Effects of Volcanic Activity on Occurrence and Runoff of Debris Flow in Sakurajima Volcano

Abstract

Sakurajima Volcano has erupted continuously with emission of ash since 1955. The frequency of eruption has varied with time. Effects of the temporal variation of eruption on rainfall for occurring the debris flow, peak discharge and total runoff of the debris flow in the volcano were examined.
The rainfall intensity for occurring the debris flow is smaller during the more frequent volcanic eruptions than during the fewer eruptions. The rainfall onditions for occurring debris flow depend on the volcanic activity.
Both the peak discharge and the total runoff of debris flow are larger during the more frequent eruptions than during the fewer eruptions under the same conditions of rainfall. The runoff characteristics of debris flow in the volcano depend on not only the rainfall but also the volcanic activity.