Induced seismicity related to geothermal projects versus natural tectonic earthquakes and other types of induced seismic events in Central Europe

• Induced seismicity at geothermal sites (ISGS) in Central Europe.
• Comparison with other 8 types of induced and tectonic seismicity.
• Maximum observed magnitude of ISGS is smallest among all types of seismicity.
• Frequency-magnitude b-value of ISGS with 1.94 the second highest of all seismicity types.
• Rate of observed relevant magnitudes at ISGS is lowest of all seismicity types.

Induced seismicity related to fluid injection in geothermal systems has gained an increased public awareness particularly in Central Europe. The paper discusses occurrence of induced seismic events at sites of geothermal projects in comparison to natural tectonic earthquakes and other types of induced or triggered seismicity in Central Europe (i.e. in Germany and adjacent areas). Other types of induced events are those in areas of mining or exploitation of coal, salt and potash, hydrocarbon and ores. Furthermore, induced seismicity in connection with water reservoirs and intense precipitation in areas of karst geology is also discussed. The subject of this study is the induced seismicity of a data set of moment magnitudes Mw ≥ 2.0, while the distinct larger natural seismicity is displayed for Mw ≥ 2.5. Parameters of the strongest seismic events of all studied sources of seismicity are listed, presented in epicentre maps, and discussed with respect to their maximum observed magnitudes and their frequency-magnitude distributions. Macroseismic intensities of strongest seismic events at geothermal project sites are compared to data of an intensity based probabilistic seismic hazard map for Germany. The general conclusion is that observed induced seismicity at geothermal sites is minor in comparison to other sources of seismicity.