An avalanche is the sudden movement or sliding of a large amount of snow down a slope. They are most common during the months of winter and spring, but can occur in the summer months as well. Avalanches move at high speeds with a tremendous amount of force and pose a serious threat in most mountainous terrains. Read on to find out what causes this to occur.
What causes avalanches?
Avalanches are more likely to occur when the weight of the collected snow becomes too heavy to maintain its shape. As snow piles up during the winter months natural weaknesses and stresses develop in a snow bank due to affect of gravity. When these stresses and weaknesses are combined with external stresses the snow breaks away and avalanches occur. There are two types of avalanches that occur, loose snow avalanches and slab avalanches. Each of these is triggered by different external stresses.
There are various natural triggers that can cause unstable snow to slide down a slope. Some of these triggers include fresh snowfall, rises in temperature, rock movements and ice fall. All of these triggers add extra weight to a snow bank causing the snow bank to break away in slabs. Triggers such as rises in temperatures and solar radiation, as well as steep gradients are associated with loose snow avalanches. Rock movement and ice falls most commonly trigger slab avalanches as they place force on internal stresses.
Avalanches can also be caused by artificial triggers. Some of the most common artificial triggers are skiers and snowboarders, snowmobiles and explosions. Skiers and snowboarders can trigger loose snow avalanches as their weight and movement unbalances the soft snow. Slab avalanches are usually triggered by dramatic and direct force to the snow bank such as jumping a snowmobile or explosions.