Falling masses of snow and ice, avalanches pose a threat to anyone on snowy mountainsides. Beautiful to witness from afar, they can be deadly because of their intensity and seeming unpredictability. Humans trigger 90 percent of avalanche disasters, with as many as 40 deaths in North America each year.

Why are avalanches so powerful?

A fractured mass of snow may flow down a slope or become airborne. As a large avalanche speeds down a mountainside, it may compress the air below it, producing a powerful wind that can blow a house apart, breaking windows, splintering doors, and tearing off the roof. Avalanches strike suddenly and can be deadly.

What damage can an avalanche do?

Avalanches can completely destroy whatever is on its pathways such as houses, cabins and shacks. This force can also cause major damage to ski resorts as well as ski lift towers near or on the mountain. Avalanches also can cause roads and railroad lines to close.