FieLd geological survey in the epicentral area of the Abrazzi (central Italy) seismic sequence of April 6th, 2009

The Ml=5.8 (Mw=6.2) earthquake that struck and devastated a broad area in the Abruzzi region of Central Italy produced a large set of surface coseismic deformations. In this work we present the field geological survey performed by the researchers involved in the EmerGeoWorking Group following the mainshock. The activities in the field consisted in the control and the characterization of the surface coseismic deformations mainly observed along previously mapped faults; in addition, a number of local coseismic effects are reported (landslides and secondary fractures) that are not directly associated to tectonic structures. A total of more than 300 sites of observation were surveyed in an area of ~900 km2. A preliminary analysis of our observations indicates that the ruptures reported along the Paganica Fault may represent the surface expression of the fault responsible for the April 6th mainshock, and that the effects observed along the Bazzano and Monticchio-Fossa Faults may reflect the coseismic reactivation of an antithetical structure.