The Swiss Seismological Service (SED) pinpoints the location of between1'000 and 1'500 earthquakes every year, but very few of them are strong enough to be felt by the local population. The vast majority of earthquakes recorded in Switzerland occur in the Swiss Alps, especially in the cantons of Valais and Grisons, and as a first approximation, they can be said to result from collisions between the European and African lithospheric plates.