抄録
Unzen volcano had many pyroclastic flows during the period from 1990 to 1995. The pyroclastic flows were thickly deposited on the flank of the volcano. At the same time the surroundings were widely covered with a fine volcaniclastic material. As a result of those, debris flows and floods have frequently occurred at the rivers on the flank of the volcano.
Observation stations of debris flows were established at two ravines on the flank of the volcano in order to examine the occurrence and runoff characteristics of debris flows and floods quantitatively. In this paper, the characteristics of debris flows and floods following the pyroclastic flows were analyzed using the records of debris flows and floods observed in 1995.
