HR: 0800h
AN: T51C-0685    [Abstracts]
TI: San Jacinto Fault Zone Structure from Body Waveforms of Local Earthquakes
AU: * Yang, H
EM: hyang4@eas.slu.edu
AF: Department of Earth and Atmospheric Sciences, Saint Louis University, 3642 Lindell Blvd., Saint Louis, MO 63108,
AU: Zhu, L
EM: lupei@eas.slu.edu
AF: Department of Earth and Atmospheric Sciences, Saint Louis University, 3642 Lindell Blvd., Saint Louis, MO 63108,
AB: We developed a new method to determine the fine structure of fault zone (FZ) usi ng direct and FZ-reflected waves from local earthquakes. Characteristic patterns of P and S-wave arrival times across a FZ allow us to determine its boundaries. Other FZ parameters (velocity drops, strike, and dip) are determined by a least-squares inversion of the arrival times. Effects of uncertainties of event locations are also considered. This method greatly reduces the trade-off between the FZ width and velocities. In this study, we used high-frequency body waves recorded by a temporary array deployed in 1999 across the San Jacinto fault. Synthetic seismograms are computed by generalized ray theory based on the newly developed technique. Preliminary results show that the low-velocity fault zone has a width around 350 m and a 50% reduction in P and S-wave velocities compared to the host rock.
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1219)
DE: 7250 Transform faults
DE: 8100 TECTONOPHYSICS
DE: 8111 Continental tectonics: strike-slip and transform
SC: Tectonophysics [T]
MN: 2007 Fall Meeting