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.

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.

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.

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).

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.

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.

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).

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.

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.

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 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 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.

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.

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.

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.

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.