Teleseismic event recordings from regional seismic arrays in the western US contain travel-time information can be used to image upper mantle velocity structure beneath much of the western US. The seismic inversions and models of other workers and results shown in this proposal show that the upper mantle is strongly heterogeneous beneath each array investigated. These upper mantle structures are thought to be fundamentally related to present-day tectonic activity, yet the relationships are not well understood. The work proposed offers an opportunity to vastly improve understanding of seismic structure beneath the western US, and it should improve general understanding of the dynamics of continental deformation.
