抄録
On 15 June 1991, Mt.Pinatubo awoke with a climactic eruption after 500 years of dormancy. The eruption produced remarkable volume of ashfall deposits and pyroclastic flow deposits over the surrounding areas. The volume of pyroclastic flow deposits in the slope of Mt.Pinatubo was estimated at 6.7 billion cubic meters with deposits as much as 200 meters in thickness. Lahar generated by heavy rain falling on pyroclastic flow deposits poses grave danger in the low-lying areas. This paper describes the process of large-scale sediment transport in alluvial fan located in the eastern river basin of Mt.Pinatubo, which have been observed during eight years after the eruption.
