Abstract
A seismicity and stress field analysis of a region in NE Bavaria reveals a complex picture of seismic dislocation. The magnitudes are generally low, the strongest event recorded had a magnitude of 2.3. In the southern part of the area investigated, earthquakes occur very rarely. During the observation period of approximately four years, only four events, two of them forming a doublet, were recorded. Hypocentral depths in the southern part are considerably great (15 to 17 km) and indicate a mafic lower crust. The seismicity of the Marktredwitz area, located in the western extension of the Eger rift, is dominated by earthquake swarms that are strongly clustered in space and time. The swarms occurred at depths between 10 and 14 km. Precise relative relocations show clear planar arrangements of the hypocentres and enable to identify the orientation of active fault planes. A comparison of the structural and geomorphological settings reveals major similarities in the occurrence of earthquake swarms compared to the situation in the bordering Vogtland/NW-Bohemia swarm area.
Focal mechanisms cover a wide range of faulting styles. Normal fault, strike slip and reverse fault mechanisms as well as movements along sub-horizontal planes were found. The focal mechanisms were used to invert for the stress field. The inversion results reveal an ambiguity for the state of stress in the area of investigation and allow two different interpretations: A clockwise rotation of the stress field from North to South as well as a predominance of two slightly different stress regimes are possibilities.
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Bohnhoff, M., Baisch, S. and Harjes, H., 2004. Fault mechanisms of induced seismicity at the superdeep German Continental Deep Drilling Program (KTB) borehole and their relation to fault structure and stress field. J. Geophys. Res., 109, B02309, doi:10.1029/2003JB002528.
Brudy, M., Zoback, M.D., Fuchs, K., Rummel F., and Baumgärtner, J., 1997. Estimation of the complete stress tensor to 8 km depth in the KTB scientific drill holes: Implications for crustal strength. J. Geophys. Res., 102, No. B8, 453–476.
Chen, W-P. and Molnar, P., 1983. Focal depths of intracontinental and intraplate earthquakes and their implications for the thermal and mechanical properties of the lithosphere. J. Geophys. Res. astr. Soc. 88, 4183–4214.
Dahlheim, H.-A., Gebrande, H., Schmedes E., and Soffel, H., 1997. Seismicity and stress field in the vicinity of the KTB location, J. Geophys. Res. 102, 18493–18506.
Dahm, T., Horálek, J., and Šíleny, J., 2000. Comparison of absolute and relative moment tensor solutions for the January 1997 West Bohemia earthquake swarm. Studia geoph. et geod., 44, 233–250.
DEKORP Research Group, 1988. Results of the DEKORP 4/KTB Oberpfalz deep seismic reflection investigations. J. Geophys. 62, 69–101.
Fischer, T. and Horálek, J., 2000. Refined locations of the swarm earthquakes in the Novy Kostel focal zone and spatial distribution of the January 1997 swarm in Western Bohemia, Czech Republic. Studia geoph. et geod., 44, 210–226.
Fischer, T., 2003. The August–December 2000 earthquake swarm in NW Bohemia: the firsts results based on automatic processing of seismograms. J. of Geodynamics, 35, No. 1–2, 59–82.
Fischer, T. and Horálek, J., 2003. Space-time distribution of earthquake swarms in the principal focal zone of the NW Bohemia/Vogtland seismoactive region: period 1985–2001. J. of Geodynamics, 35, No. 1–2, 125–144.
Gebrande, H., Bopp, M., Neurieder, P. and Schmidt, T., 1989. Crustal structure in the surroundings of the KTB drill site as derived from refraction and wide-angle seismic observations, in R. Emmermann und J. Wohlenberg (eds.), The German Continental Deep drilling Program (KTB), Springer Verlag, 151–176.
Gephart, J.W. and Forsyth, D.W., 1984. An improved method for determining the regional stress tensor using earthquake focal mechanism data: application to the San Fernando earthquake sequence. J. Geophys. Res., 89, 9305–9320.
Havir, J., 2000. Stress analyses in the epicentral area of Novy Kostel (Western Bohemia). Studia geoph. et geod., 44, 522–536.
Jost, M., Büsselberg, T., Jost, O., and Harjes, H.-P., 1998. Source parameters of injection-induced micro-earthquakes at 9 km depth at the KTB drilling site, Germany. Bull. Seism. Soc. Am., 88, 815–832.
Kissling, E., Kradolfer, U. and Maurer, H., 1995. VELEST User's Guide—Short Introduction, Institute of Geophysics and Swiss Seismological Service, ETH, Zürich.
