Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki Aza Aoba, Aoba-ku, Sendai, 980-8576 Japan
Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki Aza Aoba, Aoba-ku, Sendai, 980-8576 Japan
Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki Aza Aoba, Aoba-ku, Sendai, 980-8576 Japan
U.S.Geological Survey, MS 977 345 Middlefield Road, Menlo Park, CA 94025 United States
Department of Physics, University of Colorado, Campus Box 390 UCB, Boulder, CO 80309-0 United States