This paper proposed a moment tensor regression prediction technology based on ResNet for microseismic events.Taking the great advantages of deep networks in classification and regression tasks,it can realize the great...This paper proposed a moment tensor regression prediction technology based on ResNet for microseismic events.Taking the great advantages of deep networks in classification and regression tasks,it can realize the great potential of fast and accurate inversion of microseismic moment tensors after the network trained.This ResNet-based moment tensor prediction technology,whose input is raw recordings,does not require the extraction of data features in advance.First,we tested the network using synthetic data and performed a quantitative assessment of the errors.The results demonstrate that the network exhibits high accuracy and efficiency during the prediction phase.Next,we tested the network using real microseismic data and compared the results with those from traditional inversion methods.The error in the results was relatively small compared to traditional methods.However,the network operates more efficiently without requiring manual intervention,making it highly valuable for near-real-time monitoring applications.展开更多
In this study,we employed Bayesian inversion coupled with the summation-by-parts and simultaneousapproximation-term(SBP-SAT)forward simulation method to elucidate the mechanisms behind mininginduced seismic events cau...In this study,we employed Bayesian inversion coupled with the summation-by-parts and simultaneousapproximation-term(SBP-SAT)forward simulation method to elucidate the mechanisms behind mininginduced seismic events caused by fault slip and their potential effects on rockbursts.Through Bayesian inversion,it is determined that the sources near fault FQ14 have a significant shear component.Additionally,we analyzed the stress and displacement fields of high-energy events,along with the hypocenter distribution of aftershocks,which aided in identifying the slip direction of the critically stressed fault FQ14.We also performed forward modeling to capture the complex dynamics of fault slip under varying friction laws and shear fracture modes.The selection of specific friction laws for fault slip models was based on their ability to accurately replicate observed slip behavior under various external loading conditions,thereby enhancing the applicability of our findings.Our results suggest that the slip behavior of fault FQ14 can be effectively understood by comparing different scenarios.展开更多
The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor(CMT)automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas.Gisola...The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor(CMT)automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas.Gisola software was used to estimate the CMT solution by selecting the velocity model that best suited the local and regional geological conditions in Indonesia and the surrounding areas.The data used in this study were earthquakes with magnitudes of 5.4 to 8.0.High-quality,real-time broadband seismographic data were provided by the International Federation of Digital Seismograph Networks Web Services(FDSNWS)and the European Integrated Data Archive(EIDA)Federation in Indonesia and the surrounding areas.Furthermore,the inversion process and filter adjustment were carried out on the seismographic data to obtain good CMT solutions.The CMT solutions from Gisola provided good-quality solutions,in which all earthquake data had A-level quality(high quality,with good variant reduction).The Gisola CMT solution was justified with the Global CMT(GCMT)solution by using the Kagan angle value,with an average of approximately 11.2°.This result suggested that the CMT solution generated from Gisola was trustworthy and reliable.The Gisola CMT solution was typically available within approximately 15 minutes after an earthquake occurred.Once it met the quality requirement,it was automatically published on the internet.The catalog of local and regional earthquake records obtained through this technology holds great promise for improving the current understanding of regional seismic activity and ongoing tectonic processes.The accurate and real-time CMT solution generated by implementing the Gisola algorithm consisted of moment tensors and moment magnitudes,which provided invaluable insights into earthquakes occurring in Indonesia and the surrounding areas.展开更多
A Mw6.4 earthquake occurred in L＇Aquila, central Italy at 1：32：42 （UTC）, April 6, 2009. We quickly obtained the moment tensor solution of the earthquake by inverting the P waveforms of broadband recordings from t...A Mw6.4 earthquake occurred in L＇Aquila, central Italy at 1：32：42 （UTC）, April 6, 2009. We quickly obtained the moment tensor solution of the earthquake by inverting the P waveforms of broadband recordings from the global seismographic network （GSN） stations using the quick technique of moment tensor inversion, and further inferred that the nodal plane of strike 132°, dip 53° and rake -103° is the seismogenic fault.展开更多
One of the major factors inhibiting the construction of deep underground projects is the risk posed by rockbursts.A study was conducted on the access tunnel of the Shuangjiangkou hydropower station to determine the ev...One of the major factors inhibiting the construction of deep underground projects is the risk posed by rockbursts.A study was conducted on the access tunnel of the Shuangjiangkou hydropower station to determine the evolutionary mechanism of microfractures within the surrounding rock mass during rockburst development and develop a rockburst warning model.The study area was chosen through the combination of field studies with an analysis of the spatial and temporal distribution of microseismic(MS)events.The moment tensor inversion method was adopted to study rockburst mechanism,and a dynamic Bayesian network(DBN)was applied to investigating the sensitivity of MS source parameters for rockburst warnings.A MS multivariable rockburst warning model was proposed and validated using two case studies.The results indicate that fractures in the surrounding rock mass during the development of strain-structure rockbursts initially show shear failure and are then followed by tensile failure.The effectiveness of the DBN-based rockburst warning model was demonstrated using self-validation and K-fold cross-validation.Moment magnitude and source radius are the most sensitive factors based on an investigation of the influence on the parent and child nodes in the model,which can serve as important standards for rockburst warnings.The proposed rockburst warning model was found to be effective when applied to two actual projects.展开更多
In this study,the moment tensor of transversely isotropic shale was analyzed using a discrete element method-acoustic emission model(DEM-AE model).Firstly,the failure modes of the shale obtained from the acoustic emis...In this study,the moment tensor of transversely isotropic shale was analyzed using a discrete element method-acoustic emission model(DEM-AE model).Firstly,the failure modes of the shale obtained from the acoustic emission(AE) events and physical experiments were compared.Secondly,the relationships between AE events and seismic magnitudes,and AE events and the resulting cracks were analyzed.Finally,a moment tensor T-k chart describing the seismic source was introduced to demonstrate the differences in the transversely isotropic shale.The results showed that,for different anisotropy angles,a linear logarithmic relationship existed between the cumulative AE events and the seismic magnitude in the concentration area of the AE events.A normal distribution was observed for the number of AE events as the seismic magnitude changed from small to large.The moment tensor T-k chart indicated that the number and proportion of linear tension cracks in the shale were highest.When θ = 30°,the peak seismic magnitude was at a minimum.The average seismic magnitude in the concentration area of the AE events was also relatively small.Points close to the U=-1/3V line and the number of cracks included in a single AE event were at a minimum,and the corresponding peak stress also reached its lowest level.In contrast,when θ=90°,all related parameters were contrary to the above θ = 30° case.The DEM-AE model and the moment tensor T-k chart are suitable for analyzing the distribution of shale cracks appearing during the loading process.This study can provide constructive references for future research on the fracturing treatment of shale.展开更多
Moment tensor inversion was carried out to myert the source mechanism and source time function of the Ms=7.6November 6. 1988, Lancang-Gengma. Yunnan Province, Chin4 earthquake. Waveforms of long-period bodywaves recor...Moment tensor inversion was carried out to myert the source mechanism and source time function of the Ms=7.6November 6. 1988, Lancang-Gengma. Yunnan Province, Chin4 earthquake. Waveforms of long-period bodywaves recorded by China Digital Seismograph Network (CDSN) were used in the inversion. The inverted resultshows one nodal plane of right-lateral strike-slip faulting and another of left-lateral strike-slip faulting and a simplesource time function of a duration of about 15 s and scalar seismic moment of 6.4x 102oN-N-m From the geologicaldata and tectonic settings and also from field observations and epicentral distribution of aftershocks, the nodalplane striking in the azimuth of 313° is preferred as the fault plane. The pressure axis lies almost horizontally innorth-south direction.展开更多
Dongjiahe Coal Mine belongs to the Carboniferous Permian coal field which has a high degree of karst and fissure development.This paper takes the working face of Dongjiahe Coal Mine as an example;through the microseis...Dongjiahe Coal Mine belongs to the Carboniferous Permian coal field which has a high degree of karst and fissure development.This paper takes the working face of Dongjiahe Coal Mine as an example;through the microseismic(MS)monitoring system arranged on the working face,the moment tensor theory was used to invert the focal mechanism solution of the anomalous area of the floor MS event;combining the numerical simulation and field data,the underlying floor faults were identified by the stress inversion method.The results show that:1)Moment tensors were decomposed into three components and the main type of rupture in this area is mixed failure according to the relative criterion;2)The hidden fault belongs to the reversed fault,its dip angle is approximately 70°,and the rupture length is 21 m determined by the inversion method of the initial dynamic polarity and stress in the focal mechanism;3)The failure process of the fault is divided into three stages by numerical simulation method combined with the temporal and spatial distribution of MS events.The results can provide a reference for early warning and evaluation of similar coal mine water inrush risks.展开更多
