Avalanches

Avalanche Testing and Safety

White soft fluffy snow, hard to imagine something so innocent could be so destructive. Just picture a few tons of snow traveling down the mountain at approximately 80 miles per hour, taking down everything in its path. Avalanches have been a threat as long as there has been snow and mountains. Since I’m an avid backcountry skier it is important to learn about these life threatening snow masses. So in order to protect yourself from anything you must first learn how it works.

First off there is three main components to an avalanche, without them you can’t have an avalanche. They go as follows: 1) snow 2) slope 3) snow instability. Secondly, there are two kinds of avalanches; slab and loose snow. Loose snow are minor and usually never exceed 20 miles per hour. While slab avalanches are the destructive and deadly mountain slides. It is not uncommon for one of these to destroy a small town or forest. Since loose snow avalanches aren’t very dangerous, I will discuss slab avalanches. The fundamentals of how these snow masses occur, what to look for when testing and just all-together prevention.

The basic chemistry behind a slab avalanche is when one layer of snow does not bond to the layer below it. Any kind of temperature change, fresh snowfall, the weight of a person, all can cause the slab to break free from the lower layer. The formation of a slab is possible in many ways. One way is for the snow to develop a crust and then there be more snowfall. Since snow doesn’t bond to the crust it becomes a potential for an avalanche zone. Another way is for surface hoar to develop, or large ice crystal on the snow. This is usually caused by condensation on the snow surface. This will also have poor bonding characteristics, and cause for a potential slide. The crystal itself is also very stable and will stay in that formation until melted usually. Slab avalanches usually only occur between 35-45 degree slopes and on a concave slope. There are ways possible to test for an avalanche zone. These tests have been developed over the years by ski patrollers, avalanche safety, and seasoned mountaineers. Make sure whenever performing an avalanche test you are not in an area where you could possibly trigger or be in the path of an avalanche.

The most common test to use is the shear test.