Causes and effects of avalanches

Avalanche tumbling down a snowy hillside

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 is the most dangerous form of movement. It can be caused by:

  • heavy snowfall
  • deforestation (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 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 and people can also be killed.

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90 percent 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.