HR: 0800h
AN: S51A-09    [Abstracts]
TI: Finite-Fault Analysis Using Regional Broadband Waveforms: The 2004 Parkfield, California Earthquake
AU: * Mendoza, C
EM: cmendoza@geociencias.unam.mx
AF: UNAM, Centro de Geociencias, Queretaro, Qro , Mexico
AU: Hartzell, S
EM: shartzell@usgs.gov
AF: USGS, Box 25046, MS966, Denver, CO 80225, United States
AB: Global improvements in seismic-station coverage and data quality have resulted in the increased use of broadband waveforms in finite-fault studies of the earthquake source. These improvements have also prompted the use of regional waveforms in rapid or real-time derivations of the earthquake rupture history. We examine the applicability of regional records to identify the properties of an extended source by conducting a finite-fault analysis of the Mw 6.0 Parkfield, California, earthquake of 28 September 2004. This earthquake was recorded by more than 80 broadband stations at distances less than 5 degrees from the epicenter. We invert three- component displacement waveforms recorded at the 14 stations located within 2 degrees of the epicenter using a general Northern California crustal structure and a bandpass filter with corners of 0.2 and 1.0 Hz. The resulting rupture model shows coseismic slip extending primarily to the northwest with a peak slip of 60 centimeters at a distance of about 15 km from the hypocenter. This model is compared against results obtained using strong motion and geodetic data. We also examine the use of waveforms recorded at more distant sites by comparing them against synthetic waveforms predicted by the inferred slip model and conduct several tests using different stations at differing azimuths to evaluate the effects of station distribution on the finite-fault results. These tests are useful for assessing the limitations of finite-fault inversion schemes in the routine derivation of the earthquake rupture history using real-time regional waveform data.
DE: 7203 Body waves
DE: 7209 Earthquake dynamics (1242)
DE: 7215 Earthquake source observations (1240)
SC: Seismology [S]
MN: 2007 Joint Assembly