Switzerland is located in a tectonically active region. The Swiss Seismological Service (SED) records between 500 and 800 earthquakes every year, of which 10 to 20 are typically noticed by the public. However, not all of these vibrations are of natural origin – some are triggered by human activity. In this case, science speaks of "induced earthquakes" or "induced seismicity". Induced, man-made earthquakes are, in principle, just like any other earthquake. These too are the result of a sudden release of tension along fractures in the earth’s crust. The seismic energy released by this movement spreads though the earth and along the earth’s crust in the form of waves, causing the vibrations that we experience as earthquakes. Induced earthquakes cannot be distinguished from natural ones on the basis of their physical characteristics.
Induced seismicity is often caused by major technological interventions in the subsoil. Man-made earthquakes were already observed over 100 years ago in connection with coal mining in Germany and the UK, for example. With few exceptions, these earthquakes are very small and are unnoticeable or hardly noticeable on the surface. Worldwide, induced earthquakes have caused significant economic damage in some cases but have resulted in few injuries and even fewer or no deaths. An overview of induced earthquakes worldwide can be found in the Snapshot "Man-Made Earthquakes". In Switzerland, man-made earthquakes are related mainly to geothermal energy projects. In 2006, an earthquake in Basel with a magnitude of 3.4 was triggered by water being injected at high pressure into the ground, and an earthquake with a magnitude of 3.5 occurred near St. Gallen in 2013. Induced earthquakes have, however, also been observed in Switzerland in connection with the construction of tunnels and dams.
The induced seismicity associated with international geothermal energy projects, as well as those in Basel (2006) and St. Gallen (2013), is thus a major challenge. The focus is therefore on the question of how the necessary rock permeability for a functioning geothermal energy project can be created without causing strong vibrations.