Erdbebenschwarm

During so-called earthquake swarms, numerous quakes occur in the same place over a short time, but not in any clear sequence consisting of a foreshock, main quake and aftershock. Earthquake swarms are nothing unusual worldwide, including in Switzerland. Swarm activity usually ends after a few weeks or months, but just occasionally the quakes increase in strength and number over time.

In February 1964, hundreds of earthquakes occurred over several months in the Sarnen region. The two largest, with magnitudes of 5.0 and 5.7 shook the region on 17 February and 14 March respectively. The value of the total damage caused would be equivalent to CHF 16 million in today's money.