Seismic Tomography of western North America

Ana Luz Acevedo-Cabrera, Mei Xue and Richard M. Allen
University of California Berkeley

AGU Fall Meeting, San Francisco, December 2007.

We use teleseismic body wave travel time tomography to image the western United States using an unprecedented number of seismometers that have been deployed across the region as part of Earthscope. The resulting high-resolution images of the interior of the earth in this tectonically active zone provide new insight into the structure and interaction between known geologic objects. For example we image the subducted Juan de Fuca plate extending beneath North American. While it reaches more than 500 km beneath Washington there is a hole in the slab at 400 km depth beneath Oregon. The hole could be explained by the arrival of the Yellowstone plume head around 17Ma. The Yellowstone plume today is imaged as a shallow feature extending to around 500 km depth. Beneath California the high velocity Pacific Plate is abuts against the low velocity North America plate along the San Andreas Fault.

© Richard M Allen