Quantitative estimation of massive gas hydrate in gas chimney structures, the eastern margin of Japan Sea, from the physical property anomalies obtained by LWD.

Manabu Tanahashi, Meiji University, Gas Hydrate Research Laboratory, Kawasaki, Japan, Sumito Morita, Geological Survey of Japan, AIST, Tsukuba, Ibaraki, Japan and Ryo Matsumoto, Meiji University, Gas Hydrate Research Laboratory, Tokyo, Japan