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During underground coal mining, Mining-induced seismicity is a crucial factor leading to roadway deformation. Based on a case study of rib spalling caused by mining-induced seismicity in China, this paper utilizes the Universal Distinct Element Code to investigate the mechanism of rib spalling. It analyzes the stress evolution process of roadway surrounding rock and the damage process under the influence of mining-induced seismicity. Additionally, it examines the relationship between seismic wave amplitude, frequency and the damage characteristics of roadway surrounding rock. Findings show that seismic waves induce stress concentration zones in the deeper surrounding rock, causing shear failure, while stress concentration zones emerge in the top, bottom and shoulders of roadway, leading to tensile failure in the shallower surrounding rock. With increasing seismic wave amplitude, the critical crack length of surrounding rock decreases, resulting in a linear increase in crack count and distribution area. The roadway exhibits a ' n '-shaped damage profile primarily driven by shear failure. With increasing seismic wave frequency, the crack count in the surrounding rock of the roadway exhibits a trend of initially increasing and then decreasing. This trend becomes more pronounced with larger amplitudes. Rib spalling damage is influenced by seismic wave frequency and amplitude: frequencies of 20–25 Hz and 80–100 Hz require amplitudes exceeding 3 m for damage, while 25–30 Hz and 55–80 Hz require amplitudes over 2 m, and 30–55 Hz necessitate amplitudes exceeding 1.5 m. [ABSTRACT FROM AUTHOR]

The measurements of rotational and translational seismic signals were carried out at the Imielin and Planetarium stations located in the central part of the Upper Silesian Coal Basin, Southern Poland. Local seismicity, produced by the surrounding hard coal mines, allowed the collection of 130 seismic events. This study aimed to analyze the influence of site effects on rotational ground motion using the horizontal-to-vertical spectral ratio method. We performed the analysis using two approaches: obtaining the spectral ratio of the rotational motion and investigating the impact of the site effect on the scaling relation. The spectral ratio comparison between rotations and translations shows that the value of the rotational amplification coefficient is almost three times lower than that for the translations, and the resonance frequency of rotational motion is higher than that of translations. The comparisons of the scaling relation models, obtained for raw data and corrected by the amplification factor data, revealed that removing the site effect from the signals increases the data to model approximation, reducing the value of the SH-wave phase velocity almost three times. The studies suggest that the local site conditions independently affect the rotational and translational motions. [ABSTRACT FROM AUTHOR]

Abstract Accurate characterisation of seismic source mechanisms in mining environments is crucial for effective hazard mitigation, but it is complicated by the presence of anisotropic geological conditions. Neglecting anisotropic effects during moment tensor (MT) inversion introduces significant distortions in the retrieved source characteristics. In this study, we investigated the impact of ignoring anisotropy during MT inversion on the reliability of hazard assessment. We investigated a high-energy (2.18 $$\times$$ 106 J) induced by mining activities in the Nantun coal mine in China. The subsurface was modelled as a vertically transversely isotropic medium, incorporating four different levels of anisotropy derived from site-specific geological and tomographic data. The results demonstrate that neglecting anisotropy led to significant distortions in the retrieved source parameters, including polarity flips and the introduction of spurious non-double-couple components. These artefacts compromised the accuracy of hazard analysis and undermined the effectiveness of risk management strategies. In contrast, the sequential inversion method yields a MT solution with a 0.14 misfit, accurately retrieving the focal mechanism, which is interpreted as a normal right-lateral oblique shear failure along the F3 fault. This study highlights the importance of properly incorporating anisotropy effects when analysing induced seismicity in heterogeneous mining environments. The use of a homogeneous Green’s function for MT inversion may be inadequate for reliable hazard assessment, underscoring the need for advanced techniques that can effectively model the influence of subsurface anisotropy on seismic wave propagation and source retrieval.

Accurate characterisation of seismic source mechanisms in mining environments is crucial for effective hazard mitigation, but it is complicated by the presence of anisotropic geological conditions. Neglecting anisotropic effects during moment tensor (MT) inversion introduces significant distortions in the retrieved source characteristics. In this study, we investigated the impact of ignoring anisotropy during MT inversion on the reliability of hazard assessment. We investigated a high-energy (2.18 106 J) induced by mining activities in the Nantun coal mine in China. The subsurface was modelled as a vertically transversely isotropic medium, incorporating four different levels of anisotropy derived from site-specific geological and tomographic data. The results demonstrate that neglecting anisotropy led to significant distortions in the retrieved source parameters, including polarity flips and the introduction of spurious non-double-couple components. These artefacts compromised the accuracy of hazard analysis and undermined the effectiveness of risk management strategies. In contrast, the sequential inversion method yields a MT solution with a 0.14 misfit, accurately retrieving the focal mechanism, which is interpreted as a normal right-lateral oblique shear failure along the F3 fault. This study highlights the importance of properly incorporating anisotropy effects when analysing induced seismicity in heterogeneous mining environments. The use of a homogeneous Green's function for MT inversion may be inadequate for reliable hazard assessment, underscoring the need for advanced techniques that can effectively model the influence of subsurface anisotropy on seismic wave propagation and source retrieval. [ABSTRACT FROM AUTHOR]

Abstract—This paper examines the construction of an aftershock activity area in conditions of natural and mining-induced seismicity based after the data on the first aftershocks. The study area is apatite–nepheline deposits located in the southern part of the Khibiny massif. A significant number of variants of aftershock regions were investigated that differ in shape, location, and orientation. The size of the area has been determined by scaling based on physical and statistical characteristics calculated from both the main shock and the first aftershocks. The criterion based on an error diagram has been used to quantitatively compare a large number of different variants. As a result, the optimal area type has been selected, which showing the best results of the quantitative test based on seismicity data on the study area for 1996–2022. The technique can be used to predict the area of aftershock activity distribution at the Khibiny massif deposits after a natural–mining-induced earthquake based on operational processing data. [ABSTRACT FROM AUTHOR]

