Kenta Minamidate, Tohoku University, Graduate School of Science, Sendai, Japan, Kazuhisa Goto, Tokyo University, Department of Earth and Planetary Science, Tokyo, Japan, Masashi Watanabe, Chuo University, Faculty of Science and Engineering, Tokyo, Japan, Volker Roeber, Université de Pau et des Pays de l'Adour, Angret, France, Ken Toguchi, Ryukyus University, Nakagami, Japan, Masami Sannoh, Mikuniya Corporation, Fukuoka, Japan, Yosuke Nakashima, Ariake National College of Technology, Omuta, Japan and Hironobu Kan, Kyushu University, Fukuoka, Japan