Electronic Theses and Dissertations

Date

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Civil Engineering

Committee Chair

Shahram Pezeshk

Committee Member

Charles Camp

Committee Member

Roger Meier

Committee Member

Michali Gkolias

Abstract

Ground motion models (GMMs) are essential components of probabilistic seismic hazard analysis (PSHA) in developing engineering response spectra conditional on earthquake magnitude, source-receiver distance, and site condition. The Gulf Coast and Atlantic Coastal Plain regions of the United States, referred to as the Coastal Plain by researchers such as Chapman and Guo (2021), have site conditions systematically different from others in the Central and Eastern United States (CEUS). This study aims to develop adjustment factors for the GMMs developed for CEUS, which are developed for regions outside the Coastal Plain, to be used for sites within the Coastal Plain regions. The adjustment factors developed are a function of sediment thickness and rupture distance (R_rup) in the Coastal Plain. We use newly developed sediment thickness contour maps for the Coastal Plain (Boyd et al., 2023) and a combined dataset, that consists of the NGA-East dataset (Goulet et al., 2014), the dataset from Chapman and Guo (2021), and the newly compiled and verified dataset by Thompson et al. (2023). We compute residuals by taking the difference between the logarithms of the observed Coastal Plain data and those predicted by the CEUS GMMs and model the residuals using a mixed-effects regression model to partition the total residuals into distinct components comprising source-specific, path-specific, and site-specific terms. The initial term is referred to as the between-event component, while the combination of the latter two terms is denoted as the within-event component. To develop the adjustment factors for sites within the Coastal Plain, we fit the within-event residuals to an equation that is a function of sediment thickness and R_rup. The results, applicable for R_rup up to 1500 km, indicate that for stations within the Coastal Plain, for most periods, the residual trend has been eliminated with respect to VS30 (the time-averaged shear-wave velocity to a depth of 30 meters), sediment thickness, and R_rup, using the proposed adjustment factors. The results of this study can be utilized in seismic hazard and risk analyses for sites within the Coastal Plain.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Open Access

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