1. Department of Earth Science, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
2. Seismological Laboratory, California Institute of Technology, Pasadena, California 91125, U.S.A.
3. † Present address: Laboratoire de Géologie de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5276, Lyon, France.
4. ‡ Present address: Hawaii Institute of Geophysics and Planetology, School of Ocean and Earth Sciences, University of Hawaii at Manoa, Honolulu, Hawaii 96822, U.S.A.
5. Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan
6. Bayerisches Geoinstitut, University of Bayreuth, Bayreuth, 95440 Germany
7. Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
8. Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, 679-5198, Japan
9. National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
10. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, U.S.A.