The study area of Rodafnidia on the island of Lesbos (Greece) is considered of archaeological interest, as Paleolithic stone tools have been recovered through excavation and collected from the ground surface in recent years. Geologically, the area is mostly covered by Quaternary post-alpine deposits and volcanic rocks. This paper presents the application of a local geophysical survey to determine the volume of the upper Quaternary deposits in which the Paleolithic artefacts can be found and the identification of their ignimbrite substrates. For this reason, the geoelectrical method was selected as the most appropriate for determining the lithostratigraphic subsurface layers. More specifically, a grid of twenty-one (21) Vertical Electrical Soundings (VES) along with an Electrical Resistivity Tomography (ERT) was carried out. The interpretation of the results of these surveys, in conjunction with the results of older excavation trenches, revealed that the Quaternary deposits have been investigated at depths ranging from 0.5 up to 28.5 meters. Furthermore, the lithological boundary of these post-alpine deposits and their underlying pyroclastic ignimbrite flow (with resistivity 24.0–58.0 Ohm.m) seem to dip to the north. The volume of the Quaternary layer is proposed as the maximum depth for archaeological investigation with high chances to recover more Paleolithic material.

The coastal environment of the west and south coast of Peloponnesus, Greece is characterized as an essentially tideless coastal environment exposed to high wave activity. Regarding the identification, the thickness and characteristics of the uppermost substratum of the selected coastal zones, at Hellonitis, Kyparissiakos and Messiniakos Gulfs, a detailed geophysical research was carried out. The geophysical survey aims to determine the thickness and the characteristics of the upper substratum of the selected coastal area, leading to the quantification of the sediment budget; the latter is considered essential to address potential coastal erosion. For this reason, the geophysical techniques of Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) were implemented to profiles normal and parallel to the shoreline. The geophysical results reveal the presence of the interface between the dry and wet sand deposits, along with the structure and the downward extension of the coastal material.

The tool assesses natural factors and the impact of human activities as well as the available mitigation measures in a cost-benefit perspective and with a view to mitigating the impacts of climate change. Therefore, the tool is designed to respond to both erosion (as a natural disaster) and erosion due to human (inappropriate) intervention, as well as CM&D (eg, sea level rise, extreme wave events). The innovation of the project is based on the creation of a multi-parameter decision making tool (ILIDA_KIT) related to climate change mitigation and resilience to coastal erosion and extreme wave events in the context of integrated coastal zone management. ILIDA_KIT relies on a multi-disciplinary interactive platform in a GIS environment that through the development of a set of appropriate indicators (environmental, anthropogeographic, economic) can be parameterised. The ultimate purpose of the tool is to select the most appropriate intervention (intensity, size, time horizon) measure, based on the costbenefit analysis, considering both the protection and the sustainable development of the coastal zone.

This paper presents the methodology of an applied geophysical and remote sensing research at river deltas for their subsurface and surface structure and its application in the deltaic plain of Pineios River (Thessaly, Greece). The scope is to primarily calculate the thickness of deltaic post alpine deposits, with the contribution of Transient Electromagnetic Method (TEM), but also identify the surficial characteristics (biotic/ abiotic) of the area with the appropriate combination of spectral bands and spectral indices. Regarding the remote sensing approach, some geomorphological features were outlined. This was managed from six false color composites of the area, produced by combining spectral bands and additional five false color composites by combining several spectral indices. •The results of the TEM method along with their statistical analysis provided important information regarding the spatial distribution and thickness of the lithological units along the deltaic plain.•The combination of spectral bands 8, 7, 6 seems to adumbrate the hydrographic network of the area and even detects possible changes in the inflow.•The combination of spectral indices MSAVI2, WV-BI, WV-WI was helpful enough to geomorphological mapping of the deltaic plain.

The Athenet network is the network of the Seismological Laboratory of the National and Kapodistrian University of Athens. We present the geophysical investigation that has been carried out at six seismological stations of the Athenet network for their site characterization. More specifically, at the location of each seismological station, four geophysical methods have been carried out: Seismic Refraction Tomography (SRT), Multichannel Analysis of Surface Waves (MASW), the Horizontal to Vertical Spectral Ratio (HVSR) technique, and Electrical Resistivity Tomography (ERT). The applied geophysical survey provided important information regarding the site characterization at the selected seismological stations, including key parameters such as the fundamental frequency fo, the shear-wave velocity VS, the average shear-wave velocity for the upper 30 m depth (VS30), the seismic bedrock depth, the soil type, and the subsurface geology. Moreover, selected elastic moduli (Poisson’s ratio, shear, bulk, and Young moduli) have been calculated. The site characterization information contributes to the determination of the amplification factors for each site that can lead to more accurate calculation of Peak Ground Acceleration (PGA) or Peak Ground Velocity (PGV) and, therefore, trustworthy Probabilistic and Stochastic Seismic Hazard Assessments. The derived fundamental frequency for the seismological stations of VILL, LOUT, THAL, and EPID have been determined to be equal to 10.4, 2.7, 1.4, and 7.1 Hz and their amplification factors to be 1.9, 3.1, 1.7, and 2.6, respectively. For stations MDRA and ATAL, these parameters could not be determined.

In this paper, we present a systematic GIS-based approach for producing updated, upscaled, unified and reevaluated maps for the Ionian Islands of Greece, which is an area of great geological interest. In particular, Cephalonia and Lefkada are two islands with an increased and intense seismicity. Therefore, a common GIS geodatabase was produced for handling the geoinformation of the area. New upscaled (scale 1:50,000) geotechnical and seismotectonic maps of these islands were produced based on older ones. On the other hand, the corresponding maps of the islands, based on the categories of the Greek antiseismic code and Eurocode 8, were produced in an effort to correlate them. Beyond that, all the available isoseismal maps of the earthquakes that hit the Ionian Islands were gathered in an effort to evaluate them and to find possible correlations with the other types of maps. Based on the correlation results, the consideration of the Vs30 parameter in the Greek antiseismic code is proposed for a better categorization of the geological formations.

The present study aims to present the results of a near-surface geophysical investigation carried out ata construction site in the area of Goudi (Athens) along with its contribution to the determination of thegeotechnical characteristics. For this purpose, the Ground Penetrating Radar (GPR), ElectricalResistivity Tomography (ERT), Seismic Refraction Tomography (SRT) and Multichannel Analysis ofSurface Waves (MASW) techniques were implemented in the area. The cores of three geotechnicalboreholes existing in the area have also been taken into account. The application of the GPR and ERTtechniques did not reached a satisfactory investigation depth, however the existence of a possiblemechanically degraded zone have been adumbrated at the south part of the excavation area. Throughthe application of the SRT and MASW techniques, the seismic waves velocities of the investigatedlithological formations were calculated and the subsurface structure of the study area was outlined.Additionally, lateral variations in the P-wave seismic velocities, especially in the first investigatedseismic layer, provided further evidence for the existence of mechanically unstable zones, whichnecessitate a more detailed investigation. Finally, from the laboratory determination of the formations’densities and their seismic wave velocities, their elastic moduli and geotechnical parameters have beencalculated.

Light Detection And Range (LiDAR) data have been used in numerous case studies, related to fast-developing landslides and rockfalls, producing remarkably precise Digital Terrain Models (DTMs). When these models are coupled to classic near-surface geophysical methods, they result in the high-accuracy mapping of the open surface and subsurface morphology, an essential element for a modern coastal management study. In this work, we introduce the diachronic monitoring and detection of alterations on the surface of the active fault of Psatha (Greece), via a multiple-phase study within a period of 11 years, by using terrestrial LiDAR scans and Electrical Resistivity Tomography (ERT).The successful combination of these techniques is being used to reveal and quantify the landscape evolution involving the surface alterations at the fault adjacent coastal zone, the sea intrusion, and even the coastline displacement, in any coastal area characterized by similar features.

The coastal environment of central Kyparissiakos Gulf, located at the west coast of Peloponnesus, Greece, comprises of a sandy beach associated with an extended dune field at its backshore area. This area is characterized as an essentially tideless coastal environment exposed to high wave activity. Regarding the identification, the thickness and characteristics of the uppermost substratum of the selected coastal site a detailed geophysical research was carried out. The geophysical survey aims to determine the thickness and the characteristics of the upper substratum of the selected coastal area, leading to the quantification of the sediment budget; the latter is considered essential to address potential coastal erosion. For this reason, the geophysical techniques of Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) were implemented to profiles normal and parallel to the shoreline. The geophysical results reveal the presence of the interface between the dry and wet sand deposits, along with the structure and the downward extension of the sandy material.

The cave of Alistrati, is located in the Prefecture of Serres, Northern Greece near the foothills ofMount Menoikio, in the area of Petroto. This area is structured by crystalline limestones, where thedevelopment of a complex and multilevel karst system is favored. An extensive geomorphologicalsurvey was carried out for the accurate mapping of the karst surface above the cave, using UAS. Forthe investigation of a possible lateral extension of the existing karstic conduit, a detailed surfacegeophysical investigation was carried out. More specifically, three geophysical techniques wereimplemented: a) the Electrical Resistivity Tomography (ERT), b) the Ground Penetrating Radar(GPR) technique and c) the Very-Low Frequency (VLF) method. These 13 lines of the threegeophysical techniques are fully matched at 4 locations and were join-interpreted, yielding remarkablefindings. The comparative results of the above geophysical techniques, as well as their 3Dpresentation, highlight similar geophysical anomalies, evaluated as different types of karst systemstructures. Therefore, the combined geophysical survey has indicated the existence andinterconnection of the first two karst levels of the area, up to a depth of 50m, as well as the possibleextension of the Alistrati karstic conduit to the northeast.

Greece is a country structured by land, several islands and sea. A regional gravity model of such a country demands the involvement of several types of gravity data in order to cover all its territory. In this paper, we present the development of a regional combined gravity model of Greece and its surroundingarea, by integrating terrestrial, marine (shipborne and altimetry-derived gravity data) and satellite data (GOCE and GRACE data). These kinds of data, especially the terrestrial and marine ones, have passed quality and validation control since they were collected from different organizations, which means that they probably have been acquired and processed with different parametersand formulas. Following that, their integration was accomplished with the application of the least-squares collocation (LSC). Therefore, a newly combined regional gravity model of Greece and its surrounding areas has been developed. This gravity model can be valuable for regional geological and geophysical studies of Greece, since it provides homogeneously the distribution of Complete Bouguer anomaly (CBA) all over Greece, with updated gravity data and in good agreement with the initial gravity datasets that have been used. 

