This paper presents the evolutionary (time-dependent) power spectral density curves of six strong-motion earthquakes. The earthquake accelerograms are treated as piecewise-separable and the frequency-independent modulating function is estimated by applying the mean square minimization criterion. The results show that, as the time increases, the power spectral densities of earthquakes can vary both in magnitude and in peak location over the frequency axis. The analysis demonstrates that the nonstationary characteristics of earthquakes can be reasonably assessed by a simple computation procedure and the information thus obtained can be helpful in developing improved stochastic models for earthquake simulation.

First Page Preview

First page PDF preview
You do not currently have access to this article.