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Regional Variations in the Site-amplification Variability

Description: 

The site-amplification variability in ground motion models (GMMs) has traditionally been estimated as 0.3 ln units. The recent advances in non-ergodic GMMs and the impact of the site-amplification variability on seismic hazard demand a more precise quantification of the site-amplification variability. Recent studies based on borehole array data show that the site-amplification variability is not significantly different from 0.3, with values ranging from 0.3 to 0.35 ln units at different oscillation periods. However, more significant differences are observed when the available global data is split into regional datasets. In this study, we investigate regional variations in the site-amplification variability. We use weak ground motions recorded at 15 borehole array sites in California, 518 sites in Japan, and 30 sites in Taiwan. The site-amplification variability is quantified as the standard deviation of the empirical ratios of the surface-to-borehole ground motion pseudo-spectral acceleration response spectra. Our results indicate that the site-amplification variability in Japan and Taiwan is similar between oscillator periods ranging from 0.5 to 0.9 seconds. However, an increasing discrepancy is observed for longer periods. Meanwhile, the site-amplification variability in California is lower than it is in Japan and Taiwan. This presentation will discuss the differences in the site-response variability, the factors behind the long-period discrepancy, and the impact on forward seismic hazard estimates.

Session: Recent Advances in Modeling Near-source Ground Motions for Seismic Hazard Applications - I

Type: Oral

Date: 4/16/2025

Presentation Time: 09:00 AM (local time)

Presenting Author: Renmin

Student Presenter: No

Invited Presentation: 

Poster Number: 56

Authors