HR: 1400h
AN: S43A-02    [Abstracts]
TI: Slip-Weakening Distance Estimated from Near-Fault Stations
AU: * Fukuyama, E
EM: fuku@bosai.go.jp
AF: NIED, Tennno-dai 3-1, Tsukuba, 305-0006, Japan
AU: Mikumo, T
EM: mikumo@maia.eonet.ne.jp
AF: UNAM, Ciudad Universitaria, Mexico, 04510, Mexico
AB: We estimate the slip-weakening distance directly from the seismograms recorded at near-fault stations, taking into account its estimation error. To do this, probable spatio-temporal smoothing effects during continuous rupture propagation on the fault are evaluated through numerical modeling. For this purpose, we use a 2-D in- plane shear crack propagating with a constant rupture velocity and with a Yoffe-type source time function, which is a kinematically good approximation of dynamic slip weakening behavior. From this modeling, the displacement and velocity waveforms expected at short distances away from the fault are calculated. As a proxy of a real slip- weakening distance Dc, Dcf, which is defined as a slip at the time of peak slip velocity, can be calculated as a function of distance from the fault. This technique is applied to the observed records from the 2000 western Tottori, Japan, earthquake (Mw6.6) and also from the 2002 Denali, Alaska, earthquake (Mw7.9), both of which are mainly strike-slip events. We estimated Dcf at GSH station (~100 m away from the fault) as about 0.3 m for the Tottori earthquake, and that at PS10 station (~3 km from the fault) as about 2.5 m for the Denali earthquake, within a possible error of about 30 %. We confirmed that these estimates are not much affected by the spatio-temporal smoothing effects.
DE: 3200 MATHEMATICAL GEOPHYSICS (0500, 4400, 7833)
DE: 7209 Earthquake dynamics (1242)
DE: 7215 Earthquake source observations (1240)
SC: Seismology [S]
MN: 2007 Joint Assembly