Tremors struck Switzerland 900 times last year. In 25 cases, the magnitude exceeded 2.5 or higher, meaning that the tremors were perceptible for people in the vicinity of the epicenter. The vast majority of the tremors were admittedly too weak to be felt, but according to researchers at the Swiss Federal Institute of Technology in Zurich (ETH Zurich), earthquakes are the natural hazard with the greatest destructive potential in Switzerland.
Moderate tremors are a fact of life here. What's more, strong or even catastrophic tremors could occur anywhere at any time. According to Michèle Marti of the Swiss Seismological Service, there is a heightened risk in the cantons of Valais, Basel and Graubünden, as well as in central Switzerland and the Rhine Valley of St. Gallen. "Large earthquakes are more common in those areas than elsewhere. Quakes are rarer in Zurich than in, say, Brig, but they cause more damage," she points out. This is due to the greater building density and higher property values.
Switzerland is also vulnerable to tsunamis, as shown by research from the ETH Zurich. In the year 1601, for example, a tidal wave flooded the littoral zones around Lake Lucerne and the area around the city of Lucerne. It was preceded by a magnitude 5.9 earthquake, which triggered several landslides and a rockslide on Mount Bürgenstock. Switzerland is therefore not immune to this hazard, according to the ETH Zurich.
Admittedly, quakes that cause major damage are a rarity here. The last one occurred over 70 years ago in the canton of Valais in 1946. But when the earth shakes here, the consequences are grave due to the high building density. A major earthquake that causes damage and has a magnitude of around six is expected to occur somewhere in Switzerland every 50 to 150 years. Another earthquake like the one that hit Basel in 1356 with a magnitude of 6.6 – the strongest in Switzerland to date – would cost more than 100 billion Swiss francs according to experts from the ETH Zurich.
Earthquakes cannot be reliably predicted. Or should we say: not "yet"? "No one today can say whether it will ever be possible to predict quakes. Opinions differ greatly, even among researchers," says Marti. At the ETH Zurich, they are attempting to at least estimate the risks more reliably. To achieve this, a team at the Institute of Geophysics is developing computer models of the formation of earthquake cycles.
Risk analysis is one thing; protection is another. The situation with the latter is none too good in this country. Most Swiss are inadequately insured against earthquakes. As a rule, buildings insurance pays for only a small percentage of any damage. The Swiss Pool for Earthquake Coverage, which currently numbers 17 cantons following Bern's withdrawal on January 1, 2013, keeps 2 billion Swiss francs available in case of an incident. However, the insured buildings are worth 2 trillion Swiss francs.
"Where earthquakes are concerned, assets are gambled with, recklessly," says Reto Schweizer, head of property insurance at Zurich. In comparison: Flood protection is only an issue for five percent of the properties in Switzerland. "As regards earthquake risk, all of Switzerland is in the red zone. Yet there is far less coverage than for water," Schweizer points out. This comes as no surprise to Marti of the Swiss Seismological Service. "A major earthquake with a magnitude of at least six is expected to occur in Switzerland every 50 to 150 years. That is rare compared with other threats, which often causes earthquake prevention to take somewhat of a back seat in people's minds," she explains.
Adequate protection doesn't have to cost a lot. Zurich offers earthquake insurance to small and medium-sized enterprises (SMEs) starting at only 250 Swiss francs per year. The requirement, however, is that the company in question allow a customer advisor to provide general information on natural hazards. The basis for this is the Zurich Radar for Natural Hazards, which allows any online user to research how heavily a specific location is affected by climate hazards – and not only earthquake hazards.
