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Institute of Geophysics of the CAS, v. v. i.
Under the project "Earthquake swarms and their triggering mechanisms in diverse tectonic environments (Bohemian Massif, Mid-Atlantic Ridge, Western Alps)" we set up a seismic network on Reykjanes peninsula in the southeast Iceland. All 15 stations were placed during August/September of 2013 to monitor earthquake activity in this region for at least 2 years.
Measured data allow us to study the seismic source and to compare the seismic activity with other regions of earthquake swarms.
Map of the REYKJANET network. Pink markers represent installed stations, blue markers are all possible station locations we considered. Rectangular markers depict stations of Icelandic regional network, governed by Icelandic Met Office. Violet markers represent stations of Icelandic Geosurvey company, triangles are all other temporary stations.
Earthquake swarms occur in diverse geological units. They have been studied with respect to various perspectives but the mechanism of their origin and evolution are still unknown. The aim of this project is to reveal the cause of the swarm-like activity instead of regular main shock-after shock sequence.
In this project we study the swarms from three different swarm areas in Europe: West Bohemia/Vogtland, Southwest Iceland and French Alps. Based on the analyses we will determine the characteristics of earthquake swarms which are related to tectonic setting and characteristics wchich are not related to tectonic setting. We want to derive a model of preparation,triggering and driving process of earthquake swarms. The model will consider interactions of tectonic stress, pore pressure of fluids and Coulomb stress. A special attention will be paid to crustal fluids and magma; we will try to discover what is the role of magma or crustal fluids during the generation and evolution process of earthquake swarms.
General information about the locality:
Seismic activity on Reykjanes peninsula is frequent and the magnitudes are about one magnitude stronger (i.e. 30x more energy) in comparison with West Bohemia. The occurence of earthquakes is connected with active crustal expansion. The mutual movement of Eurasian and North American tectonic plates and gradual penetration of mantle magma cause changes in the stress field under the surface and its subsequent release in the crust through earthqukes.
Project preparation and launching:
In 2010 we initiated a cooperation with Icelandic Met Office and started a common comparative study of West Bohemian and South Icelandic earthquakes. We analyzed catalogues of over 20 years of observations and we found out that the swarms in West Bohemia and South Iceland are alike.
An overview of seismicity in studied area (violet box) during 1991-2009.
For more detailed comparison (for example the seismoc source) we need more complex data (seismograms) measured in dense local network. Therefore we applied for a grant to gain such data.During the first year of the project we got in contact with swedish researcher group from Uppsala university,which had been monitoring Reykjanes earthquake activity during 2009-2013 in cooperation with a group from MIT a Reykjavik university. Thanks to their experience we obtained valuable information about the conditions on Iceland and use their base for stations. During August/September of 2013 we installed 15 stations in 14 days to continuously monitor the activity in this region.
Grant project reference:
GAP210/12/2336 - Earthquake swarms and their triggering mechanisms in diverse tectonic environments (Bohemian Massif, Mid-Atlantic Ridge, Western Alps) (2012-2016)