As soon as the seismic stations are able to record the ground movements for an earthquake, information about the waveforms can be used to determine the location and strength of the earthquake. All recorded earthquakes are incorporated into local, regional, or global earthquake catalogs. These catalogs contain lists of the times, the places, and the magnitudes of all recorded earthquakes (see ECOS-09).
In Switzerland and its neighbouring countries, the Swiss Seismological Service has recorded just under 100 earthquakes with a magnitude of 2 or higher (noticeable in the immediate vicinity) every year, while in California there have been more than 5,000. Here, too, there are actually more earthquakes occurring, but they are too weak to be recorded by the seismic network. Only extremely sensitive, local networks installed, for example, as part of industrial projects, are able to record and determine the location of even tiny ruptures.