Using gravity in geothermal exploration: the case study of Wissembourg area, northern Alsace (France)

Abstract

We applied the concept of gravity pseudo-tomography on the existing data to the northern part of Alsace (France). The approach consists of applying a filtering of the Bouguer anomaly using different wavelengths. Each pseudo-tomography provides complementary information to the others. The obtained results revealed the presence of three important negative anomalies, two of them seem local around Rittershoffen and Seebach and the third one seems elongated from the west side of Soultz and Surbourg northward. The obtained residual anomalies were compared with new magnetotellurics results along an E-W profile crossing the Rittershoffen EGS project. Good correlation was obtained between both results. The negative gravity anomaly beneath GRT1-2, the two geothermal boreholes, corresponds well to the very conductive zone revealed by magnetotelluric.