Abstract
Area surveyed is about 220 km2, which is predominated by slopes. A half of all sloping grounds has been influenced by landslides where gentle and steep slope appear equally. An uncertain river system and watersheds are concerned in the most recent landslide movements. Topography due to such recent movements corresponds to about 10% of the whole landslide topography.
This district is divided into three parts. The northwest part of gentle slopes is almost covered by basalt, where scattered small landslides are observed. The southwest part is not covered by basalt, in which the best part of steep slopes has in various places large landslides developed in ancient times. The east half part stands in strong relief and is covered equally by basalt and other tertiary layers, where many large landslides of ancient and present movements are concentrated. Contemporary movements are considered as secondary movements of former landslides mainly to grade lower half of hill slopes.
