On 7 March 2023, Switzerland’s federal government published its first systematic assessment of the impact of earthquakes on Switzerland’s residents, buildings and infrastructure.
The work produced the first publicly accessible and most reliable earthquake risk model Switzerland has had.
Statistically speaking, every person in Switzerland will experience at least one earthquake causing serious damage in their lifetime, said the authors. This makes earthquakes among the greatest risks facing Switzerland, along with pandemics and power shortages.
Although earthquakes occur less frequently than other natural hazards, they can cause significant damage. The earthquake risk model combines detailed information on earthquake hazard, the influence of local subsoil, the vulnerability of buildings, and the people and assets affected.
The greatest risks are in urban areas where infrastructure and population are at their densest.
The greatest earthquake risk is in the cities of Basel, Geneva, Zurich, Lucerne and Bern, in that order. Although the earthquake hazard in these regions differs, all five cities have, by virtue of their size, a large number of people and assets that would be affected by an earthquake. In addition, these cities have many buildings, some particularly vulnerable and often located on soft ground that amplifies seismic waves.
The greatest building damage from earthquakes is expected in the cantons of Bern, Valais, Zurich, Vaud and Basel-Stadt. Together these cantons account for around half of the estimated financial losses.
According to the model, over a period of 100 years, earthquakes can be expected to cause economic damage of CHF 11 to 44 billion to buildings and their contents.. In total, around 150 to 1,600 people would lose their lives and an estimated 40,000 to 175,000 would become homeless on at least a short-term basis.
Earthquake risk is not evenly distributed over time, but is dominated by rare, catastrophic earthquakes that usually happen without warning, said the report.
For example, if the magnitude 6.6 Basel earthquake of 1356 were to be repeated, the expected death toll in Switzerland would be around 3,000, with building damage totalling approximately CHF 45 billion.
The probability of an earthquake of magnitude 6 is on average once every 50 to 150 years somewhere in Switzerland or its neighbouring regions.
Oddly for a nation so exposed to earthquakes few private homes are insured against earthquake damage. Many other risks such as fire and weather damage are compulsory in Switzerland. However, earthquake insurance is optional.
According to reinsurer, Swiss Re, over three quarters of private buildings in Switzerland have no earthquake coverage. Because earthquakes are rare and are quickly forgotten, public risk perception is low. Private insurance isn’t expensive and probably well worth it given the potentially high costs of earthquake damage – click here for more on the subject.