- Sara Thompson
Avalanche Awareness on the Slopes
By Sara Thompson
Special to the Enterprise
An avalanche is best known as a large amount of snow flowing down a slope but can also refer to rocks or other debris that slides and behaves in a similar way. Avalanches may seem unpredictable and random, but there are specific conditions and events that need to happen for an avalanche to occur. Knowing what to look for, snow scientists, geologists, and engineers are beginning to know what to look for and are able to prevent and predict these events.
Avalanches need three things, snow or other debris, a slope, and something to cause it called a trigger. The slope is the simplest part, as snow often accumulates in mountains and hills. Most avalanches occur on slope between 25o-60o, with the average being around 35o-45o. The snow of avalanches is complex and have layers similar to soil. As snow falls in the mountains, it has different water content and texture and can change if exposed to air or sun. For an avalanche to occur, the snow needs to have an initial bed of snow, with a weaker layer on top, and an overlaying bed of snow. As the top layer becomes heavier, the weaker middle layer will collapse and fail, causing it and the upper layer to fall and slide down the slope. Snow weight can be a trigger for avalanches, but any number of things can cause the weak layer to fail and move the snow on top of it. Earthquakes can cause avalanches, and more commonly humans trigger avalanches.
Scientists are developing ways to study and understand snow science and avalanches. During the winter months, scientists dig into the snow to view the different layers of snow. They observe the layers and can determine which is the weaker layer and how much snow is above it. They look at the size and shapes of the individual snowflakes in each layer, with larger snowflakes being weaker because they do not pack as tightly as smaller snowflakes. By studying the snow layers, scientists can close off an area if it is high risk for an avalanche. Some ski areas and communities near mountains try to artificially trigger avalanches to help control where they go and can make sure no one is in danger. This occurs by having a team trigger snow at the top of a slope, or even firing a special cannon blast at the snowpack on a mountain.
If caught in an avalanche, many professionals suggest not trying to outrun it, you will not be able to. Instead try to angle towards the side, but still downhill. That way you can pick up speed going downhill but will be heading towards the edge and possibly to safety. So when participating in snow sports, keep an eye on conditions and look for avalanche reports from local snow scientists and always be safe.
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