*Glen Snyder¹、Hitoshi Tomaru²、Shinsuke Aoki³、Teresa Nakajima⁴、Shiono Miki¹、Takanori Kagoshima⁶、Ryo Matsumoto⁵ (1.Atmosphere and Ocean Research Institute, University of Tokyo、2.Department of Earth Sciences, Chiba University、3.Faculty of Agriculture, Kagawa University、4.Marine Core Research Center, Kochi University、5.Gas Hydrate Research Laboratory, Meiji University、6.University of Toyama)