Q: What is a snowpack? A: In areas that get a lot of snow, the snow on the ground forms a snowpack. The layers within the snowpack have different qualities due to the shapes of the crystals in the layer.

Avalanches­ can be surprising, sublimely beautiful and deadly. They can sweep trains off their tracks, crush buildings, uproot trees and bury people. Some avalanches have even covered entire houses with people still inside them. Even though movies and news reports say that they "strike without warning," most deadly avalanches start when victims trigger them.

So what do you do if you're caught in an avalanche? How can you stay alive, and what does it take to rescue people who've been buried in the snow? In this article, you'll learn how avalanches form and what triggers them. You'll also learn how to survive and how to rescue others.

Avalanches are a serious danger for winter sport enthusiasts. Read all about ice climbing safety and watch video from Discovery’s Fearless Planet.

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