Abstract
In the southern part of Kyushu, Japan, covered with volcaniclastic materials, landslide and debris flow disasters have occurred frequently during rainy and typhoon seasons. Recently, two types of landslide which have rarely taken place were caused by a rise in the groundwater level in association with heavy rainfall. The one is sliding of talus slope at the valley head scarred on Shirasu (pyroclastic flow deposits) plateau in heavy rain in August 1993, and the other one is a deep-seated landslide on the western flank of the old volcano of Mt. Yahazudake in Izumi City in July 1997.
In this paper, the mechanism of these landslides, the geological and hydrogeomorphological characteristics of the landslide slope sites, and the possibility of predicting the potential landslide sites are examined based on field study.
