Nonlinear P-wave tomography of subducted lithosphere beneath central-southern Apennines (Italy)

We present new tomographic images for the P-wave velocity structure in the upper mantle beneath centralsouthern Apennines down to 510 km depth. The mo del is computed by nonlinear inversion of relative arrival times of both di rect and secondary teleseismic phases, handpicked from over 2800 waveforms recorded by the Italian seismic network during 1988-2000. Beneath central A pennines, the images reveal a continuous, SW-dipping high-velocity body, fr om similar to 150 km down to similar to 500 km. At shallower depths, a pron ounced low-velocity zone is recognized from the uppermost mantle beneath th e Apenninic belt down to similar to 200 km below the Tyrrhenian area. This feature is proposed to affect the seismic structure of the downgoing slab, weakening its velocity signature. Beneath southern Apennines, high-velocity anomalies are reconstructed in the uppermost mantle of the Apulian forelan d and below the belt in the range 100 divided by 400 km. Low-velocity regio ns, interpreted as due to asthenospheric upwelling, are recovered above or across the fast structures, as at the southeastern end of the Apennines whe re a possible complete slab breakoff is suggested.