Evidence for a high-velocity lithospheric plate under northern Nevada

P-wave residuals at stations of the Nevada seismic network are analyzed for 80 teleseisms distributed over a range of azimuth and epicentral distance. For South American earthquakes (azimuth 120° to 140° from Nevada), teleseismic P arrivals at northern Nevada stations Lovelock, Battle Mountain, and Elko are early by as much as 1.4 sec relative to the Tonopah station to the south. The North Reno station has early arrivals, relative to Tonopah, for Leeward Islands earthquakes, at an azimuth of 100° from the station. Interpretation of these residuals indicates the presence of a high-velocity lithospheric plate, striking northeast and dipping southeast, under northern Nevada. The high-velocity plate is interpreted as a paleosubduction zone.