Earth Planets Space, Vol. 63 (No. 7), pp. 831-834, 2011
Takeshi Tsuji1, Yoshihiro Ito2, Motoyuki Kido2, Yukihito Osada2, Hiromi Fujimoto2, Juichiro Ashi3, Masataka Kinoshita4, and Toshifumi Matsuoka1
1Graduate School of Engineering, Kyoto University, C1-1-110 Kyotodaigaku-Katsura, Nishikyoku, Kyoto 615-8540, Japan
2Graduate School of Science, Tohoku University, 6-6 Aramaki-aza-aoba, Aoba-ku, Sendai, Miyagi 981-8578, Japan
3Atmosphere and Ocean Research Institute, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8564, Japan
4Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-5 Natsushima-cho, Yokosuka-shi, Kanagawa 237-0061, Japan
(Received April 13, 2011; Revised May 19, 2011; Accepted May 20, 2011; Online published September 27, 2011)
Faults related to the tsunamigenic 2011 Tohoku-Oki Earthquake (Mw 9.0) were investigated by using multi-channel seismic reflection data acquired in 1999 and submersible seafloor observations from 2008. The location of the fault system interpreted in the seismic reflection profile is distributed around the area with largest slip and tsunami induction of the 2011 event. Cold-seep communities along the trace of the branch reverse fault and a high scarp associated with the trace of a normal fault suggest current activity on these faults. We interpret the fault system in the seismic profile as a shallow extension of the seismogenic fault that may have contributed to the resulting huge tsunami.
Key words: 2011 Tohoku-Oki Earthquake, tsunamigenic faults, seismic reflection data, seafloor observation, cold-seep communities, high scarp.