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

We present new tomographic images for the Pwave
velocity structure in the upper mantle beneath centralsouthern
Apennines down to 510 km depth. The model is
computed by nonlinear inversion of relative arrival times of
both direct and secondary teleseismic phases, handpicked
from over 2800 waveforms recorded by the Italian seismic
network during 1988-2000. Beneath central Apennines, the
images reveal a continuous, SW-dipping high-velocity body,
from 150 km down to 500 km. At shallower depths, a
pronounced low-velocity zone is recognized from the uppermost
mantle beneath the Apenninic belt down 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, highvelocity
anomalies are reconstructed in the uppermost mantle
of the Apulian foreland and below the belt in the range
100 400 km. Low-velocity regions, interpreted as due to
asthenospheric upwelling, are recovered above or across the
fast structures, as at the southeastern end of the Apennines
where a possible complete slab breako is suggested.