We investigate an earthquake sequence involving an Mw = 4.6 mainshock on 2 December 2020, followed by a seismic swarm in July–October 2021 near Thiva, Central Greece, to identify the activated structures and understand its triggering mechanisms. For this purpose, we employ double-difference relocation to construct a high-resolution earthquake catalogue and examine in detail the distribution of hypocenters and the spatiotemporal evolution of the sequence. Furthermore, we apply instrumental and imaging geodesy to map the local deformation and identify long-term trends or anomalies that could have contributed to stress loading. The 2021 seismic swarm was hosted on a system of conjugate normal faults, including the eastward extension of the Yliki fault, with the main activated structures trending WNW–ESE and dipping south. No pre- or coseismic deformation could be associated with the 2021 swarm, while Coulomb stress transfer due to the Mw = 4.6 mainshock of December 2020 was found to be insufficient to trigger its nucleation. However, the evolution of the swarm is related to stress triggering by its major events and facilitated by pore-fluid pressure diffusion. The re-evaluated seismic history of the area reveals its potential to generate destructive Mw = 6.0 earthquakes; therefore, the continued monitoring of its microseismicity is considered important.

The Arkalochori village in central Crete was hit by a large earthquake (Mw = 6.0) on 27 September 2021, causing casualties, injuries, and severe damage to the infrastructure. Due to the absence of apparent surface rupture and the initial focal mechanism solution of the seismic event, we initiated complementary, multi-disciplinary research by combining seismological and remote sensing data processing, followed by extensive field validation. Detailed geological mapping, fault surface measuring accompanied with tectonic analysis, fault photorealistic model creation by unmanned aerial system data processing, post-seismic surface deformation analysis by DInSAR image interpretation coupled with accurately relocated epicenters recorded by locally established seismographs have been carried out. The combination of the results obtained from these techniques led to the determination of the contemporary tectonic stress regime that caused the earthquake in central Crete, which was found compatible with extensional processes parallel to the Hellenic arc.

The current study aims to clarify the structural regime of the deltaic valley of Pineios river (Thessaly, Greece). The structural control of a deltaic area is usually a crucial parameter for its Palaio-geographical evolution and the latter needs to be clear for the contemporary conservation of such a sensitive ecotope environmentally. The investigation of the concealed subsurface tectonic structures was accomplished through the combined interpretation of gravity measurements, VES and TEM soundings. The standard gravity data reduction has been carried out and the residual anomaly was isolated with the contribution of the Fourier filters. The Euler deconvolution has been applied, providing the corresponding depth solutions between 159.8 and 1716.6 m. In the context of the qualitative interpretation, we produced several structural maps (THDR, VDR, Tilt and Theta) in order to enhance the edges of density sources that may reflect fault zones. Severe indications for the delineation of fault zones of the area were provided by these maps. Moreover, 3D density models of the area have been constructed illustrating the subsurface density distribution, up to depths of 3370 m. A main zone of lower densities in the central part of the delta has been revealed, surrounded by three zones of higher densities. Afterwards, the densities of the majority of the existing geological formations were determined with laboratory measurements from geological specimens. Therefore, three geophysical-geological profiles have been constructed, based not only on the gravity modelling but also on the geological interpretation of the geoelectrical layered models from the VES and TEM measurements. In conclusion, concealed and unknown tectonic structures of the Pineios deltaic valley have been identified beneath the surface.

Lefkada and Corfu old towns are located in the western part of Greece, in the Ionian Sea. Their proximity to the Hellenic subduction zone (HSZ) is the reason for their intense seismicity. The main goal of this study was the estimation of the geotechnical characteristics of the subsurface, with the contribution of applied geophysical techniques. Therefore, seismic refraction tomography (SRT) and multichannel analysis of surface waves (MASW) were applied. A total of thirty-three (33) seismic and geoelectrical profiles were performed in both towns in order to evaluate the geotechnical characteristics of the subsurface formations. Additionally, subsurface resistivity distributions were investigated with the application of electrical resistivity tomography (ERT). Some important elastic moduli were calculated through the combination of estimated seismic wave velocities and laboratory density measurements. The horizontal distribution of seismic velocities and mechanical properties (σ, E, K, G) of Corfu town was illustrated in maps, for the depth of 5 m. The geophysical interpretation also revealed that Lefkada’s subsurface consists of only one compact geological formation, with little or no variation of its geophysical-geotechnical characteristics. Beyond that, the ground type classifications for the two towns were determined according to the European Committee for Standardization Eurocode 8, based on VS30 values.

Coastal areas constitute a very dynamic environment, balancing between numerous natural and anthropogenic processes liable to sometimes hazardous geomorphic phenomena. Especially in tectonically active coastal regions and areas of high economic value, slope failures can have significant impacts and therefore need careful and detailed examination. This work uses Unmanned Aerial System (UAS)-aided photogrammetry and Terrestrial Laser Scanning (TLS) in tectonically active segments of the coastal zone of the Ionian Islands in Greece, to explore how their capabilities can help to improve our understanding of the structural integrity of the slopes. Results show that the two approaches are able to extract large numbers of discontinuity facets, in a more practical, rapid and safe way than conventional methods of rock slope stability analysis extending to unreachable yet important parts of the slope. Through this holistic record of the structural condition of the slope the two applications allow the identification of segments that are more prone to instability and failure. In this way, they improve our understanding of the prioritization of interventions aiming to enhance the prevention of slope failures, mitigating the associated risk and improving local development in these high-value locations.

Based on the results of a previous terrestrial gravity survey that was carried out in Athens basin (Greece) some indications of correlation between terrestrial gravity data and isoseismal maps of Athens earthquake (7/9/1999) had been revealed. In this paper, we will present a research for the same area based on a new approach, which investigates the possible correlation of the same isoseismal maps with only satellite gravity data from GOCE and GRACE but also with a combined gravity model of updated terrestrial, marine and satellite data. The combined gravity model of Greece was constructed based on the least-squares collocation. The previous correlation of isoseismal maps with the older terrestrial gravity data was quite obvious and clear since the areas with the lower gravity values were simultaneously the ones with the greatest damage distribution. On the other hand, from the satellite gravity data and the combined gravity model we could not identify a clear and obvious correlation, as was expected, due to the smaller resolution spacing of the satellite data.

Relevance. In this paper the feeding mechanism of springs distributed around the broader area of Delfini at NE side of Chios Island is explored, in an effort to locate possible fresh water paths inland before they are discharged to the sea. The drilling of hydro wells for more production is of vital importance to cover the drinking and irrigation needs of the broader area. Aim. Although Chios has been extensively drilled in the past years the demand for further investigations comes from an increased water consumption during summer time in one hand and the inefficiency of alternative water resources (e.g. construction of dams, desalination units, etc) on the other hand. Methods. Geophysical methods were used (VLF and resistivity) to explore in detail water potential areas, like the broader area of Delfini, where during winter time huge quantities of fresh water discharge through springs to sea level. Results and its discussion. The presence of a confined aquifer composed mainly of limestones, which are overlain by clastic impermeable deposits, together with the existence of water potential bearing fracture zones determine the hydrogeological regime of the nearby area. It is also explained the presence of brackish waters at positive elevations found during summer time at nearby springs. It seems that the lateral extent of impermeable clastic deposits plays a crucial role in allowing the inland flow of seawater during summer time and combined with the presence of the confined aquifer of fresh water produce an upward mixing flow of fresh and seawater at springs of positive elevations. During winter time the huge amount of fresh water discharges do not allow the inland flow of seawater

An urban gravity survey with more than 1120 measurements was carried out in order to adumbrate the deeper subsurface of Athens city basin. The aim was to gather quantitative information of the subsurface structure derived from the acquisition of gravity measurements. At first, a gravity base network has been established for the data collection. The standard data reduction has been carried out along with an additional Building Correction that has been calculated due to the urban characteristics. Subsequently, the residual anomaly was isolated with the contribution of the Fourier filters. The Euler deconvolution has been applied, with two different techniques, providing depth solutions for the residual maps. Based on these maps, we managed to retrieve quantitative information for the depths of anomalous sources, ranging between 500 and 3760 m. Moreover, unconstrained three-dimensional density models of the area have been constructed in order to obtain a good image of the subsurface, up to depths of 4500 m. For each three-dimensional density model, we provide a couple of images; one illustrating only the structures of lower densities and one other only with the structures of higher densities, in an effort to delineate better the tectonic structures. Finally, two geophysical-geological profiles (2.75D) have been constructed, along which the geotectonic regime of the subsurface seems to be adumbrated in a better way. Major known tectonic structures of Athens basin have been identified beneath the surface.

The general understanding of the major tectonic structures that are traced on Crete Island is of great importance to decipher the geodynamic regime of the leading edge of the overriding Aegean microplate and consequently Eurasia’s southernmost active margin. The aim of this multidisciplinary methodology is to provide useful information for more reliable mapping of buried structures, which in turn supplement the dynamic and kinematic model of this key area of high interest. Several indicators for the existence of oblique fault block displacement were identified with the use of earth observation data, as strike slip faulting expressions on the surface are more efficiently identified by vertical observations. Tectonic structures which are usually created along lateral displacements require different working scales. Hence, earth observation data (satellite images, aerial photographs) with various spatial characteristics need to be included. Therefore, the methodology presented in this paper involves high spatial resolution digital elevation models and several remote sensing multispectral datasets, in many cases merged with higher spatial resolution panchromatic aerial photographs. The co-registration and orthorectification of all datasets proved to be a very significant part of this work in order to produce high resolution coloured 3D scenes at selected sites in central Crete, where the observed N-S trending strike slip fault zones crosscut arc parallel low angle normal faults and higher angle fault scarps. Additionally, deep seismic reflection datasets along the major geomorphic structure of Messara basin were combined and highlighted the strike slip mechanism, since the continuation of the subvertical structures in depth has become clearer after the exact positioning of the sections and further interpretation.

The gravity method has been applied, with a total of 1.122 gravity measurements for the subsurface investigation of the geotectonic structure beneath the urban and sub-urban areas of Athens basin. The aim was to either verify previously mapped concealed fault zones or even discover new concealed faults that may affect the city in the future by generating disastrous earthquakes. Three different methods have been used to determine the densities of the existing geological formations in the best possible way: laboratory measurements, Nettleton profiles and the seismic velocity conversion. In the context of the qualitative interpretation, we took advantage of the derivatives methods in order to enhance the structural edges of density sources that may reflect fault zones. Thereby, several structural maps have been produced by applying most of the enhancement techniques, such as the Total Horizontal Derivative (THDR), the First Vertical Derivative (VDR), the Second Vertical Derivative (SVDR), the Analytical Signal (AS), Tilt (Tilt) and the Theta (cos Tilt). Their results were extremely helpful, providing severe indications for the delineation of the fault pattern of the area. These results were combined with interpretive geological 2.75-D density models in order to verify or modify fault regime of the area. Important data regarding the geological and tectonic structure beneath the Quaternary formations were retrieved. More specifically, we were able to verify and modify the locations and lengths of already proposed as concealed faults zones from older geological researches or even better to identify and propose new locations of concealed faults that have not been identified so far.

