Calibration of semi-stochastic procedure for simulating high-frequency ground motions

Earthquake Spectra
By: , and 

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Abstract

Broadband ground motion simulation procedures typically utilize physics-based modeling at low frequencies, coupled with semi-stochastic procedures at high frequencies. The high-frequency procedure considered here combines deterministic Fourier amplitude spectra (dependent on source, path, and site models) with random phase. Previous work showed that high-frequency intensity measures from this simulation methodology attenuate faster with distance and have lower intra-event dispersion than in empirical equations. We address these issues by increasing crustal damping (Q) to reduce distance attenuation bias and by introducing random site-to-site variations to Fourier amplitudes using a lognormal standard deviation ranging from 0.45 for Mw < 7 to zero for Mw 8. Ground motions simulated with the updated parameterization exhibit significantly reduced distance attenuation bias and revised dispersion terms are more compatible with those from empirical models but remain lower at large distances (e.g., > 100 km).

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Calibration of semi-stochastic procedure for simulating high-frequency ground motions
Series title Earthquake Spectra
DOI 10.1193/122211EQS312M
Volume 29
Issue 4
Year Published 2013
Language English
Publisher Earthquake Engineering Research Institute
Contributing office(s) Earthquake Science Center
Description 25 p.
First page 1495
Last page 1519