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 is in a pyroclastic flow?

A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases. ... Along the ground, lava and pieces of rock flow downhill. Above this, a thick cloud of ash forms over the fast-moving flow.

What is pyroclastic flow GCSE?

A pyroclastic flow is a mixture of hot steam, ash, rock and dust. A pyroclastic flow can roll down the sides of a volcano at very high speeds and with temperatures of over 400°C.