Is it not dangerous to ski on the flanks of the Etna volcano?

You didn’t think about that: that there would be a huge pack of snow on volcano. The island of Sicily is located in the middle of the Mediterranean Sea. But at the foot of the highest crater, far above the clouds, the skiers whirl over the volcano flanks as if they were in the Alps. Not far away, hot, black stones are stamping that bubbled out of the volcano less than a week before. On Videos on the internet It was even to see how people skied between the red, flowing lava (the term for magma once it is outside the volcano).

Does Snow not have an additional danger with an active crater? Because lava with water forms the recipe for very intense explosions: freatomagmatic eruptions.

Snow heats abruptly when it comes into contact with lava. It melts in Raptempo into water and immediately afterwards it turns into steam. The volume increases enormously.

« If a large amount of warming steam cannot go anywhere, because it is under a thick layer of lava, for example, the pressure increases enormously, » says volcanologist Bernd Andeweg from VU University Amsterdam. « Then the lava layer pops apart on top. » Even when, for example, lava flows into the ocean, the lava can suddenly splash apart. Or when a glacier is above the crater and large amounts of melt water flow into the crater.

In 2010, the latter stopped air traffic in Europe for days. Magma, which burst from the Icelandic volcano Eyjafjallajökull, came in contact with the ice of the glacier on top of the crater. Ash flew in the air about ten kilometers.

In 2017, a camera crew of the BBC and tourists were unexpectedly pelted on Etna when lava flows collapsed under the increasing pressure of steam. The people walked up head wounds, scratches and bruises, but not serious. They were lucky. « Bellins hot lava were thrown through the air about two hundred meters, projectiles of ten centimeters in diameter, » says Andeweg. Skiing (or walking) through the snow near an active crater is « absolutely very dangerous. » This was annoying locally, for people who were relatively close to the crater.

The snow lava combination can be even more dangerous for residents who live further down the crater than for crater visitors. « If large quantities of snow or ice suddenly melt due to the heat, a kind of mud flow of water and axle can arise that slides down rapidly, » says geophysicist Lennart de Groot of Utrecht University. Due to such a so -called Lahar demanded a relatively mild eruption of the Colombian volcano Nevado del Ruiz forty years ago, 23,000 lives. « An enormous amount of Slurry gathered in a valley that precisely led a village that was not prepared for that.

Last March a guide answered the Etna to the question of how he prevents hikers from walking over an explosive snow field: « I know the area. » Because they know the topography, the terrain and the snow conditions, guides know roughly in which areas of steam cannot escape and build up pressure. The walkers wear a helmet. With a radio in their pocket, the guides are constantly in contact with volcanologists who keep an eye on Etna day and night through large screens.

« Etna is one of the best monitored volcanoes in the world, » says De Groot. « But completely safe is to visit an active volcano never, certainly not with snow, » he says. But it’s beautiful. That is.

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