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Avalanches

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Avalanches are a fascinating, but above all else, a supremely dangerous phenomenon. We are therefore researching how they form and travel and how we can optimally protect ourselves. By issuing avalanche warnings for the Swiss Alps, we perform an important national service.

 

Nowadays, we have a good understanding of how avalanches form. This enables us to publish reliable avalanche bulletins for the benefit of safety officers in ski resorts and local authorities, as well as backcountry skiers, freeriders and snowshoe hikers.

However, we cannot yet predict in detail exactly why, when and where an avalanche will be triggered. We conduct laboratory and field research into how weak layers are generated in the snowpack, how fractures form and propagate in them and how the snowpack eventually begins to slide – in other words, how avalanches form and release.

Complex physical processes are at work inside an avalanche. To be able to accurately assess the scale and destructiveness of avalanches, we have to understand these processes. We therefore need to be able to see inside avalanches. Our Vallée de la Sionne avalanche test site at Arbaz in the canton of Valais has been operating since 1997. The only facility of its kind in the world, it has technical equipment that allows us to gain just this kind of insight. The data collected helps us, among other things, to develop and improve avalanche simulation programs, which are used by engineers worldwide to assess hazards and design protection measures.

Villages and roads can be protected from avalanches in a variety of ways. Refraining from building in vulnerable areas, preventing avalanche formation by planting forestry or erecting barriers, minimising avalanche impact by means of protective structures such as snow sheds, and artificially triggering avalanches using explosives before too much snow has accumulated are just a few of the possibilities. We investigate how these different approaches work and how they can best be combined, including from an economic and legal perspective.

Last but not least, we also examine avalanche accidents involving snow sports enthusiasts in open terrain, to learn lessons for future prevention.

 

Focus Areas

Das Bild zeigt einen schneebedeckten Hang, in dessen oberem Viertel eine Schneebrettlawine angerissen ist.  Eine Aufstiegsspur durchquert die Gleitfläche und im unberührten Schnee links von der Lawine schlängelt sich eine Abfahrtsspur den Hang hinunter.

Avalanche formation

Whether an avalanche occurs depends to a large extent on the structure of the snowpack. We investigate the processes involved in the formation of an...

Vallée de la Sionne avalanche test site. Image: SLF Archive

Avalanche dynamics

In order to assess the hazard correctly, we need to understand the inner workings of avalanches. 

Eine Gruppe von Skitourengänger legt eine frische Spur durch eine ansonsten unberührte Schneedecke.

Avalanche science and prevention

Most avalanche accidents happen off-piste. Preventive behaviour is required to reduce the avalanche risk to an acceptable level.

Ein Ausschnitt des Lawinenbulletins

Avalanche warning

The SLF is responsible for providing an avalanche warning service on behalf of the Swiss federal government. 

Image: Stefan Margreth/ SLF

Avalanche protection

Protecting settlements and transport routes from avalanches is indispensable for life in the Alps. We assist planners and authorities.

Auf einem grossen Lawinenkegel in der Leidbachfurka stehen zwei Rettungshubschrauber.

Destructive avalanches and avalanche accidents

We keep a detailed database of avalanche events. Winter reports and accident analyses are a long-standing part of the SLF’s work.

 

News

SLF researchers have developed a method for automatically and reliably mapping avalanches in satellite images.

The year was marked by the arrival of the new director and the launch of strategic programmes and a research centre in Davos.

A new method enables more precise calculations of avalanche pressure on buildings or cable car pylons.

Overview of the weather, snow cover, avalanche danger and selected avalanche accidents which caused damage to people or objects (in German or French).

 

Publications

 

Bergfeld, B.; Van Herwijnen, A.; Bobillier, G.; Larose, E.; Moreau, L.; Trottet, B.; Gaume, J.; Cathomen, J.; Dual, J.; Schweizer, J., 2022: Crack propagation speeds in weak snowpack layers. Journal of Glaciology, 68, 269: 557-570. doi: 10.1017/jog.2021.118