HR: 09:05h
AN: T31A-05 INVITED     [Abstracts]
TI: Interseismic plate coupling, seismic rupture, and postseismic slip at the 2003 Tokachi-oki segment of Kuril Trench
AU: * Miyazaki, S
EM: miyazaki@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Segall, P
EM: segall@pangea.stanford.edu
AF: Stanford Univerisity, 397 Panama Mall, Stanford, CA 94305, United States
AU: Johnson, K M
EM: kajjohns@indiana.edu
AF: Indiana University, 1001 E. 10th St., Bloomington, IN 47405, United States
AU: Larson, K M
EM: kristinem.larson@gmail.com
AF: University of Colorado, Aerospace ECOT 634 CB 429, Boulder, CO 80309, United States
AU: McGuire, J J
EM: jmcguire@whoi.edu
AF: Woods Hole Oceanographic Institution, Woods Hole, Woods Hole, MA 02543, United States
AU: Choi, K
EM: choik@colorado.edu
AF: University of Colorado, Aerospace ECOT 634 CB 429, Boulder, CO 80309, United States
AU: Fukuda, J
EM: jfukuda@indiana.edu
AF: Indiana University, 1001 E. 10th St., Bloomington, IN 47405, United States
AU: Hori, T
EM: horit@jamstec.go.jp
AF: JAMSTEC, Showa-cho 3173-25, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AU: Baba, T
EM: babat@jamstec.go.jp
AF: JAMSTEC, Showa-cho 3173-25, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AB: We investigate interseismic plate coupling, the 2003 Tokachi-oki rupture and its afterslip using Japanese nationwide GPS network. The 2003 Tokachi-oki earthquake (M ~ 8) occurred at the western end of the Kuril Trench on September 25, 2003 (UT). We processed 1-Hz GPS for this earthquake, and inverted GPS displacement waveform to infer the coseismic slip distribution. Then we used daily GPS time series after the quake to infer the space-time distribution of the afterslip following this earthquake. We found that the high-speed rupture and afterslip are not overlapping, and this result support the idea that the frictional property of the plate boundary is significantly different between those two regions. Because we have cumulative slip at every epoch, we are able to calculate shear stress change using dislocation theory. We investigated the slip velocity dependence of the shear stress change, and found that the frictional property of the afterslip area would be steady-state velocity strengthening. On the other hand, it is widely believed that high speed rupture occurs at the steady-state velocity weakening region. Hence we suggest that the spatial inhomogeneity of the frictional properties caused the difference between slip styles in rupture region and afterslip reagion. Interseismic coupling inferred from GPS data also support this hypothesis.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1209 Tectonic deformation (6924)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8123 Dynamics: seismotectonics
SC: Tectonophysics [T]
MN: 2007 Joint Assembly