SEGJ Technical Conference

Map of predominant period of surface waves in the Osaka basin and its application to the structure damage

Abstract To mitigate earthquake damage of the high-rise buildings, with natural period longer than 1 sec, for seismic shaking, it is important to know the characteristic of the long-period strong ground motions in the Osaka sedimentary basin. We first show that long-period earthquake recordings in basin, which occurred in Western Japan, have common site-specific predominant period irrespective to the azimuth and the magnitude. Then these predominant period are well fitted with computed peak periods (or Airy phase) of Love wave from dispersion curve, calculated for 1-D velocity structure model extracted from the 3-D Osaka basin model. Finally, we pick out high-rise buildings resonant with long-period strong ground motions by comparing the natural periods of them with the predominant period map of Love wave in the Osaka Plain. The number of the risky high-rise buildings is 16 in 256 buildings in the Osaka Plain.