Finite fault inversion of DInSAR coseismic displacement of the 2009 L’Aquila earthquake (central Italy)

Abstract

We define the geometric and kinematic characteristics of the fault activated during the Mw = 6.3, 6 April 2009 L’Aquila earthquake, from the modeling of Envisat and COSMO-SkyMed (the first ever X-band interferogram inverted for a coseismic dislocation study) DInSAR interferograms. Our best-fit solution for the main shock is represented by a normal fault ~16 km long and ~12 km wide, with a small right-lateral component, dipping 47° SW with a maximum slip of ~90 cm. Although the seismic dislocation probably ended at 1km depth, the updip projection of the fault plane corresponds to the northern segment of the mapped Paganica–S. Demetrio fault, where alignment of surface breaks was observed in the field. The absence of this fault in existing seismic source catalogues suggests that an improved approach, involving detailed surface and subsurface geological and geophysical investigations, is needed for a better assessment of the seismic hazard at the local scale.