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Effect of mining and geology on mining-induced seismicity – a case study

Khalil Heba, Chen Tuo, Xu Yu-Hang, Mitri Hani

Journal of Sustainable Mining

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2022

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Vol. 21, iss. 3

200--215

EN

Mining-induced seismicity is a commonly occurring phenomenon in underground mines. This poses a greater challenge to the safety of the mining operation. This paper presents a case study of the Young-Davidson mine in northern Ontario, Canada, where seismic events of magnitude Mn 2.0+ have been observed at mining depths of 600 to 800 m below the surface. The occurrence of large seismic events at such shallow depths is the key issue of this study. A comprehensive study of the microseismic database has been conducted to discern the root causes for the unusually strong seismic activities recorded at shallow depths. The effects of mining activities in the vicinity of two dykes intersecting the orebody on the seismic response are investigated. Variation of the b-value derived from the magnitude-frequency distribution is examined, and moment tensor inversion for three large seismic events is carried out to determine the source mechanisms. It is shown from this investigation that the influence of the sill pillar is more critical, leading to high mining-induced stress and the occurrence of large events. While the findings from this research are specific to this case study, they could be used to shed light on the causes of induced seismicity at other mines with similar conditions.

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The aftershock sequence at a deep nickel mine: temporal and spatial distribution, magnitude distribution, and aftershock decay following major events

Ma Xu, Westman Erik, Malek Farid, Nie Baisheng, Lin Shuangshuang

Acta Geophysica

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2022

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Vol. 70, no 3

1241--1252

EN

Mining-induced seismic events greatly threaten safety of underground workers and studying major seismic events would help mitigate hazards in deep mines. Characterizing the aftershock sequence of major events can contribute to developing a reentry protocol after major events occur at mines. This study uses two major events and their aftershock sequences at Creighton Mine to investigate properties of aftershock sequences focusing on the magnitude of completeness and aftershock decay pattern. Two major events with moment magnitude 3.1 and 1.4 are analyzed, respectively, and their aftershock sequence are examined in this study. The optimal magnitude of completeness is rigorously determined by evaluating the goodness of ft using the maximum likelihood method. Then, parameters of aftershock decay using the MOL are estimated. We identify that the p-value of the two studied events is slightly larger than 0.8. This parametrization process using the MOL can assist in better understanding aftershock sequences of mining-induced major events and therefore mitigating seismic hazards in mining by potentially helping establish a reentry protocol based on the seismicity dropping below a certain rate. For establishing a reentry protocol, the study of the two events can be considered as a methodological work and a future statistical work for many events with different magnitudes and locations to establish the range of the MOL parameters is needed.

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Comparison of source parameters estimated in the frequency and time domains for seismic events at the Rudna copper mine, Poland

Domański B., Gibowicz S. J.

Acta Geophysica

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2008

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Vol. 56, no. 2

324-343

EN

Source parameters estimated in the frequency domain for 100 selected seismic events from the Rudna copper mine, with moment magnitude ranging from 1.4 to 3.6, were collected to study their scaling relations and to compare them with the parameters estimated in the time domain. The apparent stress and static stress drop, corrected for the limited bandwidth recording, increase slightly in a similar manner with increasing seismic moment. The ratio of apparent stress to static stress drop, a measure of radiation efficiency, is practically constant and its mean value is close to 0.1. For 37 seismic events, with moment magnitude between 1.9 and 3.4, source parameters were estimated in the time domain from relative source time functions, that displayed unilateral rupture propagation, and their rupture velocity could be estimated. It ranges from 0.23 to 0.80 of shear wave velocity and is almost independent of seismic moment. The fault length, estimated from the average source pulse width and rupture velocity, is clearly dependent on seismic moment and is smaller than the source radius estimated from the corner frequency on the average by about 25 percent. There is no correlation between the values of static stress drop estimated in the frequency and time domains, but the time domain stress drop is in general similar to that estimated in the frequency domain. The apparent stress increases with increasing rupture velocity, and the ratio of apparent stress to static stress drop seems also to depend on rupture velocity.

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Aktywność sesjmiczna Górnośląskiego Zagłębia Węglowego - 30 lat ciagłej obserwacji przez Górnośląską Regionalną Sieć Sejsmologiczną

Stec K.

WUG : bezpieczeństwo pracy i ochrona środowiska w górnictwie

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2007

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nr 6

37-39

PL

Systematyczna obserwacja sejsmiczności indukowanej działalnością górniczą kopalń w Górnośląskim Zagłębiu Węglowym prowadzona jest od lat 50. przez Główny Instytut Górnictwa. Górnośląska Regionalna Sieć Sejsmologiczna działająca bez przerwy od 1974 roku pełni rolę nadrzędną w stosunku do sieci kopalnianych. Na podstawie uzyskiwanych sejsmogramów w sposób ciągły opracowywany jest bank danych, zawierający podstawowe parametry sejsmologiczne dla wstrząsów o energii E > 10'5 J, takie jak: data i czas wystąpienia zjawiska, energia wstrząsu, magnituda, nazwa kopalni, współrzędne epicentrum. Bank danych z lat 1974 - 2006 obejmuje 65165 wstrząsów. Dane te wykorzystywane są do badań związanych z szeroko pojeta analizą stanu zagrożenia tapaniami w kopalniach oraz oceną dynamicznych oddziaływań drgań wywołanych wstrząsami na powierzchniowe środowisko naturalne w GZW.

EN

The USCB area is one of the most seismically active mining areas in the world. Systematic observations of the mining-induced seismicrry over the USCB area have been carried out by the Central Mining Institute since the 1950s. During the period 1950 to 1973, about 350 seismic events of energy E > 106 J were recorded. The Upper Silesian Seismic Network, continuously active since 1974, has been playing a leading role in the seismological studies involving mine-operated seismic networks. A data set containing the basic seismological parameters of mine tremors such as date, origin time, energy, magnitude, mine name and the epicentre co-ordinates. The data set from the period of 1977-2006 contains more than 65165 mine tremors of energy E > 105 J. This data set was used in studies concerned with the state of rockburst hazard in mines and with an assessment of dynamic interactions between the seismic ground motions and the surface natural environment of the Upper Silesian Coal Basin.