OBSERVATION OF PERMANENT GROUND DISPLACEMENTS INDUCED BY SOIL LIQUEFACTION

Abstract

Permanent ground displacements, caused by the 1964 Niigata earthquake and the 1983 Nihonkai-Chubu earthquake, were measured by per-and post earthquake aerial surveys. The maximum detected permanent ground displacement was more than 8m along the Shinano River in Niigata City and more than 5m in Noshiro City. The damage caused to bridges, riverbanks, etc., during these two earthquakes was re-examined and it was clarified that such damage was a direct result of these permanent displacements. Furthermore, the mechanism of permanent ground displacements was discussed by inspecting the geological and topographical conditions and it was concluded that the permanent ground displacements were induced by the liquefaction of inclined sandy layers.