Earthquakes are caused by a sudden release of stress along faults in the earth's crust. The continuous motion of tectonic plates causes a steady build-up of pressure in the rock strata on both sides of a fault until the stress is sufficiently great that it is released in a sudden, jerky movement. The resulting waves of seismic energy propagate through the ground and over its surface, causing the shaking we perceive as earthquakes.Generally, earthquakes occurring in Switzerland results from collisions between the European and the African lithospheric plates. Induced quakes are caused by human activity, like tunnel construction, filling reservoirs and implementing geothermal or fracking projects.

Intensity: Measure of earthquake size in terms of the observed effects at the Earth's surface. In Europe earthquake intensities are classified from I to XII according to the European Macroseismic Scale (EMS-98), previously also known as the Mercalli Scale. (Examples: light structural damage = intensity VI; heavy structural damage = intensity VIII.)

Magnitude: Measure of earthquake size in terms of the energy released at the source. It is calculated from the amplitude of the instrumentally measured ground motion (seismograms). Magnitudes are calculated by a variety of different methods that result in slightly different values. However, ultimately they are all related to the well-known Richter Scale. The magnitudes given here correspond to the so-called moment-magnitude.

Using its digital monitoring network, on average the Swiss Seismological Service (SED) registers two earthquakes a day in Switzerland and neighboring countries, making a total of between 500 and 800 quakes a year. Usually, around 10 to 15 of these events are strong enough (i.e. have a magnitude of 2.5 or above) to be felt by the local population.In principle, near the epicenter, earthquakes with a magnitude of 2.5 or above can be felt. Only rarely do we receive earthquake notifications for events with a magnitude of just under 2. Earthquakes with magnitudes of 3 or higher are felt by large numbers of people; at magnitudes of between 4 and 5 they can be felt within a radius of up to 200 kilometers; and at magnitudes of 5 or more they can be felt up to several hundred kilometers away under some circumstances.