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Dr. Chris Van Houtte, Fellow at Harvard U., will present “Predicting peak ground motions by representing earthquakes as random vibrations”
“By treating earthquakes as Gaussian, stationary, random vibrations, we are able to approximate the peak time domain response of a signal from its Fourier amplitude spectrum. In ground motion prediction, random vibration theory (RVT) has primarily been used in the stochastic method of ground motion simulation, to efficiently generate 5%-damped response spectra from a model of the earthquake Fourier amplitude spectrum. I will examine the inherent assumptions in an RVT analysis, and investigate alternative ways of improving the theoretical basis. Compared to the previous method for applying RVT in ground motion modelling, I adopt a different duration metric that is more theoretically consistent with the method, and model oscillator nonstationarity using an evolutionary power spectral density function (PSDF). Discussion is provided on the desirable aspects of treating earthquakes as random vibrations, specifically compared to physics-based methods, as well as potential limitations.”