From words meaning "fire" & "broken", this type of flow of searing gas & rock swept down Mt. Pelee in 1902
[DOC] [TLE] 1980 eruption of Mount St. Helens - Trending Topics [PAR] On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens , a 
volcano ... of trees felled by a super-heated wall of volcanic gas and searing ash 
and rock that ... Pyroclastic flow material passed over the moving avalanche and 
spread ...