San Andreas Fault Geometry through the San Gorgonio Pass, California

Laura Dair, & Michele L. Cooke

Published 2009, SCEC Contribution #1160

Three-dimensional numerical models are needed to investigate the role of non-vertical strike-slip fault segments on the deformation within restraining bends.. Numerical models simulate geologic deformation of two alternative three-dimensional present-day configurations for the San Andreas Fault (SAF) through the restraining bend within the San Gorgonio Pass region (SGPR) in southern California. Both models produce decreasing strike-slip rates southward along the San Bernardino strand of the SAF similar to geologic data. The north-dipping SAF model better matches the available strike-slip data as well as the geologic uplift data for the southern San Bernardino Mountains than the vertical SAF model. We conclude that a north-dipping fault configuration is preferred for the SAF in the SGPR. The complexity of the active fault geometry at the SGPR promotes the transfer of strike-slip from the SAF, to the nearby but unconnected San Jacinto fault. Slip rates and uplift patterns are sensitive to fault geometry within strike-slip restraining bends

Dair, L., & Cooke, M. L. (2009). San Andreas Fault Geometry through the San Gorgonio Pass, California. Geology, 37(2), 119-122. doi: 10.1130/G25101A.1.