Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Skip to content

Gridded earthquake ground motions for the 2023 AASHTO Design Specifications

Metadata Updated: October 30, 2025

For designing bridges to safely resist earthquakes, the 2023 editions of the AASHTO (1) Guide Specifications for LRFD Seismic Bridge Design, (2) LRFD Bridge Design Specifications, and (3) Guide Specifications for Seismic Isolation Design provide risk-targeted design ground motions via this data release and the corresponding USGS Seismic Design Web Services. The web services spatially interpolate the gridded ground motions of this data release for user-specified latitudes and longitudes. The attached files below for 8 site classes each provide risk-targeted spectral accelerations (in units of g) for a grid of latitudes and longitudes and 22 spectral periods, including 0.0 seconds for peak ground acceleration (denoted SA0P0). To compare these risk-targeted spectral accelerations with uniform-hazard counterparts analogous to those in previous editions of the AASHTO Design Specifications, corresponding risk coefficients are also provided (for all of the site classes in a single ZIP file). The risk coefficients are ratios of the risk-targeted divided by uniform-hazard spectral accelerations, with the latter for a 7% probability of being exceeded in 75 years. The risk-targeted and uniform-hazard spectral accelerations were both derived from the truncated USGS seismic hazard curves released in the "Associated Item."

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources

Dates

Metadata Created Date September 13, 2025
Metadata Updated Date October 30, 2025

Metadata Source

Harvested from DOI USGS DCAT-US

Additional Metadata

Resource Type Dataset
Metadata Created Date September 13, 2025
Metadata Updated Date October 30, 2025
Publisher U.S. Geological Survey
Maintainer
Identifier http://datainventory.doi.gov/id/dataset/usgs-60d6419ad34e96039367baf0
Data Last Modified 2022-06-17T00:00:00Z
Category geospatial
Public Access Level public
Bureau Code 010:12
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Metadata Catalog ID https://ddi.doi.gov/usgs-data.json
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 6c4e6ac8-b5be-466a-bdef-8e68f7b782f9
Harvest Source Id 2b80d118-ab3a-48ba-bd93-996bbacefac2
Harvest Source Title DOI USGS DCAT-US
Metadata Type geospatial
Old Spatial -159.6, 18.7, -155.4, 22.38
Source Datajson Identifier True
Source Hash 6c1d4a61d9caea41eb38f2e89db9342578284db42266b0b9d7761da1d1572918
Source Schema Version 1.1
Spatial {"type": "Polygon", "coordinates": -159.6, 18.7, -159.6, 22.38, -155.4, 22.38, -155.4, 18.7, -159.6, 18.7}

Didn't find what you're looking for? Suggest a dataset here.