In June 2018 a geophysical campaign begun from the Department of Geology and Geoenvironment at the departmental excavation of Plasi Marathon. The geophysical survey focused on the northern part of the area, where the first excavation trenches of 2017 and 2018 revealed architectural remains of the late Classical and Hellenistic period. The main aim of the research was the investigation of the existence and spatial extent of the architectural remains in the unexcavated parts. Taking into consideration the revealed remains of the excavated parts and the geoenvironmental conditions of the area, the geoelectromagnetic method of Ground Penetrating Radar (GPR) and the high resolution geoelectrical tomography (ERT) technique, were selected to be applied. Simultaneously, a topographic ‘reference base’ was established in the area in order to record the location of the geophysical measurements with real-time dGPS measurements. From the combinational evaluation of the processed geophysical data, we adumbrate the areas of possible archaeological ‘targets’, covered with post-alpine river deposits. Future excavation trenches at the indicated areas will confirm the existence or not of the covered architectural remains.

For several years, Greece has set as a priority the strengthening of maritime tourism, such as the tourism of yachts for which tourist marinas have been created. The most important marinas of the country include the “Glyfada Marina”, whose works began on the coastal front after 1960, thus changing the area’s shape and planning. The main objective of the present work is to investigate the improvement measures and prospects for the development of the “Glyfada Marina” consisting of four basins, being one of the most beautiful and developed marinas in the country since it is an important attraction for tourist yachts.

A multidisciplinary analysis comprising neotectonic mapping, morphotectonic indices, applied geophysics and remote sensing techniques was applied in the area affected by the 2008 NW Peloponnese (Western Greece) in order to map the recently-recognized E-W striking Pineios River normal fault zone with a high degree of accuracy, and to better understand its contribution to the evolution of the ancient region of Elis during Holocene time. Quantitative constraints on deformation caused by the faulting were applied through the application of morphometric and morphotectonic indices including drainage network asymmetry, longitudinal river profiles and valley floor slope changes, the river sinuosity index (SI) of modern channels as well as mountain front indices including mountain front sinuosity (Smf) and percentage of faceting along mountain front (F%). All of the aforementioned indicated that the Pineios fault zone is a highly active structure.

Coastal zone monitoring of river deltas is essential in order to understand their evolution and incorporate sustainable coastal management practices. Frequent data collection is essential but often surveys can be costly and time-consuming. This often leads to increase the time lag between successive monitoring campaigns to reduce survey costs, with the consequence of fragmenting the data available for coastal zone management. In this study we present the ability of off-the-shelf Unmanned Aerial Systems (UAS) coupled with Structure-from-Motion (SfM) photogrammetry to map and measure coastal features (e.g. shorelines).

Mediterranean Temporary Ponds (MTPs) constitute priority habitat under the European Union Habitats’ Directive. They are inhabited by rare species and subjected to unstable environmental conditions. Lakes and ponds act as early indicators of climate change, to which high altitude ecosystems are especially vulnerable. This study presents a full dataset of the geo-environmental parameters of such habitats (MTPs) along with their current ecological status for the first time. Furthermore, this paper aims to address the lack of basic geo-environmental background on the network of MTPs of Mt. Oiti concerning their geological, geomorphological, mineralogical and geochemical characteristics along with the pressures received from various activities. The study area is located in a mountainous Natura 2000 site of Central Greece, which hosts four MTPs. Fieldwork and sampling of water and bottom sediments were carried out during dry and wet periods between 2012 and 2014. Electrical Resistivity Tomography measurements identified synforms shaped under the ponds that topography does not always adopt them, mostly due to erosion procedures. The most significant feature, distinguishing those pond waters from any other province water bodies is the extremely low content of all studied ions (including NO2−, NO3−, NH4+, PO43−, HCO3−, SO42−, Al, As, B, Ba, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Fe, Ga, Gd, Ge, Hf, Hg, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Rb, S, Sb, Se, Si, Sn, Sr, Ti, U, V, W, Zn, and Zr). MTPs water bodies are of bicarbonate dominant type, and a fresh meteoric water origin is suggested. The main pressures identified were grazing and trampling by vehicles. MTPs of Mt. Oiti were classified according to their ecological status form excellent to medium. Our results can contribute to a better understanding of the mountainous temporary ponds development in the Mediterranean environment.

The study area is located at coastal area of the Ancient Harbor of Lechaion, at the area of the outer harbor moles (Figs. 1- 2), in order to investigate a possible extension of the existing ancient settlements. It is located on the southeastern coast of the Corinthian Gulf, 3km to the west of the modern city of Corinth, Greece. The construction of the Ancient Harbor dates to the 6th-7th century BC and archaeological evidence suggest that its use continued throughout the Roman period (Rothaus, 1995; Stiros et al., 1996). Lechaion harbor site lies in the southern coastal area of the Lechaion Gulf (Fig. 1). The broader area comprises alluvial and coastal deposits including loose materials, sands, pebbles and gravels (Papanikolaou et al., 1998).

The excavation trenches by the Department of History and Archaeology of the NKUA at the archaeological site of Plasi Marathon (Attica, Greece) have already revealed several architectural remains of the Classical period. A combined GPR and ERT survey was initiated in order to determine the existence and geometry of additional buried structures in the unexcavated parts of the site. The results of this geophysical survey will not only assist the archaeologist’s planning for the next excavation steps, but will also provide valuable information for the density of habitation in the area, a significant factor for the understanding of the importance of ancient Marathon. Fifty-two GPR and eighteen ERT profiles were carried out in a selected area. After data processing, the obtained radargrams and resistivity tomograms are presented in the form of fence diagrams. Moreover, volume/depth slices have been extracted for specified depths from GPR and ERT in order to compare their results. Several identified geophysical anomalies can be interpreted as archaeological domestic remains, supporting a rather dense pattern of habitation, hence the archaeological significance of the site.

The study area is located at the broader area of Farsala (East Thessaly) and more specifically between the city of Farsala and its railway station. The main target of the geophysical survey was to investigate the subsurface litho-stratigraphic structure in order to assess the existence of two (2) possible fault zones. These zones were proposed in the primary Neotectonic Map of the area of Farsala, scale 1:25.000 (Fig. 1), produced by the Section of Dynamic Tectonics & Applied Geology of National Kapodistrian University of Athens in 2016, in the context of the Seismic Hazard Mapping of the Farsala broader area.

The gravity method has been applied, with a total of 1.122 gravity measurements for the subsurface investigation of the geotectonic structure beneath the urban and sub-urban areas of Athens basin. The aim was to gather new information for the subsurface geological and tectonic structure of Athens basin and re-assess the seismic hazard risk of the area that may damage its infrastructures. The standard corrections have been applied (drift, tide, latitude, free-air, Bouguer, terrain ones) along with an additional Building Correction that has been calculated based on the urban characteristics. Afterwards, the isolation of the residual anomaly has been accomplished with the contribution of the Fourier filters and the analysis of the power energy spectrum. The processing results provided important data regarding the geological and tectonic structure beneath the Quaternary formations that cover the basin. We managed to verify already proposed concealed fault zones or even discover and propose new ones that may affect the city in the future by generating disastrous earthquakes. In the context of the interpretation, two geophysicalgeological profiles have been constructed, along which the geotectonic regime of the subsurface is clarified.

Many researchers have presented that ground penetrating radar (GPR) is a subsurface survey method indicated to acquire important preliminary information in various geological subsurface investigations, but also in archaeological and cultural heritage studies (Conyers, 2016). GPR stands out among the geophysical methods applied in archaeology, given the fact that it is a non-destructive practical field technique. GPR results can be presented as bi-dimensional profiles (2D) and three-dimension images (3D), in the form of block diagrams, fence-diagrams and volume/depth-slices. Especially the amplitude maps (e.g., depth-slices maps) allow the identification of areas with high or low amplitude of specific deep reflectors. Therefore, they can be used to identify buried targets and their dimensions, allowing the reconstruction of the subsurface in 3D (Porsani et al., 2010).

The disastrous phenomenon of aseismic ground fissures along the eastern Thessaly basin has deteriorated since 1989. The main reason for these fissures is the over-pumping, which leads to differential vertical compaction of the aquifer system and subsidence on the land surface. In this paper, we present the results of a combined geophysical survey applied in the area (VES and TEM soundings), in order to investigate the subsurface geological conditions. The geological regime of the area is comprised of the alpine basement, transgression formations and finally a package of post-alpine deposits with respectful thickness. A peudo-3D representation of resistivity maps for several depths of investigation was produced. Additionally, a dataset of deep boreholes was used for the calibration of the geophysical data. All the borehole and sounding interpreted data were grouped into three categories in order to produce the Lithology Model of the area. The alpine bedrock was adumbrated only at the southeast and central part of the basin, where we do not observe ground fissures. The absence of alpine bedrock for depths up to 300 meters, the thick and coarse-grained deposits and finally the over-pumping seem to contribute to the creation of the ground fissures.

Data availability is severely limited in high-altitude regions (Shea et al., 2015) mainly due to the remoteness and difficulty in accessing the sites. However, high mountain ecosystems are among the most sensitive environments to changes in climatic conditions occurring on global, regional and local scales (Ruiz et al., 2008). Due to significant warming observed globally during the recent century, the international scientific community has focused more attention to understand the cause and effect interaction on the ecosystems and their individual components to climate changes (Borgaonkar et al., 2011). In many mountain regions of the world, high altitudes appear to experience a stronger warming than the surrounding lowlands (Vuille, 2011) and that the warming is more closely related to an increase in daily minimum temperature than a change in the daily maximum (Diaz and Bradley, 1997; Beniston, 2006; Giambelluca et al., 2008). The main objective of this study is to evaluate the variability of meteorological parameters measured by two high altitude meteorological stations (OITI and KALLIDROMO) that have never been analyzed before, located in two mountainous Natura 2000 sites of Central Greece, in the Region of Sterea Ellada (Figure 1). The stations were settled in the framework of the Project: Conservation of priority forests and forest openings in "Ethnikos Drymos Oitis" and "Oros Kallidromo" of Sterea Ellada. The data sets recorded in the meteorological stations cover the periods 2014-2018.

The current study aims to clarify the hydrogeological regime of the deltaic valley of Pinios river (Thessaly, Greece). Its purpose is to map the existing aquifers below the deltaic plain, but also to assess the quality of their water (detect possible seawater intrusion), through the combined application of VES and TEM soundings. The results of the geophysical data processing revealed that the shallow (phreatic) aquifer is not detected throughout the entire deltaic plain, but only in the central and northern parts of the region, with thickness of 5–10 meters. Additionally, a deeper aquifer has been detected, with a maximum thickness equal to 100 meters. The interpretation of the geophysical soundings indicated that great part of the deeper aquifer has been affected by a saline intrusion that has also been noticed by hydrochemical data. Based on the fact that Pinios deltaic plain is a highly productive agricultural area, the irrigation system has to be reevaluated in order to constrain the extension of the seawater intrusion.

A disastrous earthquake of the past (7th September 1999) was the reason for acquiring 1.122 urban gravity measurements in order to investigate and model the deeper subsurface of Athens city basin. The aim was to gather any additional quantitative subsurface information based on the gravity survey, such as the density distribution provided by the 3D density models and depths of potential anomaly sources. The standard corrections have been applied (drift, tide, latitude, free-air, Bouguer, terrain ones) along with an additional Building Correction that was calculated based on the urban characteristics. The isolation of the residual anomaly has been accomplished with the contribution of the Fourier filters and power spectrum analysis. The Euler deconvolution has been used in order to calculate the depth solutions of anomalous sources, based on the residual maps. These solutions seem to identify with several fault zones. Some of these zones have already been mapped or proposed (covered ones) but additionally some new zones have been revealed. The 3D density model of the area provides information about the geometry of the subsurface geological bodies that can also be related to the tectonic structures of Athens basin beneath the surface.

Taking into consideration the major damage caused by the disastrous earthquake of 7th September 1999 (5.9R), the need for further and deeper investigation of the geological structure of the subsurface came up. The damage distribution of an earthquake is usually related to the tectonic structures of the area (Dilalos and Alexopoulos, 2017). Unfortunately, since the areas are covered with artificial surfaces, such as buildings, industrial infrastructures, roads, bridges and generally artificial surfaces, the geological research is quite complicated. The missing geological information for the deep subsurface can only be retrieved using geophysical methods. Given the fact that the 54.5% of Athens basin is covered with artificial surfaces (Dilalos, 2018), not all the geophysical methods can be applied. The land gravity measurements seem like the most applicable method for such a deep geotectonic investigation.

In gravity surveys, many unwanted effects are produced by geological or non-geological sources. These calculable effects have to be removed through the data reduction procedure. Common corrections in gravity measurements are those for the instrument drift, the tide, the Free Air, the Bouguer and the terrain effect. However, when we deal with gravity campaigns carried out in cities, we also have to take into consideration the so-called Building Correction. This concerns the correction of the gravitational effect caused by the existence of buildings and anthropogenic constructions (stadiums, bridges etc.) close to a gravity measurement. This process can become quite demanding sometimes. Because of that, in this paper we discuss a calculation method for the Building Correction of the gravity measurements. Two types of data are crucial in that procedure. The first one is the mean building density and the other one is the volume of the existing buildings, which is related to the spatial distribution and the buildings height. The mean building density has been calculated in this paper, based on percentage contribution of the building materials (concrete, bricks etc.) of the whole building volume. The calculated mean building density was equal to 0.44 g/cm3. A Building Height Map has been produced, based on the Digital Elevation Model and the Digital Surface Model. Taking into account the building volume and their density, a simulation of the terrain correction procedure has been carried out, for the Building Correction calculation. The calculated Building Correction values range from almost zero (in the suburbs) to 0.25 mGal. A comparison for the Residual Anomaly values (affected by the Building Correction) has also been made. Differences up to 0.19 mGal revealed are considered to be quite significant for the credibility of the final data.

River deltas sustain important ecosystems with rich biodiversity and large biomass, as well as human populations via the availability of water and food sources. Anthropogenic activities, such as urbanization, tourism and agriculture, may pose threats to river deltas. The knowledge of the factors controlling the regional water quality regime in these areas is important for planning sustainable use and management of the water resources. Here, hydrochemical methods and multivariate statistical techniques were combined to investigate the shallow aquifer of the Pinios River (Thessaly) deltaic plain with respect to water quality, hydrogeochemical evolution and interactions between groundwater and surface water bodies. Water quality assessment indicated that most of the river and groundwater samples fully comply with the criteria set by the Drinking Water Directive (98/83/EC). The river is recharged mainly from springs of the Tempi valley and the shallow aquifer, and to a lesser degree from precipitation, throughout the year. The hydrogeochemical characteristics indicated a cation (Ca, Mg, and Na) bicarbonate water type, which evolves to calcium-chloride, sodium-bicarbonate and sodium-chloride water type, in the northern part of the delta. Calcite and dolomite dissolution determined the major ion chemistry, but other processes, such as silicate weathering and cation exchange reactions, also contributed. In the northern part of the plain, the interaction with the deeper aquifer enriched the shallow aquifer with Na and Cl ions. Principal Component Analysis showed that five components (PCs) explain 77% of the total variance of water quality parameters; these are: (1) salinity; (2) water-silicate rocks interaction; (3) hardness due to calcite dissolution, and cation exchange processes; (4) nitrogen pollution; and (5) non-N-related artificial fertilizers. This study demonstrated that the variation of water hydrochemistry in the deltaic plain could be attributed to natural and anthropogenic processes. The interpretation of the PCA results dictated the parameters used for the development of a modified Water Quality Index (WQI), to provide a more comprehensive spatial representation of the water quality of the river delta.

In this paper, we discuss the correlation between isoseismal contour maps and gravity residual anomaly maps and how it might contribute to the characterization of vulnerable areas to earthquake damage, especially in urban areas, where the geophysical data collection is difficult. More specifically, we compare a couple of isoseismal maps that have been produced and published after the catastrophic earthquake of 7th September 1999 (5.9R) in Athens, the metropolis of Greece, with the residual map produced from the processing and data reduction of a gravity survey that has been carried out in the Athens basin recently. The geologic and tectonic regime of the Athens basin is quite complicated and it is still being updated with new elements. Basically it is comprised of four different geotectonic units, one of them considered as the autochthon. During the gravity investigation, 807 gravity stations were collected, based on a grid plan with spacing almost 1km, covering the entire basin and supported by a newly established gravity base network comprised by thirteen bases. Differential DGPS technique was used for the accurate measurement of all the gravity stations and bases coordinates. After the appropriate data reduction and the construction of the Complete Bouguer Anomaly map, we applied FFT filtering in order to remove the regional component and produce the Residual Anomaly Map. The comparison of the Residual Anomaly Map with the isoseismal contours revealed that the areas with the most damage because of the earthquake were located in the areas with the minimum values of the Residual Anomaly Map.

In this paper we discuss the preliminary results of the Transient Electromagnetic Method (TEM) that was applied in the area of Karla Lake, located in the East Thessaly basin. A grid of 71 TEM soundings was planned and executed in order to investigate the subsurface lithological and hydrogeological conditions of the area. The geological regime of the area is comprised of the alpine basement (marbles, gneisses and schists), ophiolites, transgression formations and finally a package of post-alpine deposits with respectful thickness. Resistivity maps for certain depths of investigation along with a pseudo-3D representation were produced, based on the processed TEM data. The vertical distribution of the resistivity values revealed important information about the lithological succession of the area and the hydrogeological status of the post-alpine sediments covering the basin. Moreover, the limits of the former Karla Lake were delineated and the alpine bedrock was also adumbrated under the thick Tertiary and Quaternary deposits. Finally, taking into account older piezometric maps of 2009 and our geophysical results, we managed to indicate the decline of the groundwater level since then, in the central part of the study area and the broader area of Kileler settlement.

Climate change is expected to affect the hydrological cycle, altering seawater level and groundwater recharge to coastal aquifers with various other associated impacts on natural ecosystems and human activities. As the sustainable use of groundwater resources is a great challenge for many countries in the world, groundwater modeling has become a very useful and well established tool for studying groundwater management problems. This study investigates the impacts of climate change on the groundwater of the deltaic plain of River Pinios (Central Greece). Geophysical data processing indicates that the phreatic aquifer extends mainly in the central and northern parts of the region. A one-layer transient groundwater flow and contaminant mass transport model of the aquifer system is calibrated and validated. Impacts of climate change were evaluated by incorporating the estimated recharge input and sea level change of different future scenarios within the simulation models. The most noticeable and consistent result of the climate change impact simulations is a prominent sea water intrusion in the coastal aquifer mainly as a result of sea level change which underlines the need for a more effective planning of environmental measures.

The present paper presents measurements of water flow and suspended particulate material of Pinios River (Thessaly) during the hydrological year 2013/2014. The measurements were carried out in two positions before Pinios enters the agricultural deltaic plain and one inside the delta. Furthermore, an effort is made to estimate the water contribution to Pinios by the springs of Tempi valley and the quantity of water being diverted to the old river bed for irrigation purposes. These measurements were compared to corresponding data from the hydrological year 2012/13 and the significant differences that arose can be attributed to decreased rainfall and probably to the operation of a gate valve in Girtoni, that was initiated in the dry period of 2014.

This paper addresses the critical issue of how wrong can water resources management go if the structure and hydrodynamic evolution of the exploited system is not well known. As a case study the River Pinios estuarine groundwater system in central Greece, is discussed. The study area has a spatial extent of about 80km2 and a typical estuarine shape. Due to the neotectonic evolution and the eustatic moves, a unique geomorphological environment and a dense hydrological network have been developed. Dominant socioeconomic activity in the region is agriculture and secondarily tourism that is focused only along a narrow strip along the coastal line and occurs only seasonally. Domestic water demands are covered by groundwater abstractions mainly from deeper wells drilled at the margins of the estuarine. Shallow wells in the alluvial sediments of the basin augment irrigation demands that are predominantly catered by surface water from the river Pinios and its tributaries, and to a minor extent several springs that emerge along the marginal fans of the basin. Due to the shallow groundwater levels, a large percentage of irrigation demands is covered by direct osmosis of water from the root zone.

In tectonically active areas, such as in the northwest Peloponnese of western Greece, geomorphic processes are strongly influenced by active faulting; in many cases such faults cannot be easily identified. In this paper we apply multidisciplinary analysis (morphotectonic indices, neotectonic mapping, geophysical surveys and remote sensing techniques) to map the recently-recognized east–west trending Pineios River normal fault zone with a high degree of accuracy, and to better understand its contribution to the evolution of the ancient region of Elis during Holocene time. Fault activity seems to be related to frequent changes in river flow patterns and to displacements of the nearby shoreline. We argue that fault activity is the main reason for migration of Pineios river mouth as documented for several time periods during historical time. Quantitative constraints on deformation caused by the faulting were applied through the application of the morphotectonic indices proposed in this paper, including drainage network asymmetry and sinuosity, and mountain front sinuosity, all of which indicate that this is a highly active structure. Slip rates calculated to be as high as 0.48 mm/yr for the last 209 ka (based on previously published dating) were verified by applied geophysical methods. The fault surface discontinuity was identified at depth using vertical electrical resistivity measurements and depositional layers of different resistivity were found to be clearly offset. Displacement increases toward the west, reaching an observed maximum of 110 m. The most spectacular landform alteration due to surface deformation is the north–south migration of the river estuary into completely different open sea areas during the late Quaternary, mainly during the Holocene. The sediment transport path has been altered several times due to these changes in river geometry with and the most recent seeming to have occurred almost 2000 years ago. The river estuary migrated to its contemporary position along the southern coast, settled on the hanging wall, inducing retrograding of the northern coast, and settled on the foot wall, with rates reaching the order of 0.52 m/yr, as concluded from historical and recently-acquired remote sensing data.

The current study examines flow (Q) and suspended sediment concentration (SSC) variations, based on monthly snapshots, of the Pinios River (Thessaly), which is one of the larger rivers in Greece, characterized by limited flow control (<10% of its catchment). Monthly measurements (flow velocities and water samples) during the hydrological year (October 2012 to September 2013) were conducted at two stations; one before the river enters its delta (Agia Paraskevi bridge at Tempi) and one close to its mouth (Palaiopyrgos bridge). Monthly flows at Agia Paraskevi range from 2.5 m3 /s to 206.7 m3 /s and are in a good agreement with available historical data for the period 1975/76- 93/94, indicating a rather unchanged flow regime. The SSC values ranged from 3.5 mg/L to 165 mg/L at Agia Paraskevi and from 2.2 mg/L to 177 mg/L at Palaiopyrgos and, in general, follow the monthly trend of flow. The highest SSC value measured in February and April 2013 is attributed to a flood event and an upland slide, respectively.

A geophysical research was carried out to investigate the lithostarigraphic substratum characteristics of the dune field of the central Kyparissiakos Gulf (W. Peloponnese, Greece), which is characterised by the presence of four dune lines. For this purpose, the geophysical techniques of Electrical Resistivity Tomography (ERT) and Vertical Electrical Soundings (VES) were applied, along with detailed morphological mapping and the collection of geological and geomorphological information. The processing of the geophysical data that were collected from two ERT soundings, perpendicular to the general direction of the dune lines, and seven geoelectrical soundings revealed four geoelectrical layers with the two surficial resistive layers adumbrating the extent and thickness of the four sand dune ridges and the associated slags. The third layer, corresponding to the underlying geoelectrical formation of 50–75 Ohm.m, is interpreted as a layer of transgressive Holocene deposits saturated with fresh water, while the deepest geoelectrically identified layer seems to correspond to the “Neda” formation, which consists of marls, sandy marls and conglomerates. It is concluded that the combined application of the aforementioned techniques has the potential to provide valuable data for the investigation of complex coastal depositional environments.

In this contribution we present some preliminary findings on the chemical quality of groundwaters of the deltaic plain of R. Pinios (Thessaly), as part of the implementation of the project THALISDAPHNE. Samples were obtained from 13 groundwater drillings on a seasonal basis during the hydrological year 2012 - 2013 and analyzed for major ions, nutrients, dissolved organic carbon and trace metals. Temperature, pH, conductivity and salinity were measured in situ. In order to evaluate the groundwater quality, we compare the data obtained against the Hellenic legislation threshold values and FAO guidelines for irrigation waters. Conductivity ranged from 230 to 9180 μS/cm. Exceedance of the 700 μS/cm threshold (Type I water FAO) in 71% of the samples suggests slight to moderate restrictions in irrigation. In two drillings (No 10, 13) maximum permissible limits of conductivity, sodium and chloride concentrations were exceeded particularly in summer and autumn. Some exceedances of guidelines were also identified for nitrates and ammonium. Concentrations of dissolved trace metals, were generally below the limits, with the exception of Zn, however some concern has been raised in terms of increased levels of total dissolved Cr in drilling No. 15 (8.3 - 37.9 μg/L). On the basis of our results degradation of groundwater quality was identified together with seasonal salinization; these two factors corroborate to the need for sustainable groundwater use especially in months with increased demands for water supplies.

A geophysical survey was carried out in the archaeological site of Kyparissia (Megalopolis, Greece) applying the Very Low Frequency technique, as preliminary combined with highly detailed Electrical Resistivity Tomography. Settlements of the ancient city of Trapezous (limestone slabs 0.5m height × 0.5m width) have already been uncovered from the local Ephorate of Prehistorical and Classical Antiquities, revealing a regularly planned town of the classical period. The geophysical research was performed at the non-excavated area of the plain, vicinal to the already exposed remaining, where, according to the expected geometry, the buried walls and drainage channel should be continued to. Fifteen parallel sections with distance 5m and spacing interval 1m were carried out. The processing with the application of Fraser and Karous-Hjelt filters led to the construction of respective maps, indicating some resistive lineation which could be a result of the buried settlements. Moreover, two detailed ERT sections were carried out with spacing 0.20 and 0.25m and total length 200m. The processing using the robust inversion, which is indicated for such environments, adumbrates quite clearly a sharp resistive target that could be the limestone slabs of the ancient walls or drainage channels, confirming the expected lineated geometry of the town.

This study aims at defining the groundwater flow regime and the principal hydro-geochemical processes controlling groundwater quality in the deltaic plain of River Pinios (ThessalyGreece) and investigating whether seawater intrusion and pollution are influencing groundwater quality. Groundwater level monitoring from October 2012 to September 2013 shows that groundwater flow is seawards and that the water table of the phreatic aquifer is mainly declining during the summer period when it is over-pumping and natural recharge limited. Major ions analysed in 49 groundwater samples reveal that groundwater is mainly affected by four factors: (i) dissolution of calcite and dolomite; (ii) weathering of silicate minerals; (iii) seawater intrusion; and (iv) contaminant enrichment (e.g., NH4) mainly caused by point sources of pollution. High enrichment of Na and Cl near the coast gives an indication of seawater intrusion into the aquifer as also supported from the Na–Cl signature on the Piper diagram and the Revelle coefficient. The dissolution of calcite and dolomite results in Ca–HCO3 and Mg–HCO3 groundwater types, whereas natural geochemical processes are considered responsible for the aquifer's enrichment in minor elements (e.g., Fe, Mn). Based on the simulation results performed using PHREEQC model, groundwater is mainly supersaturated with respect to calcite and dolomite minerals, supporting a long residence time hypothesis. The relation between seasonal water level fluctuation and hydrochemistry shows that both are mainly controlled by the aquifer's recharge process.

The present study aims to assess the current groundwater quality and investigate its temporal evolution in the two identified aquifers (shallow and deep) located in the sedimentary sequence of Pinios River estuary. Significant land use changes mark groundwater management practices of the shallow aquifer over the past years, as traditional crops of high water requirements have been partly substituted by less water demanding crops, and groundwater abstractions have been reduced and substituted by surface water from Pinios River to cover irrigation needs over a large part of the study area. To study the effect of aforementioned land use changes, major groundwater physicochemical parameter values for the year 2013 were assessed and compared to the corresponding data for the years 1998 and 1999. The results indicate that the quality of the shallow aquifer in terms of groundwater salinization and nitrate pollution may be considered as satisfactory with higher groundwater salt content observed in the northern and southern parts of the system. The water quality characteristics of the deep aquifer are overall worse than the shallow aquifer as groundwater salt content is increasing towards the coast. The temporal comparison of the water quality characteristics demonstrates no significant changes for seawater intrusion related parameters such as Electrical Conductivity, and Na+ and Cl- concentrations, but also for pollution related parameters such as NO3 - concentrations.

In the region of the deltaic field of Pinios River in Thessaly and under an applied geoenvironmental research, a preliminary geophysical survey was developed. In this direction, an attempt was made to develop a grid of positions-measurements that would be able to cover the whole field in order to adumbrate the general “image” of the geoelectric parameters. From the conducted bibliographic research, it seems that it is the first time that such a coordinated and extensive geophysical survey has been made in the area. In this project and in the direction of the evaluation of the geoelectric parameters of lithology present in the deltaic area, displays of the horizontal and vertical distribution of electrical resistivity are presented. This knowledge will contribute to the emergence of new data and information on the subsurface structure of the field of the deltaic plain. The geoelectrical method with the Sclumberger array was applied, for the vertical investigation of the distribution of electrical resistivity, in order to investigate the geoelectrical parameters. These arrays are best suited, as a preliminary subsurface investigation method in such geo-environments. Thirty seven soundings were developed in an almost 'normalized' grid, aiming to the greatest possible depth of investigation. Towards this direction, despite the very difficult condition of accessibility, the development of the electrode current (AB or C1C2) reached 1.100 meters, with an investigation depth >250 meters. From the sections and the constructed maps, conductive geoelectric distributions structures detected, with a resistivity ranging in 5-30 Ohm.m, in almost the whole subsurface field of deltaic plain. From this general view, seems to differentiate the coastal zone for shallow depths (<4.5 m) of investigation, the regions of the southern part of the deltaic plain with larger resistivity values for large depths (> 100 m) and the western region (Pyrgetos), with generally high values even from the shallow depths of investigation. Finally, the overall picture of the distribution of the geoelectric parameters in the field of study appears to outline potential area of the palaeogeographic development of the Pinios River delta.

In this project the geological subsurface structure of the delta of the river Pinios is investigated through the contribution of geophysical soundings. In order to investigate the lithologic structure of the entire deltaic field, geophysical soundings were performed with the geoelectrical method of vertical investigation of the resistivity distribution at 37 locations. The Schlumberger array was applied, which is a reliable preliminary geophysical technique for such environments, achieving an investigation depth of > 200-250 meters. Obtaining information on the geoelectrical characteristics of the formations expected under the alluvial silt of Pinios, we have to evaluate the results of the geophysical survey. Therefore 14 “in situ” measurements of electrical resistivity were carried out in surface outcrops of Neogene sediments, cyanoschists and serpentinites. An extensive geological overview of the wider visual field was conducted, geological measurements were recorded and plotted on a digital background concerning the extensive volume of Neogene formations and alpine formations. After the processing of the geophysical soundings, geoelectrical sections were constructed in directions S-N and W-E, along with the description of their geological evaluation. From the preliminary results, it seems that the Neogene formations, with alternations of sands, marls and conglomerates occupying almost the entire space of the subsurface deltaic field, below the Holocene deposits. The alpine formations of Ossa (the southern part of the field research), seem only to be traced in the soundings near the margins, with a gentle inclination below from the post-alpine sediments and for the depths investigated (~ 200-250 meters). In the western part of the study area and more specifically the Pyrgetos sub basin, higher values of electrical resistivity (50-80 ohm) were calculated, differentiating the general concept that emerges from the rest of the study area.

A geophysical survey was performed at selected locations of Mt. Oiti and Mt. Kallidromon characterized by the hosting of priority habits of Mediterranean temporary ponds and the threatened plant species of Veronica oetaea, in order to understand the geoenvironment and contribute to the conservation of biodiversity. Primarily, the formation of these seasonal ponds, where Veronica oetaea occurs, seems to depend exclusively on the local hydrogeological regime. Thus, we investigated the subsurface structure of “Livadies” and “Nevropolis” ponds with the application of Electrical Resistivity Tomography for high accuracy information and Vertical Electrical Sounding for deeper data acquisition. Four ERT sections and 15 geoelectrical soundings in total were carried out. The combined results of their processing revealed differences at the geological structure beneath the ponds locations. At “Livadies” pond (Mt. Oiti), two geoelectrical layers were distinguished both corresponding to a folded flysch succession, contributing to the formation of this pond. On the contrary, at “Nevropolis” pond two geoelectrical layers were identified and interpreted as a surficial soil deposit stratum covering the geomorphological karst structure of a polje, created on the underlying limestones. The combined geophysical research offered significant data for the formation and the hydrogeological status of the priority habitats.

The present study aims to clarify the hydrogeological regime of the phreatic aquifer, primarily its spatial distribution, through a combined interpretation of the preliminary results of an extensive geophysical research conducted in the area and of the hydrogeological data collected in parallel scientific actions by previous researchers. In the context of the geophysical research that was carried out in the region, 37 Vertical Electrical Soundings, investigating the resistivity distribution (Schlumberger array), were performed during May and October 2013. Moreover, previous periodic measurements of the groundwater level of the phreatic aquifer and hydrochemical analysis were taken into consideration. The preliminary results of the geophysical data processing indicate that the phreatic aquifer is not detected throughout the whole deltaic plain but extends mainly in the central and northern parts of the region. Most of the investigated sites showed that the hosting formation’s thickness is limited up to 10 meters, since the underlying geoelectrical formation (20-40 Ohm.m) is believed to be an impermeable formation. The literature-derived hydrogeological data also indicate that the depth of the phreatic aquifer is generally small. In particular, the groundwater monitoring showed that the water table did not exceed 4m in depth. Moreover, the hydrochemical data indicated a limited seawater intrusion, which seems to be controlled by the hydraulic head of the groundwater and the sedimentological composition of the dune system covering the coastal zone, which is also indicated by the geophysical results.

In this paper we deal with a case scenario for the general geological setting and the morphotectonic evolution of the delta plain of Pineios River (Thessalia, Greece) and its margins. This work is based on the interpretation of geological and geomorphological data derived from (a) digitizing topographic map sheets of scale 1:5,000, (b) digital interpretation of recently acquired high spatial and spectral resolution satellite image, (c) tectonic geomorphology analysis, (d) field observations and (e) geophysical investigation. The fluvial deposits cover the largest part of the delta plain, whilst the coastal deposits crop out along the entire coastal zone. The remnants of a Pleistocene alluvial fan is observed in the western part of the delta plain and lies unconformably on Neogene formations comprised of sandstones, conglomerates and terra rossa. The alpine basement outcrops are found only at the southern and northern margins of the delta plain and include various lithologies such as crystalline limestones and metamorphic flysch (Ossa-Olympos unit), blue schists, gneisses and marbles (Ambelakia unit), metamorphic basic ophiolitic rocks and marbles (Pelagonian unit). The Neogene formations have undergone intense tectonic deformation resulting in several block rotations reaching the values of 10-30ο , towards south. The NW dipping normal fault zone located south of Omolio village strikes WSW-ENE and seems to play a significant role in the rotation of the Neogene formations. It is rather clear that the activity of this fault zone is highly related to the uplift of Ossa Mt along the southern margin of the delta plain and consequently to the development of extensional fractures (scarps) developed normally to the fault zone. These scarps are not tectonic faults and were created primarily by gravitational stresses. These structures have caused the segmentation of the uplifted block into smaller blocks, which were subsequently toppled. These large-scale toppling phenomena at the northwestern slopes of Ossa Mt have caused large gaps in the alpine basement rocks. These gaps have acted as selective surface water flow paths that have shaped impressive gorges. Pineios River found a new outlet to the Aegean Sea through the westernmost of the gorges, the Tempi gorge. It seems to have happened after the overall tectonic uplift of Olympos-Ossa-Pelion mountain range and the paleo-Pineios River flow blocking at the area south of Ossa Mt. Immediately after the aforementioned process, the area extending east of Tempi gorge began to evolve as the delta plain of Pineios River resulting in the progressive natural seaward shift of the shoreline due to the accumulation of Pineios fluvial deposits.

The scope of the research project is to investigate the consequences of climate change on deltaic plains, as one of the most vulnerable coastal and wealth-producing ecosystems. The Pinios river delta, located in the region of Thessaly (Greece) has been selected as a case study, as one of the largest Greek rivers with very limited flow controls. But, despite the fact that deltaic plain is part of the NATURA network, human intervention continuous to occur at an increasing rate. The main objectives of the project are to: (i) study the relative contribution of fluvial fluxes (water/sediment), nearshore hydrodyanmics and climate conditions in the formation and evolution of deltas; (ii) evaluate the impact of human activities in the evolution of the River Pinios delta (e.g., alteration of riverine fluxes, agricultural pollution, over-pumping of the aquifer); (iii) assess and to evaluate quantitatively changes in the deltaic environment for different climate change scenarios, i.e. water balance, issues of water quality, desertification, coastal erosion, inundation; (iv) investigate the interaction between natural processes and parameters associated with socio-economic development and use; (v) develop Sustainable Development Strategies for the natural deltaic system, in order to mitigate the consequences of the climate change, towards a better management of the wealthproducing resources (i.e. fresh water yield); (vi) contribute to the training of young scientists in environmental issues, related to the impact of the climate change on coastal environments; and (vii) disseminate science based management strategies to the local and scientific communities. During the first phase of project implementation, the study of the surface and ground water and their interrelationship is investigated through: (i) the climatological conditions of the deltaic plain and the drainage basin; (ii) the determination of the subsurface geological/stratigraphical information provided by geophysical data; (iii) surface and water fluxes estimated on monthly measurements (quantitative and qualitative) of river flow and phreatic water table.

A coastal management study at areas with steep anaglyph requires detailed knowledge of the onshore surface and subsurface regime regarding the erosional procedures. Active faults produce dynamic and continuously evolving geomorphological structures, which require investigation and continuous monitoring. Detailed mapping on and adjacent to these surfaces is required in order to study the complexity of various tectonic discontinuities, which contribute significantly to erosion and rock-falls resulting rapid and significant changes on the landscape. The technology of ground-based Light Detection and Range (LiDAR) capturing devices is a powerful and valuable tool, providing detailed mapping and surface change detection of inapproachable and nearly vertical surfaces. In this paper we introduce the diachronic monitoring and detection of alterations on the surface of the shore-side active fault of Psatha (Greece), with terrestrial LiDAR scanning, for a state of the art mapping of the almost vertical limestone fault surface. The monitoring procedure includes high-detailed topographic survey at the adjacent area using Real Time Kinematics Global Positioning System equipment (RTK-GPS), which is consisted of a large pile of brittle debris, laying on top the fault surface, by the sea. The described methodology involved the production of a high resolution DEM based on historic topographic maps (scale 1:5,000) of the regional area and comparing it with the higher resolution DEM representing the contemporary morphology, produced by the combination of the fault wall LiDaR “point cloud” and the dense grid of the RTK-GPS measurement points. The comparison between these datasets and recently acquired high resolution IKONOS satellite images revealed impressive surface changes caused mainly by the human intervention as well as the erosional processes which were accelerated due to the absence of safety measures along the coastal zone. Furthermore, the regional subsurface of the hanging wall zone area was also investigated, especially underneath the brittle debris formation, applying the highresolution near surface geophysical technique of Electrical Resistivity Tomography (ERT). Several sections were conducted aiming to represent the subsurface extension of the visible structures in three dimensions and combine it with the aforementioned datasets. The successful combination of different techniques revealed and quantified the landscape evolution involving the surface alternations at the fault adjacent coastal zone, the sea intrusion and even the coastline displacement, during the last four decades. Most of these yielded to the anthropogenic interference on the brittle debris formation and even the construction of the coastal road.

Extensive ground fissures frequently occur within the eastern Thessaly basin, in central Greece and have been since 1989. This paper aims to give a preliminary explanation for their generation reasons by interpreting the results of a dense geophysical survey along the basin. This is combined with drilling data, as well as field work tectonic measurements, morphotectonic analysis and remote sensing data interpretation throughout the marginal areas of the basin. The gathering, homogenisation and organisation of different types of geo-data by using various GIS software packages led to the discovery of the alpine basement surface, which is covered by recent sediments, and possible structures that contributed to the development of the basin. The methodology of producing a 3D basement surface model and various lithology profiles across the basin, along with sediment isopach maps by combining surface with subsurface data, is described in this paper.

In this paper we present a combination of several near surface geophysicalΒ investigation techniques with high resolution remote sensingΒ image interpretations, in order to define the groundwater flow pathsΒ and whether they can be affected by future seismic events. A seasonalΒ spring (Amvrakia) located at the foot of Meteora pillars near the villageΒ of Kastraki (Greece) was chosen as a test site. The Meteora conglomeraticΒ formations crop out throughout the study area and areΒ characterized by large discontinuities caused by post Miocene till presentΒ tectonic deformation [Ferriere et al. 2011, Royden and PapanikolaouΒ 2011]. A network of groundwater pathways has been developedΒ above the impermeable marls underlying the conglomeratic strata. OurΒ research aims to define these water pathways in order to investigate andΒ understand the exact mechanism of the spring by mapping the exposedΒ discontinuity network with classic field mapping and remote sensingΒ image interpretation and define their underground continuity with theΒ contribution of near surface geophysical techniques. Five Very Low FrequencyΒ (VLF) profiles were conducted with different directions aroundΒ the spring aiming to detect possible conductive zones in the conglomeraticΒ formations that the study area consists of. Moreover, two ElectricalΒ Resistivity Tomography (ERT) sections of a total length of 140m wereΒ carried out parallel to the VLF profiles for cross-checking and verifyingΒ the geophysical information. Both techniques revealed important conductiveΒ zones (<200 Ohm m) within the conglomerate strata, which weΒ interpret as discontinuities filled with water supplying the spring, whichΒ are quite vulnerable to displacements as the hydraulic connections betweenΒ them might be easily disturbed after a future seismic event.

The role of remote sensing in the identification of NNE-SSW trending strike slip fault zones and the implications on the development of the E-W trending Messara basin in Central Crete is examined in this paper. The examination of several tectonic and mophotectonic criteria along with high and medium resolution remote sensing image interpretation are leading to the conclusion that this quite recently formed basin on the top of the hanging wall of the Southern Crete extensional detachment fault is still evolving and the lateral slip of faults trending oblique to the Hellenic trench are very significant. The history of this supra-detachment basin starts during Middle Miocene only after the compressional phase of the alpine units’ nappe pile stacking has been accomplished at the southern part of the Hellenic Arc system. The Iraklion basin, delimitated by two nearly N-S trending fault zones, which is located to the north of Messara and also including the area at the easternmost part of it, begins to get filled with lacustrine sediments, during Serravallian. The eastern marginal fault zone is almost vertical with some fault surfaces dipping to the west and has a strong left lateral component, which is active at least since Tortonian, as this has been proved by tectonic analysis of syn-sedimentary faults found on marine sediments, along the faulted area. During Messinian time, left-slip displacement was relocated to the fault system bounding the western margin of the Heraklion-Messara basin. These oblique fault activations are causing the segmentation of the south dipping Cretan detachment fault and the variation of the slip rates of each of the –at least– three segments that were identified. The westernmost segment of the detachment seems to have the highest slip rate as the largest structural omission related to the alpine units has been detected along its trace. The continuous subsidence of the hanging wall is boosting Messara to be formed as an individual basin trending E-W differentiated by the Iraklion basin, the area of which is reduced and finally remained on the footwall of the Southern Crete detachment fault. The new independent supradetachment basin is stabilizing whilst internal deformation takes place and becoming homogenous during the Holocene as the modern topography shows. Remote sensing image interpretation based on spectral analysis led us to high detail and accuracy geological mapping of these major and in many cases blind structures and eventually build the evolution model of a very complicated area at the edge of the Hellenic trench.

