A pyroclastic flow is a fast-moving current of hot gas and volcanic matter that flows along the ground away from a volcano at average speeds of 100 km/h but is capable of reaching speeds up to 700 km/h.

What does a pyroclastic cloud do?

Pyroclastic flows destroy nearly everything in their path

With rock fragments ranging in size from ash to boulders that travel across the ground at speeds typically greater than 80 km per hour (50 mph), pyroclastic flowsknock down, shatter, bury or carry away nearly all objects and structures in their path.

What is a pyroclastic cloud made of?

Pyroclastic density currents are hot, fast moving "clouds" of gas, ash, and rock debris known as tephra.