Affiliation: | Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093,;USA. E-mail: Ecole et Observatoire de Sciences de la Terre, Universite Louis Pasteur-CNRS, Strasbourg, France. E-mail:;Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125,;USA. E-mail: |