Constraints of the Non-ergodic Path Effects for Short Distances in GMMs using the Modified Mercalli Intensity Data
Description:
The new Modified Mercalli Intensity (MMI) dataset for the western United States, developed by Fathian-Sabet et al. (2025), has much denser spatial sampling than the empirical ground-motion data sets. As a result, the MMI data may be able to provide better spatial resolution for non-ergodic path effects than the empirical ground-motion data. In this study, we utilize MMI and NGAW3 ground-motion data from California crustal earthquakes to compare the path effects derived from both datasets, with the objective of assessing if the MMI data can yield valuable constraints for non-ergodic path effects that can be used to test or constrain updated non-ergodic ground-motion models (GMMs) for California. The non-ergodic path effects for both data sets are estimated using the methodology established by Sung et al. (2023), which quantifies path effects related to the 3-D velocity structure. We find a significant correlation between path terms for lower MMI values and short-period spectral accelerations. Conversely, for higher MMI values, the correlation of the path effects is strongest for the long-period ground motions (greater than 2 seconds). For the sparse empirical data, the epistemic uncertainty for the path effects is often large. The non-ergodic path terms derived from the MMI data are found to be within the epistemic uncertainty range of the path terms obtained from NGAW3 empirical data. This suggests that incorporating MMI results into the ground-motion model could enhance the accuracy of path effects in areas with limited empirical data, particularly at shorter distances. We also discuss the implications of using nonergodic GMMs with path effects based on the MMI data for the evaluation of probabilistic hazard curves.
Session: Macroseismic Intensity: Past, Present and Future [Poster]
Type: Poster
Date: 4/17/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Chih-Hsuan
Student Presenter: No
Invited Presentation:
Poster Number: 24
Authors
Chih-Hsuan Sung Presenting Author Corresponding Author karensung@berkeley.edu University of California, Berkeley |
Norman Abrahamson abrahamson@berkeley.edu University of California, Berkeley |
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Constraints of the Non-ergodic Path Effects for Short Distances in GMMs using the Modified Mercalli Intensity Data
Session
Macroseismic Intensity: Past, Present and Future