| Summary: | English abstract Most earthquakes occur as accompanying activity of large tectonic earth- quakes at the edges of lithospheric plates. Another type of seismic activity are earthquake swarms, which are characterized by series of earthquakes with several dominant shocks of similar strength. The origin of earthquake swarms is mostly combination of tectonic stress and movement of hydrothermal flu- ids along the fault plane. Mainly, swarms are observed within volcanic areas but even in areas without recent volcanic activity, like in West Bohemia. This region lies above an intra-continental rift zone the Eger Rift and it has been seismologically active in past years, including swarms in 2008, 2011, 2013 and 2014 monitored by the local seismic network WEBNET with dominant shocks of magnitudes below ML 4.5. All these events are located in depths between 7 and 11 km and they create 8 km long focal zone with N-S orientation. However, the latter swarm changed its character from a continuous occurrence with a dominant shock to a main shock and aftershock activity. Contrary, the region of Reykjanes peninsula in Iceland is located above the Mid-Atlantic Ridge, which results in shallower depths between 2 to 9 km. Additionally, the seismic energy in this area is released as a typical swarm-like activity and migrates along. Institute of Hydrogeology, Engineering Geology and Applied Geophysics Ústav hydrogeologie, inž. geologie a užité geofyziky Faculty of Science Přírodovědecká fakulta
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