抄録
Many slope failures and debris flows occurred in 1993, in the area of fallen trees by the 19th typhoon of 1991. We thought to be disturbed and weakened the slope surface layer by shaking due to the typhoon, because there was not an amount of rainfall caused slope failures. In this paper, considering that the vitality of trees indicates the weakness of slope surface layer, the relation between vitality of trees and slope failures was studied. As the results, it was appeared that the decrease of normal vegetation index (NVI) obtained by airbone MSS data agreed well with slope failures occurred in a medium amount of rainfall areas.
