Earthquakes cannot currently be systematically predicted. However, phenomena that could herald earthquakes are being monitored, including earthquake lights, earthquake clouds, elevated concentrations of radon, seismic quiet, electromagnetic signals, conspicuous animal behaviour and foreshocks, which sometimes precede main quakes (though only after a main quake does it become clear that they were actually foreshocks). But so far no patterns have been observed that could enable us to predict earthquakes reliably.

Nonetheless, three factors are known to have close links with earthquake prediction:

  • Earthquake early warning: The Swiss Seismological Service (SED) is currently testing an earthquake early warning system. Monitoring stations close to an earthquake immediately register the seismic waves it generates and trigger a warning for areas further away. Such warnings can be issued because the measurements are transmitted at the speed of light, i.e. faster than the speed at which seismic waves are propagated (around 3.5 km per second). However, since earthquake early warnings can only be given at a certain distance from the epicentre and are only useful for more powerful earthquakes, their practical use for Switzerland remains to be determined.

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Picture for The principles of an Earthquake Early Warning System
  • Earthquake hazard: The seismic hazard shows where within a certain timeframe and how frequently certain incidents of horizontal acceleration are likely to occur.
  • Earthquake models: Sophisticated models allow increasingly accurate statements on how probable an earthquake of a specific magnitude is within a specific region at a specific time:
    • Large earthquakes are often preceded by smaller ones
      Smaller earthquakes significantly increase the probability of a subsequent severe earthquake occurring. However, in absolute terms, the probability is still very low.
    • Strong earthquakes are only rarely followed by even stronger ones
      The probability of an earthquake with a magnitude of 5.0 being followed within the next seven days by an earthquake of equal or greater magnitude is around 10 percent. This means that in 9 out of 10 cases, no earthquake with a magnitude of 5.0 or above will occur over the following week.
    • Aftershocks are the norm
      Very strong ground movements triggered by an aftershock are around 1,000 times more likely than the statistical mean to occur on the first day after an earthquake with a magnitude of 5.0.

Learn more

Earthquake hazard in Switzerland

Earthquake prediction