Evidence for upper mantle anisotropy beneath southern Germany from Love and Rayleigh wave dispersion

We advance evidence for the existence of seismic anisotropy in the upper mantle beneath Southern Germany from the dispersion of Love and Rayleigh waves. The evidence is based upon a substantial Love‐Rayleigh discrepancy observed between periods of 40 s and 120 s. An isotropic mantle model clearly fails to explain the observed dispersion curves. Systematic inversion experiments with transversely isotropic models show that anisotropy at depths between 70 km and 200 km is sufficient to explain the observed dispersion curves. Our data require neither anisotropy at greater depths nor anisotropy in the crust though we cannot exclude its presence there. A search for azimuthal anisotropy of Rayleigh wave propagation indicates a weak, but possibly insignifant azimuthal anisotropy of about 1% for periods less than 40 s with fast directions between 20 and 50 degrees east of north. At larger periods azimuthal anisotropy is less than 1% and the fast directions scatter considerably as period varies.