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Basel 1356

What Happened in Basel in 1356?

Following at least one foreshock on the afternoon of 18 October 1356, at around 10.00 p.m. an earthquake with a magnitude of 6.6 shook the city of Basel. This is the largest documented earthquake in Swiss history.

Expected ShakeMap if an earthquake with a magnitude of 6.6 was to strike Basel today (based on Seismo 12 scenario). A ShakeMap depicts the ground shaking triggered by an earthquake at every point in Switzerland.

Numerous houses collapsed, causing several fires that took a long time to extinguish (due to the prevalence of shingle or straw roofs and open fireplaces or heated ovens at the time). Considering the strength of the earthquake and the destruction caused, relatively few people were killed because most had remained outside after the foreshock.

A relatively comprehensive picture of the disaster can be pieced together from the 20 or so documents drawn up shortly after the earthquake that have survived to this day. Further numerical data and descriptions of the event stem from 1,356 documents written in the 15th, 16th, 17th or even 18th centuries. Indeed, this period was characterised by a very large number of writings about the earthquake, amounting to a veritable 'Basel seismophilia'.

The main reason for strong earthquakes in the area is the geological structure of the Rhine Plain, the southern end of which lies in the Basel region. After Valais, the area around Basel the second highest seismic hazard zone in Switzerland. There has been evidence of earthquakes in the history of Basel and its immediate surroundings since the 14th century. There may have even been a major earthquake near the Roman settlement of Augusta Raurica in around 250 A.D.

In May 2012, the federal government and cantons assessed how well prepared they were for the repercussions of a strong earthquake in Switzerland. The Seismo 12 exercise was based on the scenario of a magnitude 6.6 earthquake near Basel.

According to this scenario, the potential impact of such an earthquake in Basel today would be as follows:

  • Between 1,000 and 6,000 fatalities
  • 60,000 people seriously or slightly injured
  • 1,600,000 people homeless in the short term
  • 50% of buildings damaged
  • Property damage totalling between CHF 50 billion and 100 billion