Ground-motion characterization for the 2025 U.S. National Seismic Hazard Model for Puerto Rico and the U.S. Virgin Islands

Earthquake Spectra
By: , and 

Metrics

Cited by publications in Crossref
Web analytics dashboard Metrics definitions

Links

Abstract

We develop the ground-motion characterization (GMC) for the 2025 U.S. National Seismic Hazard Model for Puerto Rico and the U.S. Virgin Islands (NSHM-PRVI) for earthquakes in active crustal, subduction interface, and subduction intraslab regimes. Using ground-motion models (GMMs) from the Next-Generation Attenuation (NGA)-West2 and NGA-Subduction projects, the GMC is parameterized by scaled-backbone models for median ground motions and by independent logic trees of aleatory variability. We introduce several novel GMC features into the U.S. NSHM: (1) use of regional ground-motion data for modeling median ground motions; (2) development of scaled-backbone models for median ground motions; and (3) development of independent logic trees of aleatory variability from variance components of GMMs and computed from multiple ground-motion datasets, and incorporating regional ground-motion data effects on variability. We compute probabilistic seismic hazard curves and maps to evaluate the contributions from the GMC components and for comparison with the 2003 GMC. Contributions of the GMC to epistemic uncertainty in seismic hazard are evaluated through spatial variations in epistemic uncertainty in hazard maps, comparisons between mean hazard curves and fractiles, as well as investigations of the contributions of logic-tree branches to hazard maps and curves. Comparisons between seismic hazard from the 2025 and 2003 GMCs allow examination of the changes in hazard curves and mapped values with 2% and 10% probabilities of exceedance in 50 years. The 2025 GMC exhibits modest changes in median predictions, relative to the 2003 GMC; overall, values of aleatory variability are higher, except at long periods (mathematical equation), resulting in changes to probabilistic ground motions at low probabilities of exceedance (<10% probability of exceedance in 50 years). Changes in hazard at 2% and 10% probabilities of exceedance in 50 years are also relatively modest (within 20%) at most sites, with the impacts from the 2025 GMC exhibiting minor reductions and increases at 0.2 and 1.0 s periods, respectively, relative to the 2003 GMC.

Suggested Citation

Moschetti, M.P., Aagaard, B.T., Withers, K.B., Milner, K., Altekruse, J.M., Herrick, J.A., Powers, P.M., Rezaeian, S., Shumway, A.M., and Stephenson, W.J., 2026, Ground-motion characterization for the 2025 U.S. National Seismic Hazard Model for Puerto Rico and the U.S. Virgin Islands: Earthquake Spectra, v. 42, no. 2, e70026, 26 p., https://doi.org/10.1002/esp4.70026.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Ground-motion characterization for the 2025 U.S. National Seismic Hazard Model for Puerto Rico and the U.S. Virgin Islands
Series title Earthquake Spectra
DOI 10.1002/esp4.70026
Volume 42
Issue 2
Publication Date April 16, 2026
Year Published 2026
Language English
Publisher Wiley
Contributing office(s) Geologic Hazards Science Center - Seismology / Geomagnetism
Description e70026, 26 p.
Country United States
Other Geospatial Puerto Rico, U.S. Virgin Islands
Additional publication details