought of summer 2024, which led to significant shortages in multiple regions. In response, a nationwide survey was conducted to examine public perceptions of water scarcity and local water resource management. The survey, structured into seven sections, explored awareness levels, personal conservation habits, policy perspectives, and regional disparities in water availability and governance. Beyond assessing public opinion, this study investigates spatial patterns that may reveal connections between perceived water scarcity and local limitations in water resources or management strategies. Findings indicate notable regional variations in concern levels, conservation efforts, and trust in governmental responses. Notably, areas that experienced more severe shortages demonstrated heightened awareness and a stronger inclination toward water-saving behaviours. Additionally, a significant majority of respondents expressed the need for environmental education programs in schools, recognising their potential to cultivate long-term sustainable practices. By integrating public perceptions with spatial insights, this study provides valuable input for policymakers to develop targeted, region-specific strategies for sustainable water management. The findings underscore the necessity of both technical improvements in water governance and widespread educational initiatives to foster a culture of water conservation in Greece.

ABSTRACT. Mediterranean region is hotspot of climate change, posing numerous challenges for local communities. Since ancient times, water management has played a significant role in social and economic stability. Implementing a sustainable technique for the storage and use of rainwater, especially in the current era of climate crisis, remains a challenge to address. Rainwater harvesting systems offer a potential relief to drought and water scarcity, particularly for islands in arid and semi-arid areas, such as the island of Nisyros, which has unique climatic and demographic characteristics. In this study, a daily water balance model was used to explore scenarios for meeting household water needs. To ensure the model’s reliability, daily rainfall data were collected from a local weather station for the period 2017-2023, covering six hydrological years. Specifically, the reliability of the rainwater harvesting system was assessed for various scenarios ivolving collection surface area (20-120sq.m), tank volume (5-30cbm), household size (Ncap=1-3), and satisfaction rate of their water needs. Additionally, future climate projections were used to examine system performance under climate change conditions, specifically for the two climate scenarios, RCP 4.5 and RCP 8.5. Future rainfall time series data were obtained from the DEAR-Clima website, covering the period from 2026 to 2060. The analysis yielded valuable insights and conclusions regarding the efficiency of the rainwater harvesting system, both for the observed period and under future climate scenarios of Nisyros.

ABSTRACT. This study examines the efficiency of domestic rainwater harvesting (RWH) systems on Fourni Island, Greece, under past and future climate conditions. Different scenarios were tested, considering household size, rooftop collection area (40-140 m²), and tank volume (5-30 m³). Results show that the rooftop area is the key factor for system performance. In two-member households, a 30% water demand coverage was achieved with rooftops of at least 80 m², while larger households struggled to reach this target. Climate projections (RCP 4.5 & RCP 8.5) indicate a 15% drop in efficiency, especially for smaller collection areas (≤60 m²). While RWH cannot fully replace other water sources, it can serve as a useful additional supply, particularly during peak demand periods like the tourist season. Future research should explore the economic feasibility of RWH and its combination with other solutions, such as desalination and greywater reuse, to improve water sustainability on small islands.