Gridded earthquake ground motions for the 2023 AASHTO Design Specifications
type: Dataset
description: 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). The spectral accelerations for Site Class BC and spectral periods of 0.0, 0.2, and 1.0 seconds were directly derived from the USGS seismic hazard curves released in the "Associated Item"; from these three values, the spectral accelerations for the other site classes and spectral periods were derived indirectly via the FEMA P-2078 "Procedures for Developing Multi-Period Response Spectra at Non-Conterminous United States Sites," because corresponding USGS hazard curves were not yet available for Guam and the Northern Mariana Islands.
issued: 2025-11-21T11:03:48.797722
modified: 20220617
spatial: Location
contact point: Organization
  fn: Nicolas Luco
keyword: amerigeo
keyword: amerigeoss
keyword: ckan
keyword: earthquakes
keyword: engineering-sciences
keyword: geo
keyword: geoss
keyword: guam
keyword: hazards
keyword: national
keyword: north-america
keyword: northern-mariana-islands
keyword: seismology
keyword: standards
keyword: united-states
keyword: usgs-624afe86d34e21f827635bb7
theme: {geospatial}

Digital Data
type: Distribution
description: Landing page for access to the data
format: XML
issued: 2022-07-28T20:32:51.476059
modified: 2025-11-21T11:03:48.788330
access URL: https://doi.org/10.5066/P9I27ODJ
media type: application/http

Original Metadata
type: Distribution
description: The metadata original format
format: XML
issued: 2022-07-28T20:32:51.476049
modified: 2025-11-21T11:03:48.787886
access URL: https://data.usgs.gov/datacatalog/metadata/USGS.624afe86d34e21f827635bb7.xml
media type: text/xml

US Migrating
type: Agent