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.