HR: 1340h
AN: T13C-1379    [Abstracts]
TI: Estimation of Timing and Coseismic Seafloor Displacement along Enshu Fault, off Tokai, Central Japan
AU: * Soh, W
EM: soh@jamstec.go.jp
AF: Japan Agency for Earth-Marine Science and Technology, 2-15, Natsushima, Yokosuka, 237-0061 Japan
AU: Machiyama, H
EM: bucci@jamstec.go.jp
AF: Japan Agency for Earth-Marine Science and Technology, 2-15, Natsushima, Yokosuka, 237-0061 Japan
AU: Kanamatsu, T
EM: toshiya@jamstec.go.jp
AF: Japan Agency for Earth-Marine Science and Technology, 2-15, Natsushima, Yokosuka, 237-0061 Japan
AU: Ashi, J
EM: ashi@jamstec.go.jp
AF: Ocean research Institute, University of Tokyo, 1-15-1, Minamidai, Nakano, Tokyo, 164-8639 Japan
AU: Matsumoto, H
EM: hmatsumoto@jamstec.go.jp
AF: Japan Agency for Earth-Marine Science and Technology, 2-15, Natsushima, Yokosuka, 237-0061 Japan
AU: Oguri, K
EM: oguri@jamstec.go.jp
AF: Japan Agency for Earth-Marine Science and Technology, 2-15, Natsushima, Yokosuka, 237-0061 Japan
AB: Enshu Fault is an active submarine fault, running over 120 km long, from off Hamaoka, Shizuoka, to off Shima Peninsula, Mie, Japan. General geomorphologic feature of the fault is reconstructed based on high resolution bathymetry and seismic profiles, to date the Enshu fault is known to be a transpressional fault to be a right-lateral slip component with a landward uplift component, parallel to the Nankai Trough (Tokuyama et al., 1999). The Enashu fault runs along the escarpment but the several submarine channels dissect the escarpment to cross the fault. The seepage driven, white-colored sea floor mat had been directly observed by submersible Shinkai 2000 (No.1601 cruise), right above the fault. Taking new ROV (NSS), the piston cores to be precisely positioned were obtained from both between the hanging- and foot-wall sides of the fault. The both core samples are consisted of thin-bedded turbidites. The result of bulk magnetic susceptibilities analysis enables to make the core-to-core correlation whereas the correlation based on the sand layer intercalated was not succeeded. In addition, the comparative study of the both cores in AMS fabrics and CAT image help us to identify the internal structure of the fault-displacement induced chaotic deposit to fill the depression in the hanging wall side. 14C age method taking foraminifer test in the cores tells us the accumulation time of the deposit due to the earthquake event. These data sets suggest the time when the most recent earthquake took place, and thickness of the deposit suggest us the amount of sea floor displacement in the time. In this study case, for example, the vertical displacement in the last single event reaches more than 40 cm. We calculated magnitude of the tsunami and way of the propagation as one of basic data of the hazard map.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting