Nothing makes a winter sports enthusiast happier than white slopes and pistes. At the beginning, the winter sports centres in Germany, Austria, France and Switzerland were very pleased with the snowfalls of the last few weeks. But the old saw is true also for snow: too much of a good thing can be dangerous. Consequently avalanche warning systems in many parts of the Alps have been set to the highest danger levels.
When snow slides
in January this year snow fell in many skiing centres to a depth of a hundred centimetres each day. With so much in a snow falling in a short time onto a slope, the load on the original snow cover grows as a result of the additional weight more rapidly than the individual layers settle and bind to each other. Additional factors of importance are temperature, wind strength and also the angle of the slope and the condition and composition of the ground.
Not all avalanches are the same
Slab avalanches can be recognised by the linear cracks they leave at right angles to the slope. In this type of avalanche large areas of the upper snow layers detach themselves from the underlying layers and slide down the slope, first of all as one piece “like a board”. These can be seen often on slopes with an angle between 25 and 50°. A loose snow avalanche consists, as is to be expected, mainly of loose snow. Small areas slide down the slope as a number of individual dots, gathering up on the way other snow crystals, with a result that the avalanche grows. This type of avalanche occurs often on slopes with an angle of between 40 and 60°. On slopes as steep as this, powder snow avalanches occur with speeds of over 300 km an hour. The snow is blown up into the air, leading to the formation of an aerosol – a snow and air mixture
Powerful and dangerous
When several tons of snow start to move and the movement gets out of control, it can lead often to people and animals being in extreme danger and also to considerable destruction. Victims of avalanches are threatened by suffocation through lack of oxygen, frostbite and injuries caused by impact with rocks. The snow masses, rushing down into the valley at high speeds, often lead to the complete destruction of buildings and trees.
Protection against avalanches
We can all do without avalanches and their terrifying consequences. Towns and other communities in mountain regions use a number of measures for protection against the “white giants”. In areas recognised as being a danger, the first measure is to stop all development of residential and business properties. Instead support structures, embankments and avalanche galleries are constructed. Furthermore many winter sports areas plant trees as protection. As a precaution large continuous snow masses are dynamited before they can slide down the slopes as avalanches.
Be careful at all times
Many winter sport enthusiasts find it difficult to resist the attractions of remote slopes covered with deep snow and not subjected to being “groomed”. Anybody who takes the risk involved should at least have an avalanche transceiver, an avalanche airbag, an avalanche balloon and a mobile radio. However, the probability of being caught by an avalanche is low provided that you, as someone used to winter sports, follow simple rules. A basic rule is that you should only ski on slopes for which there is a local mountain rescue service. And then you don't mind even if within limits there's even more snow.