Electrical Resistivity Tomography across the Paganica-San Demetrio fault system (L'Aquila 2009 earthquake)

The M(w) 6.3, 2009 earthquake (L'Aquila, central Italy) was characterized by discontinuous surface rupture along the 19-km long NW-SE trending Paganica-San Demetrio fault system. The earthquake nucleated just below the town of L'Aquila at a depth of ca. 9 km, rupturing mainly toward SE. Due to the high urbanization of the area and to centuries-long agricultural works, the surficial traces of this fault system are not clear everywhere. In order to provide more detailed and accurate information concerning the Paganica fault segment, four Electrical Resistivity Tomographies (ERT) were carried out around the Paganica village area. ERT results were supported by interpretation of aerial photos, morphotectonic investigation, geological field survey, borehole data and a paleoseismological trench. The electrical images showed the cumulated offset of the fault at depth and the existence of other splays parallel to the main strand which depict a staircase geometry of the fault in the Paganica area.