Conterminous U.S. Site Parameter Maps for Ground Motion Models
Description:
The amplitude of earthquake ground motions depends on parameters related to the source (e.g., magnitude and stress drop), path (e.g., geometric spreading and path attenuation), and site. The site component has typically been characterized in terms of VS30, the time-averaged shear-wave velocity to 30-meters depth and in some cases, Z1.0 or Z2.5, the depths to a shear-wave velocity of 1.0 and 2.5 km/s, respectively. Other parameters have been proposed including 1) a site’s fundamental period at which there is a peak in site amplification, 2) k0, which represents the site’s scattering and anelastic attenuation, and 3) sediment thickness, the last of which is being modeled in the Atlantic and Gulf Coastal Plains for the 2023 update of the U.S. National Seismic Hazard Model. Application of these parameters and the concomitant improvement in hazard assessments is limited to where these models are available. Whereas there are global and regional models for VS30, models of Z1.0, Z2.5, and sediment thickness are spatially restricted. With the completion of the USGS National Crustal Model for Seismic Hazard Studies (NCM), conterminous U.S. models of VS30, Z1.0, Z2.5, and sediment thickness are available, in addition to other potentially explanatory site parameters. In this study, we derive conterminous U.S. site-parameter maps from the NCM that can be used in ground motion model development and application. Site parameters considered include VS30, Z1.0, Z2.5, ZX derived from time-averaged velocity profiles, sediment thickness, sediment travel time, fundamental period, and k0. In this preliminary study, we compare these maps to existing measurements and models and present correlations between site parameters and ground motion residuals in the western U.S.
Session: The 2023 USGS National Seismic Hazard Model and Beyond [Poster Session]
Type: Poster
Date: 5/1/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Oliver
Student Presenter: No
Invited Presentation:
Authors
Oliver Boyd Presenting Author Corresponding Author olboyd@usgs.gov U.S. Geological Survey |
James Smith jamesasmith@usgs.gov U.S. Geological Survey |
Morgan Moschetti mmoschetti@usgs.gov U.S. Geological Survey |
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Conterminous U.S. Site Parameter Maps for Ground Motion Models
Session
The 2023 USGS National Seismic Hazard Model and Beyond