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25.01.2017

Natural hazards fatalities have been falling since 1946

Natufgefahren
Flooding in Switzerland in 2015. (Photo: Egli Engineering AG, naturgefahr.ch)
Todesfälle_EN

The map shows the death toll from natural hazard events between 1946 and 2015, with avalanches and rockfalls occurring mainly in the alpine and subalpine regions, whereas deaths brought about by storms and flooding are especially frequent on the Swiss Plateau. (Image: A. Badoux et al., Nat. Hazards Earth System Sci., 2016).

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Since 1946, events associated with natural hazards have claimed more than 1,000 human lives. Researchers at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) have now compiled a database of these fatalities to analyse the development of casualty figures over time.

"Our aim was to create a database going back 70 years and covering all deaths caused by floods, landslides, debris flows, rockfalls, storms and avalanches", explains Alexandre Badoux, an earth scientist at the WSL and lead author of the study. The only accidents included in the database were those which concerned the protection of the population in residential areas and along transport routes. This allowed for the first time determining and comparing when and where fatalities occurred and which natural hazards had claimed most lives.

Newspaper archive combed

To find out how many casualties had occurred in the past, the researchers searched the digital archive of the Neue Zürcher Zeitung (NZZ) for corresponding keywords. "We opted for the NZZ because it's comprehensive and trustworthy. Furthermore, it reports on events all over Switzerland", says Badoux. The study also took account of the victims listed in the destructive avalanche database, kept by the WSL Institute for Snow and Avalanche Research (SLF) since winter 1936-37, as well as casualties listed in the storm damage database co-financed by the Federal Office for the Environment (FOEN) and run by the WSL since 1972. Unlike these, the new database also includes lightning and storm victims.

Since the aim of the study was to improve civil protection measures, it excludes those victims who died while engaging in leisure activities on unsecured terrain, for example, off-piste and backcountry skiers. This is a challenge, for "today such avalanche accidents occur about 30 times more frequently than those affecting roads and villages", says Frank Techel, an avalanche forecaster at the SLF and co-author of the study. Moreover, many mountaineers and climbers are killed by lightning or rockfalls. This is confirmed by figures compiled by the Swiss Alpine Club (SAC).

Avalanches and lightning strikes

The research showed that over the period in question 1,023 people were killed in the course of 635 natural events. More than a third of all these fatalities were caused by avalanche accidents, with lightning strikes as the second most common cause of death, claiming 164 lives. Over the past 70 years the numbers of deaths caused by both types of event have clearly fallen, and this fact also explains the general drop in the number of victims. The main reason for this improvement is intensive research into avalanches, which has greatly improved their prediction . Other reasons include added protective structures and better hazard maps. The number of accidents caused by debris flows, landslides, flooding, rockfalls and storms remained roughly stable.

In a worldwide comparison, the number of deaths in Switzerland caused by natural hazards is lower than average. "Nevertheless, the Swiss population's awareness of the risks of flooding, in particular, could be raised, so that even more lives can be saved in future", says geographer Norina Andres, another co-author of the study.

Major disasters are rare

Over the past millennium, Switzerland has repeatedly experienced major natural disasters causing hundreds of fatalities, like the earthquake that hit Basel in 1356 or the landslide in Goldau in 1806. But Switzerland was spared any such events over the last 70 years. The biggest disaster over that period occurred in 1965, when 88 people were killed by an ice avalanche during construction work on the Mattmark dam in the canton of Valais. Avalanches in Reckingen (VS) in the winter of 1970 claimed 30 lives, and 19 more died in those occurring in Vals (GR) in January 1951.

"However, natural disasters in Switzerland account for only a small proportion of all fatal accidents", stresses Badoux. Between 1946 and 2015, 60 times more people were killed in road traffic accidents and about five times more died in rail accidents than were killed by natural hazards.

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