According to the Colorado Avalanche Information Center (CAIC), there were 30 fatalities in the US during the 2011-2012 season, eight of which occurred in Colorado. Avalanches are a serious threat to any backcountry snowboarder, skier, or snowmobiler, and many deaths are due to unheeded warnings.
As a result, Bruce Jamieson, NSERC Research Chair in Snow Avalanche Risk Control and a member of the Department of Civil Engineering at the University of Calgary, presented on “Snow Avalanche Risk to Recreationists and Workers.” He described how working as an avalanche forecaster in the field is one of the most dangerous jobs in Canada. According to him, “If you want to [have] a twenty-five year career working with avalanches, there’s about a three percent probability of fatality, a ten-year career, one percent.”
Currently, this fatality rate is twelve times higher than the average US construction worker and six times higher than US miners. Jamieson said, “This was a totally unacceptable statistic.”
In the last five years, though, there have been changes and the death rate has dropped dramatically. This drop in the death rate was mostly due to a change in the culture and new safety measures, such as risk controls, better field observations, and a veto system where if one field member did not want to ski the face due to avalanche risk, no one would ski it.
Avalanches are essentially massive amounts of snow sliding down slopes. There are several types, but the most dangerous are slab avalanches. Slab avalanches can form when stronger snow overlies weaker snow. The difference in strength varies and can be difficult to predict at times. Often, human triggered slab avalanches are 1-2 feet deep, have an area about half the size of a football field, and can reach speeds of over 20 mph within seconds.
Avalanches are a result of fractures and are caused by an external disturbance (such as a skier or dynamite), that propagates through weak layers. Oftentimes they do not propagate far enough to present an avalanche threat, but if they do it can be disastrous. Jamieson added, “It might seem a good thing to do to avoid the backcountry when there are weak layers. There are almost always weak layers out there and if we did that we wouldn’t be enjoying the mountains.”
The other problematic avalanche type in Colorado is a loose snow avalanche. Loose snow avalanches are a greater issue in the spring, when the snowpack surface is rapidly warming and losing strength. Loose snow avalanches happen when the surface snow does not have the strength to hold onto the snow beneath it. They usually start from a point, often under trees or cliffs and are usually less devastating than slab avalanches. A chunk of snow starts tumbling, and knocks more snow loose. The danger is that loose avalanches fan out as they descend. They can be big enough to tumble a rider or climber around, and can have serious consequences if they carry a recreationist or a worker into trees, confined gullies, or even over cliffs.
Being properly prepared when skiing in the backcountry is a necessity. Before going skiing in any avalanche threat area, a skier should at the very least have an avalanche beacon, a probe, and a shovel and know how to use each of them correctly. Jamieson added that it is paramount “to make terrain decisions before going out,” because once a skier is out on pristine snow they are “pretty good at rationalizing why an avalanche on the neighboring mountain doesn’t affect their line.” He advised skiers to be fussy about whom they travel with in the backcountry, to share close calls with each other, and get some training.