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European feedback on post-mining seismicity

Contrucci Isabelle, Namjesnik Dalija, Niemz Peter, Primo Paloma, Kotyrba Andrzej, Mutke Grzegorz, Konicek Petr, Dominique Pascal, Rudolph Tobias, Möllerherm Stefan, Kinscher Jannes, Klein Emmanuelle, Cesca Simone

Journal of Sustainable Mining

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2023

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Vol. 22. iss. 3

195--218

EN

Following the Paris Agreement adopted in 2015, Europe has committed to reducing its greenhouse gas emissions. In this context, the abandonment of coal as an energy source, both in terms of consumption and production, will lead to the closure of many mines in the years to come. Mine closure guidelines to manage residual mining risks already exist in European countries. However, they do not include post-mining seismic risk management due to a lack of sufﬁcient studies and knowledge on this subject. After mining closure, the ﬂooding of the mining works leads to hydromechanical loading of the underground and, in the longer term, to diffusion and an increase in the pore pressure. These conditions can lead, in certain situations, to the reactivation of tectonic faults, which may cause seismic events strong enough to be felt on the surface or even produce damage. Events of lower magnitudes, usually attributed to the remobilization of old mining works, are referred to as post-mining seismic hazards. The European RFCS PostMinQuake project, which started in 2020, aims to study this hazard at ﬁve mining basins located in France, Germany, Poland and the Czech Republic, known to have experienced signiﬁcant seismicity during their operation. This analysis, based on the feedback of the partners of the project, aims to frame an inventory of the ﬁve studied mining basins, which all encounter post-mining seismicity problem today. Three basins out of ﬁve show events with local magnitudes of the order of 3-3.5, which took place between nine and thirteen years after the closure of the mines. Even though the magnitudes of these earthquakes are small to moderate, they are felt on the surface as they occur at shallow depths. In all of the considered countries, a national seismological network exists, however, none of them is fully dedicated to post-mining seismic monitoring. These networks generally consist of a sparse mesh of stations, which does not allow the detection of events of magnitude less than 1 and the location of events have high spatial uncertainties. France is not an exception, but it relies on microseismic monitoring to detect early signs of instability at the level of mining structures and to anticipate the possible appearance of surface disorders. Out of the ﬁve basins that are studied, the Gardanne basin, which has been monitored since 2008, is the most documented case study of post-mining seismicity. This article also shows the difﬁculty in identifying the key conditions and factors that can lead to the remobilization of faults.

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Pomiary amplifikacji drgań od wstrząsów górniczych w Górnośląskim Zagłębiu Węglowym

Mutke Grzegorz

Przegląd Górniczy

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2020

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T. 76, nr 5

10--18

PL

Przedstawiono wyniki pomiarów amplifikacji drgań przez nadkład warstw czwartorzędowych wykonanych na trzech wybranych poligonach badawczych w Górnośląskim Zagłębiu Węglowym, charakteryzujących się wysoką sejsmicznością indukowaną działalnością górniczą. Na każdym z nich rejestrowane były drgania na stanowisku powierzchniowym oraz w otworze 30 m pod ziemią. Taki pomiar pozwalał na bezpośrednią ocenę współczynnika amplifikacji prędkości drgań PGV w domenie czasu, który jest kluczowy do określania drgań powierzchni terenu od zaistniałych i prognozowanych wstrząsów górniczych. Współczynnik ten na poligonach badawczych osiągał dla składowych poziomych prędkości drgań, PGVHmax wartości do 2,4. Ponadto, parametr ten jest wykorzystywany do oceny stopnia intensywności drgań według Górniczej Skali Intensywności Sejsmicznej, GSIS-2017. Przedstawiono również wyliczenia podstawowej częstotliwości rezonansowej dla nadkładu warstw na poszczególnych poligonach pomiarowych oraz obliczono współczynniki amplifikacji na podstawie równań falowych dla dwuwarstwowego modelu ośrodka lepkosprężystego. Wykazano, że wartości współczynnika amplifikacji prędkości drgań w domenie czasu wyznaczone z pomiarów oraz obliczone analitycznie są porównywalne.

EN

The results of measurements of vibration amplification by the overburden of Quaternary layers made on three selected testing sites in the Upper Silesian Coal Basin characterized by high seismicity have been presented. At each test site, vibrations were recorded at the surface and in the 30m borehole. Such measurement allows direct assessment of the amplification coefficient of PGV vibration velocity in the time domain. This parameter is used to predict vibrations from existing and forecast mining shocks. On the testing fields an amplification coefficient reached PGVHmax up to 2.4 for horizontal components of vibration velocity. Moreover, using the PGVHmax parameter, the intensity degree is assessed according to the Mining Seismic Intensity Scale, GSIS-2017. Also calculations of the first frequency resonance for the overburden of Quaternary near surface layers on individual measurement site have been presented as well as the amplification coefficients were calculated on the basis of wave equations for a two-layer model of visco-elastic medium. It has been shown that the amplification coefficient of the vibration velocity in the time domain determined from the measurements and calculated analytically are comparable.