Measurements of seismic activity induced by mining operations are a basic tool for assessing the level of dynamic load associated with the occurrence of tremors. Knowledge of the location of the source of vibrations and the nature of seismicity is the basis for the safe planning of operations and design of both underground and surface infrastructure. The key parameter influencing the quality and reliability of seismic measurements is the coverage density of the analysed area with measurement stations. Unfortunately, the cost of seismic networks using standard devices is so high that in most cases the density of the network is much lower than needed for a good resolution and low event detection threshold. A certain breakthrough in this area may be the introduction of cost-effective measuring devices based on MEMS technology. This study compares the seismic data collected with the use of MEMS-IMU accelerometers with standard accelerometers for field seismic monitoring. The basis for the comparison was the analysis of data recorded by both devices located on the same site for two months. The comparison was carried out in terms of the characteristics of seismic waveforms, their amplitude distribution, frequency characteristics and effective duration of vibrations. Based on the results of the analysis, it was shown that MEMS-IMU accelerometers can be successfully used to monitor seismicity induced by mining activities in the near wave field. [ABSTRACT FROM AUTHOR]

Multistage hydraulic fracturing of horizontal wells (MFHW) is a promising technology for controlling coal burst caused by thick and hard roofs in China. However, challenges remain regarding the MFHW control mechanism of coal burst and assessment of the associated fracturing effects. In this study, these challenges were investigated through numerical modelling and field applications, based on the actual operating parameters of MFHW for hard roofs in a Chinese coal mine. A damage parameter (D) is proposed to assess the degree of hydraulic fracturing in the roof. The mechanisms and effects of MFHW for controlling coal burst are analyzed using microseismic (MS) data and front-abutment stress distribution. Results show that the degree of fracturing can be categorized into lightly-fractured (D≤0.3), moderately fractured (0.3

This article focuses on the analysis of academic literature on technogenic seismicity from a bibliometric perspective. Specifically, it examines the period from 1980 to 2022, inclusive. Over 10,000 scientific documents on this topic were sourced from the SCOPUS database. These documents were analyzed using VOSviewer software to evaluate the most productive journals, books, articles and their keyword co-occurrences, as well as to identify co-authorship among the most prolific countries. Ordinary Least Square Regression was then employed to establish a relationship between scientific production and its driving factors. Based on the results, three main subject areas were identified: (1) case studies on the primary causes of induced seismicity; (2) in-depth knowledge of man-made seismicity from geological and geophysical perspectives; and (3) numerical modeling of induced seismicity. A high correlation was found between the number of published documents and the key driving factors of induced seismicity. As a novel study using bibliometric analysis methods in the field of technogenic and induced seismicity, this research provides a reliable scientific tool for quickly identifying major research areas, current research boundaries, and general knowledge on the topic of interest. Bibliometric analysis can be used by scientists and researchers involved in the study of man-made seismicity to better understand the current intellectual structure, analyze scientific progress, and detect future research directions in this field. [ABSTRACT FROM AUTHOR]

Determining the advanced mining influence range of an underground working face is crucial for preventing dynamic disasters, such as coal bursts and gas outbursts. In this study, the occurrence of advanced seismicity before the working face as well as its correlation with the acoustic emission (AE) activity of coal and rocks under axial loading was analyzed. Based on the results, a novel statistical method to determine the advanced mining influence range based on advanced seismicity data was proposed and then validated with a case study. The results show that advanced seismicity is caused by the combined effects of static and dynamic stresses at the working face. This seismicity can be used to assess the mining influence degree of the working face on the advanced coal and rock mass, and determine the advanced mining influence range. Using the novel statistical method, the normalized curves for the total number and total energy of the advanced mining-induced seismicity can be plotted. Then, the advanced mining influence range can be determined using thresholds. The thresholds can be established based on the AE activities observed in coal and rock samples under axial static loading. In the case study in this research, the thresholds for the total seismic number and total seismic energy are 0.076 and 0.052, respectively. The corresponding advanced mining influence ranges are 275 m and 245 m, respectively. Field monitoring confirms an advanced mining influence range of 255 m, which validates the results obtained using the novel statistical method. [ABSTRACT FROM AUTHOR]

An investigation of risk factors has been identified as a crucial aspect of the routine management of rockburst. However, the identification methods for principal impact factors and the examination of the relationship between seismic energy and other source parameters have not been extensively explored to conduct dynamic risk management. This study aims to quantify impact risk factors and discriminate hazardous high-energy seismic events. The analytic hierarchy process (AHP) and entropy weight method (EWM) are utilized to ascertain the primary control factors based on geotechnical data and nearly two months of seismic data from a longwall panel. Furthermore, the distribution law and correlation relationship among seismic source parameters are systematically analyzed. Results show that the effect of coal depth, coal seam thickness, coal dip, and mining speed covers the entire mining process, while the fault is only prominent in localized areas. There are varying degrees of log-positive correlations between seismic energy and other source parameters, and this positive correlation is more pronounced for hazardous high-energy seismic events. Utilizing the linear logarithmic relationship between seismic energy and other source parameters, along with the impact weights of dynamic risks, the comprehensive energy index for evaluating high-energy seismic events is proposed. The comprehensive energy index identification method proves to be more accurate by comparing with the high-energy seismic events based on energy criteria. The limitations and improvements of this method are also synthesized to obtaining a wide range of applications. [ABSTRACT FROM AUTHOR]

Clustering methods aim to categorize data or samples into distinct groups based on their similarity. When applying clustering methods to earthquake events, it is crucial to establish a metric for quantifying the similarity between these events. Directly applying this clustering method to a catalog of mining-induced seismicity may lead to clustering earthquake events induced by different mining activities or accidents into the same group. To address this issue, a two-step clustering method has been proposed and applied for analyzing a catalog of mining-induced seismicity. The first step involves spatial distance-based clustering of seismic events, while the second step focuses on moment tensor analysis-based clustering of these events. The results obtained from the MT-based clustering method are visualized using Hudson Graphs, and box plots serve as an evaluation tool for assessing the quality of MT clustering. Most box plots demonstrate desirable quality in terms of MT cluster results, indicating successful outcomes. By the proposed two-step clustering method combined with actual mining activities, the potential accident locations and categories can be hypothesized while valuable recommendations provided for mining operations. [ABSTRACT FROM AUTHOR]

