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| Titel |
Mechanism of fluid-induced micro-earthquakes near Landau, Upper Rhine Graben, Germany |
| VerfasserIn |
Joachim Ritter, Michael Frietsch, Laura Gassner, Joern Groos, Michael Grund, Jens Zeiß |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093948
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| Publikation (Nr.) |
 EGU/EGU2014-9177.pdf |
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| Zusammenfassung |
| Since 2006 micro-earthquakes (ML < 2.8) occur in the area of Landau, a town in the Central
Upper Rhine Graben, Germany. These events are related to the injection of fluids into
2,500-3,500 m deep boreholes. Within the MAGS project (www.mags-projekt.de) the
seismicity was monitored with a dense network of recording stations and the seismic
waveforms were analysed in details. The complex 3-D geological structure complicates
the application of 1-D methods, and tests were done using 3-D seismic waveform
modelling with the SOFI3D FD method. About 1,300 events were detected with
cross-correlation analyses, although the signal amplitudes are quite low and the
noise level in the study area is high. A part of the events was localised with an
absolute (HYPOSAT) and relative (hypoDD) method. The determined hypocentres
are aligned along discrete elongated structures which are interpreted as preferred
rupture zones. Fault plane solutions with FOCMEC indicate normal and strike-slip
shear mechanisms. The preferred strike of the faults is NNW-SSE to NNE-SSW
which is similar to the regional maximum horizontal stress direction (NNW-SSE).
The study of seismic shear wave anisotropy indicates a fast polarisation direction
which is also in NNW-SSE direction. This azimuth-dependent anisotropy as well as
the other seismological and tectonic models are consistent with fluid-filled faults
oriented in NNW-SSE direction which are (re-)activated by fluid injection at depth. |
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