HR: 1340h
AN: OS23A-1045    [Abstracts]
TI: Relation between methane hydrate-bearing formations and geological phenomena on the seafloor in the eastern Nankai Trough, Japan
AU: * Nagakubo, S
EM: nagakubo-sadao@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2 Hamada, Mihama-ku, Chiba-city, Chiba, 261-0025, Japan
AU: Kobayashi, T
EM: kobayashi-toshiaki@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2 Hamada, Mihama-ku, Chiba-city, Chiba, 261-0025, Japan
AU: Inamori, T
EM: inamori-takao@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2 Hamada, Mihama-ku, Chiba-city, Chiba, 261-0025, Japan
AU: Saeki, T
EM: saeki-tatsuo@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2 Hamada, Mihama-ku, Chiba-city, Chiba, 261-0025, Japan
AU: Shimoda, N
EM: shimoda-naoyuki@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2 Hamada, Mihama-ku, Chiba-city, Chiba, 261-0025, Japan
AU: Fujii, T
EM: fujii-tetsuya@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2 Hamada, Mihama-ku, Chiba-city, Chiba, 261-0025, Japan
AU: Morita, S
EM: morita-s@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 1-1-1, Higashi, Tsukuba, Ibaragi, 305-8567, Japan
AU: Tanahashi, M
EM: tanahashi-m@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, 1-1-1, Higashi, Tsukuba, Ibaragi, 305-8567, Japan
AB: In 2002, a series of high-resolution 3D seismic surveys was conducted in the Tokai-Oki, the Daini-Atsumi Knoll, the Kumano-nada in the eastern Nankai Trough, Japan. Research Consortium for Methane Hydrate Resources in Japan (MH21) conducted resource assessment of methane hydrate in the eastern Nankai Trough by various seismic data analyses combining results of the exploratory wells conducted in 2005. By these analyses, occurrence of methane hydrate in the eastern Nankai Trough is coming to light. The MH21 has also interpreted the relation between methane hydrate-bearing formations and various geological phenomena on the seafloor, such as pockmarks and carbonate outcrops, using the 3D seismic data in the three survey areas. Bathymetric maps and seafloor amplitude maps constructed by the high-resolution 3D data provided lots of information on the seafloor. Some areas show very high intensity on the seafloor amplitude maps. It is expected that the areas showing strong amplitude correspond to the distribution of carbonate outcrops which are likely precipitated by methane seep activities. By checking the seafloor amplitude maps, seismic sections and methane seep sites observed by the previous submersible dives, some significant correlations are recognized between methane hydrate-bearing formations and various phenomena on the seafloor. It may be likely that the occurrence of methane hydrate and the geological phenomena on the seafloor have a strong implication with some typical geologic structures, e.g. shallow fault, highly-permeable sediments and hydraulic fractures, which may control the fluid migration. Besides, in this study we learnt that bathymetric map and seafloor amplitude map constructed by the high- resolution 3D seismic data are very useful not only for interpretation of relation between methane hydrate-bearing formation and various phenomena on the seafloor but also for designing the following seafloor investigations. This study is conducted by the MH21.
DE: 0930 Oceanic structures
DE: 0935 Seismic methods (3025, 7294)
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 3004 Gas and hydrate systems
DE: 3045 Seafloor morphology, geology, and geophysics
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting