The Swiss Seismological Service (SED) at ETH Zurich recently completed ten years of earthquake research. Their new model shows that earthquakes are a serious hazard for Switzerland and the natural hazard with the greatest potential for causing damage.
The SED published a model showing possible future earthquakes and the associated ground movements, which vary by location. The newly-published, seismic hazard model uses new and more exact data and improved predictive models. It replaces the model from 2004. Experts will use the new model to make decisions regarding earthquake mitigation and risk management.
Estimates of the hazard level in individual regions have changed only slightly since 2004. Valais remains the region at highest risk, followed by Basel, Graubünden, the St. Gallen Rhine Valley, and central Switzerland. Only the canton of Graubünden, and in particular the Engadine, has higher risk estimates than previously assumed.
The largest earthquake in Switzerland’s recorded history occurred in Basel in 1356 and measured 6.6. This quake and nine other notable ones since are shown in red on the SED map below. The major tremor closest to Lake Geneva occurred in Aigle in 1584 and measured 5.9. The most recent occurred in 1946 in Sierre in Valais and was registered at 5.8.
SED estimates that an earthquake with a magnitude of 6.5 to 7, like the Basel quake of 1356, will occur every 1,500 years. Such a quake would cause damage more than 100 kilometres from its centre. Several thousand deaths and tens of thousands of injuries would result. Property damage could run as high as CHF 50 to CHF 100 billion. According to SED, the most likely locations for such an event are the Alpine and Basel regions.