Frequency–Magnitude Distribution of −3.7 ≤ M W  ≤ 1 Mining-Induced Earthquakes Around a Mining Front and b Value Invariance with Post-Blast Time

Naoi, Makoto; Nakatani, Masao; Horiuchi, Shigeki; Yabe, Yasuo; Philipp, Joachim; Kgarume, Thabang; Morema, Gilbert; Khambule, Sifiso; Masakale, Thabang; Ribeiro, Luiz Felipe Brandini; Miyakawa, Koji; Watanabe, Atsushi; Otsuki, Kenshiro; Moriya, Hideshige; Murakami, Osamu; Kawakata, Hironori; Yoshimitsu, N.; Ward, A. K.; Durrheim, Raymond; Ogasawara, Hiroshi

doi:10.1007/s00024-013-0721-7

Cited by 28 publications

(40 citation statements)

References 22 publications

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“…Second, the non-linearity was attributed to the local geology and tectonics, i.e., heterogeneity and discontinuity of the rock structures with different thickness, strength, different in various parameters. For example, Naoi et al (2014) showed that the distribution of magnitudes is consistent with the G-R relationship only when events closely linked to blasting are not taken into account.…”

Section: Discussionmentioning

confidence: 99%

Time-dependent seismic hazard in Bobrek coal mine, Poland, assuming different magnitude distribution estimations

et al. 2017

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The purpose of this study is to evaluate seismic hazard parameters in connection with the evolution of mining operations and seismic activity. The time-dependent hazard parameters to be estimated are activity rate, Gutenberg-Richter b-value, mean return period and exceedance probability of a prescribed magnitude for selected time windows related with the advance of the mining front. Four magnitude distribution estimation methods are applied and the results obtained from each one are compared with each other. Those approaches are maximum likelihood using the unbounded and upper bounded Gutenberg-Richter law and the non-parametric unbounded and non-parametric upper-bounded kernel estimation of magnitude distribution. The method is applied for seismicity occurred in the longwall mining of panel 3 in coal seam 503 in Bobrek colliery in Upper Silesia Coal Basin, Poland, during 2009-2010. Applications are performed in the recently established Web-Platform for Anthropogenic Seismicity Research, available at https://tcs.ah-epos.eu/.

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Section: Discussionmentioning

confidence: 99%

Time-dependent seismic hazard in Bobrek coal mine, Poland, assuming different magnitude distribution estimations

et al. 2017

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“…16 Three of the accelerometers have a flat frequency response up to 25 kHz (Wilcoxon Model 736) and the other three up to 10 kHz (Wilcoxon Model 728). The AE sensors (GMuG, Bad Nauheim, Germany) cover up to 50 kHz and are very sensitive.…”

Section: Observation Of Ae Events At the Cooke 4 Minementioning

confidence: 99%

“…During our analysis period from 7:21 on 12 July to 00:00 on 2 September 2011, 291 230 AE events were identified as satisfying these conditions. Their magnitudes, estimated from the spectra, 16 ranged from M w À 5.3 to 1.3. Fig.…”

Section: Observation Of Ae Events At the Cooke 4 Minementioning

confidence: 99%

“…We visually inspected the travel-time readings, theoretical travel times, and observed waveforms for several hundred of these events and confirmed that obvious mistakes in readings led to erroneous hypocenter determinations in fewer than 1% of events. 16 The velocities of the P-and S-waves used in the analysis were 5700 and 3600 m/s, respectively, as estimated by transmission tests in which elastic waves from active ultrasonic sources were received by network sensors. 17 For this study, we used AE events that had at least 10 P-wave travel-time readings and root-mean-square (RMS) residuals of 0.2 ms or less, occurring in a volume measuring approximately 100 m (N-S) Â 180 m (E-W) Â 50 m (depth).…”

