Using the ERT method in tectonically active areas: Hints from Southern Apennine (Italy)

Abstract

Electrical Resistivity Tomography (ERT) method has been used to study two tectonically active areas of southern Apennine (Caggiano Faults and Ufita Basin). The main aim of this job was to study the structural setting of the investigated areas, i.e. the geometry of the basins at depth, the location of active faults at surface, and their geometrical characterization. The comparison between ERT and trench/drilling data allowed us to evaluate the efficacy of the ERT method in studying active faults and the structural setting of seismogenic areas. In the Timpa del Vento intermontane basin, high resolution ERT across the Caggiano Fault scarps, with different arrays, electrode spacing (from 1 to 10 m) and penetration depth (from about 5 to 40 m) was carried out. The obtained resistivity models allowed us to locate the fault planes along the hillslope and to gather information at depth, as later confirmed by paleoseismological trenches excavated across the fault trace. In the Ufita River Valley a 3560-m-long ERT was carried out across the basin, joining 11 roll-along multi-channel acquisition system with an electrode spacing of 20 m and reaching an investigation depth of about 170 m. The ERT allowed us to reconstruct the geometry and thickness of the Quaternary deposits filling the Ufita Valley. Our reconstruction of the depositional setting is in agreement with an interpretative geological section based on borehole data.