What is a pyroclastic flow?
Pyroclastic flows are high-density mixtures of hot, dry rock fragments and hot gases that move away from the vent that erupted them at high speeds. Most pyroclastic flows consist of two parts: a basal (bottom layer) flow of coarse fragments that moves along the ground, and a turbulent cloud of ash that rises above the basal flow. Ash may fall from this cloud over a wide area according to the direction of the wind from the pyroclastic flow.
Are pyroclastic flows destructive?
Yes! A pyroclastic flow will destroy nearly everything in its path. With rock fragments
ranging in size from ash to boulders traveling across the ground at high speeds, pyroclastic flows bury or carry away nearly all objects and structures in their way. The extreme temperatures of rocks and gas inside pyroclastic flows, generally between 200°C and 700°C, can cause combustible material to burn, especially petroleum products, wood, vegetation, and houses. People and animals may die or suffer severe injuries from burns and breathing in hot ash and gases.