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| Titel |
Static and dynamic scaling relations from cm- to m- scale: A case study from in-situ geomechanical laboratory at Mponeng deep gold mine, South Africa |
| VerfasserIn |
Grzegorz Kwiatek, Katrin Plenkers, Georg Dresen |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055275
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| Zusammenfassung |
| We investigate the static and dynamic scaling relations of pico- and nanoseismic events
(MW > -4.1) recorded with a high-sensitivity seismic network at Mponeng deep
gold mine, South Africa. Our aim is to link the laboratory experiments on rock
samples to seismic events recorded in-situ and provide new insights into the ongoing
discussion whether the self-similarity is preserved for extremely small seismic
events. The in-situ JAGUARS (JApanese-German acoUstic emission Research in
South Africa) laboratory is located at a depth of 3543 m, close to the on-going
exploitation. Together with the local geological feature, the Pink Green dyke, the
investigated area is highly stressed and seismically active. The JAGUARS network,
composed of 3C accelerometer and 8 acoustic emission (AE) sensors covers the
limited volume of rocks of approx. 300 à 300 à 300 m and it is capable to record
the seismicity in a high frequency range (50 Hz–170 kHz, MW - 5.0 to MW0).
During the project, the acquisition system recorded more than 500,000 events. In this
study, the waveform data of two datasets are analyzed: (1) aftershock sequence of a
MW > 1.9 event that occurred 30 m from our network and (2) post-blasting activity
located at the exploitation level. Two different approaches are used to calculate
the source parameters: an absolute source inversion method and a spectral ratio
method. The calculated values of MW ranged from -0.8 down to -4.1 with source
sizes from 1.3 m to 8 cm. We do not observe a dependency of the static stress drop
and apparent stress on seismic moment, but definitely a self-similar behavior of
earthquake rupture process in the analyzed magnitude range. We find indications for slow
rupture velocities and high stress offshoot of analyzed seismicity, the signature
that the rupture process is friction-dominated for extremely small seismic events. |
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