Local earthquake tomography in the Southern Tyrrhenian region of Italy: Geophysical and petrological inferences on subducting litosphere

We obtained a high-resolution seismic tomography of the Ionian lithosphere subduction using a new approach based on: (a) the Double-Difference technique for inversions and (b) the statistical post-processing of a great number of preliminary models (Weighted Average Model, WAM method); the latter was used to increase reliability and resolution. In the tomographic model, the high-velocity portion of the steeply dipping Ionian slab is well imaged, as is an underlying low-Vp (≈7.0 km/s) aseismic region. We propose that the low-velocity region can be assigned to a partially hydrated (serpentinized) mantle of the subducting Ionian slab, which progressively dehydrates with depth in dense high-pres…