Seismic Anisotropy Beneath the Dinarides: Implications for Adria-Eurasia Convergence

Seismic anisotropy can provide important constraints about deformation processes within the lithosphere and underlying asthenosphere, as well as mantle flow patterns in tectonically complex regions. This study presents observations of seismic anisotropy in the upper mantle beneath the Dinarides and adjacent regions based on teleseismic SKS phase recordings from the AdriaArray temporary deployment, complemented by selected stations from the Croatian permanent seismic network and other available stations in the region. The combined datasets provide improved spatial coverage and allow for a more continuous regional assessment of anisotropic structure beneath the Dinarides.

Seismic anisotropy is investigated using a splitting-intensity approach, applied to teleseismic SKS phases. The splitting intensity quantifies the relative amplitude of the transverse component with respect to the radial component and provides a more robust measure of anisotropic effects. From the azimuthal variation of splitting intensity, the splitting parameters, fast-axis orientation and delay time, can be estimated, enabling direct comparison with earlier shear-wave splitting studies.

The inferred anisotropic pattern beneath the southern Dinarides is regionally coherent with fast axes in the direction perpendicular to the strike of the mountain chain. The fast axes in the Internal Dinarides, on the other hand, are generally pointing in the direction parallel to the strike of the mountain chain, which is also supporting previously published results. New and previously unpublished measurements are presented for stations in the northern Dinarides and in the transitional zone between the Dinarides and the Pannonian Basin, providing improved spatial coverage across this geodynamically important boundary.

This study highlights the importance of dense seismic observations and complementary analysis approaches for resolving anisotropic structures in complex orogenic settings. The expanded dataset and inclusion of splitting intensity measurements provide new constraints on upper-mantle deformation beneath the Dinarides and contribute to a more comprehensive understanding of the coupling between lithospheric tectonics and mantle dynamics in the central Mediterranean region.