1. Department of Geophysics, Stanford University, Mitchell Building, 397 Panama Mall, Stanford, California 94305, USA
2. U.S. Geological Survey, Western Region Geology and Geophysics Science Center, 345 Middlefield Road, Menlo Park, California 94025, USA
3. Legg Geophysical, 16541 Gothard Street, #107, Huntington Beach, California 92647, USA
4. Department of Geological Sciences, California State University–Long Beach, 1250 Bellflower Boulevard, Long Beach, California 90840, USA