Abstract
This paper presents an idea of the processing of strong motion accelerograms considering causality of seismic waves. It is presented that, by the technique of FFT shown in Fig. 1, and by considering causality condition shown in Fig. 2, permanent displacements with some errors (in this paper, we call such displacements as drifts) can be obtaind even from accelerograms. The flowchart to calculate the drifts is indicated in Fig. 3. Examples of the drifts are shown in Figs. 7 and 8. For Imperial Valley earthquake, 1979, the calculated drift components can well explain the permanent displacements deduced from the fault motion.
