*Yoshio Murai¹, Kei Katsumata¹, Tetsuo Takanami², Tomoki Watanabe³, Tadashi Yamashina⁴, Ikuo Cho⁵, Masayuki Tanaka⁶, Ryosuke Azuma⁷ (1.Institute of Seismology and Volcanology, Faculty of Science, Hokkaido University, 2.Department of Terrestrial Magnetism, Carnegie Institution of Washington, 3.Marine Works Japan LTD, 4.Kochi University, 5.National Institute of Advanced Industrial Science and Technology, 6.Meteorological Research Institute, 7.Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University)

*Tetsuo Takanami^1,2 (1.Carnegie Institution for Science, 2.Hokkaido Research Center of Geology)