Repeatable Source, Path and Site Effects on Ground Motion Variability Based on Dataset From the Central and Eastern United States
Description:
This study analyzes the repeatable source, path, and site effects on ground-motion variability using a dataset from the Central and Eastern United States (CEUS). We used the ground motion models (GMMs) developed by Pezeshk et al. (2018) for outside the Coastal Plain and Akhani et al. (2024) for inside the Coastal Plain to compute empirical residuals of the response spectral values. Our analyses used a combination of datasets from Goulet et al. (2014), Chapman and Guo (2021), and Thompson et al. (2023), which comprise horizontal peak ground acceleration (PGA) and spectral acceleration (SA) at periods ranging from 0.01 to 10 seconds. Total residuals were calculated as the difference between the natural logarithm of the observed ground motion and the natural logarithm of the ground motion predicted by the GMMs. The total residuals are used to identify the repeatable source, path, and site effects by removing the ergodic assumption. We used a mixed-effects regression algorithm to decompose the total residuals into between-event (δBe) and within-event (δWes) components. The study area (CEUS) was divided into a grid of 2 by 2 degrees, with each cell considered an individual region. We further partitioned δBe into repeatable (δL2Lr) and purely random (δB0) parts. Then, δWes was split into between-station (δS2Ss) and event-site corrected residuals (δWSes). δWSes was divided into a systematic path term (δP2Psr), and the remaining within-event residual δW0es. We also presented the epistemic uncertainties associated with each component and the pure aleatory variability (single-path standard deviation). The results show that single-path standard deviations are lower than those derived under the ergodic assumption. These findings can be applied to nonergodic probabilistic seismic hazard analysis (PSHA).
Session: Accuracy and Variability of Physics-based Ground Motion Modeling - II
Type: Oral
Date: 4/15/2025
Presentation Time: 05:30 PM (local time)
Presenting Author: Mehran
Student Presenter: No
Invited Presentation:
Poster Number:
Authors
Mehran Davatgari Tafreshi Presenting Author Corresponding Author mdvtgrtf@memphis.edu University of Memphis |
Shahram Pezeshk spezeshk@memphis.edu University of Memphis |
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Repeatable Source, Path and Site Effects on Ground Motion Variability Based on Dataset From the Central and Eastern United States
Session
Accuracy and Variability of Physics-based Ground Motion Modeling