Pyroclastic flow will destroy nearly everything in its path. With rock fragments ranging in size from ash to boulders traveling across the ground at speeds greater than 80 km per hour, pyroclastic flows knock down, shatter, bury or carry away nearly all objects and structures in their way. The extreme temperatures of rocks and gas inside pyroclastic flows, between 200°C and 700°C, can cause combustible material to burn, especially petroleum products, wood, vegetation, and houses. -- Samuel…
Pyroclastic flow sweeps down the side of Mayon Volcano, Philippines, during an explosive eruption on 15 September 1984. Note the ground-hugging cloud of ash (lower left) that is billowing from the pyroclastic flow and the eruption column rising from the top of the volcano. Credit: Photograph by C. Newhall on 15 September 1984.
Small pyroclastic flow from Unzen. http://volcano.oregonstate.edu/book/export/html/367
▶ Extreme Pyroclastic Flows At Sinabung Volcano, Indonesia 21st Jan 2014 - Mount Sinabung is a Pleistocene-to-Holocene stratovolcano of andesite and dacite in the Karo plateau of Karo Regency, North Sumatra, Indonesia, 25 miles from Lake Toba supervolcano.