WSL Institute for Snow and Avalanche Research SLF

Long-term statistics

The SLF has been collecting comprehensive data on all the avalanche accidents that have occurred in Switzerland since the winter of 1936/37. These data are compiled and analysed in the annual accident reports published by the SLF (German only). The most important statistics are presented here in a short overview.

Avalanche victims since 1936

The annual average number of fatalities over the entire period is 24 (Fig. 1).

Figure 1:Avalanche fatalities in Switzerland since 1936/37. The graph illustrates the fall in the number of fatalities in buildings and on transportation routes. The black line shows the 20-years mean values. Its maximal value is 31 and its actual value 21. The long-year mean value since 1936/37 (86 years) is 24.

Avalanche accidents are life-threatening events!

According to statistics, only a little more than one in two people who are completely buried by an avalanche (head in the snow) survive. The most common cause of death among those who are completely buried is asphyxiation because the person often has no air supply or has access to only a small pocket of air. The chances of a person surviving a complete burial therefore reduce significantly after just 15 minutes (Fig. 3, for details refer to Procter et al., 2016). For this reason, companions have a crucial role to play in quickly locating and freeing the person who is buried.

Life is also endangered if a person is swept along by an avalanche, even if the victim is not completely buried: at least one in seven fatalities occurs as a consequence of serious injury.

Figure 3: Survival curve showing the proportion of victims surviving complete burial in open terrain (backcountry, off-piste) from 2005/06 until 2012/13. During this period the probability of a person surviving complete burial stood at a little more than 50%. All persons who were completely buried and did not die from trauma injuries were considered.

Avalanche accidents per danger level

According to long-term average figures, most fatal accidents occur when danger level 3 (considerable) applies (Fig. 4).

Figure 4: Fatal avalanche accidents per danger level for persons caught while engaging in backcountry or off-piste activities (accidents between 2013/14 and 2022/23). Attention: this graph does not correspond to an individual's risk because only the absolute numbers of accidents are shown without reference to the sizes of the risk populations surveyed in each category. At hazard levels 4 and 5, the risk of an individual dying in an avalanche is therefore not statistically lower than at the other hazard levels.