HR: 09:30h
AN: S31C-07    [Abstracts]
TI: A plan of continuous monitoring of seismic signature at the top of the subducting Philippine Sea Plate using the ACROSS active monitoring method
AU: * Kasahara, J
EM: kasahara.junzo@jnc.go.jp
AF: Tono Geoscience Center, JNC, 1-63 Yamanouchi, Akeyocho, Mizunami, Gifu, 509-6132 Japan
AU: Tsuruga, K
EM: tsuru@tono.jnc.go.jp
AF: Tono Geoscience Center, JNC, 1-63 Yamanouchi, Akeyocho, Mizunami, Gifu, 509-6132 Japan
AU: Hasada, Y
EM: hasada@tono.jnc.go.jp
AF: Tono Geoscience Center, JNC, 1-63 Yamanouchi, Akeyocho, Mizunami, Gifu, 509-6132 Japan
AU: Yamaoka, K
EM: yamaoka@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1 Bunkyo, Tokyo, 113-0032 Japan
AU: Kunitomo, T
EM: kunitomo@tono.jnc.go.jp
AF: Tono Geoscience Center, JNC, 1-63 Yamanouchi, Akeyocho, Mizunami, Gifu, 509-6132 Japan
AU: Watanabe, T
EM: watanabe@seis.nagoya-u.ac.jp
AF: Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602 Japan
AU: Fujii, N
EM: fujii@seis.nagoya-u.ac.jp
AF: Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602 Japan
AU: Yoshida, Y
EM: yyoshida@mri-jma.go.jp
AF: Meteorological Research Institute, JMA, 1-1 Nagamine, Tsukuba, Ibaraki, 305-0052 Japan
AU: Kumazawa, M
EM: mkz@tono.jnc.go.jp
AF: Tono Geoscience Center, JNC, 1-63 Yamanouchi, Akeyocho, Mizunami, Gifu, 509-6132 Japan
AB: Recently, a very strong reflected PP phase from the subducting plate boundary was found beneath the aseismic forearc slope of the Japan Trench (Fujie et al., 2003, Kasahara et al., 2003). This strong PP reflection is interpreted as a reflection from the non-asperity region along the plate boundary caused by the presence of low-Vp material. Similar strong PP reflection phase was observed near the plate boundary of the subducting Philippine Sea Plate and the Eurasian Plate, in the western part of Shizuoka Prefecture along the NS seismic survey line across the central part of Japan using explosive sources (Iidaka et al., 2003, Kodaira et al., 2004). This region is match to the aseismic slip zone since 2000 observed by GPS (Ozawa et al., 2002). This region is supposed to the lower edge of future Tokai or Tonankai earthquake along the Nankai Trough. The "ACROSS" (Accurately Controlled and Routinely Operated Signal System) (Kunitomo and Kumazawa, 2004) can continuously transmit accurately-controlled seismic waves in amplitude, frequency and phase. Using continuous transmission of seismic waves from the ACROSS source located in Toki City, Japan and /or the new ACROSS source under planning in the western part of Shizuoka Prefecture and the high sensitivity seismometers along the NS traverse line, we can delineate the temporal variation of seismic wave properties of the anomalously reflected PP phase along the boundary of subducting Philippine Sea Plate. This observation can give information on variation of the physical state of frictional slip and clues for the earthquake generation. It is also very useful for the monitoring of precursory slip and/or after-slip of the future Tokai and Tonankai earthquakes (or any large earthquakes) with sources along the Philippine Sea Plate.
DE: 7200 SEISMOLOGY
DE: 7218 Lithosphere and upper mantle
SC: Seismology [S]
MN: 2004 AGU Fall Meeting