Affiliation: | (1) Branch of Earthquake Geology and Geophysics, U.S. Geological Survey, MS-977, 345 Middlefield Rd., 94025 Menlo Park, CA, U.S.A.;(2) Department of Earth, Atmospheric and Planetary Sciences, 54-724, Massachusetts Institute of Technology, 02139 Cambridge, MA, U.S.A. |