Geological investigation along the Sulmona active normal fault (central Italy) and its effects on the seismic microzoning of the area

Abstract: Due to its ~2 kyr “silent state”, the active Sulmona normal fault represents one of the most hazardous faults in central Italy, and the associated seismic risk is increased by the occurrence of important cities and several historical buildings and critical facilities. We investigated the central sector of the Sulmona fault through geological-geomorphological, geophysical and paleoseismological studies. The complex fault architecture has been analyzed along some gully exposures between Sulmona and Roccacasale villages. Here, two major fault zones have been mapped. The eastern one extends for 50 m from the rock fault scarp which marks the contact between the carbonate bedrock and the Quaternary deposits. Major evidence of late Quaternary faulting are observed along the further to the west (300-500 m basin-ward) fault zone. Our observations confirm that a multidisciplinary approach is useful to better assess the paleoseismic behaviour of complex fault zones and to define the areas of fault-rupture hazard during standard seismic microzonation work.