Kazuo Nakahigashi, Tokyo University of Marine Science and Technology, Tokyo, Japan, Takeshi Akuhara, Earthquake Research Institute, The University of Tokyo, Tokyo, Japan, Tomoaki Yamada, University of Tokyo, Bunkyo-ku, Japan, Kimihiro Mochizuki, University of Tokyo, Earthquake Research Institute, Bunkyo-ku, Japan, Hajime Shiobara, The University of Tokyo, Tokyo, Japan and Masanao Shinohara, Univ Tokyo, Tokyo, Japan