Study on the estimation of snowmelt due to pyroclastic material considering enthalpy of evaporation

Hiroaki IZUMIYAMA, Daizo TSUTSUMI, Kohei NOIKE, Naoki FUJIMURA and Hideaki MIZUNO

When a volcano erupts and snow deposits in the vicinity of the volcano, pyroclastic flow and surges melt the snow and trigger catastrophic lahar. To mitigate the inundation area, it is important to set an appropriate hydrograph as boundary condition. However, the process of heat exchange between the pyroclastic material and snow is not so clear that drastic assumptions are often adapted. Sublimation occurs whenever pyroclastic material contacts with ice or water and could be treated physically. Hence, to estimate physically the heat energy of sublimation, experiment and heat conductivity analysis are carried out. In the analysis, sublimation of ice is calculated with Hertz]Knudsen formula. The results indicate that the sublimation of ice should be considered in order to predict precisely the time series variation of snow depth, and about 83 percent of heat energy from hot gravel supplies to snow.

Key wordsFvolcanic debris flow, melting snow, heat conductivity analysis, Hertz]Knudsen formula, hydrograph