François Louchet of the “Laboratoire de Glaciologie et de Géophysique de l’Environnement, Université Joseph Fourier Grenoble/CNRS” (CNRS is the French equivalent to the US National Research Council) and Alain Duclos (Avalanche expert and consultant as well as founder of the data-avalanche.org site) have done a lot of research on avalanche dynamics and published extensively in this field. What I particularily like about their work is the constant effort to link the fundamental research to actionable data i.e. making sure that the knowledge translates into meaningful recommendations for actions on the field. All too often I feel we get bombarded with “avalanche science” that leaves us wondering how this knowledge makes us any safer. It doesn’t help that the knowledge presented sometimes leads to conflicting conclusions with the prior “knowledge”… In any case the article here describes slab release (avy) as a four stage process:
1. Skier’s weight ‘breaks” the weak layer and thereby disrupts an unstable balance
2. Break propagates now under the slabs weight (up and down)
3. A localized crown crack occurs
4. Crown crack propagates (left and right)
An interesting fact to remember is that these four conditions are all necessary for the release of an avalanche i.e. if any one of these factors is missing there is no avalanche no matter how “bad” or unstable the conditions. This is of real interest for two reasons:
It focuses the skier’s attention on what really matters.
It helps us take nearby slopes really seriously, not only the one we are on.
Click here to access the article by François Louchet and Alain Duclos as well as the animations I made to (hopefully) illustrate and therefore facilitate the understanding of this four step process.
If you only want to access part of above, here are the links to the individual items :
Animation of 4-step process
Animation of avalanche on flat