GROUND DISPLACEMENT AND CHANGE IN RESERVOIR WATER LEVEL DUE TO SEISMIC RUPTURING OF A HIDDEN FAULT UNDERLYING A DAM SITE

Abstract

During the 2000 Western Tottori-prefecture earthquake, strong motion records at Kasho Dam showed as much as 2051gal at the dam crest and 531gal at the dam base, respectively. Integration of the accelerogram resulted in permanent displacement of 28cm to the north, 7cm to the west and uplift of 5cm. The dam is a 46m-high concrete gravity dam, and survived the earthquake without damage to the dam body. However, the reservoir water level showed sudden drop of 6cm followed by damped free vibration, Numerical simulation has proved that these ground displacement and water level change are direct influence of the seismic faulting underlying the dam site.