Travel times of S and SKS: implications for three-dimensional lower mantle structure beneath the central Pacific

The travel times of S and SKS phases from deep-focus Fiji-Tonga events exhibit a strong azimuthal dependence. The differential times of S-SKS exhibit relatively little scatter and are used to investigate three-dimensional mantle models for the central Pacific region. Anomalously large S-SKS times suggest a slow lower mantle beneath the central Pacific. These results are compared to the predictions of three tomographic models. The three-dimensional whole mantle models have been parametrized into 11 spherical shells. Qualitative agreement between the tomographic model predictions and observations is encouraging, varying from fair to good. -with Authors