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Accession Number PB2013-101795
Title Calibration of Semi-Stochastic Procedure for Simulating High-Frequency Ground Motions.
Publication Date Dec 2011
Media Count 68p
Personal Author E. Seyhan J. P. Stewart R. W. Graves
Abstract Broadband ground motion simulation procedures typically utilize physics-based modeling of source and path effects at low frequencies coupled with semi-stochastic procedures at high frequencies. The high-frequency procedure considered here combines a deterministic Fourier amplitude spectrum that is a function of closed-form source, path, and site models with a random phase. Previous analysis of the simulation procedure in the ShakeOut exercise demonstrated faster distance attenuation and lower intra-event dispersion of high-frequency ground motions than in empirical ground motion equations. We increase crustal damping (Q) to remove the distance attenuation bias and introduce random site-to-site variations to the Fourier amplitudes using a log-normal standard deviation ranging from 0.45 for Mw < 7 to zero for Mw 8. We repeat the simulation of the ShakeOut event with the increased crustal damping and a revised source characterization, with increased slip heterogeneity reflecting more recent recommendations. The revised simulation procedure for ShakeOut produced ground motions without a distance attenuation bias and with near-source dispersion that is generally compatible with empirical models. However, far-field dispersion remains lower than empirical models.
Keywords Amplitudes
Fourier analysis
Ground motion
Stochastic processes

Source Agency US Geological Survey
University of California Earthquake Engineering Research Cent Berkeley
NTIS Subject Category 48F - Geology & Geophysics
46 - Physics
Corporate Author California Univ., Berkeley. Pacific Earthquake Engineering Research Center.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1302
Contract Number N/A

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