Author: Maria Temming / Source: Science News

Dumping literal tons of hot volcanic material down a lab flume may finally have revealed how searing mixtures of hot gas and rock travel so far from volcanic eruptions.
These pyroclastic flows can travel tens to hundreds of kilometers over rough terrain and even uphill (SN: 7/7/18, p. 32). Despite being made of gritty volcanic rock, “they seem to have as much friction with the ground as if they were made of water,” says Alain Burgisser, a geologist at the University Savoie Mont Blanc in France not involved in the new study. The driving force behind these flows “has always been a mystery.”
Now, lab experiments and computer simulations suggest that inside pyroclastic flows, a dense layer of volcanic material glides across the ground atop a low-friction layer made largely of air. These findings, reported online April 8 in Nature Geoscience, may help create more accurate forecasts of the speed and spread of these flows.
Gert Lube, a volcanologist at Massey University in Palmerston North, New…
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