The measurements of rotational and translational seismic signals were carried out at the Imielin and Planetarium stations located in the central part of the Upper Silesian Coal Basin, Southern Poland. Local seismicity, produced by the surrounding hard coal mines, allowed the collection of 130 seismic events. This study aimed to analyze the influence of site effects on rotational ground motion using the horizontal-to-vertical spectral ratio method. We performed the analysis using two approaches: obtaining the spectral ratio of the rotational motion and investigating the impact of the site effect on the scaling relation. The spectral ratio comparison between rotations and translations shows that the value of the rotational amplification coefficient is almost three times lower than that for the translations, and the resonance frequency of rotational motion is higher than that of translations. The comparisons of the scaling relation models, obtained for raw data and corrected by the amplification factor data, revealed that removing the site effect from the signals increases the data to model approximation, reducing the value of the SH-wave phase velocity almost three times. The studies suggest that the local site conditions independently affect the rotational and translational motions.

Abstract The assessment of Coal burst risk (CBR) is the premise of bump disaster prevention and control. It is the implementation criterion to guide various rock burst prevention and control measures. The existing static prediction and evaluation methods for CBR cannot be effectively combined with the results of underground dynamic monitoring. This study proposed a mining-induced seismicity information quantification method based on the fractal theory. Deep learning methods were used to construct a deep learning framework of coal burst risk (DLFR) based on the fractal dimension of microseismic information. Gray correlation analysis (GRA), information gain ratio (IGR), and Pearson correlation coefficient are used to screen and compare factors. Statistical evaluation indicators such as macro-F1, accuracy rate, and fitness curve were used to evaluate model performance. Taking the Gaojiapu coal mine as a case study, the performance of deep learning models such as BP Neural Network (BP), Support Vector Machine (SVM) and its optimized model based on particle swarm optimization (PSO) algorithm under this framework is discussed. The research results' reliability and validity are verified by comparing the predicted results with the actual results. The research results show that the prediction results of CBR in DLFR are consistent with the actual results, and the model is reliable and effective. The mining-induced seismicity quantification can solve the problem of insufficient training samples for the CBR. With this, different pressure relief measures can be formulated based on the results of the CBR predictions to achieve "graded" precise prevention and control.

Coal mining in thick-hard roof areas leads to frequent high-energy seismicity and may even induce coal–rock dynamic disasters such as rockburst. It is important to explore the focal mechanism of mining-induced seismicity to understand the failure behaviour of the coal–rock mass and the characteristics of the stress field. It is helpful to propose a seismic absorption method. Taking the 6306 working face of the Dongtan coal mine as the study area, the rupture type, focal mechanism, characteristics of the local stress field, and main controlling factors of the mining-induced 22 high-energy seismic events were investigated using the probabilistic full-waveform optimization inversion and the stress field inversion. The main conclusions were as follows: (1) the rupture types of 22 seismic events were shear, tensile, compression, and mixed failure, and the corresponding number of events was 11, 4, 1, and 6, respectively; (2) the focal mechanism of the above events was eight strike-slips, twelve reverse fault slips, and two normal fault slips; and (3) the stress field using the inversion of focal mechanisms was discovered. There was no significant variation of the maximum compressive stress σ1 and minimum compressive stress σ3 directions in the seismicity concentration area, fold 1, and fold 2. The principal stresses σ1 and σ3 were the main controlling factors inducing seismicity. This study is helpful in revealing the mechanism of the mining-induced high-energy seismicity and proposing corresponding prevention measures in the future. Highlights: A possible full-waveform optimization inversion method is developed to analyse the focal mechanism of a thick-hard roof zone The main controlling factors of the induced seismic activity are investigated through the stress field inversion The stress field inversion results have excellent potential to guide the design of hydraulic fracturing in the coal mine [ABSTRACT FROM AUTHOR]

This paper aims to identify the optimal reinforced concrete bridge construction for regions at risk of mining-induced seismic shocks. This study compares the performances of two common bridge types made of the same structural tissue, i.e., a reinforced concrete beam bridge and rigid-frame bridge under real mining-induced tremors using uniform and spatially varying ground motion models. This study investigates the dynamic responses of the bridges depending on wave velocity and assesses their susceptibility to mining-triggered tremors based on the contribution of quasi-static and dynamic effects in the global dynamic responses of the bridges. This study revealed significant changes in dynamic response under spatially varying ground excitation for both bridge types. It was observed that rigid-frame bridges show higher susceptibility to quasi-static effects due to their stiffness, whereas beam bridges are more susceptible to dynamic stresses. This study recommends that in regions with mining tremors, the choice between bridge types should consider the possibility of limiting individual components of stress. A solution may involve the reduction in quasi-static components through structural reinforcement or decreasing dynamic components by using vibration absorbers. It was found that beam bridges are more cost-effective and practical in mining-affected areas, especially when founded on weak grounds. [ABSTRACT FROM AUTHOR]

Deep coal mining activities close to a fault generally cause shear stress concentration and slipping of the fault. This increases the risk of coal bumps and severely endangers miners' lives as well as the effectiveness and productivity of mines. In this study, seismicity distribution resulting from fault slipping induced by mining in the graben structural area and the coal bump seismic precursors are investigated using high-precision seismic monitoring technology. Subsequently, the evolution of stresses in rock masses and fault reactivation characteristics during the mining process is analysed via numerical simulation. With the advancement of the working face, the maximum principal stress difference between the two sides of the fault gradually increases, resulting in shear slipping of the fault (i.e., fault reactivation). Seismicities occur frequently because of the repeated release of accumulated elastic energy. The number and total energy of mining-induced seismicities in the hanging wall of the fault are higher than those in the footwall. The frequency and number of mining-induced seismicities decrease before the occurrence of the coal bump. Additionally, the mechanism of the coal bump induced by fault slipping, caused by the superposition of static and dynamic stresses during coal mining, is investigated. [ABSTRACT FROM AUTHOR]

