Western U.S. deformation models for the 2023 update to the U.S. National Seismic Hazard Model

Seismological Research Letters
By: , and 

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Abstract

This report describes geodetic and geologic information used to constrain deformation models of the 2023 update to the National Seismic Hazard Model (NSHM), a set of deformation models to interpret these data, and their implications for earthquake rates in the western United States. Recent updates provide a much larger data set of Global Positioning System crustal velocities than used in the 2014 NSHM, as well as hundreds of new faults considered as active sources for the 2023 NSHM. These data are interpreted by four geodetic models of deformation that estimate fault slip rates and their uncertainties together with off‐fault moment release rates. Key innovations in the 2023 NSHM relative to past practice include (1) the addition of two new (in addition to two existing) deformation models, (2) the revision and expansion of the geologic slip rate database, (3) accounting for fault creep through development of a creep‐rate model that is employed by the four deformation models, and (4) accounting for time‐dependent earthquake‐cycle effects through development of viscoelastic models of the earthquake cycle along the San Andreas fault and the Cascadia subduction zone. The effort includes development of a geologic deformation model that complements the four geodetic models. The current deformation models provide a new assessment of outstanding discrepancies between geologic and geodetic slip rates, at the same time highlighting the need for both geologic and geodetic slip rates to robustly inform the earthquake rate model.

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Publication type Article
Publication Subtype Journal Article
Title Western U.S. deformation models for the 2023 update to the U.S. National Seismic Hazard Model
Series title Seismological Research Letters
DOI 10.1785/0220220143
Volume 93
Issue 6
Year Published 2022
Language English
Publisher Seismological Society of America
Contributing office(s) Earthquake Science Center, Geologic Hazards Science Center
Description 19 p.
First page 3068
Last page 3086
Country United States
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