Development of a Site Response and Hazard Model for the U.S. Atlantic and Gulf Coastal Plains With a Geology-Based Shear Wave Velocity Model
Description:
The Atlantic and Gulf Coastal Plains consist of low-velocity sediments and sedimentary rock overlying high-velocity bedrock, which significantly impacts the amplitude and duration of earthquake ground motions. Evaluating seismic hazards in the U.S. Coastal Plains requires a thorough understanding of how both geology and sediment thickness influence seismic wave propagation in the region. Existing site amplification and seismic hazard models for the coastal plains are limited in their characterization and modeling of these factors. Our project seeks to improve the characterization of site response in the coastal plains and incorporate it into probabilistic seismic hazard estimations for the region. In this study, a new grid-based model of site response in the coastal plains has been developed based on an integration of Vs measurements, knowledge of the geology in the region, and a literature review on representative Vs values at reference bedrock conditions. The resulting model was compared to other available amplification models by focusing on the input variables of sediment thickness and ground shaking intensity. Existing measured Vs profiles located throughout the coastal plains were sorted into five geologic groups. A median Vs profile was determined for each geologic group and assigned within the grid-based site amplification model according to the spatial distribution of geologic units at the surface. The modulus-reduction and damping curves used in the site response analyses were also selected on the basis of geology. These critical model updates provide a significant advancement in the characterization of site responses at regional scales and their effective incorporation in seismic hazard maps.
Session: USGS National Seismic Hazard Models: 2023 and Beyond
Type: Oral
Date: 4/18/2023
Presentation Time: 11:00 AM (local time)
Presenting Author: Cassie Gann-Phillips
Student Presenter: Yes
Invited Presentation:
Authors
Cassie Gann-Phillips Presenting Author Corresponding Author cvgann@ncsu.edu North Carolina State University |
Ashly Cabas, Ph.D. amcabasm@ncsu.edu North Carolina State University |
Chris Cramer, Ph.D. ccramer@memphis.edu University of Memphis |
James Kaklamanos, Ph.D. KaklamanosJ@merrimack.edu Merrimack College |
Zachary Militello zmmilite@ncsu.edu North Carolina State University |
Oliver Boyd, Ph.D. olboyd@usgs.gov United States Geological Survey |
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Development of a Site Response and Hazard Model for the U.S. Atlantic and Gulf Coastal Plains With a Geology-Based Shear Wave Velocity Model
Category
USGS National Seismic Hazard Models: 2023 and Beyond