Avalanches, rapid movements of large masses of snow down a slope of a mountain, kill an average of about 150 people a year, according to National Geographic. Avalanches are not unique to certain massifs. Under the right conditions, they can occur anywhere, even in mid-summer. Geography and weather make some locations naturally more risky than others.
A large avalanche in North America might release 230,000 cubic meters (300,000 cubic yards) of snow, as per the National Snow and Ice Data Center (NSIDC). That is the equivalent of 20 football fields filled 10 feet deep with snow.
A significant number of deaths occur in May and June, according to the University of Wisconsin, demonstrating the hidden danger behind spring snows and the melting season that catches many recreationists off-guard.
Contrary to popular belief, shouting and loud noises don’t cause an avalanche. It is usually triggered by weight – a person walking in the wrong spot is enough – or wind.
When a weak layer of snow under a slab cracks, which often happens when pressure, such as weight, is quickly applied, an avalanche is likely to occur. Rising temperatures will cause melting, weakening the layers of snow, and strong winds will blow it faster than any storm.
Avalanches generally occur on slopes steeper than 35 degrees. The two main types of snowslides are slab, known as “white Death,” which are often fatal, and sluff. Slab avalanches occur when a cohesive slab of snow releases over a wide area and sluff avalanches occur when loose superficial snow releases at a point and fans out as it descends, according to the National Avalanche Center. The harder it snows or rains, the more difficult it is for the snowpack to adjust, and the more likely it is for the snowpack to avalanche.
If you are ever caught in an avalanche, lose the ski poles and make yourself lighter. Try to stay on top of the snow by pretending you’re swimming. Stick your arms up so rescuers can see you and quickly come to you. If you’re not near the surface, punch the snow to create an air space. Try not to panic so you can keep breathing steadily and not use all the air you have quickly.