Section: Observation Of Ae Events At the Cooke 4 Minementioning

confidence: 99%

“…This paper presents our analysis of the seismicity around an advancing mining front using AE monitoring data in the Cooke 4 Mine (previously known as the Ezulwini Gold Mine) in South Africa. Deployed as part of the Science and Technology Research Partnership for Sustainable Development (SATREPS) program, [15][16][17][18][19][20] sensors have located AEs as small as À 4 in moment magnitude (M w ) or even smaller. We applied the joint hypocenter determination (JHD) method 21 to these AE data to improve the absolute location accuracy followed by the double difference (DD) method 22 to improve the relative location accuracy.…”

Section: Introductionmentioning

confidence: 99%

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Delineation of large localized damage structures forming ahead of an active mining front by using advanced acoustic emission mapping techniques

Moriya

Naoi

Nakatani

et al. 2015

International Journal of Rock Mechanics and Mining Sciences

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a b s t r a c tWe applied advanced mapping techniques to 291 230 acoustic emission (AE) events as small as around M À 4 that were recorded over 50 days by an ultra-high resolution network close to the active front of a tabular mining stope being advanced northward at 1 km depth in the Cooke 4 Gold Mine in South Africa. We first applied joint hypocenter determination (JHD) to improve absolute locations, and then applied the double-difference relative location algorithm to the JHD output. These steps resolved the seemingly continuous, dense cloud of AEs that extend about 20 m ahead of the stope front into several discrete, steeply dipping tabular clusters a few meters thick and 10-30 m in dip extent, separated by quiet intervals a few meters thick. The clusters have a strike parallel to the stope face and a dip of about 65°, resembling commonly observed large shear fractures along the plane of maximum shear (Ortlepp shears). In general, the activity of the clusters changed in similar ways as the stope face advanced, but each cluster remained stationary and the gaps between clusters were impressively quiet. This study demonstrates that high-resolution AE mapping can delineate the formation of large structures of localized damage in the highly stressed intact rock mass ahead of the stope face, a process that may culminate in hazardous seismic events.

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Quasi‐static slip patch growth to 20 m on a geological fault inferred from acoustic emissions in a South African gold mine

et al. 2015

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Three months of acoustic emission (AE) monitoring in a South African gold mine down to M w À5 revealed a newly emergent planar cluster of 7557 events À3.9 ≤ M w ≤ À1.8 (typical rupture radius of 6-70 cm) that expanded with time to reach a size of 20 m on a preexisting geological fault near an active mining front 1 km beneath the ground. It had a sharply defined, planar configuration, with hypocenters aggregated within a thickness of only several decimeters. We infer that the zone defines an aseismic slip patch on the fault, wherein the individual AEs represent failures of very small asperities being loaded by the aseismic slip. Additional support for the interpretation was obtained by analyzing composite focal mechanisms and repeating events. The patch expansion over 2 months was likely quasistatic because all individual AEs ruptured much smaller areas than the cluster size at the corresponding time. The b values dropped gradually from 2.6 to 1.4, consistent with a significant increase in shear stress expected of the mining style. Another cluster with similar characteristics emerged later on a neighboring part of the same fault and grew to a 10 m extent in the last weeks of the study period. The quasi-static expansion of inferred localized slow-slip patches to sizes of 10-20 m suggests that the critical crack length on natural faults can be at least as large, much exceeding the decimeter range derived from laboratory stick-slip experiments on saw-cut rocks.

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Frequency–Magnitude Distribution of −3.7 ≤ M W ≤ 1 Mining-Induced Earthquakes Around a Mining Front and b Value Invariance with Post-Blast Time

Cited by 28 publications

References 22 publications

Time-dependent seismic hazard in Bobrek coal mine, Poland, assuming different magnitude distribution estimations

Time-dependent seismic hazard in Bobrek coal mine, Poland, assuming different magnitude distribution estimations

Delineation of large localized damage structures forming ahead of an active mining front by using advanced acoustic emission mapping techniques

Quasi‐static slip patch growth to 20 m on a geological fault inferred from acoustic emissions in a South African gold mine

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