Deep structure of peninsular Italy from seismic tomography and subcrustal seismicity

Abstract

The upper mantle structure beneath peninsular Italy is investigated through tomographic reconstruction of the P- wave velocity field down to 600 km and spatial distribution of subcrustal earthquakes. The tomographic images are computer using a non-linear technique to invert an improved dataset of teleseismic arrival times recorded by the Italian National seismic network in the last fifteen years. For the deep seismicity analysis, we selected 445 events from the database of subcrustal earthquakes that occurred in the period 1988-2004 (1191 events). A subset of 30 earthquakes including most of the deepest foci were relocated using the Hypoellispe location program and an upper mantle velocity structure based on the spherical ak135 global model. The velocity maps show a remarkable complexity of the lithosphere-asthenosphere system of the region, depicting different styles of lithospheric sinking along peninsular Italy from the Northern Apennines to the Calabrian Arc. The subducting slabs include most of the upper mantle events, but only in part they are seismically active.