Avalanche

:This article refers to the natural event. For other uses, see Avalanche (disambiguation)

Causes

Avalanches occur when the load on the upper snow layers exceeds bonding forces (bonding to layer beneath, support from anchors such as rocks and trees, stress support from top or bottom of slope).

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Critical load may be exceeded naturally by adding new snow or by rapid loading, by falling ice, cornices and similar means. Forty-three climbers were killed in one avalanche in the Pamirs in 1990 when a serac crumbled on a slope above them and swept them into a crevasse http://www.fourteenerworld.com/Trivia/KenNolanArticle2.htm. The bonding forces within a snowpack are affected by temperatures (e.g., a lubricated melt layer, or a fragile crystal layer) before, during and after snowfall.

Related Topics:
Cornice - Pamir - 1990 - Serac - Crevasse

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Avalanches are also triggered by humans - because of the additional weight, kicks during skiing (e.g. during jumps) or intentionally by explosives, slope-cuts and other means. Contrary to common thought, avalanches are rarely caused by loud sounds. More than 90% of avalanche victims worldwide are due to avalanches triggered by the victim or someone in the victim's party.

Related Topics:
Skiing - Explosive

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