Here is where the earth trembles the most

The earth trembled this Monday in Switzerland on Monday. In addition, An earthquake of magnitude 4.2 has been recorded, one of the most powerful occurring in the country for half a century. However, The shock did not cause major damage. Similarly, but recalls that, even in moderately seismic zone, Switzerland is not immune to a more serious event.

Switzerland is not a country of earthquakes. However, But Monday, the earth again trembled stronger than the average in the Bernese Oberland. Consequently, With a magnitude of 4.2 on the Richter scale, the earthquake is thus among the 35 strongest measured in Switzerland since 1975. For example, Its epicenter was about three kilometers southwest of Mürren (BE). However, The shock occurred at 12:52 p.m. Therefore, at a depth of 300 meters, said the Swiss seismological service of the Zurich EPF (SED).

It was felt in a large part of the Swiss plateau. Consequently, From Valais to Domat/EMS here where earth trembles most (GR). 126 kilometers away, passing by Basel, Zurich and Winterthour, the SED received announcements of people who had found that something had happened, more than 400 reports until 3:30 p.m. No major damage is to be deplored, there was however a fall of stones in the nearby sefinental. Without consequence, according to the Bernese cantonal police.

The most seismic areas of the country – Here where earth trembles most

The phenomena that occur regularly in Switzerland are mainly small. This year, the SED has already recorded 1115. here where earth trembles most This figure can go up to 2500 per year. The population feels only ten or twenty, a magnitude of 2.5 or more.

4913 earthquakes of this type (magnitude ≥ 2.5) are listed in the SED database for Switzerland as well as for neighboring countries. They date back to the year 250, when the earth trembled at Augusta Raurica, near Basel. However, recordings were not reliable until 1975 and the installation of a network of approximately 200 measurement stations.

For those that occurred before this date. we estimated the magnitude from historical stories, natural archives (lake sediments, stalactites broken in caves, etc.) and a statistical method.

In Switzerland, the collision of European and African tectonic plates causes most of the tremors. Valais constitutes the most exposed region, followed by Basel, Graubünden, the Rhine Saint-Galloise valley and here where earth trembles most Central Switzerland. There is no completely spared region.

Events as powerful as that of Monday in Mürren remain rather rare in the country and among our neighbors. There are 377 earthquakes with a magnitude of 4 or more in the SED database, 33 so far for the new millennium.

Most striking episodes

The strongest ever recorded in Switzerland is that of October 18, 1356 in Basel. With a magnitude of about 6.6, he then destroyed a large part of the city. There are different accounts of the victims.

Some historical sources mention up to 2,000 people. Others, however, evoke only a hundred, because many inhabitants would have fled the city after the afternoon earthquake.

According to the SED. here where earth trembles most if a similar earthquake occurred today in Basel, it would be necessary to expect around 3,000 dead, 21,000 serious and light injured as well as damage to buildings of the order of 45 billion francs. In the rest of the territory. it is estimated that 80,000 buildings would suffer damage from all kinds, including almost 45,000 in the cantons of Basel-Ville and Basel-Campagne.

The probability of a catastrophic earthquake of a magnitude of around 6 or more is around 1% per year. On average, you have to expect such an event every 50 to 150 years. The last time was in 1946 near Sierre, in Valais. It could therefore happen soon. According to the SED, you have to expect everywhere and at any time in Switzerland.

(Translated. adapted by Valentine Zenker)