Record details

    Magma intrusions and earthquake swarm occurremce in the western part of the Bohemian Massif
Statement of responsibility
    Aleš Špičák, Josef Horálek, Alena Boušková, Čestmír Tomek, Jiří Vaněk
    Boušková, Alena
    Horálek, Josef
    Špičák, Aleš
    Tomek, Čestmír
    Vaněk, Jiří
Source title - serial
    Studia geophysica et geodaetica
    Roč. 43, č. 1
    s. 87-106
    9 obr.
    Obsahuje bibliografické odkazy
    Zkr. název ser.: Stud. geophys. geod. (Praha)
Subject group
    geologie regionální
    kenozoické vulkanity Českého masivu
    měření seizmické
    zemětřesení indukované
    zemětřesný roj
Geographical name
    Česká republika
Abstract (in english)
   We are proposing a hypothesis that earthquake swarms in the West Bohemia/Vogtland seismoactive region are generated by magmatic activity currently transported to the upper crustal layers. We assume that the injection of magma and/or related fluids and gases causes hydraulic fracturing which is manifested as an earthquake swarm at the surface. Our statements are supported by hree spheres of evidence coming from the western part of the Bohemian Massif: characteristic manifestations of recent geodynamic activity, the information from the neighbouring KTB deep drilling project and from the 9HR seismic reflection profile, and the detalied analysis of local seismological data. (1) recent manifestations of geodynamic activity include Quaternary volcanism, rich CO2 emissions, anomalies of mantlederived 3He, mineral springs, moffets, etc. (2) The fluid injection experiment in the neighbouring KTB deep borehole at a depth of 9 km induced hundreds of micro-earthquakes.
   This indicates that the Earth's crust is near frictional failure in the western part of the Bohemian Massif and an addition of a small amount of energy to the tectonic stress is enough to induce an earthquake. Some pronounced reflections in the closely passing 9HR seismic reflection profile are interpreted as being caused by recent magmatic sills in the crust. (3) The local broadband seismological network WEBNET provided high quality data that enable precise localization of seismic events. The events of the January 1997 earthquake swarm are confined to an extremely narrow volume at depths of about 9 km. Their seismograms display pronounced reflections of P- and S-waves in the upper crust. The analysis of the process of faulting has disclosed a considerable variability of the source mechanism during the swarm. We conclude that the mechanism of intraplate earthquake swarms generated by magma intrusions is similar to that of induced seismicity.
   As the recent tectonic processes and manifestations of geodynamic activity are similar in European areas
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    6. 3. 2008
Import date
    8. 8. 2012