Abstract: | One of the severe problems in the semi-empirical method for the prediction of strong ground motions is that there is no objective criterion for choosing empirical Green's functions. It is undesirable that synthesized strong ground motions are affected by the source process of an earthquake whose record is adopted as an empirical Green's function. Through the analysis of strong motion accelerograms of two aftershocks of the 1983 Japan Sea earthquakes, it is found that characteristics of the accelerograms are dependent on the moment rate function derived from teleseismic observations. A procedure is presented for removing the effect of the source process from observed strong motion accelerograms. The thus obtained empirical Green's function expresses approximately the impulse response of the medium between the earthquake source and the observation site. |