ABSTRACT Many caisson type quay walls were damaged in Kobe Port during the 1995 Hyogoken-Nambu earthquake. Seaward displacements of the caisson walls were about 5 m maximum and 3 m average. Although the caisson walls also tilted and settled, they did not collapse or overturn and deformed quite uniformly maintaining almost straight face lines of the walls along the port front alignment (pier head). The high seismic resistant quay walls of a caisson type, which were specifically designed for unloading emergency supplies, performed very well and resisted the strong earthquake motion. Geotechnical investigations including in-situ soil freezing sampling and shake table tests were performed in order to understand the mechanism of deformation in the caisson walls. The displacements of the caisson obtained from the shake table tests agreed very well with those measured in Kobe Port after the earthquake. The results of these investigations suggested that the excess pore water pressure increase in the foundation soil underneath the caissons and in the backfill soil significantly increased the deformation of the caisson walls.