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Abstract

The correlation between mantle flow and seismic anisotropy emphasizes its key role in understanding tectonic processes. While global geodynamic modelling of asthenospheric mantle flow results in a good correlation, the large spatial variation of seismic anisotropy beneath continents indicates a considerable complex contribution of the shallow lithosphere, which is not yet well understood. A detailed imaging of anisotropy with depth is therefore an important challenge for seismic investigation.Here, we present our current advances in improving the depth resolution based on receiver function and SKS-splitting techniques applied at the continental margins of the European Alps and Central Appalachians. Classical shear-wave splitting techniques are mostly used to infer a single anisotropic layer. This becomes misleading for continental margins with complex deformation. An azimuthal variation of splitting parameters is an indication for vertical layering of anisotropy and can be analyzed systematically providing insight into these complexities. However, this approach allows no direct constraint on the depth distribution. Recent developments involve the calculation of sensitivity kernels for Splitting Intensity observations, which allows us to consider the laterally broadened sensitivity for the anisotropic structure with depth. A requirement of this tomographic technique is a dense station spacing, which is satisfied by a growing number of seismic deployments.The increased lateral stress in deformational regimes at shallow levels results in a possible contamination of shear-wave splitting by crustal anisotropy. We suggest a stepwise approach in which receiver functions are examined for their harmonic variation with backazimuth to determine and correct for significant anisotropic crustal effects.