HR: 1340h
AN: T13C-1371    [Abstracts]
TI: Pinpoint core sampling at active faults in the Nankai subduction zone by new ROV "NSS"
AU: * Ashi, J
EM: ashi@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo, 164-8639 Japan
AU: Shirai, M
EM: shirai@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo, 164-8639 Japan
AU: Tokuyama, H
EM: tokuyama@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo, 164-8639 Japan
AU: Soh, W
EM: soh@jamstec.go.jp
AF: JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061 Japan
AU: Kinoshita, M
EM: masa@jamstec.go.jp
AF: JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061 Japan
AU: Machiyama, H
EM: bucci@jamstec.go.jp
AF: JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061 Japan
AU: Kanamatsu, T
EM: toshiyak@jamstec.go.jp
AF: JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061 Japan
AU: Hirono, T
EM: hirono@jamstec.go.jp
AF: JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061 Japan
AU: Ikehara, K
EM: k-ikehara@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, Higashi-1-1-1,Tsukuba, Ibaraki, 305-8567 Japan
AU: Arai, K
EM: ko-arai@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, Higashi-1-1-1,Tsukuba, Ibaraki, 305-8567 Japan
AU: Omura, A
EM: a.omura@aist.go.jp
AF: National Institute of Advanced Industrial Science and Technology, Higashi-1-1-1,Tsukuba, Ibaraki, 305-8567 Japan
AB: Piston coring across active faults in shallow water depth, as well as drilling or trenching of fault zone on land, provides us with information about earthquake timing, recurrence of fault activity and fault displacement. In contrast, it is not easy to take samples from deep-sea with pinpoint accuracy. In order to identify the position of the core sampler and approach the target for sampling, a transponder is recently installed on the cable just above the sampler. The pilot vehicle of new ROV "NSS" (Navigable Sampling System) can move by four thrusters, observe seafloor by video cameras, release samplers and measurement tools by command from a mother ship, and real time geophysical or geochemical monitoring through an armored cable. The whole system including winches is removal. The ship with large deck can be equipped with NSS system. Depth capability of the pilot vehicle is 4000m and maximum payload weight is 1.5 Tons. First cruise using NSS was conducted in the Nankai Trough and the Sagami Trough using JAMSTEC R/V "Kaiyo" in 2003. Piston cores were taken from active faults off the Central Japan in the Nankai Trough, and the cold seep sites along the blind fault off Hatsushima, Sagami Bay. NSS using seafloor video camera and thrusters has accuracy of pinpoint sampling within 2m, and allows us to take samples from narrow fault zone or small clam colony. Core samples derived from active fault zones show different sedimentation histories; lack of strata and differences of layer thickness across dip-slip faults and lithological changes with time across strike-slip faults near submarine canyon, and provide information about recurrence time and fault displacement. NSS is one of tools that break through difficulties of pinpoint sampling in deep-sea and will proceed studies of active submarine faults.
UR: http://ofgs.ori.u-tokyo.ac.jp/~ashi/NSS/
DE: 9805 Instruments useful in three or more fields
DE: 8010 Fractures and faults
DE: 3022 Marine sediments--processes and transport
DE: 3045 Seafloor morphology and bottom photography
DE: 3094 Instruments and techniques
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting