A twelve-year-old boy from London has survived despite being buried under snow for 40 minutes following an avalanche at the ski resort of La Plagne in the Savoie Department in the Auvergne-Rhône-Alpes Region on Wednesday 26 December 2018. The boy was part of a group of off-piste skiers (people skiing away from a marked trail) but had become slightly separated from the group when he was hit by the avalanche, which swept him about 100 m from where he was last seen, making it impossible for the rest of the party to locate him. Despite this, and the fact that he was not wearing an avalanche detector, he was located after about 40 minutes by a Belgian Malinois rescue Dog. The boy was airlifted to a local hospital by a rescue helicopter suffering from a broken leg, with local authorities describing his survival as 'miraculous', since very few people survive for more than about 15 minutes after being buried by an avalanche.
Avalanches are caused by the mechanical failure of snowpacks; essentially when the weight of the snow above a certain point exceeds the carrying capacity of the snow at that point to support its weight. This can happen for two reasons, because more snow falls upslope, causing the weight to rise, or because snow begins to melt downslope, causing the carrying capacity to fall. Avalanches may also be triggered by other events, such as Earthquakes or rockfalls. Contrary to what is often seen in films and on television, avalanches are not usually triggered by loud noises. Because snow forms layers, with each layer typically occurring due to a different snowfall, and having different physical properties, multiple avalanches can occur at the same spot, with the failure of a weaker layer losing to the loss of the snow above it, but other layers below left in place - to potentially fail later.
Diagrammatic representation of an avalanche, showing how layering of snow contributes to these events. Expedition Earth.
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