CAREER: Bridging Earthquakes and Earth Structure along the Northern San Andreas Fault

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This research will illuminate how deformation adjacent to the northern San Andreas Fault Zone that is sustained during earthquakes produces, over thousands to millions of years, the mountains and geologic structures that are observed along the plate boundary. Theproject will use high resolution GeoEarthScope Airborne Laser Swath Mapping and more broadly available lower resolution topography, the abundance of cosmogenic isotopes in river sands, low-temperature thermochronometry, and numerical models of crustal deformation to link earthquake-cycle and geologically-observed deformation. The key hypotheses to be tested include: 1) While elastic and viscoelastic constitutive rules appear to well-characterize deformation during and following earthquakes, frictional failure and fatigue of crustal materials that ignored by these constitutive rules are principal contributors to the pattern of permanent deformation observed over tens of thousands to several million years; 2) Differential yielding of crustal blocks leads to large variations in deformation that accrues over thousands to millions of years; and 3) Spatial variations in the geometry of the San Andreas Fault Zone dominate the observed off-fault deformation, and result from long-term changes in plate tectonic motions and the initial configuration of geologic terranes with different constitutive properties. The results of this research will help to link the deformation observed over human time-scales to that observed in the geologic record. Additionally, the research in this proposal will serve as a springboard for improving undergraduate education, fostering graduate student and postdoctoral education and career development, providing hands-on research experience to local high-school students, training local high-school teachers to introduce students to earth sciences in the field, and constructing a real and virtual educational driving tour through the Santa Cruz Mountains that teaches the general public about the landscapes produced by plate-boundary deformation over thousands to millions of years.