HR: 1340h
AN: T53A-1107    [Abstracts]
TI: Crustal structure around the asperity regions of large earthquakes along the southernmost Kuril trench revealed by two Airgun-OBS seismic profilings
AU: * Machida, Y
EM: yuya@mail.sci.hokudai.ac.jp
AF: Hokkaido Univ., N10W8, Kita-ku, Sapporo, 060-0810, Japan
AU: Takanami, T
EM: takanami@mail.sci.hokudai.ac.jp
AF: Hokkaido Univ., N10W8, Kita-ku, Sapporo, 060-0810, Japan
AU: Murai, Y
EM: murai@mail.sci.hokudai.ac.jp
AF: Hokkaido Univ., N10W8, Kita-ku, Sapporo, 060-0810, Japan
AU: Amamiya, S
EM: isv_amamiya@mail.sci.hokudai.ac.jp
AF: Hokkaido Univ., N10W8, Kita-ku, Sapporo, 060-0810, Japan
AU: Nishimura, Y
EM: yns@mail.sci.hokudaia.c.jp
AF: Hokkaido Univ., N10W8, Kita-ku, Sapporo, 060-0810, Japan
AU: Shinohara, M
EM: mshino@eri.u-tokyo.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Mchizuki, K
EM: kimi@eri.u-tokyo.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Yamada, T
EM: yamada@eri.u-tokyo.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Nakahigashi, K
EM: kazuo@eri.u-tokyo.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Kuwano, A
EM: kuwano@eri.u-tokyo.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Kanazawa, T
EM: kanazawa@eri.u-tokyo.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Hino, R
EM: hino@aob.geophys.tohoku.ac.jp
AF: Tohoku Univ., 6-6, Aramaki-Aza-Aoba, Aobaku, Sendai, 980-8578, Japan
AU: Azuma, R
EM: azuma@aob.geophys.tohoku.ac.jp
AF: ERI, Univ. of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
AB: In the southeast off Hokkaido, Japan, large earthquakes have occurred repeatedly with temporal and spatial regularities along the Kuril trench due to the subduction of Pacific plate at a rate of 80 mm/year (DeMets et al., 1990) [e.g. the 1952 Tokachi-oki earthquake (Mw=8.2), the 1973 Nemuro-oki earthquake (Mw=7.8) and the 2003 Tokachi-oki earthquake (Mw=8.2)]. It is considered that the next large earthquake will occur at the source region of the 1973 Nemuro-oki earthquake in the near future because a low seismic activity has been found in the off shore region of the Nemuro peninsula. In order to clarify the relation between asperity and the recurrence of large earthquake, it is necessary to determine a detailed crustal structure running across the two asperities of the 2003 Tokachi-oki earthquake and 1973 Nemuro-oki earthquake. Therefore we conducted a wide-angle survey across the coseismic rupture areas of the 2003 Tokachi-oki and 1973 Nemuro-oki earthquakes and the afterslip area of the 2003 Tokachi-oki earthquake parallel (profile-A) and perpendicular (profile-B) to the Kuril trench using Ocean Bottom Seismometers (OBSs). In profile-A, 19 OBSs were deployed at a spacing of about 10km and three 25 liter air-guns were fired every 90 seconds which corresponds to a shot interval of about 230m. In profile-B, 11 OBSs were deployed at a spacing of about 11km and two 25 liter airguns were fired every 60 seconds which corresponds to a shot interval of about 150m. In this presentation, we report on the crustal structure using the data obtained in the profile A and B and compare our results with past researches around this region. This study is founded by the Ministry of Education, Culture, Sports, Science and Technology, Japan.
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8038 Regional crustal structure
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting