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.<\/p>\n
These pyroclastic flows<\/a> can travel tens to hundreds of kilometers over rough terrain and even uphill (SN: 7\/7\/18, p. 32<\/em>). Despite being made of gritty volcanic rock, \u201cthey seem to have as much friction with the ground as if they were made of water,\u201d 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 \u201chas always been a mystery.\u201d <\/p>\n 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<\/a>. These findings, reported online April 8 in Nature Geoscience<\/em>, may help create more accurate forecasts of the speed and spread of these flows.<\/p>\n Gert Lube, a volcanologist at Massey University in Palmerston North, New Zealand, and colleagues created mini pyroclastic flows in the lab by piling volcanic material into a giant hopper and heating the rock up to 130\u00b0 Celsius. After using an elevator-like device to hoist the hopper into the air, the researchers dumped the hot volcanic material down a 12-meter shoot and tracked the flow with high-speed video.<\/p>\n\n\n
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