Encyclopedia of earthquake engineering

0450044 - GFÚ 2016 RIV DE eng M - Monography Chapter
Horálek, Josef - Fischer, T. - Einarsson, P. - Jakobsdóttir, S. S.
Earthquake swarms.
Encyclopedia of earthquake engineering. Berlin: Springer, 2015 - (Beer, M.; Kougioumtzoglou, I.; Patelli, E.; Au, I.), s. 871-885. ISBN 978-3-642-35343-7
R&D Projects: GA ČR GAP210/12/2336
Institutional support: RVO:67985530
Keywords : clustering of events * driving forces * earthquake location
Subject RIV: DC - Siesmology, Volcanology, Earth Structure

We present a review of knowledge of earthquake swarms. They are sequences of numerous events closely clustered in space and time and do not have a single dominant mainshock. Earthquake swarms are observed worldwide, typically accompany volcanic activity but also occur in intracontinental areas. Many swarms exhibit the b-value of the frequency-magnitude distribution ≈ 1, which is also a typical b-value for mainshock-aftershock sequences. Depths of swarm earthquakes range approximately between 2 and 20 km with the majority of swarm events located around 10 km and shallower. Earthquake swarms exhibit usually pronounced migration of the foci, particularly the swarms that are closely connected with intrusion of dikes. The source mechanisms signify that the swarm earthquakes are mostly shear-slips along a fault just as ordinary tectonic earthquakes. Triggering mechanisms and driving are mainly related to activity of pressurised hydrothermal fluids, magma injection, or dyke intrusion, and also to aseismic loading by creeping faults. Accordingly, numerous models trying to explain the seismic-energy release in the form of earthquake swarms have been proposed.
Permanent Link: http://hdl.handle.net/11104/0251427