Determining the advanced mining influence range of an underground working face is crucial for preventing dynamic disasters, such as coal bursts and gas outbursts. In this study, the occurrence of advanced seismicity before the working face as well as its correlation with the acoustic emission (AE) activity of coal and rocks under axial loading was analyzed. Based on the results, a novel statistical method to determine the advanced mining influence range based on advanced seismicity data was proposed and then validated with a case study. The results show that advanced seismicity is caused by the combined effects of static and dynamic stresses at the working face. This seismicity can be used to assess the mining influence degree of the working face on the advanced coal and rock mass, and determine the advanced mining influence range. Using the novel statistical method, the normalized curves for the total number and total energy of the advanced mining-induced seismicity can be plotted. Then, the advanced mining influence range can be determined using thresholds. The thresholds can be established based on the AE activities observed in coal and rock samples under axial static loading. In the case study in this research, the thresholds for the total seismic number and total seismic energy are 0.076 and 0.052, respectively. The corresponding advanced mining influence ranges are 275 m and 245 m, respectively. Field monitoring confirms an advanced mining influence range of 255 m, which validates the results obtained using the novel statistical method.

An investigation of risk factors has been identified as a crucial aspect of the routine management of rockburst. However, the identification methods for principal impact factors and the examination of the relationship between seismic energy and other source parameters have not been extensively explored to conduct dynamic risk management. This study aims to quantify impact risk factors and discriminate hazardous high-energy seismic events. The analytic hierarchy process (AHP) and entropy weight method (EWM) are utilized to ascertain the primary control factors based on geotechnical data and nearly two months of seismic data from a longwall panel. Furthermore, the distribution law and correlation relationship among seismic source parameters are systematically analyzed. Results show that the effect of coal depth, coal seam thickness, coal dip, and mining speed covers the entire mining process, while the fault is only prominent in localized areas. There are varying degrees of log-positive correlations between seismic energy and other source parameters, and this positive correlation is more pronounced for hazardous high-energy seismic events. Utilizing the linear logarithmic relationship between seismic energy and other source parameters, along with the impact weights of dynamic risks, the comprehensive energy index for evaluating high-energy seismic events is proposed. The comprehensive energy index identification method proves to be more accurate by comparing with the high-energy seismic events based on energy criteria. The limitations and improvements of this method are also synthesized to obtaining a wide range of applications.

Coal pillars are often set up to protect roadways from rockburst hazards in the working face; however, the presence of coal pillars is a "double-edged sword" because unreasonable settings can increase the risk of coal mining. In this study, we used the 73upper11 working face in the Baodian coal mine as the engineering background to explore the instability characteristics of coal–rock mass in coal pillar areas. The failure types and focal mechanisms of 21 events (ML ≥ 1.2) in coal pillars were investigated using the moment tensor inversion method. Considering the limitation that moment tensor inversion assumes a point source, we inverted the stress field of the remnant coal pillar area on both sides of the working face to find the dominant controlling factor of seismicity. These inversion results were then used as input terms for a static Coulomb stress simulation to identify the characteristics of the coseismic stress caused by induced seismicity clusters and the influencing mechanism of subsequent seismic activities. Our results indicate that (1) the 21 high-energy (HE) seismic events were primarily compression failures, generally distributed on the floor, and the focal mechanisms of these events were primarily characterised by normal fault slips, whilst a few high-position events were reverse fault slips. Furthermore, (2) the stress field of the coal pillars differed from that of the in situ stress measurement; therefore, we inferred that these events were induced by mining, with their dominant control factor being the maximum compressive stress (σ1) extrusion with a high plunge. Lastly, (3) the locations of 37 microseismic (MS) events on August 1 and August 2, 2022 confirm that the mining-induced events triggered subsequent MS activities at a rate as high as 81%. Notably, 20 (54%) of these MS events were close to the isolines zero of the Coulomb stress changes. Highlights: Stability optimization of moment tensor inversion is proposed to analyze the focal mechanism of the coal pillar. Stress filed inversion reveals the main controlling factor and real fault plane information of the coal pillar rupture. The calculation of static Coulomb stress has excellent potential for predicting coal mine high-energy (HE) seismic events. [ABSTRACT FROM AUTHOR]

High-magnitude events (HMEs) are commonly observed in underground mines, and they can lead to violent rock failures, such as rockbursts. While moment tensors (MTs) have been widely used to investigate the triggering mechanism of HMEs, the cluster properties of MTs before HMEs have rarely been systematically studied. This hinders the application of MTs to predict HMEs and manage dynamic hazard risks. This study aims to characterize the cluster properties of MTs before HMEs and apply them to predict HMEs. A seismic clustering method suitable for the hybrid MT inversion was proposed to acquire reliable source mechanism solutions. Based on a case study, the MTs and decompositions were retrieved for seventeen HMEs and seismic events in the week preceding their occurrence. Cluster analysis results show that HMEs are close in location but still have entirely different source mechanisms. Pre-HME events show a distinct difference in strikes and dips in the cases dominated by roof movement or coal mass failure. The analysis of the cluster probabilities associated with source location errors, radius, and mechanisms was then conducted based on the seismic failure mechanisms; and a refined cluster possibility index, the number of possible clustered events (NPCE), was proposed to identify abnormal risk zones. A risk assessment index, namely the number of possible clustered events (INPCE), was proposed to evaluate the degree of a cluster of seismic events. A posteriori analysis of seventeen cases showed a prediction accuracy of up to 60% of HMEs, and a risk threshold of 0.4 was recommended in the case of acceptable completeness of seismic data. The low sensitivity of the monitoring system and the poor seismicity would be the two main limitations, and deep learning based automatic location and source mechanism inversion techniques could be used to improve the application. Highlights: An agglomerative hierarchical cluster-based source cluster determination method is proposed for hybrid moment tensor inversion. The moment tensor solutions of seismic events before high-magnitude events (HMEs) are analyzed. A rockburst assessment method is proposed based on cluster probability associated with source location errors, radius, and mechanisms. A risk-based assessment back analysis is conducted to discuss the advantages and limitations of the method. [ABSTRACT FROM AUTHOR]

