The moving land slide body, with a volume of 1.55 million
m3, partially flowed in to the reservoir, the water level rose 2.42 m, and a tsunami with about 2.5-m high waves was
generated. According to witnesses, part of the generated
tsunami overflow the spillway on the rightbank of the
dam. Moreover, the tsunami continued the small river
flow ingin to the reservoir at the right bank sideand moveda
bridge girder by about 80 m toward the upstream side.
However, the damage to the Aratosawa Dam, rockfill
dam facentral core type,74.4 min height, due to the earthquake by the shaking is small;only about 20cm of
subsidence occurred in the rock-fill part.