<P> A pyroclastic flow ( also known as a pyroclastic density current ) is a fast - moving current of hot gas and volcanic matter ( collectively known as tephra ) that moves away from a volcano reaching speeds of up to 700 km / h ( 430 mph ) . The gases can reach temperatures of about 1,000 ° C ( 1,830 ° F ) . </P>
<P> A pyroclastic flow ( also known as a pyroclastic density current ) is a fast - moving current of hot gas and volcanic matter ( collectively known as tephra ) that moves away from a volcano reaching speeds of up to 700 km / h ( 430 mph ) . The gases can reach temperatures of about 1,000 ° C ( 1,830 ° F ) . </P>
how fast was the pyroclastic flow in pompeii
how fast was the pyroclastic flow in pompeii
up to 700 km / h ( 430 mph )
up to 700 km / h ( 430 mph )