Abstract
It has already been shown that phases defined in time and frequency domain are closely related with nonstationary properties of seismic motions by introducing complex envelope to Fourier analysis of seismic motions. In this paper, descriptions of evolutionary spectrum and time-varying phase based on complex envelope are given so that nonstationary properties of seismic motions simulated by using those are discussed on the basis of above-mentioned relations. Furthermore, such properties of simulated seismic motions modeled on an observed motion are revealed by means of instantaneous frequency, group delay time and strength demanded spectrum. Those of seismic motions simulated by a conventional method are also examined in detail.
