Pn anisotropic tomography of the Euro-Mediterranean region: new insight into subduction and mantle dynamics

  Over the past few decades, the number of high-quality seismic stations monitoring the Euro-Mediterranean region has increased significantly, leading to a corresponding improvement in structural constraints. Hear, we present a new high-resolution Pn-wave anisotropic tomography model of the uppermost mantle beneath the Alps and surrounding areas, derived from the inversion of a large dataset of high-quality Pn arrival times, which were picked utilizing the PickNet deep learning method. Our model reveals strong lateral heterogeneities in both isotropic velocity and azimuthal anisotropy. Distinct high Pn velocities are observed under the Adriatic Sea, Mediterranean Sea, and Pannonian Basin, while prominent low Pn velocity anomalies are revealed beneath the orogenic belts, including the Alps, Apennines, and Dinarides. Generally, regions characterized by stable structures and low lithospheric temperatures exhibit high Pn velocities, whereas low Pn velocities indicate the upwelling of hot materials associated with plate subduction and continental collision processes. Pn anisotropic fast directions show consistent orientations subparallel to major orogenic structures, such as the Apennines, Calabrian Arc and Alps. Our newly obtained images of the uppermost mantle velocity and anisotropy structure provide further information and insights into continental collision processes and associated dynamic mechanisms.