Abstract
A catastrophic debris avalanche that ensued from the 1923 Great Kanto Earthquake occurred near the rim of the Hakone crater, Kanagawa Prefecture; destroying Nebukawa town with loss of many lives. Its debris mass travelled along the Shiraito River; uprooting trees on both river walls, burying many houses, and pushed Nebukawa Railway Bridge to the sea. A simplified iterative approach is applied to this debris event for estimation of the velocity of debris slurry. Documented super-elevations of the flowing material along the bends of the flow path are used in this paper. An old topographical map is compared with the current terrain and real field data used as input parameter for the iterative procedure. Several stretches of the river channel are analyzed with the proposed approach and velocities of the debris flow are estimated for the chosen stretches.
