Gesto Italia Activities in the Exploration of Italian Geothermal Resources and Preliminary Results

Abstract

Geothermal exploration activities of GESTO Italia in the past two years resulted in awards of four geothermal research permits in south Tuscany, Italy. The four areas cover a total area of 289 km2, Mazzolla (52,5 km2) are located in the vicinity of Larderello geothermal field while the remaining three areas are at neighborhood of Monte Amiata geothermal field, Cinigiano (141,20 km2), Montalcino (65,74km2) and Montenero (30,19 km2). MT and gravity data have been jointly used in order to provide a geophysical characterization of the geothermal areas under exploration. The acquisition and processing of MT data have been mainly focused on the noise characterization and on the effectiveness of the robust processing algorithms adopted. A full-three dimensional resistivity distribution has been defined by using a three dimensional inversion of MT data that provided relevant information about the structural lineaments of the geothermal reservoir. The MT survey highlighted also the limitations of such method in the studied areas that are affected by very high EM anthropic noise. For two of the studied areas (Cinigiano and Montalcino) the results of the resistivity modelling have been used to update a geologic model that was assessed through the full three-dimensional modelling of gravimetric data too.