Regional calibration of hybrid ground‐motion simulations in moderate seismicity areas: Application to the Upper Rhine Graben

Bulletin of the Seismological Society of America
By: , and 



This study presents the coupling of the spectral decomposition results for anelastic attenuation, stress drop, and site effects with the Graves‐Pitarka (GP) hybrid ground‐motion simulation methodology, as implemented on the Southern California Earthquake Center (SCEC) broadband platform (BBP). It is targeted to applications in the Upper Rhine graben (URG), which is among the seismically active areas in western Europe, yet a moderate seismicity area. Our development consists of three main steps: (1) calibration of regional high‐frequency (HF) attenuation properties; (2) modification of the hybrid approach to add compressional waves in the HF computation and examine various strategies to evaluate site amplification factors in the Fourier domain (e.g., VS30VS30‐based or site‐specific factors); (3) testing of the simulations using earthquake records from the URG (3.7<Mw<53.7<Mw<5). The validation process of the simulated time histories is performed first on rock sites, and, then subsequently at all stations, whatever their site conditions. The performance of the simulations for rock sites is assessed through the standard validation technique in the BBP (comparison of the waveforms, intensity measures, and estimation of the response spectra model bias). We additionally compare the Fourier amplitude spectrum of the simulations and observations, and compute their corresponding bias. The results show that the simulated ground motions match the general characteristics of the recorded motions, and that the model bias generally fluctuates around zero across the broadband frequency range. Hence, the hybrid ground‐motion methodology implemented in the SCEC BBP can be successfully applied outside high‐seismicity areas and outside those areas for which it had been generally calibrated. Our results also show that HF modification and calibration were necessary to improve the fits with the observation, and demonstrate the potential benefits of using site‐specific amplification factors compared to VS30VS30‐based amplification factors.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Regional calibration of hybrid ground‐motion simulations in moderate seismicity areas: Application to the Upper Rhine Graben
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120200287
Volume 111
Issue 3
Year Published 2021
Language English
Publisher Seismological Society of America
Contributing office(s) Earthquake Science Center
Description 23 p.
First page 1422
Last page 1444
Country France, Germany, Switzerland
Other Geospatial Upper Rhine Graben
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