Active faulting usually produces a dynamic and continuously evolving morphology along the fault trace but also at the adjacent area. The morphologic discontinuities which are often created due to the relative displacement of the fault walls, host quite a few structures that are vulnerable to erosion and surface alterations. The technology of Light Detection and Range ground based instruments is a valuable tool used for topographic micro-analysis of recently exposed fault surfaces and consequently for detailed mapping and structural measuring. In this paper we suggest a methodology for monitoring the stability of an almost vertical active fault surface with lots of tectonic structures on it but also with a large amount of brittle debris material lying on top of it. This methodology was based on several laser scans with a ground LiDaR and the detailed mapping of weak zones along the fault surface led to the construction of a rock-fall hazard model.

The Amvrakia spring is located at the bottom of Meteora pillars and more specifically near the village of Kastraki (Kalambaka municipality). It is a seasonal spring since it functions only during the wet period. The Meteora conglomerates which dominate the area are characterized by large discontinuities creating a network of groundwater pathways above the impermeable strata of the underlying marls. The research targets was to define these water pathways in order to understand the mechanism of Amvrakia spring, by mapping the exposed discontinuity network and define their underground extension with the contribution of geophysical techniques. Electrical Resistivity Tomography (ERT) and Very Low Frequency (VLF) methodologies were applied. The VLF method is indicated for the detection of water-bearing fracture zones, but before the application of their filters they had to be processed for topographic corrections, as the area had not smooth relief. Five (5) VLF profiles were conducted with different directions around the spring’s area, in order to detect possible conductive zones in the conglomerates surrounding the study area. Moreover, two (2) ERT sections of a total length of 140m were carried out, parallel to existent VLF sections, for crosschecking the geophysical information. Both techniques revealed important conductive zones (<200 Ohm.m) from the south-eastern Meteora conglomerate pillars, possibly interpreted as discontinuities filled with water feeding the spring.

The effects of the geological, tectonic and neotectonic structure and the impact of the human presence and activity on the drainage network of Pineios river are presented here in order to determine the causes of its diversion and the implications to the shoreline. We used, analyzed and evaluated (a) geomorphological, geological, tectonic and neotectonic data of the study area, (b) historical information and archaeological findings from buried and eroded archaeological sites of the wider study area, (c) published data related to drill cores and radiocarbon dates, and (d) remote sensing datasets, as satellite and aerial photos of different capturing periods, as well as real-time kinematic differential GPS measurements for the definition of the current shoreline. It is concluded that the detected shoreline displacements and drainage diversions are the result of the combination of active tectonics and human activity during the last 100 kyrs.

A combined geophysical survey was conducted to investigate the possibility of detecting aquifer horizons characterized by secondary porosity development due to variations in textural structure. The SE part of Aegina Isl. (Perdika area) which is composed of volcanic rocks, namely of lower seated dacitic lavas overlain by pyroclastic rocks, was chosen for further investigation. Schlumberger soundings carried out along the long axis of the drainage system showed the existence of four geoelectrical layers instead of two which are the basic geological units of the whole area under investigation. This discrepancy is due to the presence of two distinct geological phenomena. The first, in the upper structure, results as a consequence of weathering and fracturing processes and is strongly dependent on lithologic phase changes of volcanic rocks. As a result a phreatic horizon could be developed in areas that are highly weathered and/or fractured. The deeper structure, on the other hand, is tectonically affected showing a great number of discontinuities filled mainly with water. The high transverse resistance value (T>5000 Ohm.m2 ), of the layer just above the deepest and conductive layer is attributed to dry dacitic lavas. The deepest conductive layer with intense deformation does not seem to be affected by sea water intrusion even at depths lower than sea level. The top surface of the conductive layer is not regularly spread over the area of investigation showing that the potentially developed aquifer within the fractures depends on the pre-existing topographic relief. The aim of the VLF survey was to detect any vertical or oblique conductive zones that could be associated with large scale tectonic features. Linear elements drawn from aerial photographs are strongly connected with anomaly zones outlined from VLF data. A model of the deep seated aquifer for the area under investigation to explain the recharging mechanism based on geophysical results as well as geologic and tectonic evidence is proposed.

During the last years the broader area of Koropi (Mesogheia-Greece), has faced rapidly increasing problems concerning irrigation and watering of the town, due to the brackish water in the water supply boreholes. Our main target is to determinate the subsurface geological structure of the study area, located NE of the Koropi city, where alterations of schists and carbonates, from three different post-alpine units, mainly appear and relate it with the groundwater flow paths. The dominant geological outcrops of the area are the Athenian Schist (Laurion-Attica Unit), the dolomitic marbles (Vari-Kirou Pira Unit) and the Lower Marble (Hymittos Unit). A geophysical research was carried out in the area mainly based on the geoelectrical methodology, including by executing fifteen Vertical Electrical Soundings and one Electrical Resistivity Tomography. The interpretation results of the geophysical data have been evaluated and combined with “in-situ” resistivity measurements and calibrated with cores coming from drilled boreholes revealing the area. Through this combining process important elements of the local geological subsurface structure have been determined, as the formation of the dolomitic marbles (massive or karstified) was found tilting southwards beneath the Athenian Schist. From a hydrogeological point of view, this alone adds a significant parameter to the subsurface geological structure which is highly related to the groundwater flow that is responsible for many problems and could be used for solving many others.

The elaboration of analytical microzoning studies involves a multidisciplinary approach comprising geological, geotechnical, seismological, geophysical and dynamic soil analysis data. In an attempt to incorporate the maximum available amount of information and in the view of the continuously expanding use of GIS, as a tool for analyzing and integrating data, a new software environment called AUTO-SEISMO-GEOTECH has been developed for handling these multi-parameter data. This user friendly package is presently implemented for the cities of Heraklion (Crete island- province of Heraklion) and Thiva (province of Viotia) in Greece. The pilot methodologies applied in these urban areas, aimed also at determining a minimum package of tasks/methods needed for the elaboration of a microzoning study, are described and evaluated here. Next, a database with appropriate architecture was formed in order to handle all available geo-information for each city separately and produce thematic maps, such as geological, tectonic, hydrogeological, seismic hazard and microzonation ones. These maps can be easily reproduced, integrated and used for building safer constructions contributing so to mitigation of earthquake consequences. Geo-information obtained by a) existing regional seismicity maps and installation of local portable seismographic networks around both cities, to monitor the microseismic activity and define possible active fault zones, b) geological mapping of the broader urban area in scale 1:5000, c) evaluation of existing geotechnical data as well as new data coming from boreholes, d) geophysical data resulting from surface and borehole techniques, for Vp, Vs and dynamic elastic parameters estimation and e) consideration of historical seismological data for seismic hazard estimation, have been incorporated in this GIS based platform, to be easily handled for further use. The output of this information combined with the dynamic soil analysis produces detailed microzonation maps. Such maps are valuable for city planners and urban designers.

The elaboration of analytical microzoning studies involves a multidisciplinary approach comprising geological, geotechnical, seismological, geophysical and dynamic soil analysis data. In an attempt to incorporate the maximum available amount of information and in the view of the continuously expanding use of GIS, as a tool for analyzing and integrating data, a new software environment called AUTO-SEISMO-GEOTECH has been developed for handling these multi-parameter data. This user friendly package is presently implemented for the cities of Heraklion (Crete island- province of Heraklion) and Thiva (province of Viotia) in Greece. The pilot methodologies applied in these urban areas, aimed also at determining a minimum package of tasks/methods needed for the elaboration of a microzoning study, are described and evaluated here. Next, a database with appropriate architecture was formed in order to handle all available geo-information for each city separately and produce thematic maps, such as geological, tectonic, hydrogeological, seismic hazard and microzonation ones. These maps can be easily reproduced, integrated and used for building safer constructions contributing so to mitigation of earthquake consequences. Geo-information obtained by a) existing regional seismicity maps and installation of local portable seismographic networks around both cities, to monitor the microseismic activity and define possible active fault zones, b) geological mapping of the broader urban area in scale 1:5000, c) evaluation of existing geotechnical data as well as new data coming from boreholes, d) geophysical data resulting from surface and borehole techniques, for Vp, Vs and dynamic elastic parameters estimation and e) consideration of historical seismological data for seismic hazard estimation, have been incorporated in this GIS based platform, to be easily handled for further use. The output of this information combined with the dynamic soil analysis produces detailed microzonation maps. Such maps are valuable for city planners and urban designers.

The closed intra-mountainous Levidi basin (average altitude 680 m), characterized by an asymmetric spatial extension, drains at its south-eastern part by the homonymous sinkhole, and its paleorelief is covered by homogeneous quaternary sediments. The boundaries of the basin consist mostly of carbonate and clastic sediments of the Pindos unit, while carbonate sediments of the Tripoli unit are limited to the south and south-western parts. In order to investigate the alpine basement of the quaternary deposits, the geometry of the prequaternary topography of the basin and the lithology of the quaternary sediments, geophysical investigation was employed. The study involved 27 geoelectrical soundings and 7 resistivity measurements, both in boreholes and surface outcrops of the alpine formations. The results of the geophysical investigations facilitated the constructing of (i) the sub-terrain morphological map of the alpine basement, where the thickness of Pleistocene sediments in the central part of the basin does not exceed 15 m, although in the area of Palaeopyrgos (to the north-east) the sediments appear to reach a thickness up to 60 m, and (ii) the sub-terrain geological map. Structurally, the Levidi basin can be characterised as a polje, formed as a result of alpine deformation and subsequent karsting, accentuated by the lack of impermeable flyschic formations in the area.

In the current paper are presented the results of a multidisciplinary study (stratigraphical, sedimentological, geophysical and geochemical) combined with modern techniques (G.I.S. and remote sensing). This study aims at integrating the natural and anthropogenic factors affecting the Korissia lagoon. It is a shallow coastal lagoon, communicating with the sea via an artificial channel. The area around the lagoon consists of alluvial sediments hosting, in places, newly formed and/or “old” (pre – Holocene) sand-dunes. The broader area constitutes a postalpine sedimentary basin characterised by smooth morphological relief. The lower stratigraphic unit of the post-alpine sequence is a Pleistocene marly formation, which was detected as the basement (5-15 Οhm.m) by the geophysical survey. The resistivity-based basement map implies the existence of a “palaeo-gulf” trending EW. These marls constitute the impermeable basement of a shallow aquifer hosted in the area. The salinity of the lagoon is very high during summer (>40psu) but it does not affect significantly the wells around it. The lagoon is well oxygenated, while the wells have lower D.O. values. Ammonia and nitrates are the main inorganic Nitrogen forms, in the lagoon and the wells, respectively. Phosphorus is the limiting factor for phytoplankton growth. Human activities affect the area that is in need of an environmental management plan in order to prevent ecological degradation.

