Avalanche

A snowslide is more commonly referred to by which term?

And the answer: avalanche.    

Photo credit: Earth.Nautil

Common in snowy mountain ranges around the world, an avalanche normally occurs on a steep mountain slope without a lot of trees. Mountain climbers, skiiers, and snowmobile drivers cause 90% of avalanche disasters, triggering snow and ice to rapidly fall down mountainsides.

Avalanches come in many forms. "Sluffs" are cascades of loose snow that pick up speed as they race down the mountain, while "slab" avalanches occur when large sections of snow-pack crack off and crash down the slope. Sluffs are often triggered by outdoor recreationists, and tend to be less intense or disastrous.

Slab avalanches are far more deadly. When massive slabs of snow break loose from a mountainside, the mass of snow shatters like broken glass as it races downhill. These hazards can travel as fast as cars on a freeway– up to 100 miles per hour.

As snow falls, it begins to build up layer upon layer. With enough time, the layers will harden and bond to one another. However, when the layers form weak bonds, snow falls on an unstable foundation and can be easily triggered by movement. The most unstable part of the slope is called the "starting zone"– aptly named for the tip-off point for the avalanche. Once it starts to slide, it travels down the "avalanche track" (if you've ever noticed lines of fallen trees on a slope, it's likely from being unfortunately positioned on this track). Finally, the avalanche comes to a stop at the bottom of a slope, in the runout zone, where the snow and debris pile up.

To learn more about avalanches, and see a few in action, check out the videos below.


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