| We develop a consistent set of simple and practical attenuation relations for peak ground acceleration and 5% damped response spectral acceleration in terms of earthquake magnitude and distance. The strong ground motion data analyzed in the present study consist of 432 horizontal components of acceleration records from 40 earthquakes in Japan. We employ a two-step stratified regression procedure in order to decouple the determination of magnitude coefficient from the determination of distance coefficient, and demonstrate the validity of this technique by comparing the result with that obtained by general non-stratified regression analysis. We also propose a method to modify the developed attenuation relations by soil condition. |
