Resolving Seismic Anisotropy of the Lithosphere–Asthenosphere in the Central/Eastern Alps Beneath the SWATH-D Network

The Alpine orogeny is characterized by tectonic sequences of subduction and collision accompanied break-off events possibly preceded a flip polarity. evolution the transition to Eastern Alps has thus been under debate. dense SWATH-D seismic network as complementary experiment AlpArray provides unprecedented lateral resolution address this ongoing discussion. We analyze shear-wave splitting data set including stations backbone in region obtain new insights into deformation at depth from anisotropy. Previous studies indicate two-layer anisotropy Alps. This supported azimuthal pattern measured fast axis direction across all analyzed stations. However, temporary character deployment requires joint analysis multiple increase number adding information anisotropic properties mantle. We, therefore, perform cluster based on correlation energy tensors between are assembled remaining transverse after trial correction effect two consecutive layers. leads main groups different properties, separated approximately 13°E. identify layer with constant (measured clockwise respect north) about 60° over whole area, possible dip west east. lower shows N–S upper east 115°. propose likely scenarios, both slab eastern part. continuous can either be interpreted frozen-in lithospheric origin or an asthenospheric flow evading retreat European that would precede event. In result through gap formed break-off. driven retreating but might also deep-reaching fault-related