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Formation of an avalanche requires only snow and a slope for it to slide down. Majority of avalanches begin during or soon after snowstorms. At this time, new layers of snow bind with the exisiting layers. This additional weight prevents the snow layers from binding well. Hence, starting an avalanche. As mentioned previously, avalanches can also occur during spring (wet-snow) The melting snow creates a slippery layer such that existing layers of snow can slide easily. These are some factors of avalanche formations. Explosions An avalanche can be set in motion through loud exploding sounds (e.g. low-flying aeroplane. The sounds produce causes vibrations, which might cause the snowpack to vibrate and thus, loosen, causing an avalanche. Heavy snowfalls The weight from deep piles of falling or drifting snow can produce an avalanche. Heavy snowfall exerts more pressure on the snowpack due to the additional weight. Cornices Hard winds cause the snow to gather in one direction to form a cornice, which hangs over the top of the slope. When a cornice falls, it can trigger an avalanche. Earth tremor Similar to the case of explosions, where large vibrations are produced, earth tremors can trigger avalanches especially when there is too much snow. Snow on ice Water below the surface freezes, forming a layer of slippery ice under the snow. Hence, there is less friction and the upper layers are more likely to slide, forming an avalanche. As avalanches are not only caused by natural occurences. As long as conditions apply, an avalanche can occur just by the very slightest movements. |