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San Andreas Fault System Normal Stress
Normal stress due to both fault motion (calculated at 1/2 locking depth for each fault segment) and California topography (isostatically compensated, cacluated at 6 km) are displayed here. At seismogenic depths, deviatoric normal stress along the San Andreas system varies from 5 MPa of compression in low-lying areas, to 12 MPa of extension in the Transverse Ranges of the Big Bend area. Because the method of faulting through the Big Bend area is primarily strike-slip, either the deviatoric horizontal shear stres must exceed 12 MPa, or there must be an equal and opposite tectonically-induced normal stress. Preliminary results suggest that 350-800 years are required to achieve a balance of normal stresss along the San Andreas Fault system. These results are approximately 3 times longer than typical earthquake recurrence intervals, suggesting that earthquakes relieve only 1/3 of the total deviatoric shear stress.
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| Normal Tectonic Stress |
Normal Stress due to Topography |
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