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Geography

Avalanches

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There is a significant risk of avalanches occurring in glacial areas such as the Alps. They can cause widespread disruption, damage and sometimes loss of life.

Causes of avalanches

Alaska avalanche

An avalanche is a sudden downhill movement of snow. It is a significant hazard to people living in, or visiting, glacial areas. A slab avalanche [slab avalanche: A type of avalanche where there is a fast movement of less powdery heavy snow. ] is the most dangerous form of movement. It can be caused by:

  • heavy snowfall
  • deforestationdeforestation: the process of cutting down a large number of trees in a forest and not replacing them (for example because of new ski runs) making the slope less stable
  • steep slopes, as this helps to increase the speed of movement
  • vibrations (for example from an earthquake, noise or off-piste [off-piste: When someone does not ski on the designated runs. ] skiers)
  • layering of snow - for instance where snow is already on the mountain and has turned into ice, and then fresh snow falls on top which can easily slide down
  • the wind direction piling snow which can overhang a mountain

Effects of avalanches

An avalanche is able to obstruct anything in its path. Roads and railways can be blocked. Power supplies can be cut off.

A powerful avalanche can even destroy buildings.

People can also be killed.

90 per cent of people who die in avalanches trigger them themselves.

People usually die from a lack of oxygen when buried in snow, rather than from getting too cold.

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