To improve the positioning accuracy of a mining-induced seismicity monitoring system, reduce the monitoring blind area, and reduce the monitoring cost, based on the distributed idea, this paper proposes a positioning method of mining-induced seismicity based on the smartphone sensor network. First, smartphones used by workers and their families near the mining area were utilized to establish a mobile sensor network. Second, the simulated source points were meshed, and the objective function based on the standard deviation was constructed. An improved firefly optimization strategy was proposed. The inflection point backtracking method and smartphone sensor network exclude the discrete points strategy, namely, EDPS, to reduce the positioning error. Verification is done by the simulation experiment of the mining-induced seismicity location. Experimental results show that under the ideal condition of no arrival time error in the smartphone sensor network, all simulated source points can converge to the source position accurately with a positioning error of less than 1 m. However, compared to the detector, the arrival error of the smartphone is higher, and the positioning error is correlated with the arrival error. When the mobile phone arrival error is −1.0–1.0 s, the traditional algorithm positioning error is 216 m, which cannot achieve high-accuracy positioning. Researching the relationship between objective function value and positioning error, this work proposes and uses two optimization methods: (1) inflection point backtracking method and (2) EDPS. The absolute positioning error of the algorithm is reduced to 73 m. When the time error is −0.2–0.2 s, the absolute positioning error is reduced to 17 m, and the positioning accuracy is improved by 76.1%. The location method of the mining-induced seismicity based on the crowdsensing of a phone mobile sensor network provides a new method for mining-induced seismicity monitoring. It can be considered to combine with an underground microseismic system in the future, which is of great significance in saving the monitoring cost and improving the positioning accuracy.

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Induced seismicity has been a serious problem for many coal mines in the Upper Silesian Coal Basin in Poland for many decades. The occurring mining tremors of the rock mass generate seismic vibrations that cause concern to the local population and in some rare cases lead to partial damage to buildings on the surface. The estimation of peak ground acceleration values caused by high energy mining seismic tremors is an important part of seismic hazard assessment in mining areas. A specially designed bootstrapping procedure has been applied to estimate the ground motion prediction model and makes it possible to calculate the confidence intervals of these peak ground acceleration values with no assumptions about the statistical distribution of the recorded seismic data. Monte Carlo sampling with the replacement for 132 seismic records measured for mining seismic tremors exceeding 150 mm/s2 have been performed to estimate the mean peak ground acceleration values and the corresponding upper limits of 95% confidence intervals. The specially designed bootstrap procedure and obtained ground motion prediction model reflect much better the observed PGA values and therefore provide more accurate PGA estimators compared to the GMPE model from multiple regression analysis. The bootstrap analysis of recorded peak ground acceleration values of high-energy mining tremors provides significant information on the level of seismic hazard on the surface infrastructure. A new tool has been proposed that allows for more reliable determination of PGA estimators and identification in the areas in coal mines that are prone to high-energy seismic activity. [ABSTRACT FROM AUTHOR]

Mining-induced seismicity-triggered coal bursts (MISTCB) have become a major impediment to the safety of underground coal mining. Based on a severe MISTCB that occurred in China, this paper investigates the mechanism and control strategy of the MISTCB. A large-scale numerical model was built using the Universal Distinct Element Code (UDEC). Crack development and stress evolution of the MISTCB is analysed. In addition, the effect of mining-induced seismicity amplitude on the MISTCB is discussed. It is shown that severe dynamic failure occurred at both sidewalls and the floor of the roadway, including tensile failure near the roadway surface and shear failure in regions further away from the surface. After the coal burst, the distances between the two sidewalls and between roof and floor are 2.7 m and 3.1 m (4 and 5 m before the MISTCB). The maximum ejection velocity is up to 27.2 m/s. Mining-induced seismicity plays a key role for a MISTCB, whereas the amplitude (energy) is decisive for the strength of the dynamic failure. Increasing amplitude means increasing dynamic stresses, increasing ejection velocities of fragments and increasing deformations. However, the changes in dynamic stresses and deformations incl. damage patterns in the plastic, elasto-plastic and elastic zones are different. A zonation failure mechanism is proposed for the MISTCB. The obtained numerical results are in good agreement with the field measurements. The results are helpful for deeper understanding of the mechanism and to control the MISTCB. [ABSTRACT FROM AUTHOR]

The impact of the dynamic soil-structure interaction (DSSI) on the response of a single-span footbridge to mining-induced shocks was assessed. Firstly, the eigen values, modes and damping of the footbridge were evaluated based on in-operation field tests. Then, natural frequencies were determined numerically by a model usually used in static calculations, i.e., a simple supported beam with overhangs. The numerical natural frequencies turned out to be inconsistent with the experimentally determined values. In turn, the model, assuming the overhangs' ends translationally restrained, gave natural frequency values closer to the experimental ones. However, for the third mode, that is lateral, the frequency error (~26%) can be considered greater than usually accepted values. Hence, the three-dimensional numerical model of the footbridge was tuned by considering the DSSI between the overhangs and the ground, and implementing springs (in three directions) at the overhangs' ends. To estimate the impact of DSSI on the dynamic performance of the footbridge, time history analyses were carried out for the model with fixed overhang ends and for the model with additional springs. Two different types of mining-induced tremors were used as excitations. Those two tremors (narrow and wide band) induced different dynamic responses in the models with and without the springs. Hence, the impact of the DSSI on the dynamic footbridge performance needs to be considered to predict the effect of mining-induced shocks. [ABSTRACT FROM AUTHOR]

