HR: 0830h
AN: S31F-0823    [PDF]
TI: Configuration of the Subducting Philippine Sea Plate and the Crustal and Upper Mantle Structure Beneath the southwestern Japan arc, Revealed by Seismic Refraction/Wide-angle Reflection Profiling
AU: * Kurashimo, E
EM: ekura@eri.u-tokyo.ac.jp
AF: The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Japan
AU: Iwasaki, T
EM: iwasaki@eri.u-tokyo.ac.jp
AF: The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Japan
AU: Iidaka, T
EM: iidaka@eri.u-tokyo.ac.jp
AF: The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Japan
AU: Kawamura, T
EM: tkawa@eri.u-tokyo.ac.jp
AF: The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Japan
AU: Moriya, T
EM: moriya@ep.sci.hokudai.ac.jp
AF: Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, 060-0810 Japan
AU: Ito, K
EM: ito@rcep.dpri.kyoto-u.ac.jp
AF: Kyoto University, Gokanosho, Uji, 611-0011 Japan
AU: Shibutani, T
EM: shibutan@rcep.dpri.kyoto-u.ac.jp
AF: Kyoto University, Gokanosho, Uji, 611-0011 Japan
AU: Miyamachi, H
EM: miya@sci.kagoshima-u.ac.jp
AF: Kagoshima University, 1-21-35 Korimoto, Kagoshima, 890-0065 Japan
AU: Sato, H
EM: satow@eri.u-tokyo.ac.jp
AF: The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-0032 Japan
AU: Miller, K
EM: miller@geo.utep.edu
AF: The University of Texas at El Paso, 500 West University Avenue El Paso, El Paso, 79968 United States
AU: Harder, S
EM: harder@geo.utep.edu
AF: The University of Texas at El Paso, 500 West University Avenue El Paso, El Paso, 79968 United States
AU: Ito, T
EM: tito@earth.s.chiba-u.ac.jp
AF: Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, 263-8522 Japan
AU: Kaneda, Y
EM: kaneday@jamstec.go.jp
AF: JAMSTEC, 2-15, Natsuhima, Yokosuka, 237-0061 Japan
AU: Onishi, M
EM: onishi@jgi.co.jp
AF: JGI, Inc., 1-5-21, Otsuka, Bunkyo-ku, 112-0012 Japan
AB: The Nankai trough region, where the Philippine Sea Plate is subducted beneath the SW Japan arc, is a well-known seismogenic zone of interplate earthquakes. A detailed crustal and upper mantle structures of the subducted Philippine Sea Plate and the overlying SW Japan arc is inevitably important to constrain the physical process of earthquake occurrence as well as the evolution process of this margin. In the summer of 2002, we conducted an onshore-offshore seismic experiment across the SW Japan arc. In this experiment, about 2,300 seismometers were deployed on a 235-km-long onshore line with NS direction, on which 10 explosives shots were fired. Data collected from on the onshore line have high signal-to-noise ratios, from which we can easily recognize prominent wide-angle reflections from the deep crust and the subducted plate boundary. Analyzing these explosive data, we could obtain a detailed configuration of the subducting Philippine Sea plate and the crustal and upper mantle structure beneath the SW Japan arc. Beneath the southern edge of the land profile, the top of the subducting Philippine Sea plate is located at a depth of about 18 km with a dip angle of approximately 12 degrees. The top of the subducting plate can be traced to a depth of about 35 km. The island arc Moho is about 33 km deep beneath northeastern Shikoku Island and the crustal thickness is thinning toward the north.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 0905 Continental structures (8109, 8110)
DE: 7205 Continental crust (1242)
DE: 8150 Plate boundary--general (3040)
DE: 9320 Asia
SC: Seismology [S]
MN: 2003 Fall Meeting