ATTENUATION RELATION OF RESPONSE SPECTRA IN JAPAN CONSIDERING SITE-SPECIFIC TERM

Since May 1996, the National Research Institute for Earth Science and Disaster Prevention (NIED) of the Science and Technology Agency, Japan has been operating a strong motion network that contains 1000 stations throughout in Japan. In this study to investigate the characteristics of the ground condition and site-specific response, attenuation relations of absolute acceleration and relative velocity response spectra for the thirty-five structural periods are developed, using accelerograms from Kyoshin Network (K-NET). The selected acceleration records consist of 6,017 three-component sets from 94 earthquakes, which recorded by K-NET95-type accelerometers at 823 free field sites in the period of May 1996 to December 1998. Using obtained regression coefficients for each structural period, the spectra of station coefficients and the site-specific response spectra for K-NET stations were presented. The predicted horizontal and vertical acceleration and velocity response spectra from the K-NET data were compared with those from JMA (Japan Meteorological Agency) data set that contains 3,990 records from 1,020 earthquakes recorded by JMA-87-type accelerometers at 77 stations.