In the paper, an advanced model of spatiotemporal mining-induced kinematic excitation (SMIKE) for multiple-support bridges exposed to mining-induced seismicity is proposed. The uniqueness of this model results from the possibility of its application in any region of mining activity, as it is based on empirical regression functions characterizing such regions. In the model, the loss of coherency resulting from the scattering of waves in the heterogeneous ground, the wave-passage effect originating in different arrival times of waves to consecutive supports, and the site-response effect depending on the local soil conditions are taken into account. The loss of coherency of mining-induced seismic waves is obtained by applying a random field generator based on a spatial correlation function to produce time histories of accelerations on consecutive structure supports based on an originally recorded shock. The deterministic approach is used to account for temporal wave variability. The proposed SMIKE model is applied to assess the dynamic performance of a five-span bridge under a mining-induced shock recorded in the Upper Silesian Coal Basin (USCB), Poland. The first model's parameter (space scale parameter) is identified on the basis of regression curves defined for the USCB region. The estimation of the second parameter (the mean apparent wave passage velocity) is based on discrete experimental data acquired via the vibroseis excitation registered in the in situ experiment. The impact of the model application on the dynamic performance of the bridge is assessed by comparing the dynamic response levels under SMIKE excitations, classic uniform excitations, and the "traveling wave" model—accounting only for the wave passage effect. The influence of wave velocity occurs to be crucial, modifying (either amplifying or reducing, depending on the location of the analyzed point) the dynamic response level up to a factor of two. The introduction of the space scale parameter changes the results by 20% in relation to the outcomes obtained for the "traveling" wave only. [ABSTRACT FROM AUTHOR]

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 fit 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. [ABSTRACT FROM AUTHOR]

The paper considers the distribution of magnitudes of the strongest aftershocks–depending on the time after the main shock–that occur during the extraction of minerals in tectonically loaded rock massifs. The study is based on the data of long-term seismological observations at the apatite-nepheline deposits of the Khibiny Massif located in the Kola Peninsula. The article demonstrates that the distribution of the difference between the magnitudes of the strongest aftershock and the main shock is described by the dynamic Båth law, previously obtained by the authors during the study of the regularities of aftershock processes of tectonic earthquakes.

Abstract—The spatial distribution of the triggered seismic events in mining conditions in the tectonically loaded rock masses is studied using the example of seismicity in the Khibiny Mountains. It is shown that the distribution of distances from the triggering to triggered events, on average, obeys the power-law with a parameter independent of the magnitude of the triggering event. The model of the maximum distances from a triggering event's hypocenter to the triggered shocks expected with a given probability is derived. It is shown that the model is consistent with the real data. Based on the error diagram analysis, the guidelines are proposed for the practical use of the model. [ABSTRACT FROM AUTHOR]

In the paper, an advanced model of spatiotemporal mining-induced kinematic excitation (SMIKE) for multiple-support bridges exposed to mining-induced seismicity is proposed. The uniqueness of this model results from the possibility of its application in any region of mining activity, as it is based on empirical regression functions characterizing such regions. In the model, the loss of coherency resulting from the scattering of waves in the heterogeneous ground, the wave-passage effect originating in different arrival times of waves to consecutive supports, and the site-response effect depending on the local soil conditions are taken into account. The loss of coherency of mining-induced seismic waves is obtained by applying a random field generator based on a spatial correlation function to produce time histories of accelerations on consecutive structure supports based on an originally recorded shock. The deterministic approach is used to account for temporal wave variability. The proposed SMIKE model is applied to assess the dynamic performance of a five-span bridge under a mining-induced shock recorded in the Upper Silesian Coal Basin (USCB), Poland. The first model’s parameter (space scale parameter) is identified on the basis of regression curves defined for the USCB region. The estimation of the second parameter (the mean apparent wave passage velocity) is based on discrete experimental data acquired via the vibroseis excitation registered in the in situ experiment. The impact of the model application on the dynamic performance of the bridge is assessed by comparing the dynamic response levels under SMIKE excitations, classic uniform excitations, and the “traveling wave” model—accounting only for the wave passage effect. The influence of wave velocity occurs to be crucial, modifying (either amplifying or reducing, depending on the location of the analyzed point) the dynamic response level up to a factor of two. The introduction of the space scale parameter changes the results by 20% in relation to the outcomes obtained for the “traveling” wave only.

This paper presents a numerical investigation on the influence of the mining environment on seismic sources, with a focus on pillar failure mechanisms in tabular mining. We investigate the influence of the mining stope (underground excavation or void) on seismic inversions for the scalar moment, corner frequency, source radius, stress drop and moment tensor using synthetic events created within elastodynamic numerical modelling software, WAVE3D. The main objective is to determine whether the source parameters calculated from the recorded waveforms are due to a combination of the stope source and the pillar sources, rather than being related only to crushing of the pillar or shearing in the pillar footwall. The main finding is that the presence of stopes, and types of pillars, have a significant impact on the seismic moment and other source parameters. This is important since the moment is viewed as a robust parameter on which seismic magnitude is often based; however, this study indicates that moments calculated for pillar failure in a tabular stoping environments are less representative of the shearing or crushing source than originally thought. This article is part of the theme issue 'Fracture dynamics of solid materials: from particles to the globe'. [ABSTRACT FROM AUTHOR]

Ground control is multi-tasking and continuous process for the stability of underground openings. Balya underground lead and zinc mine is an important case study area due to its deepest working condition and the highest production amount among Turkish underground metalliferous mines. Mining-induced seismicity needs to be investigated especially for deep as well as tectonically active mine sites. Increasing depth will increase the stress around an underground opening that is a key factor of rock-burst hazard. Rock burst potential can be estimated from analytical approaches based on the relation between rock mass strength and stress around openings; however, one of the best way is to monitor the mining-induced seismicity. The support system is designed based on the actual geotechnical conditions determined from the excavated working face prior to support applications in the mine. Empirical methods are then used to make a decision about the support system. If the location is designated as a seismically active region based on micro-seismic event results, support components are selected as a dynamic support system that must absorb the energy released from the surrounding rock masses. The purpose of this study is to investigate seismically active locations according to mining-induced seismicity and the support system design principles for that locations to protect the openings against seismic loads. [ABSTRACT FROM AUTHOR]

