A simple approach to the joint inversion of seismic body and surface waves applied to the southwest U.S.

Abstract

Body and surface wave tomography have complementary strengths when applied to regional‐scale studies of the upper mantle. We present a straight‐forward technique for their joint inversion which hinges on treating surface waves as horizontally‐propagating rays with deep sensitivity kernels. This formulation allows surface wave phase or group measurements to be integrated directly into existing body wave tomography inversions with modest effort. We apply the joint inversion to a synthetic case and to data from the RISTRA project in the southwest U.S. The data variance reductions demonstrate that the joint inversion produces a better fit to the combined dataset, not merely a compromise. For large arrays, this method offers an improvement over augmenting body wave tomography with a one‐dimensional model. The joint inversion combines the absolute velocity of a surface wave model with the high resolution afforded by body waves—both qualities that are required to understand regional‐scale mantle phenomena.