Fatalities caused by floods, debris flows, landslides, fall processes and avalanches
Natural hazard events can claim human lives. The number of fatalities depends, first, on the severity of the events and, second, on individual behaviour and the measures taken to provide protection against natural hazards. Thus this indicator demonstrates the success of preventive measures and the level of hazard-appropriate behaviour among the affected populations.
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Between 1946 and 2023 floods claimed a total of 125 lives, debris flows claimed 24 , landslides claimed 54 and fall processes claimed 96. Since 1946 an average of 2.6 fatalities were recorded annually as a result of floods, debris flows and landslides and 1.2 were recorded to fall processes. If extreme hazard events, for example the Goldau rockfall of 1806, are excluded, this figure has scarcely changed since the 19th century. The average number of fatalities for the period 1900 to 1971 alone is lower because fewer severe natural hazard events were recorded.
Avalanches claimed an average of 2.9 lives per year in the period 1936/37 - 2022/23. This figure does not include fatalities in open terrain (off-piste skiers and tourers).
Compared to the 19th century, the average number of fatalities has remained stable (Floods, debris flows, landslides and fall processes until 1945). Thus, in view of the considerable increase in the population, it has actually declined as a proportion of the total population. This development is not due to the fact that there are fewer severe natural hazard events today, but to the fact that numerous hydraulic engineering and forestry protection measures were implemented over the past 100 years. It also reflects the improvement in organisational measures and the comprehensive possibilities available today for alerting and rescuing people. The number of fatalities caused by natural hazards is at a low level today, which must be maintained.
As mandated by the FOEN, the Swiss Federal Institute of Forest, Snow and Landscape Research WSL has been systematically collecting data on storm damage in Switzerland since 1972. The hazard processes floods, debris flows, landslides and fall processes (since 2002) are surveyed. Up to now, the data collected has only included fatalities reported in connection with material damage caused by the processes mentioned above.
In order to conduct a more comprehensive survey, the WSL created a new database in 2015 based on systematic newspaper research to record all fatalities caused by floods, landslides, debris flows, rockfall, windstorms, lightning strikes, avalanches and other (rare) events such as earthquakes and ice avalanches since 1946. It includes all fatalities of people who had unwittingly or unintentionally exposed themselves to an obvious risk. Avalanche fatalities are recorded separately by the SLF).
For the period prior to 1946, the statistics are completed by the number of fatalities reported in the historical record of damage caused by weather events in Switzerland (WSL Report 330) published by the WSL in 1991. The data, although incomplete, shows the number of fatalities before 1946 to be just as high as today if not higher despite a significantly lower population back then.
A complete overview of fatalities caused by natural hazards is provided on the Portal EnviDat.
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