Location of possibly productive geothermal fracture zones/faults using integrated geophysicals methods over lesvos island geothermal field, Greece

Abstract

In 1988, Geotest Hellas carried out a geophysical survey on Lesvos island using gravity, vertical electrical soundings and self-potential methods in order to study the geothermal potential of the island. This paper is based on the primary results presented by Geotest Hellas, which were re-examined and presented in a different form to facilitate the selection of the areas of strong geothermal interest. In particular, application of the gravity, vertical electrical sounding (VES) and self-potential (SP) methods has provided information on the geophysical structure of the geothermal target areas of Lesvos island. The gravity survey provided valuable information on the morphology and tectonics of the crystalline basement (and on the peridotitic body and pyroclastic sediments), for the study of the geothermal potential of the area. The electrical survey provided information on the highly conductive zones (usually associated with geothermal fields), the electrical stratigraphy and the tectonics of the main geological units of the target area. The SP survey mapped areas where electrical polarization is observed in the faulting system. An integrated interpretation of the results of all these surveys led to the selection of five target areas considered to be of high geothermal potential. The location of these target areas is shown in Fig. 14, ranked from 1 to 5 in decreasing order of priority.