2025 Puerto Rico and U.S. Virgin Islands Long-term National Seismic Hazard Model

Summary

The U.S. Geological Survey has updated the National Seismic Hazard Model (NSHM) for Puerto Rico and the U.S. Virgin Islands (PRVI). The first version of the PRVI NSHM was released in 2003, and therefore this 2025 update includes over 20 years of new geologic, geophysical, and engineering data, methods, and models. Updates follow similar efforts performed in the recent 2023 50-state NSHM. However, this is the first NSHM in which we 
(1) apply an inversion methodology to subduction interface fault sources in the earthquake rupture forecast (ERF) model; 
(2) develop scaled backbone median ground-motion models and independent aleatory variability models that are applied in the ground-motion characterization (GMC) model; 
and (3) calculate epistemic uncertainty related to alternative scenarios in the ERF and GMC models for all grid points in the study region. 

Long-term time-independent mean hazard calculations were performed for peak ground acceleration and 5%-damped pseudo-spectral acceleration at 21 spectral periods from 0.01- to 10.0-s, for eight National Earthquake Hazards Reduction Program site conditions ranging from V_S30 = 150 to 1500 m/s, and for 2%, 5%, and 10% in 50-year probabilities of exceedance (return periods of 2475, 975, and 475 years, respectively). Epistemic uncertainty, in the form of selected percentiles, is also provided for a suite of test sites and all grid points in the study region for limited periods, site conditions, and probabilities of exceedance. The 2025 PRVI NSHM is applicable for return periods greater than ~475 or less than ~10,000 years.
 

Overview Documentation, Data, and Software

2025 USGS NATIONAL SEISMIC HAZARD MODEL PUERTO RICO & THE U.S. VIRGIN ISLANDS: Media Guide (summary and highlights)

Supporting Documentation:
(Input data, models, and methods)

Review Process Documentation