Swiss Earthquakes in 2013: A Review

In 2013, the Swiss Seismological Service registered and localized around 600 earthquakes in Switzerland and its neighboring countries. Additionally, local seismic networks in the St. Gallen and Sargans regions detected nearly 300 microearthquakes over the same period. The magnitude of the earthquakes recorded in 2013 ranged between –0.6 and 4.1 on the Richter magnitude scale. Compared to the two previous years, this represents a slight increase in earthquake activity. The number of eathquakes with a magnitude of 2.5 or greater was 21, which is close to the average of 23 events per year over the past 38 years.

Three earthquakes were clearly felt by the population in 2013: the earthquake near St. Gallen on July 20 (magnitude of 3.5) and the two earthquakes near Sargans on December 12 and 27 (magnitudes of 4.1 and 3.7). The St. Gallen earthquake was part of a sequence of over 300 localized events between July and November that are linked to test and simulation activities carried out as part of the planned geothermal energy project. The earthquake with a magnitude of 4.1 on December 12 near Sargans was followed by a series of over 30 aftershocks that were sustained into the second half of January 2014.

Generally speaking, the earthquakes in 2013 were concentrated in Valais and the canton of Graubünden, not unlike past years. There were also more earthquakes in Central Switzerland, the canton of Fribourg, and along the Jura than in the rest of Switzerland.