The paper describes a software package developed for automated monitoring of seismic activity of the Khibiny mountain massif. The general structure of the software package is described, and the applied methods and algorithms are considered in detail. In particular, the algorithm for locating the source of a seismic event via grid searches, which are specified as sets of circles and are categorized during execution of the algorithm, is described in detail. The proposed location methods are combined into several packages—scenarios to optimize the time spent by a geophysicist in routine interactive processing of a large dataset. Because the described software package was created to process data from seismic networks located directly in the mining area, much attention is paid to increasing the reliability of detecting target signals in a high-noise environment and the accuracy in determining the arrival times of body waves. To solve these problems, the system implements a new approach to locating close events, based on the idea of a holistic perception of a signal record, which is very close to the concept of human perception of objects. The algorithms and methods for detecting and locating seismic event generation sites implemented in the software package can significantly increase the reliability of the solutions obtained and increase the accuracy and efficiency of the final interactive processing of seismic signal records. [ABSTRACT FROM AUTHOR]

Mining-induced seismicity has been reported almost in every mining country. Large seismic events with high-energy (HE) radiation can pose a serious threat to safe mining operations, which are the direct cause for rockbursts in underground mines. Over the last 30 years, statistical techniques to parameterise seismic data and predict seismic hazard have been developed significantly with promising results. However, similar to earthquake prediction, the prediction accuracy of HE seismic events remains a challenging task due to the complex nature of mining-induced seismic events. This paper aims to parameterise spatial, temporal and energy information conveyed by past seismic activities to provide early warnings for HE events. The 4D spatial–temporal seismic data were transferred to a 2D plane using principal component analysis (PCA) and then applied with a kernel density estimator to calculate their probability density function. The mode of probability density distribution, ρ(x)max, was proposed as a measure to quantify the clustering degree of past seismic events in the PCA space. The peaks of ρ(x)max were found as an effective precursor to predicting the onset time of future HE events. After inverse transformation, the spatial locations of ρ(x)max also indicate the potential high-risk areas that susceptible to HE events, which can be used to predict the onset location of HE events. As a supplement to the spatial–temporal information, energy/magnitude information was parameterised by the modified cumulative Benioff strain and b value. The accuracy of using these seismic parameters for the prediction of HE events has been assessed based on the seismic data collected from a Chinese coal mine. [ABSTRACT FROM AUTHOR]

Reducing seismicity during excavation is a challenge faced by mining and the associated slip development on a near‐excavation fault under deep‐mining stress conditions is considered as an analog for understanding earthquake initiation mechanisms. In this paper, the quasi‐static slipping on a dipping fault near a horizontal tunnel was numerically studied by incrementally increasing horizontal stress. The equilibrium of the fault, which obeys a slip‐weakening friction law, is formulated by a boundary integral approach. The calculated rupture size is a function of the dimensionless factors derived by scaling from geometrical, loading, and friction conditions. The results show that the rupture becomes runaway at a critical stress level and prior to this, the slip zone either extends continuously and aseismically or experiences finite rapid extensions. Energy dissipated in friction in the presence of tunnel‐induced stress heterogeneity can arrest fast rupture events resulting in regained equilibrium. The energy radiated from arrested events, using an energy budget analysis, depends on the resulting fault strength change, the rupture arrest length, and the strain energy change during the event. These preceding energy radiations can mitigate the magnitude of runaway events. As the critical slip‐weakening distance decreases, the critical stresses for nucleation of both runaway and arrested events are reduced, but the energy radiated by arrested events does not always decrease because the rupture arrest length varies. The results of this study may help identify the initiation mechanisms for runaway ruptures and assess the seismic potential of a rock mass during excavation. Key Points: Fault slip development arising from tunnel‐induced stress perturbation is studied using a quasi‐static modelFast slip movement on a near‐tunnel fault can be arrested and the radiated energy depends on fault frictional propertiesInduced near‐excavation seismicity can be reduced by prior low‐magnitude arrested events [ABSTRACT FROM AUTHOR]

This work aims to examine the stress redistribution with evolving seismicity rates using a passive seismic tomographic tool. We compiled a total of 26,000 events from two underground mines and partitioned them into multiple clusters in a temporal sequence, each of which contains 1000 events. To image stress redistribution associated with seismicity rates, we then run the tomographic studies using each cluster to yield seismic tomograms and computed the corresponding seismicity rate. We found that high velocity anomalies grew with the increase of seismicity rates, and they switched to a shrinking tendency under low seismicity rates. Results of this study imply that seismicity rates increase with increasing stress concentration and decrease with decreasing stress concentration. This study highlights the value of utilizing passive seismic tomography for estimating stress evolution associated with the change of seismicity rates at underground mines. Our findings illuminate the applications of using mining-induced seismicity to assess stress redistribution associated with seismicity rates at hard-rock mines, providing insights into seismic hazards for deep mining. [ABSTRACT FROM AUTHOR]

The paper addresses the study of the ability of mining-induced earthquakes to generate successive shocks. Based on the example of the Khibiny natural–technogenic system, it is shown that the number of the initiated shocks (the productivity) has the exponential distribution with the form independent on the magnitude and depth of the events. This result is consistent with the similar productivity law previously established for the tectonic earthquakes on the global and regional levels, expanding the validity of this law to the lower energy scales of seismic events ~104 J (M ≥ 0). [ABSTRACT FROM AUTHOR]

