ATTENUATION RELATIONSHIP FOR RESPONSE SPECTRA ON ENGINEERING BEDROCK CONSIDERING EFFECTS OF FOCAL DEPTH

Abstract

The purpose of this study is to develop attenuation relationship for acceleration response spectra on engineering bedrock for predicting strong ground motion. For developing the attenuation relationship, 3198 strong motion data from 52 earthquakes, which occurred in and around Japan from 1978 to 2003, with monent magnitude 5.5 to 8.3 are compiled in a database. By performing regression analysis using maximum likelihood method, new attenuation relationship is developed. In this relationship, effects of focal depth on the ground motion intensity and the focal depth dependence of the geometrical spreading coefficient are considered. The results show that the earthquake with deeper focal depth generates stronger ground motion.