Four people have been killed in two separate avalanches in the state of Colorado in the past week. On Monday 1 February 2021 three skiers were killed by an avalanche at Ophir Pass near Silverton in San Juan County. They have subsequently been identified as Seth Bossung, Andy Jessen and Adam Palmer, all residents the town of Eagle in Eagle County. A fourth skier was also caught in the avalanche and buried, but onlt received minor injuries. On Thursday 4 February another Colorado man, identified as John Kuo, 41, of Vail, again in Eagle County, was caught in an avalanche in the East Vail Chutes, which was described as being about 700 m wide, and to have run downslope for about a kilometre. This brings the number of people killed by avalanches in Colorado so far this winter to eight, compared to six in the entire winter of 2019-2020.
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.
See also...
Follow Sciency Thoughts on Facebook.
Follow Sciency Thoughts on Twitter.