Strong ground motion simulation ofthe Wenchuan earthquake

Theoretical seismology method based on deterministic source function is mainly used in the low frequency wave simulation, since it is hard to simulate high frequency component precisely. High frequency wave can be simulated with stochastic approach or using empirical greenrsquo;s function, but these technique does not work for low frequency. Based on the deterministic simulation method, we try to simulate the broadband frequency (0.1mdash;10 Hz) strong ground-motion by subdividing the slip distribution across the fault plane. This method is to discretize the fault in second order and decompose the rise time variation to increase the high frequency components in the source function, so as to avoid the dependence on the accuracy and richness of seismic records. We simulated ground motions of Wenchuan earthquake at 8 selected stations located near the fault. The results show an overall agreement on the peak acceleration and duration within plusmn;50% tolerance between the simulated and observed accelerations. The simulated Fourier spectra have the components as high as 10 Hz. The simulated Fourier spectrum at the stations in Sichuan basin attenuate faster than the observed because the method did not consider site effect. The strong ground motion simulation should take all the source, propagation path and site effect into consideration. Result of this study indicates that this deterministic method of changing input source function can be applied to simulation of near fault strong ground motion in broad frequency band.