Pyroclastic flow

A pyroclastic flow, pronounced pie-roh-class-tick, (also known as a pyroclastic density current) is a flow of hot volcanic gas and tephra, during a volcanic eruption. A cloud forms over the current of hot rock. This boiling column of superheated gas, sand, tephra, obsidian, and pumice can reach soaring temperatures of  and its average speed ranges from  to . 

They are extremely dangerous and can be deadly. A person cannot outrun a pyroclastic flow. Learn more at USGS.gov.

Category:Volcanology