IMPROVEMENT OF THE SHAPING WINDOW IN THE STOCHASTIC METHOD AND REPRODUCTION OF ACCELERATION RECORDINGS OF THE HYOGO-KEN NANBU EARTHQUAKE

The stochastic method is widely used to simulate high-frequency earthquake motions. However, it still has a crucial defect that simulated high-frequency motions are underestimated in amplitude and duration. This is mainly caused by neglecting the effects of multiply reflected and transmitted waves and scattered waves. We remove this defect from the method in a simple practical way. We firstly introduce into the method the hypocentral-distance dependent shaping window which is inferred from borehole data provided by KiK-net network. We secondly introduce the radiation coefficients transiting along with propagation from the theoretical respective value for SH and SV waves to the isotropic value common to the two wave types. The usefulness of the improved method is demonstrated by reproducing three-component acceleration time histories of the 1995 Hyogo-ken Nanbu earthquake in amplitude and duration as well as spectra at all the sites in the Osaka Basin.