| To determine the extent of foundering lithosphere beneath the Sierra Nevada, I conducted a P-wave teleseismic travel time tomography inversion using approximately 27,000 arrivals recorded at SNEP (Sierra Nevada EarthScope Project) and other seismometers in the Sierra. Within the SNEP array, stations are spaced about 25 km apart and extend roughly 400 km along the range and 150 km normal to the range. The tomography results indicate that no substantial lithospheric downwelling exists between the previously recognized "Isabella anomaly" at the southern end of the range and the south edge of the Gorda slab, and the high-velocity Redding anomaly. Another high-velocity body, the Western Sierra anomaly, is imaged at shallow depths to the west of the range. My results show the Sierra is in varying stages of root removal from complete removal in the south, to initial stages of removal in the north. The central portion has an in-situ root. |
