HR: 0830h
AN: T11D-0427    [PDF]
TI: Implications of Microseismicity and Earthquake-Induced Transient Fault Creep for the Earthquake Potential on the Hayward Fault, Eastern San Francisco Bay Area
AU: * Gans, C R
EM: cgans@geodyn.psu.edu
AF: Pennsylvania State University, 542 Deike Building, University Park, PA 16802 United States
AU: Furlong, K P
EM: kevin@geodyn.psu.edu
AF: Pennsylvania State University, 542 Deike Building, University Park, PA 16802 United States
AU: Malservisi, R
EM: rmalservisi@mail.rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Science, Geodesy Lab 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AB: The Hayward fault is considered to be one of the primary hazards in the San Francisco Bay region. Although it is documented to undergo significant creep, with some creeping patches accommodating 50% or more of the long-term fault displacement, the fault also experiences moderate to large earthquakes (most recent M $\sim$6.8 in 1868). In order to link seismic potential to the rate at which moment accumulates on the fault plane, we need to understand the patterns and distribution of creep over time. As might be expected, the microseismicity observed on the fault produces only a negligible percentage of the seismic moment dissipated on the Hayward fault, whereas aseismic creep releases about 25% of the moment accumulating on the fault. It is also important to understand how the distribution of creep on the fault can change throughout the earthquake cycle, in particular after major seismic events. Although our creep models do a good job of representing the observed surface creep, they have not previously incorporated the effects of transient post-seismic strain recovery, which can have significant effects on creep rate. We test the temporal variation from "steady-state" creep models by incorporating an 1868-type earthquake in our model to observe changes in creep distributions and recovery rates throughout the fault plane. Both the distribution and magnitude of creep on the fault vary substantially after the simulated earthquake. Although at present the post-seismic transients have mostly decayed, the pattern of accumulated moment is significantly different when these transients are included.
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 8107 Continental neotectonics
DE: 8150 Plate boundary--general (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting