A skier has been killed and another injured in an avalanche in Upper Weber Canyon in Summit County, Utah, at about 3.30 pm on Thursday 9 March 2023. The avalanche was triggered when a guided group of skiers, inadvertently skied onto a slope where a slab of hard-packed snow overlay a weaker layer, which gave way. The slab, which was about 400 m wide traveled about 1250 m downslope, carrying two of the skiers with it. When found both were fully buried. One of the victims was taken to a nearby hospital, where they are described as being in a stable condition, while the other had stopped breathing and could not be revived.
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.
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