Because of the causality nature of earthquake motion, its amplitude and phase cannot be assigned independently to simulate realistic earthquake motion. We therefore develop a relationship between Fourier amplitude and phase spectrum of the causality earthquake motion. The phase spectrum, on the other hand, it modeled based on the concept of group delay time. Regression relationships of statistical characteristics of group delay time are obtained as the functions of epicenter distance and earthquake magnitude in a certain frequency band. We finally succeed in synthesizing the non-stationary earthquake motion, which can take into account the causality restriction, only from phase information.

Copyright (c) 2003 Railway Technical Research Institute