Three‐dimensional P wave attenuation and velocity upper mantle tomography of the southern Apennines–Calabrian Arc subduction zone

Abstract

We propose a 3‐D crust–upper mantle seismic attenuation (QP) model of the southern Apennines–Calabrian Arc subduction zone together with a 3‐D velocity (VP) model. The QP model is calculated from relative t* using the spectral ratio method and the VP from traveltime data. The final data set used for the inversion of the VP model consists of 2400 traveltime arrivals recorded by 34 short‐period stations that are part of the Italian National Seismic Network, and for the QP model, 2178 Pn phases recorded by a subset of 32 stations. Traveltimes and waveforms come from 272 intermediate‐depth Calabrian slab events. This 3‐D model of attenuation, together with the 3‐D velocity model, improves our knowledge of the slab/mantle wedge structure and can be a starting point in determining the physical state of the asthenosphere (i.e., its temperature, the presence of melt and/or fluids) and its relation to volcanism found in the study area. Main features of the QP and VP models show that the mantle wedge/slab, in particular, the area of highest attenuation, is located in a volume underlying the Marsili Basin. The existence and shape of this main low‐QP (and low‐VP) anomaly points to slab dehydration and fluid/material flow, a process that may explain the strong geochemical affinities between the subduction‐related magmas from Stromboli and Vesuvius. Other interesting features in the models are strong lateral variations in QP and VP that are put in relation with known important tectonic structures and volcanic centers in the area.