Crust and Upper Mantle Seismic Structure Across the Calabrian Arc, Italy, From Receiver Function Analysis

We use data from the CAT/SCAN seismic deployment in southern Italy to reconstruct the crust and uppermost mantle structure above one of the narrowest active subduction zones worldwide, the Calabrian Arc. Both isotropic and anisotropic properties are investigated using Receiver Function (RF) analysis. First, an E-W profile composed of radial RF shows the geometry of the main isotropic seismic discontinuities. A complementary analysis of both radial and transverse RF for the stations deployed along the Tyrrhenian coast is used to map the anisotropy in the mantle wedge. The computed RF profile provides a clear image of the subducting Ionian plate at shallow depth where it bends and starts to descend into the mantle. The depth of the Ionian Moho increases from ~35 km in the east to ~80 km in the west. The change in dip corresponds to the transition from an uplifted plateau to an extensional basin at the surface. The RF harmonics components of the show the presence of anisotropy in the mantle wedge, and point out the rotation of the anisotropy axes from NE (for the northernmost station) to SE (for the southernmost), following the strike of the Calabrian Arc.