noun
large pyroclastic flow
Technical term in volcanology for a large-scale pyroclastic flow, often used in disaster contexts.
大火砕流は時速100キロ以上で広がることがある。
A large pyroclastic flow can spread at over 100 kilometers per hour.
この火山の大火砕流は過去に大きな被害をもたらした。
The large pyroclastic flows from this volcano have caused great damage in the past.
火砕流 is the general term for pyroclastic flow; 大火砕流 specifically refers to a large-scale one.
Compound of 大 (large) + 火砕流 (pyroclastic flow).