The 2023 update to the National Seismic Hazard (NSHM) model is informed by several deformation models that furnish geodetically estimated fault slip rates. Here I describe a fault-based model that permits estimation of long-term slip rates on discrete faults and the distribution of off-fault moment release. It is based on quantification of the earthquake cycle on a viscoelastic model of the seismogenic upper crust and ductile lower crust and mantle. I apply it to a large dataset of horizontal and vertical Global Positioning System (GPS) interseismic velocities in the western United States, resulting in long-term slip rates on more than 1000 active faults defined for the NSHM. A reasonable fit to the GPS dataset is achieved with a set of slip rates designed to lie strictly within a priori geologic slip rate bounds. Time-dependent effects implemented via a “ghost transient” have a profound effect on slip rate estimation and tend to raise calculated slip rates along the northern and southern San Andreas fault by up to several mm/yr.
CITATION STYLE
Pollitz, F. F. (2022). Viscoelastic Fault-Based Model of Crustal Deformation for the 2023 Update to the U.S. National Seismic Hazard Model. Seismological Research Letters, 93(6), 3087–3099. https://doi.org/10.1785/0220220137
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