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The U.S. Geological Survey 2025 National Seismic Hazard Model for Puerto Rico and the U.S. Virgin Islands

The U.S. Geological Survey recently 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 updated 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 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-years probabilities of exceedance (return periods of 2475, 975, and 475 years, respectively). Epistemic uncertainty, in the form of selected percentiles, were also calculated for a suite of test sites and all grid points in the study region for limited periods, site conditions, and probabilities of exceedance. Selected results, including comparisons with the 2003 PRVI NSHM, will be shown and discussed for selected periods, site conditions, and probabilities of exceedance. When comparing the 2025 PRVI NSHM with the 2003 PRVI NSHM, hazard is generally higher at shorter periods and lower at longer periods, as a result of updates in both ERF and GMC models.

Session: Advancing the U.S. Geological Survey National Seismic Hazard Models [Poster]

Type: Poster

Room: Exhibit Hall A+B

Date: 4/17/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Allison Shumway

Student Presenter: No

Invited Presentation: 

Poster Number: 51

Additional Authors