Pyroclastic Flows are liable to cause extensive and catastrophic destruction. In order to prevent and mitigate the such disasters, there is an urgent need to clarify the flow mechanism.
There have, however, been very few studies of Pyroclastic Flows being analysed from the viewpoint of dynamics, and little is known about the mechanism of them at present.
A kinematic model of Pyroclastic Flows was studied in this study.
Accoding to this model that grains can be suspended by pressure and shearing force associated with inter-particle friction and collision, deposit area of debris avalanche as a part of Pyroclastic Flows is mainly governed by grain concentration, which is effected by gradient actively. Debris avalanches begin to deposit at the point that its gradient is smaller than half of the coefficient of inter-particle friction.
This model was applied to simulate the Agatsuma and Kanbara Pyroclastic flow occurred at Mount Aasama in 1783. As a result, a good simulated results are produced.
Countermeasure possibility agaist Pyroclastic Flows was also studied on the base of this model. As a measure for debris avalanches, dams, training dykes, channels would be available considering its gravitationl flow characteristics.
As a measure for dust storms from debris avalanches slits or gridirons which can fall and deposit small suspended particles would be available.
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