Klinge, K., Plenefisch, T. and Stammler, K., 2003. The earthquake swarm 2000 in the region Vogtland/NW-Bohemia- earthquake recording at German stations and temporal distribution of events. J. of Geodynamics, 35, No. 1–2, 83–96.
Lienert, B.R.E. and Havskov, J., 1995. A computer program for locating earthquakes both locally and globally, Seism. Res. Lett., 66, 26–36.
Müller, B., Zoback, M.L., Fuchs, K., Mastin, L., Gregersen, G., Pavoni, N., Stephansson, O. and Ljungren, C., 1992. Regional patterns of tectonic stress in Europe. J. Geophys. Res., 97, 1178–11803.
Peterek, A. and Schröder, B., 1997. Neogene fault activity and morphogenesis in the basement area north of the KTB drill site (Fichtelgebirge and Steinwald), Geol. Rundschau, 86, 185–190.
Plenefisch, T. and Bonjer, K.-P., 1997. The stress field in the Rhine Graben area inferred from earthquake focal mechanisms and estimation of frictional parameters. Tectonophysics, 275, 71–97.
Plenefisch, T. and Klinge, K., 2003. Temporal variations of focal mechanisms in the Novy Kostel focal zone (Vogtland/NW-Bohemia) – Comparison of the swarms of 1994, 1997 and 2000. J. of Geodynamics, 35, No. 1–2, 145–156.
Rabbel, W., Beilecke, T., Bohlen, T., Fischer, D., Frank, A., Hasenclever, J., Borm, G., Kuck, J., Bram, K., Druivenga, G., Lüschen, E., Gebrande, H., Pujol, J. and Smithson, S., 2004. Superdeep vertical seismic profiling at the KTB deep drill hole (Germany): Seismic close-up view of a major thrust zone down to 8.5 km depth. J. Geophys. Res., 109, B09309, doi:10.1029/2004JB002975.
Scherbaum, F. and Johnson, J., 1992. PITSA, Programmable Interactive Toolbox for Seismological Analysis, IASPEI Software Library, Vol. 5.
Sibson, R.H., 1982. Fault zone models, heat flow, and the depth distribution of earthquakes in the continental crust of the United States, Bull. Seism. Soc. Am., 72, 151–163.
Slancová, A. and Horálek, J., 2000. Analysis of state of stress during the 1997 earthquake swarm in Western Bohemia. Studia geoph. et geod., 44, 272–291.
Snoke, J.A., Munsey, J.W., Teague A.G. and Bollinger G.A., 1984. A program for focal mechanism determination by combined use of polarity and SV-P amplitude ratio data, Earthquake Notes, 55, 15.
Sonnleitner, M., 1993. Vergleich unterschiedlicher Methoden der Spannungsinversion von Erdbebendaten – am Beispiel von Erdbeben aus der Region Vogtland/westl. Böhmen. Diploma thesis, Munich University, 101 p.
Stettner, G. (1971). Die Beziehungen der kohlensäureführenden Mineralwässer Nordostbayerns und der Nachbargebiete zum rhegmatischen Störungssystem des Grundgebirges. Geologica Bavarica 64, 385–394.
Švancara, J., Gnojek, I., Hubatka, F. and Dědáček, K., 2000. Geophysical field pattern in the west Bohemian geodynamic active area. Studia geoph. et geod., 44, 307–326.
Waldhauser, F. and Ellsworth, W.L., 2000. A double-difference earthquake location algorithm: Method and application to the Northern Hayward Fault, California, Bull. Seism. Soc. Am., 90, 1353–1368.
Waldhauser, F., 2001. HypoDD – A program to compute double-difference hypocenter locations, U.S. Geological Survey Open-File Report 01–113.
Wessel, P. and Smith, W.H.F., 1998. New, improved version of Generic Mapping Tools released. Eos Trans., 79 (47), 579.
Wirth, W., Plenefisch, T., Klinge, K., Stammler, K. and Seidl, D., 2000. Focal mechanisms and stress field in the region Vogtland/Western Bohemia. Studia geoph. et geod., 44, 126–141.
Zoback, M.D. and Harjes, H.-P., 1997. Injection-induced earthquakes and crustal stress at 9 km depth at the KTB deep drilling site, Germany. J. Geophys. Res., 102, 18477–18491.
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Seht, M.Iv., Plenefisch, T. & Schmedes, E. Faulting style and stress field investigations for swarm earthquakes in NE Baveria/Germany – the transition between Vogtland/NW-Bohemia and the KTB-site. J Seismol 10, 197–211 (2006). https://doi.org/10.1007/s10950-005-9008-5
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DOI: https://doi.org/10.1007/s10950-005-9008-5