HR: 1330h
AN: T52B-0253    [PDF]
TI: Microseismicity in the rupture area of the 1994 Sanriku-Oki Earthquake determined by long-term ocean bottom seismographic observation
AU: * Kuwano, A
EM: kuwano@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578 Japan
AU: Hino, R
EM: hino@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578 Japan
AU: Nishino, M
EM: nishino@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578 Japan
AU: Sato, T
EM: satot@earth.s.chiba-u.ac.jp
AF: Faculty of Science, Chiba University, 1-33 Yayoi-Cho, Inage-ku, Chiba, 263-8522 Japan
AU: Shiobara, H
EM: shio@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, niversity of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Kasahara, J
EM: kasa2@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, niversity of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Yabuki, T
EM: tetsuichirou-yabuki@kaiho.mlit.go.jp
AF: Hydrographic and Oceanographic Department, Japan Coast Guard, 5-3-1 Tsukiji, Chuo-ku, Tokyo, 104-0045
AU: Fujimoto, H
EM: fujimoto@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578 Japan
AB: Long-term seismic observations to monitor spatial and temporal variations of seismic activity are essential to understanding seismogenic processes along fault zones. Therefore, in subduction plate boundaries where most of the interplate earthquakes occur beneath the ocean, long-term observations on the seafloor are necessary. In recent years, a pop-up type ocean-bottom seismometer enabling us to conduct long-term observations for more than one year has been developed (e.g., Kanazawa et al., 2002). By using five long-term ocean bottom seismometers (LTOBS), we carried out a seismic observation in the rupture area of the 1994 Sanriku-Oki Earthquake, in the northern Japan Trench area, for about nine months from October 2000 to July 2001. Here we report the hypocenter distribution relocated by combining the arrival time data obtained by the LTOBSs and the land seismic network operated by Tohoku University. Owing to the LTOBSs data, resolution of the hypocenter distribution is much improved and most of the hypocenters are relocated along the landward dipping plane corresponding to the plate boundary. In the Japan Trench subduction zone, Uchida et al. (2002) identified many groups of similar earthquakes. They interpreted these similar earthquakes as repetitive failures of tiny asperities along the plate boundary although it was difficult to obtain precise hypocenter locations only from the land network data. Our LTOBSs observed one of the repeating events for several similar earthquake sequences and we are able to relocate their hypocenters. The hypocenters of the repetitive similar earthquakes are within the concentration of earthquakes along the landward dipping plane, supporting the idea that these events are taking place along the subduction plate interface.
UR: http://www.aob.geophys.tohoku.ac.jp
DE: 7230 Seismicity and seismotectonics
SC: Tectonophysics [T]
MN: 2003 Fall Meeting