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SCEC2023 Plenary Talk, San Andreas Fault System (SAFS)

How expanding SCEC and starting CRESCENT will accelerate our understanding of faulting and related hazards

Ray J. Weldon

Oral Presentation

2023 SCEC Annual Meeting, SCEC Contribution #12857
Our knowledge of fault behavior and particularly its application to seismic hazards has been driven by the study of active faults in Southern California and the Basin and Range. While these regions provide tremendous insight they don’t capture the full range of fault behavior or provide enough examples to span the full range of possible ruptures to constrain our hazard forecast models. Expanding SCEC and establishing a SCEC-like initiative in the Pacific Northwest will expand study of creeping faults, volcano-tectonic faults, distributed faulting both within isolated fault zones and proximal to major boundaries like the subvertical SAF and shallowly-dipping Cascadia forearc wedge. It will help eliminate artificial regional and State boundaries in our current representation of faults and hazards, provide more examples of interseismic and postseismic transients associated with creep, viscoelastic response, fault/earthquake interaction and nontectonic transients including hydrology and postglacial rebound. These initiatives will shift research from narrowly-focused single PI projects to more collaborative research including a broader community, including the usual University and Federal activity with greater State, Industry, and International participation (there’s only 1 SAF in California and 1 subduction zone in the Pacific Northwest but dozens of analogues globally!). It will increase interaction between geology, seismology and geodesy, and broaden training and outreach. To illustrate these points, I’ll present recommendations developed in the recent update of the National Seismic Hazard Model, including how to better integrate geology, seismology and geodesy, and I’ll present examples of variable fault behavior from the Western US and the 12 International field schools I’ve taught on active faults.