Narumi Tsugeki, Matsuyama University, Matsuyama, Japan, Michinobu Kuwae, Ehime University, Matsuyama, Japan, Masanobu Yamamoto, Hokkaido Univ, Sapporo, Japan, Yukinori Tani, University of Shizuoka, Shizuoka, Japan, Takayuki Omori, University of Tokyo, Bunkyo-ku, Japan, Keitaro Yamada, Graduate School of Science, Kyoto University, Kyoto, Japan, Ken Ikehara, Geological Survey of Japan, AIST, Tsukuba, Japan, Hikaru Takahara, Kyoto Prefectural University, Kyoto, Japan, Tsuyoshi Haraguchi, Osaka City Univ, Osaka, Japan and Keiji Takemura, Kyoto Univ, Beppu, Japan