2D-3D GPR as an efficient tool for paleoseismology: A successful case history across the Castrovillari fault (southern Apennines, Italy)

The Castrovillari basin is located in Northern Calabria, along a sector of the Southern Apennines (Italy). This area is classified by the seismologists as a seismic “gap”, anyway capable of strong earthquakes generation, in a similar way as the adjacent active basins. A 2D and 3D GPR survey, integrated by geological, morphological and paleo-seismological studies, was done across one branch of the Castrovillary fault, a normal fault highlighted on the surface by a series pronounced scarps. The principal aim of the present study was the detection and characterization of the main fault zone and of possible faults strands. We first recorded several 2D common offset GPR profiles along a E-W valley that intercepts the scarps, to focus a smallest area on which acquire a 3D dataset. We used classic interpretative techniques, employing vertical sections, horizontal slices and horizon tracking, together with the calculation of amplitudes and phase related attributes. The information achieved, were useful to plan and realize a new paleo-seismological trench, necessary to intercept events of Holocene faulting, attesting the recent seismic activity of the area. As results, the detection and interpretability of faults, fractures and sedimentary bodies were significantly improved, demonstrating optimal agreement between geophysical and geological datasets.