In this study, close examination about the safety factors of gravity type quay walls that had been stricken by strong earthquake motion during two big earthquakes that occurred in Hokkaido Island, “1993 Kushiro-oki” and “1994 Hokkaido Toho-oki” earthquakes, was conducted. And the characteristics on the seismic earth pressure were discussed based on the extent of damage and seismic forces estimated by the seismic coefficient method.
