Integrated geoelectrical and magnetotelluric exploration at Gran Sasso d'Italia range (Central Apennines)

We carried our three electrical soundings, with continuous polar dipole-dipole array, and three magnetotelluric stations at Gran Sasso d'Italia, in the area of Campo Imperatore. Geoelectrical data show the existence of a resistive background with exceptionally high values of resistivity (greater than 25 000 Ohm . m) at a depth of about 250 m The magnetotelluric data were used to constrain the thickness of this resistive layer, below which we find an intermediate conductive structure and a deeper resistive background. The geological interpretation of this result is still open to discussion, but we can exclude that the shallow resistive layer consists of Cretaceous limestones, since their resistivity has been estimated to be about 5000 Ohm . m.