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Updated Regional Seismic Velocity Model for the US Atlantic and Gulf Coastal Plains Based on Measured Shear Wave Velocity, Sediment Thickness, Varying Geologic Structure With Depth, and Lateral Variations

Description: 

The Atlantic and Gulf Coastal Plains (CPs) consist of thick and soft sediments that overlie a stiff bedrock that increase the amplification and duration of earthquake ground motions. Understanding both the depth and the dynamic properties of these sediments is critical yet challenging at a regional scale. Sediment thickness and geology have been shown to be good indicators for regional characterization of shear wave velocity (V_S). Due to limited characterization of the velocity structure within site amplification models in the region, a new geology-based V_S model was previously developed to better characterize the CP sediments so that amplification and hazard levels can be estimated. This geology-based model was based on measured shear-wave velocity and sediment thickness, but geologic grouping was only based on surface geology. Median profiles were developed for five surface geologic groups with no lateral variation within each group. Thus, to further improve the characterization of the regional velocity structure, the previously developed velocity model has been updated to include correlations with stratigraphic sequences, constraints with depth, and lateral variations within geologic groups. Additional measured V_S data are also incorporated within the model to increase coverage in data-sparse areas. These updates will be helpful for the development of new GMMs aiming to characterize systematic site effects via the time-averaged V_S in the top 30 meters (V_S30) and sediment thickness in the region.

Session: Physics-Based Ground Motion Modeling [Poster Session]

Type: Poster

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Cassie

Student Presenter: Yes

Invited Presentation: 

Authors