Kinematics and Dynamics of the Southern San Andreas Fault System
Abstract
We use geodetic data in the Salton Trough region of southern California to constrain elastic and viscoelastic finite element modeling of San Jacinto and San Andreas fault slip rates and the effects of heterogeneous upper crustal elastic and lower crustal viscous rheology. Results suggest that the San Andreas is the dominant plate-boundary fault, the effects of the sediment-filled Salton Trough on regional crustal deformation is minimal and the lower crust must be fairly strong (~> 5e19 Pa-s) to maintain the high strain gradient near the San Andreas fault. This high strength lower crust couples upper crustal deformation to motion of the lithospheric mantle, and together with shear stress transmitted laterally across faults drives mountain building, basin formation and the generation of earthquakes. Analysis of the force budget acting on the Salton block suggests tectonic shear stress on major faults in the San Andreas system are ~30-60 MPa at 15 km, larger than earthquake stress drops but lower than that predicted by laboratory experiments.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSM.G21A..03F
- Keywords:
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- 1236 Rheology of the lithosphere and mantle (8160);
- 1242 Seismic deformations (7205);
- 8110 Continental tectonics: general (0905);
- 8120 Dynamics of lithosphere and mantle: general