1. Department of Geological Sciences, San Diego State University, MC‐1020, 5500 Campanile Drive, San Diego, California 92182‐1020 U.S.A., dsinglet@ucsd.edu
2. Also at Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093‐0225 U.S.A.
3. Murbach Geotech, 3130 North Evergreen Street, San Diego, California 92110 U.S.A.
4. 34351 Camino El Molino, Capistrano Beach, California 92624 U.S.A.