Teleseismic P wave travel time residuals are used to detect lateral velocity heterogeneities in the upper mantle beneath Washington and N Oregon. The results of an inversion for 3-D velocity variations resolves an E dipping high-velocity zone that we interpret as the subducting Juan de Fuca plate. The plate is characterized by 3-8% higher velocities than those in the surrounding upper mantle. Inversion of the travel time data and ray trace modeling indicate that the plate extends to a depth of 200- 300 km. Based on changes in the geometry and velocity structure of the subducted Juan de Fuca plate 6 of about 123oW, we propose that the subducted slab is segmented into 3 sections beneath Washington and N Oregon. -from Authors
Additional Publication Details
Upper mantle structure from teleseismic P wave arrivals in Washington and northern Oregon ( USA).