HR: 1340h
AN: G13A-0917    [Abstracts]
TI: Measurements of Early Afterslip using 30-sec GPS data: the Tokachi-Oki Earthquake
AU: * Miyazaki, S
EM: miyazaki@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, Tokyo, 113-0032, Japan
AU: Larson, K M
EM: kristinem.larson@gmail.com
AF: University of Colorado, UCB 429, Boulder, CO 80309, United States
AB: Thirty-second GPS are are used to infer the early phase of afterslip following the 2003 Tokachi-oki earthquake. GPS data from the GEONET network were analyzed using GIPSY-OASIS and standard models. No constraints are put on the position estimates, so the the 30-second data sense both the static offset of the mainshock, large aftershock, and postseismic deformation. The GPS time series at this stage of processing contain significant common-mode errors. The time-dependent inversion method [Segall and Matthews, 1997] is then employed to infer the space-time evolution of afterslip. Common-mode errors are simultaneously estimated with fault slip, thus significantly improving the resolution of the 30-second GPS positions. This analysis concentrates on two periods (i) between the main shock and the largest aftershock and (ii) 24 hours after the largest aftershock. The inferred slip for period (i) is significant in the southwest side of the main rupture region. The slip pattern is similar in the begining of period (ii), but the slip starts to propagate to the northeast. In contrast, afterslip in the first 30 days was marked both in the southwest and northeast sides of the rupture zone [Miyazaki et al., 2004]. Such a difference in the triggered slip time may be a manifestation of the spatial heterogenity in frictional properties.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
SC: Geodesy [G]
MN: 2007 Fall Meeting