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Distribution of peak ground vibration caused by mining induced seismic events in the Upper Silesian Coal Basin in Poland

Dubiński Józef, Mutke Grzegorz, Chodacki Jacek

Archives of Mining Sciences

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2020

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Vol. 65, no. 3

419--432

EN

The solutions presented permit the practical determination of the physical parameters of peak ground vibration, caused by strong mining tremors induced by mining, in the Polish part of the Upper Silesian Coal Basin (USCB). The parameters of peak ground horizontal velocity (PGVH) and peak ground horizontal acceleration (PGAH10) at any point of earth’s surface depend on seismic energy, epicentral distance and site effect. Distribution maps of PGVH and of PGAH10 parameters were charted for the period 2010-2019. Analysis of the results obtained indicates the occurrence of zones with increased values of these parameters. Based on the Mining Seismic Instrumental Intensity Scale (MSIIS-15), which is used to assess the degree of vibration intensity caused by seismic events induced by mining, and using the PGVH parameter, it was noted that the distribution map of this parameter includes zones where there vibration velocities of both 0.04 m/s and 0.06 m/s were exceeded. Vibrations with this level of PGVH correspond to intensities in the V and VI degree according to the MSIIS-2015 scale, which means that they can already cause slight structural damage to building objects and cause equipment to fall over. Moreover, the reason why the second parameter PGAH10 is less useful for the evaluation of the intensity of mining induced vibrations is explained. The PGAH10 vibration acceleration parameter, in turn, can be used to design construction of the objects in the seismic area of the Upper Silesian Coal Basin, where the highest acceleration reached a value of 2.8 m/s2 in the period from 2010 to 2019.

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Sonda do pomiaru prędkości kątowej drgań rotacyjnych w podziemnych wyrobiskach górniczych

Logiewa Hubert, Mutke Grzegorz, Lurka Adam

Przegląd Górniczy

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2019

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T. 75, nr 12

18--25

PL

W ciągu ostatniej dekady temat rotacyjnych drgań gruntu stał się istotny w zakresie badań sejsmologicznych, a szczególnie inżynierii sejsmicznej. Do tej pory nie prowadzono jednak obserwacji drgań rotacyjnych w podziemnych wyrobiskach kopalnianych, ze względu na brak odpowiednich czujników pomiarowych. W Głównym Instytucie Górnictwa opracowano prototyp sondy rotacyjnej LMLROT do pomiaru prędkości kątowej drgań gruntu w warunkach zagrożenia wybuchowego. Sonda może współpracować z systemami obserwacji sejsmologicznej SOS oraz innymi urządzeniami odbierającymi sygnały prądowe z linii transmisyjnej. Trójskładowa sejsmiczna sonda rotacyjna LMLROT umożliwia pomiar prędkości kątowej drgań w zakresie do 100 mrad/s dla częstotliwości od 2 do 200 Hz. Sonda LMLROT może być wykorzystana między innymi do badań dotyczących wpływu wstrząsów sejsmicznych na stateczność wyrobisk górniczych.

EN

Over the last decade, the subject of rotational vibrations has become important in the field of seismological research, and in particular earthquake engineering. Until now, however, no rotational vibration observations have been carried out in underground mine workings, due to the lack of appropriate measuring sensors. At the Central Mining Institute, a prototype of the LMLROT rotary probe was developed to measure the angular velocity of ground vibrations in explosive conditions. The probe can cooperate with SOS seismological observation systems and other devices receiving current signals from the transmission line. The three-component seismic LMLROT rotary probe measures angular velocity up to 100 mrad/s for frequencies from 2 to 200 Hz. The LMLROT probe can be used, inter alia, for studies on the impact of mining seismic quakes on the stability of mining excavations.

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Upper Silesian Geophysical Observation System - a unit of the EPOS project

Mutke Grzegorz, Kotyrba Andrzej, Lurka Adam, Olszewska Dorota, Dykowski Przemysław, Borkowski Andrzej, Araszkiewicz Andrzej, Barański Adam

Journal of Sustainable Mining

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2019

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Vol. 18, iss. 4

198--207

EN

The aim of the paper is to present the structure and research potential of the newly created measurement and information system for observing dynamic phenomena occurring in the Earth's crust in the Upper Silesian Coal Basin (USCB) in Poland as a result of mining activities. The structure of the system is similar to the one developed for monitoring the movements of the European tectonic plate under the European Plate Observation System (EPOS) programme. The measurement part of the system consists of stationary devices and sensors working in monitoring mode, installed in various locations of the USCB, both on the surface and underground, as well as data sets from periodically performed measurements using land, air and satellite techniques. The IT part of the system will create a local data centre with specialized and dedicated processing and modelling software in which all measurement data will be archived and processed to a form which enables the analysis of the short and long-term impact of mining operations on the environment. As one of the elements of the system will be observations of the short and long-term gravity and morphology changes, the collected data will enable research in the field of the geodynamics of mining areas to be conducted.