Anisotropic seismic structure of the lithosphere beneath the Adriatic coast of Italy constrained with mode-converted body waves

[1] P-S converted waves observed near Ancona on the Adriatic coast of central Italy, as revealed by teleseismic receiver functions (RFs), vary with earthquake back-azimuth and epicentral distance in a manner consistent with a 1-D anisotropic seismic structure. Using reflectivity calculations, we develop a profile of anisotropic seismic velocity through the Adriatic lithosphere at this locality. We infer crustal thickness of similar to45 km. Anisotropy within the crust appears at similar to15-km depth, suggesting a decollement between the subducting Adriatic lithosphere and the overriding crustal wedge. Lineation of inferred rock fabric is compatible with simple shear in ENE-WSW direction. In the upper mantle, we infer an anisotropic layer at 80-90 km depth. If caused by olivine crystals alignment, the nearly north-south lineation of the inferred rock fabric would be consistent with some nearby shear-wave splitting observations. This anisotropic layer may be related to mantle deformation induced by the rollback of Adriatic lithosphere.