HR: 08:00h
AN: G31A-01 INVITED     [Abstracts]
TI: Transient slip episode in central and southwest Japan.
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: McGuire, J J
EM: jmcguire@whoi.edu
AF: Woods Hole Oceanographic Institution, Woods Hole, Woods Hole, MA 02543, United States
AU: Kato, T
EM: teru@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032, Japan
AU: Hatanaka, Y
EM: hata@gsi.go.jp
AF: Geographical Survey Institute, Kitasato-1, Tsukuba, Ibaraki, 305-0811, Japan
AB: We have studied transient slip episodes in central and southwest Japan, where the Philippine Sea plate is subducting at the annual rate of ~ 6.5cm/yr. A slow thrust slip event occurred in Bungo Channel, in southwest Japan, and anomalous displacements were found in at multiple GPS time series for stations in Shikoku and Kyushu islands. We analyzed those GPS data with time-dependent inversion method, and found that the slip initiated at a deeper part (~ 40km) of the plate boundary. The acceleration and following decelelation took longer than one year. The second event is the 2000 Tokai slow slip event, which initialed in early 2000. We also applied the same time-dependent inversion method to infer the space-time distribution of slip and slip-rate at the plate boundary. The slip initiated at the deeper part of the plate boundary (~ 40km), and migrated upward to the depth of ~ 30km. This event lasted for longer than 5 years. Having cumulative slip at each epoch, we are able to calculate shear stress change with dislocation theory. We examined velocity-dependence of the shear stress change to compare with a numerical simulation based on rate-state friction. The observed stress-velocity path is similar to what obtained for high-speed rupture, suggesting that slow slip events occurred in velocity weakening friction. This makes a clear contrast to what we obtained for the afterslip for the 2003 Tokachi-oki earthquake.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2007 Joint Assembly