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Scientists believe they have understood how pyroclastic flows, which cause death during volcanic events, can travel such incredible distances and speeds despite friction between the volcanic material and the soil.
Pyroclastic flows are hot mixtures of volcanic materials and gases that travel explosively over the slopes of volcanoes, sometimes crossing tens of kilometers to hundreds of kilometers per hour. They are responsible for some of the deadliest volcanic events, such as the Krakatoa eruption in 1883 and the 79th century eruption of Vesuvius that destroyed Pompeii. Although vomited rocks are expected to slow down due to friction, new research by scientists from New Zealand, Australia and the United States appears to show that the flow is flowing on a lube air cushion .
The volcanic material has a static friction of approximately 35 to 45 degrees, which means that it would not slide before being placed on a slope of 35 to 45 degrees, according to the article published today in Nature. Geoscience. And yet, pyroclastic flows can travel from tens to hundreds of kilometers on slopes with angles of only 8 to 9 degrees. How can the material move so far so long has remained a mystery? After all, it is difficult to mathematically model a death column that is accelerating.
The researchers explored the issue with the help of an experiment called PELE, the large-scale experiment on the eruption of a pyroclastic flow. The experiment consists essentially of a large heated container containing a ton of naturally aerated and natural volcanic particles, which are then deposited on a high friction chute 15 meters long and 1.5 meters wide leading to a concrete base . This is a sandpaper slide in the theme park of death.
During experiments recorded by researchers with a high-speed camera, the mixture separates into a denser underflow below and a cloud of ash 6 to 15 feet above. The cloud would reach 115 feet, while the undercurrent would reach 87 feet. The researchers performed a number of calculations and numerical modeling with the data and examined the sequences. The saw only areas with less particles developed near the ground. They hypothesized that, in these flows, materials moving faster upward generate high pressure areas closer to the ground, but not quite so. This would cause the gas particles to move to the lower pressure region closer to the ground and inflate an air pocket on which the flow could slip almost without friction.
Alain Burgisser, a scientist at the Savoie Mont Blanc University in France, wrote in a Nature Geoscience commentary: "The exact conditions in which this layer appears seem to be accurately determined." But the effect is exciting. to experimentally discover, and numerical modeling of researchers demonstrates that air lubrication could explain these pyroclastic flows in nature.
But these air cushions might not only describe pyroclastic flows. The authors may write that avalanches and landslides are also propelled by similar air cushions. It's physics for you. This can help you understand the mysteries of the Universe, but it will not stop your almost instantaneous death if you find yourself in the path of a pyroclastic flow.
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