pyroclastic flow
A fast-moving current of hot gas and volcanic matter that flows along the ground during an eruption. Used in geology and disaster reporting.
Pyroclastic flows can rush down at over 100 kilometers per hour.
The pyroclastic flows at Mount Unzen in 1991 caused many casualties.
A pyroclastic flow occurred near the crater.
The village was hit by a pyroclastic flow and completely destroyed.
The pyroclastic flow swept down the mountainside all at once.