Geometrical impact of the San Andreas Fault on stress and seismicity in California


Qingsong Li and Mian Liu


Department of Geological Sciences, University of Missouri, Columbia, Missouri, USA.


Most large earthquakes in northern and central California clustered along the main trace of the San Andreas Fault (SAF), the North American-Pacific plate boundary. However, in southern California earthquakes were rather scattered. Here we suggest that such along strike variation of seismicity may largely reflect the geometrical impact of the SAF. Using a dynamic finite element model that includes the first-order geometric features of the SAF, we show that strain partitioning and crustal deformation in California are closely related to the geometry of the SAF. In particular, the Big Bend is shown to reduce slip rate on southern SAF and cause high shear stress and strain energy over a broad region in southern California, and a belt of high strain energy in the Eastern California Shear Zone.