Geomagnetic depth sounding in the Northern Apennines (Italy)

A Geomagnetic Depth Sounding (GDS) survey covering the Northern Apennines o f Italy has been carried out in the period 1992-94. Induction arrows maps a nd hypothetical event Fourier maps were constructed to obtain an electromag netic imaging of this area. Since the two dimensional (2-D) character comes out from those maps for periods greater than 32 minutes, a 2-D inverse mod eling was carried out. The model responses show that a deep conductive laye r (> 5000 S) underlies the Apennine chain at about 20 km depth. The transit ion between the Adriatic and the Tyrrhenian domains is marked by a rather s harp vertical offset in this conducting layer. In the northwest sector of t he studied area an anomalous high conductivity behavior is superimposed on the regional trend, which corresponds to the geothermal field of Larderello -Travale.