AN EMPIRICAL SCALING OF STRONG-MOTION SPECTRA WITH APPLICATION TO ESTIMATE OF SOURCE SPECTRA

A new regression model of strong-motion spectra is derived by incorporating the conception of the dummy variables to the conventional regression model. The dummy variables are available not only to obtain the amplification factors due to local soil conditions of each observation site but also to estimate the non-linear dependences of spectral amplitude on earthquake magnitude and hypocentral distance. The new regression model is applied to 228 strong-motion spectra obtained in Japan. The regression results are used to estimate the source spectra, as well as being discussed in detail, in particular, from the view points of faulting and wave propagation mechanisms. It is finally coneluded that the specific barrier model is more connected with the present statistical source spectra than the stochastic ω-square model.