HR: 11:50h
AN: S42B-07    [Abstracts]
TI: The rupture process of the 2003 Tokachi-Oki earthquake using 1-Hz GPS data and its afterslip history inferred from GPS data.
AU: * Miyazaki, S
EM: miyazaki@eri.u-tokyo.ac.jp
AF: Stanford University, 397 Panama Mall, Stanford, CA 94305 United States
AU: * Miyazaki, S
EM: miyazaki@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Larson, K M
EM: Kristine.Larson@Colorado.edu
AF: University of Colorado, Aerospace ECOT 634 CB 429, Boulder, CO 80309-0429 United States
AU: Choi, K
EM: choik@colorado.edu
AF: University of Colorado, Aerospace ECOT 634 CB 429, Boulder, CO 80309-0429 United States
AU: Segall, P
EM: segall@pangea.stanford.edu
AF: Stanford University, 397 Panama Mall, Stanford, CA 94305 United States
AU: Hikima, K
EM: hikima@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Koketsu, K
EM: koketsu@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Bodin, P
EM: pbodin@memphis.edu
AF: University of Memphis, University of Memphis, Memphis, TN 38112 United States
AU: Haase, J
EM: jhaase@purdue.edu
AF: Purdue University, Purdue University, West Lafayette, IN 47907-1397 United States
AU: Gordon, E
EM: gemore@purdue.edu
AF: Purdue University, Purdue University, West Lafayette, IN 47907-1397 United States
AU: Fukuda, J
EM: fukuda@eri.u-tokyo.ac.jp
AF: Stanford University, 397 Panama Mall, Stanford, CA 94305 United States
AU: Kato, T
EM: teru@eri.u-tokyo.ac.jp
AF: Stanford University, 397 Panama Mall, Stanford, CA 94305 United States
AU: Yamagiwa, A
EM: yamagiwa@gsi.go.jp
AF: Geographical Survey Institute, Kitasato-1, Tsukuba, Ibaraki, 305-0811 Japan
AB: We analyzed GPS data to infer the rupture process of and afterslip distribution following the 2003 Tokachi-Oki earthquake. Firstly, we processed 1-Hz GPS data with kinematic GPS analysis [Larson et al., 2003] for 90 minutes (approximately 45 minutes before and after the quake) to obtain the displacement waveform. Then we inverted those waveform to infer the rupture process of the main shock using multi time window inversion method. We use the Freq-Wavenumber (FK) codes developed by Zhu and Rivera [2003] to calculate the green's function. We find the slip is not significant in the epicenter. The rupture propagated downdip, and maximum slip as large as $\sim$ 9 m is found $\sim$ 50 km downdip. This result is consistent with those inferred from teleseismic and strong motion inversions. Secondly, we processed postseismic daily GPS data with precise point positioning, and inverted the time series with the Network Inversion Filter [Segall and Matthews, 1997]. It is notable that afterslip is absent in the area where the complementary spatial pattern of coseismic rupture and afterslip may indicate along strike spatial variations of frictional properties, although other interpretations can not be ruled out. We calculated shear stress change due to afterslip in the direction of plate convergence. The stress change follows a quasi-linear trend with log of slip-rate, suggestive of a decay back to steady-state slip on a velocity strengthening fault.
DE: 7209 Earthquake dynamics and mechanics
DE: 7212 Earthquake ground motions and engineering
DE: 1204 Control surveys
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
SC: Seismology [S]
MN: 2004 AGU Fall Meeting