Mining-induced seismicity in the area of development works and proper mining operations is one of the major determinants of the rockburst hazard level in underground mines. Rockburst hazard assessment in Polish collieries is performed by a variety of mining and geophysical methods, including seismic and seismoacoustic techniques, borehole surveys, small diameter drilling, rock strata profiling and analyses of geomechanical properties of rocks, geological structure and geological mining conditions. In the case of zones particularly exposed to potential hazards, it is recommended that analytical or numerical forecasts of the state of stress in the vicinity of workings should be used already at the stage of planning of mining operations. This study summarises the comparative analysis of seismic test data and analytical forecasts of the state of stress in five selected headings in one of the burst-prone collieries within the Upper Silesia Coal Basin in Poland (USCB). As regards the seismic data, duly defined quantitative indicators and energy criteria of the registered seismic activity are recalled in the assessment of rockburst hazard level during the roadheading operations. Analytical simulations utilise a developed geomechanical model and stress–strain relationships stemming from the principles of elastic media mechanics. From the standpoint of mining engineering practice, interpretation of results obtained by the two methods reveals how effective analytical models will be in prognosticating or verification of rockburst hazard conditions.

High magnitude seismic events (HMSE), also called major events, triggered at underground mines can severely threaten safety and structures in mines. The aims of this work are to assess stress evolution with the occurrence of them and identify patterns in stress change. Several methods were used to help understand the stress redistribution and rock mass behavior related to two HMSE with moment magnitude greater than 1.0 in a deep nickel mine. Approximately 46,500 seismic events were compiled with 2 HMSE at this mine and used seismic tomography to obtain high-resolution images and temporal-spatial velocity changes before and after these events. This work exhibited surrounding stress evolution and geological structures. Seismic imaging results show that velocity increased in the nearby regions of HMSE before they were triggered. Stress subsequently reduced in the relaxation process after the occurrence of HMSE. Conversely, regions predominantly occupied by low-velocity anomalies increased to higher stress levels after HMSE. Overall, the stress redistributed toward an equilibrium state following HMSE. This study highlights the value of utilizing seismic tomography for estimating stress evolution associated with HMSE. The findings illuminate the applications of seismic imaging around HMSE of hard-rock mines, providing insights into seismic hazard mitigation for deep mining. [ABSTRACT FROM AUTHOR]

Early detection of rockburst risk areas is a prerequisite for ensuring safe production in coal mines. A reliable and efficient detection method is essential for identifying stress distribution and disturbances in coal and rock masses during mining. In this study, we employed seismic traveltime tomography to study the three-dimensional velocity structure of a continuous mining and excavation area of a coal mine by inverting a number of P-wave arrival times from the induced micro-earthquakes (M < 2.0). The response characteristics and stress evolution of the inversion areas at different mining stages were investigated by examining the obtained time-lapse velocity structure. The microseismic (MS) dataset was partitioned into two clusters in a temporal sequence, with each cluster containing 367 relocated events. A series of checkerboard and restoring resolution tests, as well as field investigations, confirmed the resolution, robustness, and reliability of the tomographic results. In addition, absolute velocity change patterns were proposed to assess and predict rockburst risk areas caused by mining activities. The results showed that high-velocity zones could be attributed to roof subsidence, stress transfer after coal and rock mass rupture, and areas with special geological conditions in isolated working face situations. The coupled effects of stress evolution and geological conditions may lead to more pronounced stress concentrations during the mining process. Furthermore, induced events occur not only in areas between high and low stress but also near the isoline edges of pattern changes. Our established velocity patterns have significant potential for predicting hazardous areas with a timeliness of up to 10 days. [ABSTRACT FROM AUTHOR]

The impact of seismicity on structures is one of the key problems of civil engineering. According to recent knowledge, the reliable analysis should be based on both rotational and translational components of the seismic wave. To determine the six degrees of freedom (6-DoF) characteristic of mining-induced seismicity, two sets of seismic posts were installed in the Lower Silesian Copper Basin, Poland. Long-term continuous 6-DoF measurements were conducted with the use of the R-1 rotational seismometer and EP-300 translational seismometer. In result data collection, the waveforms generated by 39 high-energy seismic events were recorded. The characteristic of the rotational component of the seismic waves were described in terms of their amplitude and frequency characteristics and were compared with translational measurements. The analysis indicated that the characteristic of the rotational component of the seismic wave differs significantly in comparison to translational ones, both in terms of their amplitude and frequency distribution. Also, attenuation of rotational and translational components was qualitatively compared. Finally, the empirical formulas for seismic rotation prediction in the Lower Silesian Copper Basin were developed and validated.

In this paper, the dynamic responses of a large-scale multiple-support road viaduct to mining-induced seismic events registered in two regions of mining activity were compared. The regions differ in geological structure, which results in discrepancies in the dominant frequency content. Spatial variation of ground motion causing the kinematic excitation non-uniformity was accounted for in the dynamic analyses of this large-scale structure. Non-uniform mining-induced kinematic excitation models were proposed, with respect to the specificity of mining origin quakes. The dynamic performance of the viaduct was determined using three different methods of calculation: the time history analysis, the response spectrum analysis, and the multiple support response spectrum analysis. Both the uniform and non-uniform kinematic excitation models were adopted for the dynamic performance assessment. The research revealed that the dynamic response of some members of the structure, determined using the non-uniform excitation model, was significantly greater than that obtained for the uniform one. Hence, in the dynamic analysis of multiple-support structures under mining-induced events, the effect of spatial variation of ground motion should be considered. The study pointed out that the commonly used response spectrum analysis may lead to the underestimation of the dynamic response of large-scale multiple-support structures. Instead, the multiple support response spectrum method, which takes into account the non-uniformity of ground motion, is recommended as a conservative approximation. This method provides a safe upper estimation of the full-dynamic analysis results of large-scale structures under mining-induced tremors. Finally, the research indicated that the dynamic performance of a structure strongly depends on the frequency range attributed to a specific mining region. The dynamic performance of identical engineering structures under tremors of similar maximal amplitudes may differ significantly due to discrepancies in frequency contents of shocks occurring in various mining regions.