We saw these pictures of a massive avalanche in Facebook a few weeks ago, but when I read Arttu’s story in Vapaalasku.Com I thought HBS readers might also be interested. So this news article is based on the original news in Vapaalasku.Com, clearly the best Finnish-language freeride blog on Earth.
Aadne Olsrund is our mate living in Tamokdalen, Norway. Although early January is pretty quiet up there, a fellow skier told Aadne about the remains of a huge avalanche. Aadne decided to take a look, and what he found was maybe not the biggest avalanche on Earth but very big and literately massive.
“My hand reaches about 2,3 meters”, says Aadne Olsrund
This “avalanche from hell” was a wide giant of about 700-800 meters that slid over one kilometer pushing the snow down into a valley. According to Aadne, the thickest part of the slab was well over 3,5 meters. The slope is only about 20-25 degrees steep, but in lower section the grade becomes 30-40 degrees.
Avalanches are classified by their morphological characteristics, and are rated by either their destructive potential or the mass of the downward flowing snow. Some of the morphological characteristics used to classify avalanches include the type of snow involved, the nature of the failure, the sliding surface, the propagation mechanism of the failure, the trigger of the avalanche, the slope angle, direction, and elevation. Avalanche size, mass, and destructive potential are rated on a logarithmic scale, typically made up of 4 to 7 categories, with the precise definition of the categories depending on the observation system or forecast region.
I guess in the European avalanche size table this avalanche is considered “large” (biggest one on scale 1-4). Any arguments?
In avalanches the snow pack is composed of deposition layers of snow that are accumulated over time. The deposition layers are stratified parallel to the ground surface on which the snow falls. Each deposition layer indicates a distinct meteorological condition during which the snow was accumulated. Once deposited a snow layer will continue to evolve and develop under the influence of the meteorological conditions that prevail after deposition.
For an avalanche to occur, it is necessary that a snow pack have a weak layer (or instability) below a slab of cohesive snow. “I wasn’t able to recognize layers in snow cubes, but they I can say they were huge and hard as concrete“, says Aadne.
Avalanches are always caused by an external stress on the snow pack, they are not random or spontaneous events. Natural triggers of avalanches include additional precipitation, radiative and convective heating, rock fall, ice fall, and other sudden impacts; however, even a snow pack held at a constant temperature, pressure, and humidity will evolve over time and develop stresses, often from the down slope creep of the snow pack.
Human triggers of avalanches include skiers, snowmobiles, and controlled explosive work. The triggering stress load can be either localized to the failure point, or remote. Localized triggers of avalanches are typified by point releases from solar heated rocks. Remotely triggered avalanches occur when a tensile stress wave is transmitted through the slab to the start zone, once the stress wave reaches the start zone a fracture initiates and propagates the failure.
These pictures from Aadne are truly impressive. Personally I have never seen anything similar out there and I hope I never get the chance to either. I mean I would rather stay away from such avalanches. I just wonder if Aadne was worried about a second avalanche when standing in front of that giant snow wall..
Have you witnessed anything similar? If yes, please share your experience by leaving a comment. If you have photos and you would like to share them with our readers, please send them to info@fiercermedia.com.
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Here are few examples of huge avalanches.
This is what a huge avalanche can do. This occurred in Argentiere, France back in 99. I woke up 6 am in Chamonix and went photographing when I saw helicopters flying. In an hour I started receiving phone calls and heard about the disaster. It was a sad day for many.
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[...] it is sunny and calm with fresh snow. Then I came across the picture posted above, which is from a frightening large avalanche from Tamokdalen, Norway, and suddenly I felt much safer sitting here in the office. There has been all sorts of avalanche [...]
[...] In case you didn’t notice our previous article check how massive and avalanche can be. [...]