Toward a new 3-D radial anisotropy model of the upper mantle and transition zone

Surface wave phase velocity measurements are sensitive to upper mantle elastic structure and boundary topography. In this study, we aim at obtaining new constraints on lateral variations in upper mantle and transition zone radial anisotropy. We use published fundamental mode phase and group velocities as well as higher mode phase velocities and new prior constraints on the topography of the 410 km and 670 km seismic discontinuities obtained with SS precursor travel times. We first performed a regularized inversion of the data corrected for the effect of the 410 and 670 topography and for crustal structure using non-linear crustal corrections based on CRUST1.0. Then, we used the resulting model as a starting point to perform a fully non-linear transdimensional model space search with the goal of determining quantitative model uncertainties on 3-D radial anisotropy and shear-wave velocities in the shallow and deep upper mantle.