[1] Univ Calif Berkeley, Dept Earth & Planetary Sci, Berkeley, CA 94720 USA
[2] Stanford Univ, Sch Earth Sci, Stanford, CA 94305 USA
[3] San Diego State Univ, Dept Geol Sci, San Diego, CA 92115 USA
[4] Univ Calif Berkeley, Pacific Earthquake Engn Res Ctr, Berkeley, CA 94720 USA
[5] Univ So Calif, Dept Earth Sci, Los Angeles, CA 90089 USA
[6] US Geol Survey, Menlo Pk, CA 94025 USA
[7] Univ Calif Los Angeles, Dept Civil & Environm Engn, Santa Monica, CA 90095 USA