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Accession Number
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PB2013-101795
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Title
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Calibration of Semi-Stochastic Procedure for Simulating High-Frequency Ground Motions.
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Publication Date
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Dec 2011
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Media Count
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68p
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Personal Author
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E. Seyhan J. P. Stewart R. W. Graves
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Abstract
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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.
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Keywords
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Amplitudes
Attenuation
Calibration
Damping
Earthquakes
Fourier analysis
Ground motion
Simulation
Stochastic processes
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Source Agency
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US Geological Survey
University of California Earthquake Engineering Research Cent Berkeley
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NTIS Subject Category
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48F - Geology & Geophysics
46 - Physics
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Corporate Author
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California Univ., Berkeley. Pacific Earthquake Engineering Research Center.
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Document Type
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Technical report
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Title Note
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N/A
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NTIS Issue Number
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1302
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Contract Number
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N/A
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