The risk of serious seismic events occurring in Switzerland is classed as moderate to medium, but earthquakes are nevertheless considered by the Swiss environment office as the country’s greatest natural hazard. The potential cost of damage from a magnitude 7 quake could be as high as 60 billion francs, it says.
Around 800 earthquakes are recorded in the country every year but only around ten are large enough to be felt. Last year 31 quakes registered above 2.5 on the Richter scale, more than the average for the past four decades, however such fluctuations are normal, according to the Swiss Seismological Service (SED).
Strong earthquakes, classified as 6 magnitude or above, occur in Switzerland once every 50-150 years. The last was a 6.2 in Sierre in 1946. The probability of another occurring in the next century is a rather significant 75 percent, according to the SED.
Canton by canton
The canton of Valais is most at risk from earthquakes, followed by the Basel region, Graubünden, St Gallen and central Switzerland, where Monday's earthquake occurred. As such, Valais takes this natural danger seriously and has implemented a number of measures including carrying out earthquake response testing in 2015 and establishing an earthquake awareness and prevention centre (CPPS) in Sion last year. Members of the public can find out what it’s like to experience an earthquake in the centre’s simulator.
Reporting on the subject in 2006, the federal environment office said up to 90 percent of existing buildings in Switzerland were inadequately protected against earthquakes due to a lack of regulations at the time they were built. Though there is now a seismic building code specifying earthquake-resistant standards in Switzerland, seismic safety within construction is regulated by the cantons rather than the federal government. While some cantons – including Valais, Fribourg, Jura and Basel-City – require new buildings to adhere to the code, others do not.
Safe as the houses of parliament
In case of an earthquake, one safe place to be could be inside the Swiss federal parliament. Though there are no nationally-applied seismic safety rules in Switzerland, in 2000 the federal government decided to apply earthquake-resistant building standards to all newly built federally-owned buildings. All existing buildings were inspected and, if found lacking, would be earthquake-proofed during the course of renovations. Bridges and roads owned by the government were also assessed.
Following the 2011 Fukushima disaster in Japan Switzerland's five nuclear power plants were required to provide proof they could withstand a powerful earthquake, which they did. Last year, the Swiss federal nuclear inspectorate (ENSI) asked them to do so again, by 2020, to ensure they “comply with the latest scientific evidence,” ENSI said in a statement.
“Although nuclear power plants are some of the most earthquake-resistant buildings in Switzerland, earthquakes are a major part of the risk of nuclear power plants”, it noted.