large pyroclastic flow
Technical term in volcanology for a large-scale pyroclastic flow, often used in disaster contexts.
A large pyroclastic flow can spread at over 100 kilometers per hour.
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).