Hazards Resulting from Tectonic Processes

A nuée ardente is a turbulent, fast moving cloud of hot gas and ash erupted from a volcano. They form during explosive eruptions as columns of erupted material collapse or during non-explosive eruptions when volcanic rock collapses. Nuées ardentes (pl) flow downslope into valleys at speeds that often exceed 50 mph and temperatures of 700 deg C. They spread laterally, travel near the ground, and are often accompanied by larger rocks and boulders from the eruption. These materials collectively are better known as pyroclastic flows, and the term nuée ardente is now considered outdated.

Pyroclastic flows are very dangerous due to their speed, temperatures, and tendency to travel near the ground. They can engulf victims within seconds. Escape on foot or by vehicle is nearly impossible, and they can incinerate nearly anything in their path. People outside the destroyed area can suffer burn injuries or asphyxia from inhaling hot toxic gases and ash. Pyroclastic flows are behind many of the deadliest eruptions on record. These facts have prompted earth scientists worldwide to seek tools that can provide early clues on pending eruptions and enable evacuations in advance.