Abstract
In Chausuyama landslide area, drainage works have been performed repeatedly since 1966, and the lowering of the groundwater level in the upper part of the sliding area has been attained by about 20 meters. The movement of soil mass is on the decrease from 1971 to 1975 and the sliding activity is fairly stabilized. The Y-Y measuring lines area in the middle of the secondary sliding area and the south part of Sankaku-yama at the top of the sliding area grow stable. The stabilization of soil mass between the middle and the southwest side of the upper of the sliding area is remarkable. The main problem to be settled in future is to control the movement of soil mass along the C-C measuring lines.
