An avalanche is a mass of snow that travels down a mountain at high speed, capable of traveling across buildings or burying people alive. They are dangerous enough to destroy structures and be deadly when skiing or snowboarding – however people can survive them provided they’re adequately prepared.
Avalanches can be caused by fresh deposits of snow or the weight of skiers, snowmobilers or snowboarders. Earthquakes or explosions may also trigger them; even small vibrations could trigger them if the snowpack is loose and unstable.
Avalanches can be unpredictable events, moving anywhere from several feet per second up to hundreds of miles per hour and leaving trails of destruction in their wake that destroy bridges, cover roads and even bury or kill people.
How can you tell when it is unsafe to ski? Natural warning signs are usually the best indicator. Unstable snow will send out its message by cracking, collapsing or producing hollow sounding noises; hollow noises from wet snow indicate weak layers below its surface layer. People can measure risk levels through digging snow pits, watching for avalanches or consulting local advisors.
Most avalanches are caused by storms that add layers to the snowpack, creating conditions where thawing and refreezing of top layers may create lower friction surfaces that allow snowflakes to slide more easily downhill. Sometimes this means an instantaneous slide; sometimes more layers will follow.
As an avalanche moves downstream, it can cover entire mountainside terrain and all in its path – leaving behind debris such as trees, boulders and rocks as it heads towards its destination – at which point it eventually stops at what is known as its runout zone.
People can avoid an avalanche by moving either uphill or to either side of its flow, using air pockets in the snow to lift themselves out of its path, and by building barriers out of timber or boulders to slow or stop its flow.
Experiments were conducted to test whether offering participants opportunities to self-evaluate their understanding of avalanche risk could decrease the time needed to complete an avalanche problem graphic. Our findings demonstrated its success and indicate that bulletins should include such feedback opportunities to better inform users on potential risks they are exposed to.
