Since 1962, strong ground motions and earthquake responses of structures have been observed inthe major ports in Japan. By the end of December 2004, 6980 accelerograms had been accumulated andanalyzed at the Port and Airport Research Institute.
　The strong-motion earthquake observation network in Japanese ports consists of 110 strong-motionaccelerographs installed at 60 ports as of December 2004. 67 accelerographs out of 110 are installed onground surface, 33 accelerographs are in ground by using bore-hole and the rest 10 are on structuressuch as quay walls. Currently two types of accelerographs are used in the network, namely, the ERSaccelerograph and the SMAC-MDU accelerograph, both of which are of an electrical type equippedwith a digital recorder.
　This report presents results of observation and preliminary analysis of records obtained in 2004.ASCII data of the reproduced accelerograms for all the records in 2004 are available on the attached CDin user-friendly CSV format. Also, computer plots of reproduced accelerograms are available on the CDfor the records with peak accelerations exceeding 20 Gals. For the records with peak accelerations exceeding50 Gals, computer plots of reproduced accelerograms, integrated velocities and displacements,Fourier spectra and response spectra are available on the CD.