Korissia lagoon located in the southwest end of Corfu separated from the open Ionian Sea by a narrow (<250 m) stip of land. It has a surface of 4,2 km2 and depths <2m, communicating with the sea via an artificial-dredged channel. The bed of the lagoon consists of fine-grainned sediment (sandy silt – silty sand). Its drainage basin covers an area of 16 km2 and is characterized by low relief. It receives the freshwater inputs form a low relief (maximum elevation 319 m) of the drainage basin. The influx of fresh water is surficial includes also an underground flow, as indicated by the presence of a phreatic aquifer and a large number of wells at its nearby surrounding area. The water budget of the lagoon is characterised by a wet (October-March) and a dry (April-September) period. During the wet period the incoming volume of fresh water (5,3x106 m3 ) is much larger than its total volume (2,5 x 106 m3 ); this implies an outflow of lagoonal waters whilst lagoonal waters are characterised by relatively lower salinity values (<20 ppt) compare to those of the Ionian Sea (38 ppt). In contrast, during the dry period, the fresh water influx (1,2 x106 m3 ) is smaller than the volume of the lagoon; this induces an influx of sea water, which in association with the high levels of evaporation moduled hyper-saline (>50 ppt) hydrologic conditions within the lagoonal basin.

In an effort to investigate the deep geological structure in the broader area of central-western Attica, that suffered severe damage during the destructive Athens earthquake of September 7th, 1999, the Department of Geophysics-Geothermics of the Faculty of Geology and Geoenvironment of Athens University, in collaboration with the Geodynamic Institute of National Observatory of Athens and the Department of Geological Sciences of Durham University, carried out a combined geophysical survey. For the first time in Attica, seismic and gravity geophysical methods were applied along profiles, in such an extensive scale. Within the framework of this investigation the following tasks were accomplished: a) Three (3) seismic lines of about 30 kilometres of total length, two (2) in the area of Thriassion plain and one (1) along the Parnitha-Krioneri-Drosia-Ekali-Dionysos axis (Attica plain) and b) 338 gravity measurements distributed along eight (8) gravity profiles, four (4) of which in Thriassion plain, three (3) in Petroupoli-Aharnes-Thrakomakedones region (Attica plain) and one (1) along Parnitha-Krioneri-Drosia-Ekali-Dionysos axis (Attica plain). Preliminary results of the geophysical investigation combined with existing geological and tectonic data are presented in this paper. Significant variation in the elevation of the alpine basement has been detected, expressed by manifestation of low and high subsurface areas which are well correlated with existing fault zones. In the area of Thriassion plain the thickness of post-alpine sediments is estimated of a few hundred meters (<500 meters) and huge thickness of several hundred meters (~800 meters) of post-alpine sediments were detected in Thrakemakedones and Krioneri areas. The relief of alpine basement is more intense in fault zones areas, such as Thriassion plain (WNW-ESE), Pathitha and Kifissos (NE-SW) as well as along the fault zone outline the Fili and Aharnes graben and is covered by postalpine formations.

A short shear (SH) wave profile was collected as a part of a wider experiment involving P- and S-wave reflection and refraction measurements for further processing. The purpose of the experiment was to examine the efficiency of ultra shallow bedrock surface by SH reflection imaging commonly implemented in engineering applications. The original SH data suffer from direct, refracted, guided and surface waves interference. In some Common Shot Gathers the presence of significant P wave energy is also obvious, despite the use of special designed SH-wave detectors and the use of a pure horizontal energy source, i.e. a hydraulic seismic generator device. We tested the efficiency of successive processing steps focusing on multiple energy attenuation, followed by the implementation of a technique for reducing the source generated noise, both based on forward and reverse linear and parabolic Radon transformations. The proposed scheme was applied on the data collected along a 49-shot records SH wave reflection profile.

The surface waves method was used in this case study as an alternative and efficient tool for geological and geotechnical investigation. The site is located at Glyfada, Athens where neogene formations, mainly composed by clayish layers with intercalations of conglomerates, are present. The results were compared with data from geotechnical investigation and seismic refraction data.

The elaboration of analytical microzoning studies involves a multidisciplinary approach comprising geological, geotechnical, seismological, geophysical and dynamic soil analysis data. In an attempt to incorporate the maximum available amount of information and in the view of the continuously expanding use of GIS, as a tool for analyzing and integrating data, a new software environment called AUTOSEISMO-GEOTECH has been developed for handling these multi-parameter data. This user friendly package is presently implemented for the cities of Heraklion (Crete island) and Thiva (province of Beotia) in Greece.

Deep seismic and gravity measurements were conducted along profiles in CW Attica to investigate the subsurface structure of the area that suffered heavy damages after the Mw=5.9 of September, 7th 1999 earthquake. Within the framework of this investigation the following tasks were accomplished: a) Three long seismic lines of about 10km each, two of which in the epicentral area of Thriassion plain (west part of Athens) and one along the Parnitha Mtn-Penteli Mtn axis (central part of Athens) and b) eight gravity profiles, comprising 338 gravity measurements, four of which in the Thriassion plain, three in the meizoseismal area of Petroupoli, Aharnes and Thrakomacedones (east of Parnitha Mtn) and one along the Parnitha Mtn-Penteli Mtn axis.

A small aperture seismic array was installed by the University of Athens, in the area of Tripoli, Greece, on July 16th 2003, in order to test the performance of seismic array processing in the area of Greece and assess its contribution to earthquake location, especially in offshore areas not azimuthally covered by the existing, conventional seismological networks. The array consists of four three-component seismological stations, one of them in the middle of a small, almost equilateral triangle, formed by the deployment of the other three stations. Despite the fact that array siting is a compromise of array installation criteria, equipment safety and logistics, the test character of the experiment can be served successfully. The array transfer function depicts good azimuthal coverage nonetheless the existence of side-lobes and a rather wide main lobe is characteristic of spatial aliasing and low resolution in the two-dimensional wavenumber domain. The resolvable wavenumber passband of the array permits the determination of most of the common seismic body wave phases (Pn, Pg, Sn, Sg, etc.) for local and regional events in the area of Greece. Location of recorded events was performed using slowness and backazimuth data, calculated by f-k analysis of the seismic waveforms. Preliminary results have been compared to epicentres calculated by the Geodynamic Institute of the National Observatory of Athens. Although some differences are observed, these are not significant and location results as well as overall array performance can be improved by array calibration and travel-time, azimuth and slowness correction calculations.

This thesis describes an effort to combine various specialties of earth sciences (applied geophysics, hydrogeology, tectonics, stratigraphy, geomorphology), with the final objective to determine the subsurfacial geological conditions of the basin located on the plateau, north of the city of Tripolis and the assessment of its hydrogeological conditions. The wider region of the Tripolis plateau faces shortage problems for fresh water supply and irrigation. The small number of water consuming infrastructures and natural springs, that lie around the margins of this plateau with relatively small supplies, cannot satisfy the existing irrigation and watering needs of the wider region and particularly those of the city of Tripolis. For the successful exploitation of the water consuming infrastructures, the investigation of the geological and hydrogeological conditions of the Tripolis plateau was highly required. The geological and borehole data for this area were limited, mostly based on projects that had been accomplished in the past, but no systematic study on the determination the subsurface geological and hydrogeological conditions of area was carried out. Given that homogeneity in the distribution of measurement points is required for the best coverage of the research area, the (geophysical) geoelectrical soundings, using the Schlumberger array, proved to be the most suitable for this application. Seventy two (72) in situ electric resistivity measurements were scheduled on the geological formations outcropping throughout the area, ten (10) in situ electric resistivity measurements were scheduled next to already drilled boreholes and two hundred thirty five (235) resistivity soundings (VES), were carried out for investigating the deeper structures.After the interpretation of the geological and geophysical data, ƒ the lithology, the thickness and the hydrogeological behaviour of the postalpine sediments were investigated, ƒ the shape of the alpine basement was clarified, and ƒ the tectonic structure of the alpine basement was mapped.In particular, the shape and the thickness of the post-alpine sediments were determined. Two different environments of deposition were detected and two individual sub basins were located (a) the northernmost sub basin of NestaniMantineia and (b) the southernmost sub basin of Tripolis. The shape and the depth of the alpine basement were defined in detail for the majority of the measurement sites, with the exception of an area around the Tripolis Industrial Region (VI.PE.), where the thickness of the recent sediments is estimated to be exceeding 250 metres. By applying this methodology, the investigation of several structural zones (faults, thrusts) and the delimitation of reversed structures (Nestani, Merkovouni) of the Pindos unit formations, were made possible. The collected information and data were organised and imported in a Geographic Information System for future enhancement, acting as a dynamic digital geodatabase for the whole area. From this process new information was derived concerning ƒ the assessment of hydrogeological conditions, regarding the subsurface water reservoirs, and ƒ the investigation of the sinkhole system growth and operation throughout the basin. Typical optimum conditions for water reservoir existence were located at the regions where -due to the reversed structure of Pindos unit formations- the permeable limestone overlie the semi-permeable marly layers or the impermeable flysch. Such regime was detected in the region of eastern Mantineia. Similar regime was detected at the Merkovouni reversed structure, with the difference of the limited volume of the limestone and therefore the control of the regulative reserves should be very careful. Favourable conditions for water reservoirs can also exist in regions where the alpine basement consists exclusively of carbonate formations of either Pindos unit or Tripolis unit. The water existence is controlled by the purity of carbonate formations regarding the argillaceous or siliceous admixture, the degree and level of karstification and the orientation of the main tectonic structures (faults, thrusts). Regarding the Pindos unit carbonate formations, the geophysical measurements showed that the limestone with resistivity values less than 350 Ohm.m, are compatible with water existence, while resistivity values larger than 450 Ohm.m, imply the predominance of compact and arid Pindos unit limestone. Water reservoirs inside limestone beds were detected in the central parts of the Saga-Nestani sub basin, in the central parts of the Milia sub basin and at the Tripolis industrial region. On the contrary, the regions where the alpine basement consists of either the semipermeable marly limestones or the impermeable flysch, are characterised by the lack of water presence and consequently these areas are not ideal for new water consuming infrastructures.As far as the growth of sinkhole systems, the results of this thesis made clear that the development of the karst network is connected exclusively with the presence of the pure carbonate formations of Tripolis unit. It is remarkable that in the cases of Nestani and Kanata sinkhole systems, developed within the Pindos unit formations, the geophysical research revealed that they tectonically overlie the Tripolis limestones, without the interference of the Tripolis flysch, at a relatively small depth, thus facilitating the development of karst networks in these regions.