Attenuation Tomography of the San Andreas Fault Near Parkfield, CA
Abstract
P and S wave spectra from about 400 local earthquakes recorded by the Parkfield Area Seismic Observatory (PASO) network were used to determine spatial variations in seismic attenuation (1/Q) in the region around the San Andreas Fault near Parkfield, CA. Starting with wave speed images derived from arrival time tomography using the same data set, we adapted the finite difference algorithm of Hole and Zelt (1995) to the attenuation tomography algorithm of Shotterbeck and Abers (2002) to account for severe ray bending effects in a medium with strong lateral variations in structure. Results thus far show high attenuation within the heterogeneous Franciscan rocks east of the fault and low attenuation in the Gabilan granites to the west. The fault zone itself is characterized by a region of exceptionally low Q.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.T21A1057G
- Keywords:
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- 7203 Body wave propagation;
- 7205 Continental crust (1242);
- 7230 Seismicity and seismotectonics;
- 8110 Continental tectonics: general (0905)