Abstract
There are two kinds of the method for predicting strong ground motions. One is the method based on the fault model, which has been developed by seismologists to simuate earthquake motions deterministically in the longer period range. The other method has been developed by earthquake engineers to calculate earthquake motions stochastically in the shorter period range. The engineering method usually consists of amplitude spectrum, envelope function, and duration time of strong ground motions. They are usually estimated under the regression analysis for the empirical relations to earthquake magnitude and hypocentral distance. In the present study, the engineering method is improved on the basis of the theories of seismic-wave radiation and propagation. The new method is applied to simulate accelerograms observed at 3 stations for the 1978 off Miyagi prefecture earthquake (M = 7.4). The characteristics of all the accelerograms, e. g. the effect of rupture propagation on the fault plane, can be expressed by the simulated waves in the frequency range higher than 1 Hz, though the three stations are located at the different distances and directions from the earthquake fault. These results suggest that the new method is applicable for predicting strong ground motions of large earthquakes.
