*Tomomi Kani¹, Keiji Misawa², Noritoshi Morikawa³, Kohei Kazahaya³, Fumitake Kusuhara⁴, Shigekazu Yoneda⁵, Yasutaka Terakado⁶ (1.Department of Earth and Environmental Sciences, Kumamoto University, 2.National Institute of Polar Research, 3.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 4.Central Research Institute of Electric Power Industry, 5.National Museum of Nature and Science, 6.Graduate School of Human Development and Environment, Kobe University)