Pn Anisotropy in the Northern Apennine Chain (Italy)

Pn travel times recorded by the stations of the Italian seismic network have been used to image the azimuthal variations of seismic velocity in the uppermost mantle beneath the northern part of the Apennine chain. The azimuthal variation of Pn velocity is interpreted here in terms of seismic anisotropy. We have found that about 5% anisotropy characterizes the uppermost mantle of the studied area, and that the fastest direction of Pn follows the arcuate trend of the chain. This suggests that seismic anisotropy is strongly related to the tectonic regime that originated the northern Apennine arc.