Slip Rates on the Southern San Andreas Fault: Implications for Neotectonic, Seismic and Geodetic Models

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The PI proposes to determine the slip rate of the San Andreas Fault at several sites in southern California using 10Be and 26Al measurements of the exposure ages of offset geomorphic surfaces. Determination of a millennial slip rate north of Los Angeles, on the flank of the Mojave Desert, would provide a critical constraint to the interpretation of geodetic data there. Rates of slip across the fault on each side of the San Gorgonio Pass stepover would constrain the relative importance of the several strands of the fault in that region. Within the complex restraining stepover, rates and dates of fault slip and folding would test a new model of transpressional deformation. They would do this by constraining the evolution of deformation there throughout the late Quaternary period. A quantitative understanding of active deformation would also provide a basis for forward models of future large earthquakes involving this ominously historically dormant section of the San Andreas Fault.