In normal circumstances, you should be safe in villages and on marked and open pistes in Europe and open areas within the ski area boundary in North America. But as soon as you venture outside these avalanche-controlled areas, the risks escalate. The vast majority of avalanche victims are holiday skiers or riders who have gone off-piste. And, according to the Swiss Federal Institute of Snow and Avalanche Research, almost all fatal avalanches are set off by the victims themselves.
What is an avalanche?
Avalanches occur when the stress trying to pull the snow downhill (gravity) is greater than the strength of the snow cover (the bonding of snow crystals). The four ingredients for an avalanche are:
- A steep slope - 90 per cent of all avalanches start on slopes of 30-45 degrees.
- Snow cover - more than 80% of avalanches occur during or just after heavy snowfalls and strong winds.
- A weak layer in the snow cover - fresh avalanches or cracks in the snow indicate unstable snow cover. Snow that has become wet from thaw or rain can be dangerous.
- A trigger of some sort - a skier or boarder's weight on the unstable snow pack can often be enough of a trigger to set off an avalanche.
What to do in an avalanche?
If you are unlucky enough to be taken by an avalanche, try to escape to the side or grab a rock or a tree. If you are knocked down, try to ditch your equipment and swim to try to stay on top and avoid obstacles. As the avalanche slows down, try to swim to the surface or make an air pocket around your mouth and nose. Try to keep your mouth shut at all times.
It is imperative that you are found and dug out as rapidly as possible. A study of avalanche accidents by researchers at the University of Innsbruck showed that 92 per cent of skiers completely buried by snow were still alive after 15 minutes. After 45 minutes the survival rate had dropped to 25 per cent. The last 25 per cent survived for one more hour on average. So rescuing avalanche victims quickly is the key to saving lives. Carrying and being able to use the proper safety equipment off-piste is essential.
How do you avoid an avalanche?
All resorts do their best to minimise the risk of avalanches. Pistes that could be at risk are closed and they often trigger off explosions on any potentially dangerous areas - cornices etc. Daily avalanche hazard ratings are posted for skiers and boarders to better assess the conditions (in Europe these are done on a scale of one to five, while in North America, they use colour coding).
- Level One (GREEN) indicates LOW RISK - natural avalanches are very unlikely. The snow is generally stable. Travel around the mountains is generally safe although normal caution is advised.
- Level Two (YELLOW) indicates MODERATE RISK - natural avalanches are unlikely, although, human-triggered avalanches are possible. There may be unstable slabs on steeper terrain. Use caution on steeper terrain on certain aspects.
- Level Three (ORANGE) indicates CONSIDERABLE RISK - natural avalanches are possible and human-triggered avalanches are probable. Unstable slabs are probable on steeper terrain. Use increasing caution and be aware of potentially dangerous areas of unstable snow.
- Level Four (RED) indicates HIGH RISK - natural and human-triggered avalanches are likely. Unstable slabs are likely on a variety of aspects and slope angles. Travel in avalanche terrain is not recommended. The safest travel is on windward ridges or gentler slopes without steeper terrain above.
- Level Five (RED WITH BLACK BORDER OR BLACK) indicates EXTREME RISK - widespread natural or human-triggered avalanches certain. Extremely unstable slabs on most aspects and slope angles. Large destructive avalanches are possible. Travel in avalanche terrain should be avoided and travel should be confined to gentle terrain well away from avalanche-path runouts.
If you do venture off-piste, it is essential that you do so with a trained guide and the proper equipment.