Etymology

Noun

1. A flow of volcanic ash, dust, rocks and debris that cascades down the slope of a volcano during an eruption. Pyroclastic flows are very dangerous, reaching speeds greater than 60 miles per hour and temperatures in excess of 800 degrees Fahrenheit.
   • 2004, China Miéville, Iron Council, p. 465 (2005 Trade paperback edition) -- In burning slabs like pyroclastic flow the top of the tower slewed off, militia pods falling out and tumbling.