In the major ports in Japan the strong-motion earthquake and the earthquake response of structures have been observed since 1962, and as of December 1971 about 660 accelerograms were accumulated.
　The observation network consists of 57 strong-motion accelerographs.
The present report is the seventh publication in the series, reporting accelerograms obtained in major ports in 1971. Analog records which are computer plots of the digitized records with maximum acceleration exceeding 20 gals are shown. Digitized records response spectra, and Fourier spectra are provided on the records ex
ceeding 50 gals.