Earthquakes in Switzerland are quite frequent but rarely severe. If a major magnitude 6 or higher earthquake does occur, damage is immense. Earthquake-proof construction costs an average of just 1% of the total cost of a new building.
On average, the earth quakes in Switzerland twice a day. Of around 800 earthquakes per year, only around ten are perceptible. Precisely this fact can lull us into a false sense of security, because what many do not know is: earthquakes are the natural hazard with the greatest destructive potential in our country.
The last serious earthquakes in Switzerland were many years ago: 1946 in Sierre, 1855 in Visp-Stalden. Consequently, it is difficult for people to comprehend such a catastrophe and even more so to correctly assess one. As such, earthquakes pose an increased risk to people and their property.
According to statistics, in Switzerland we can expect an earthquake with a magnitude of 6 every 100 years. This could lead to enormous damage to houses, bridges and streets in a 25 kilometer radius around the epicenter. Should a quake as severe as that of 1356 in Basel – with a magnitude of 6.6, the most destructive earthquake in central Europe – occur in the same region today, it would claim up to 2,000 lives and cause from 50 to 100 billion francs' worth of damage to fixtures and furnishings. Currently only around 3 billion francs are insured by the united earthquake pool across the whole of Switzerland; this is less than a thousandth of the value of all buildings, contents and infrastructure in Switzerland. Obligatory earthquake insurance could therefore become a reality, in order to address this insurance deficit.
The most severe earthquakes have been measured in the St. Gallen Rhine Valley, in Engadin, in Mittelbünden, central Switzerland and above all in Wallis and in Basel. But there is no region in Switzerland where the risk of earthquakes should be ignored. This is the position of the Federal Office for the Environment. But what exactly is it that causes earthquakes in Switzerland? For millions of years, the Eurasian and African plates have been pressing against one another. Like two ice floes, the tectonic plates are intermeshed and grate against one another. When the rock finally breaks from excessive pressure, the tension is suddenly released deep underground, which causes the earth to quake. This is also perceptiblein Switzerland – the Alps were ultimately formed by the collision of these plates.