HR: 1330h
AN: T12C-0487    [PDF]
TI: Deep Seismic Reflection Profiling Across the Northern Fossa Magna: the ERI 1997 and the JNOC 1996 Seismic Lines, Active Faults and Geological Structure
AU: * Elouai, D
EM: driss@eri.u-tokyo.ac.jp
AF: Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526 Japan
AU: * Elouai, D
EM: driss@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Sato, H
EM: satow@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Hirata, N
EM: hirata@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Kawasaki, S
EM: kawasaki@jgi.co.jp
AF: Japan Geosciences Institute, JGI, Inc. Meikei Building 1-5-21, Otsuka Bunko-Ku, Tokyo, 112-0012 Japan
AU: Takeshita, T
EM: toru@letitbe.geol.sci.hiroshima-u.ac.jp
AF: Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526 Japan
AB: View the fact that Japan is situated on a puzzle of tectonic plate boundaries; it is considered one of the most countries threatened by hazardous phenomena, mainly volcano and earthquakes. The Itoigawa-Shizuoka tectonic line (ISTL) is one of these boundaries, which separate the NE Japan from the SW Japan. In between these parts of Japan, the Neogene Fossa magna basin has been developed since the Miocene and is considered an active tectonic area, thus it has attracted different research groups. Our research group has conducted this research in order to investigate the geometry of the active faults and to get a better understanding of the relationship between the Pre-Neogene basement and the subsequent thick package of the sediments and the accompanied igneous rocks. Reprocessing the NF-97 line (17km in length) of the Earth Research Institute of Tokyo University (ERI) and the NS96-A line (19km) of the Japan National Oil Company (JNOC), has improved the quality of these lines. Despite of the difference in their strikes, EW for the former and NE-SW for the latter, we could merge both of them in a single line. Applying the migration process, we could partially filled in the 4km gap in between the two lines. Thus we could visualize the main structures, faults and folds existing in this area with their extension in the deep part. In the western part of the seismic line, the Itoigawa-Shizuoka active fault and the Otari-Nakayama fault appear as thrusting faults. These thrusts are dipping towards the East, with a westward vergence. The ISTL constitute a detachment fault system, which probably has played a key role of the tectonic evolution of the whole Fossa magna. In the East part of the seismic line, two backward reverse faults have been observed, the active fault of the West Nagano Basin and the Saigawa fault.
DE: 8010 Fractures and faults
DE: 8015 Local crustal structure
DE: 8102 Continental contractional orogenic belts
DE: 9320 Asia
SC: Tectonophysics [T]
MN: 2003 Fall Meeting