Using Surface Observations to Constrain the Direction and Magnitude of Mantle Flow Beneath Western North America

on mantle shear velocity at a depth of 150 km from (3). We only use data from ‘red ’ (slow) areas, where influence of lithosphere on anisotropy is expected to be small. Observations of surface deformation (GPS velocities (1) and Quaternary fault slip rates (2)) and upper mantle seismic anisotropy (3) are combined for the first time, to provide a direct estimate of the mantle flow field beneath western North America. This is an example of what can be achieved when seismic observations collected in the USArray com-ponent of Earthscope are combined with the surface deformation results collected in the PBO and InSAR component. With more detailed observations in to-mography, anisotropy, and surface deformation, our understanding of the flow field, and hence dynam-