Skip to main content
U.S. flag

An official website of the United States government

The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States

February 29, 2024

We update the ground-motion characterization for the 2023 National Seismic Hazard Model (NSHM) for the conterminous United States. The update includes the use of new ground-motion models (GMMs) in the Cascadia subduction zone; an adjustment to the central and eastern United States (CEUS) GMMs to reduce misfits with observed data; an updated boundary for the application of GMMs for shallow, crustal earthquakes in active tectonic regions (i.e. western United States (WUS)) and stable continental regions (i.e. CEUS); and the use of improved models for the site response of deep sedimentary basins in the WUS and CEUS. Site response updates include basin models for the California Great Valley and for the Portland and Tualatin basins, Oregon, as well as long-period basin effects from three-dimensional simulations in the Greater Los Angeles region and in the Seattle basin; in the CEUS, we introduce a broadband (0.01- to 10-s period) amplification model for the effects of the passive-margin basins of the Atlantic and Gulf Coastal Plains. In addition, we summarize progress on implementing rupture directivity models into seismic hazard models, although they are not incorporated in the 2023 NSHM. We implement the ground-motion characterization for the 2023 NSHM in the US Geological Survey’s code for probabilistic seismic hazard analysis, nshmp-haz-v2, and present the sensitivity of hazard to these changes. Hazard calculations indicate widespread effects from adjustments to the CEUS GMMs, from the incorporation of Coastal Plain amplification effects, and from the treatment of shallow-basin and out-of-basin sites in the San Francisco Bay Area and Los Angeles region, as well as locally important changes from subduction-zone GMMs, and from updated and new WUS basins.

Publication Year 2024
Title The 2023 US National Seismic Hazard Model: Ground-motion characterization for the conterminous United States
DOI 10.1177/87552930231223995
Authors Morgan P. Moschetti, Brad T. Aagaard, Sean Kamran Ahdi, Jason M. Altekruse, Oliver S. Boyd, Arthur Frankel, Julie Herrick, Mark D. Petersen, Peter M. Powers, Sanaz Rezaeian, Allison Shumway, James Andrew Smith, William J. Stephenson, Eric M. Thompson, Kyle Withers
Publication Type Article
Publication Subtype Journal Article
Series Title Earthquake Spectra
Index ID 70263570
Record Source USGS Publications Warehouse
USGS Organization Geologic Hazards Science Center - Seismology / Geomagnetism
Was this page helpful?