Monday 24 December 2018

Avalanche kills snowmobiler in Wyoming.

A man has been died in an avalanche whilst snowmobiling near Horse Creek in Sublette County, Wyoming, on Saturday 22 December 2018. Dustin Lapant, from Rock Springs in Sweetwater County is believed to have triggered the event himself while attempting to ascend a steep gully. Mr Lapant was reportedly trapped beneath his snowmobile under the snow, and died before rescuers could locate him.

The approximate location of the 22 December 2018 Sublette County fatal avalache. Google Maps.

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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