To improve the accuracy of microseismic inversion,seismic anisotropy and moment tensor source should be carefully considered in the forward modelling stage.In this study,3D microseismic anisotropy wave forward modelli...To improve the accuracy of microseismic inversion,seismic anisotropy and moment tensor source should be carefully considered in the forward modelling stage.In this study,3D microseismic anisotropy wave forward modelling with a moment tensor source was proposed.The modelling was carried out based on a rotated-staggered-grid(RSG)scheme.In contrast to staggered-grids,the RSG scheme defines the velocity components and densities at the same grid,as do the stress components and elastic parameters.Therefore,the elastic moduli do not need to be interpolated.In addition,the detailed formulation and implementation of moment-tensor source loaded on the RSG was presented by equating the source to the stress increments.Meanwhile,the RSG-based 3D wave equation forward modelling was performed in parallel using compute unified device architecture(CUDA)programming on a graphics processing unit(GPU)to improve its efficiency.Numerical simulations including homogeneous and anisotropic models were carried out using the method proposed in this paper,and compared with other methods to prove the reliability of this method.Furthermore,the high efficiency of the proposed approach was evaluated.The results show that the computational efficiency of proposed method can be improved by about two orders of magnitude compared with traditional central processing unit(CPU)computing methods.It could not only help the analysis of microseismic full wavefield records,but also provide support for passive source inversion,including location and focal mechanism inversion,and velocities inversion.展开更多
Moment tensor inversion for the focal mechanism of the 12 earthquakes of the Dongfang (Hainan) earthquakeswarm occurred from June to August 1992 with near-source broadband data recorded by a temporal small-aperturenet...Moment tensor inversion for the focal mechanism of the 12 earthquakes of the Dongfang (Hainan) earthquakeswarm occurred from June to August 1992 with near-source broadband data recorded by a temporal small-aperturenetwork consisting of DCS-302 digital three-component accelerographs. The results inverted indicate that thepredominant components of sources of all these 12 earthqualles were shear dislocations. The principal pressureaxis and the principal tension axis are in NW-SE direction and in NE-SW direction, respectively, and their dips arealmost horizontal. It could infer that these earthquakes occurred within the same ambient stress field.展开更多
Breakthrough point source model, extended earthquake source model is used to calculate more seismic source parameters in this paper. We express seismic source using higher degree moment tensors, to reduce a Iarge numb...Breakthrough point source model, extended earthquake source model is used to calculate more seismic source parameters in this paper. We express seismic source using higher degree moment tensors, to reduce a Iarge number terms originally presenting in higher degree moment tensor representation, Haskell rupture model is used. We in verted the source parameters of Mani earthquake in Tibet using broad-band body wave of 32 stations of Global Seismograph Network (GSN), the results show that it is a strike-slip fault, rupture direction is 75°, rupture duration is 19 s, the fault plan is φ=77°， δ5=88°, A=0°, the auxiliare plane is φ=347°, δ=90°, k=178°, and the fault dimension is 47 km×28 km. These results will give new quantitative data for earth dynamics and have practical meaning for seismic source tomography research.展开更多
Using the technique of seismic moment tensor inversion, the source mechanisms of 10 earthquakes with Ms5.2that occurred in China from November 1996 to January 1998 were determined rapidly. The determined resultswere s...Using the technique of seismic moment tensor inversion, the source mechanisms of 10 earthquakes with Ms5.2that occurred in China from November 1996 to January 1998 were determined rapidly. The determined resultswere sent as 'Bulletins of Source Mechanism Parameters of Earthquakes' to the Seismic Regime Guards' Office,China Seismological Bureau, and the relevant provincial seismological bureaus. These bulletins have played rolein the fast response to large earthquakes.展开更多
The moment tensor solutions of 51 small to moderate earthquakes occurred in the Capital Region in the year of 2004 are obtained by inverting the broadband waveform data. Accordingly, other source parameters, such as s...The moment tensor solutions of 51 small to moderate earthquakes occurred in the Capital Region in the year of 2004 are obtained by inverting the broadband waveform data. Accordingly, other source parameters, such as scalar seismic moments, moment magnitudes, double-couple （DC） components and compensated-linear-vector-dipole （CLVD） components, are determined as well as fault parameters and stress-axis parameters. The inverted results are evaluated by groups of numerical tests.展开更多
Two earthquakes of Ms=6.0 and Ms=6. 1 consecutively occurred on December 31, 1994 and January 10, 1995 in Beibuwan region, China. By using the generalized reflection-transmission coefficient matrix and the discrete sl...Two earthquakes of Ms=6.0 and Ms=6. 1 consecutively occurred on December 31, 1994 and January 10, 1995 in Beibuwan region, China. By using the generalized reflection-transmission coefficient matrix and the discrete slowness integration method in the calculation of Green's functions, we obtained the focal mechanisms of these earthquakes using long-period waveforms of regional body waves recorded by the China Digital Seismograph Network (CDSN) by means of moment tensor inversion method in frequency domain. The results inverted indicate that the focal mechanisms of these two earthquakes were similar to each other. Their principal compressional stresses are in NW-SE direction and principal tensional stresses are in NE-SW direction. It turns out that the occurrence of the two earthquakes was controlled by the same tectonic environment related to the collision of the Philippine Plate and the Eurasian Plates. On the other hand, the results imply that the stress field in the seismogenic region has a significant change after the Ms=6.0 earthquake. It may be proposed that the occurrence of the Ms=6. 1 earthquake could be related to the stress field adjustment caused by the Ms=6.0 earthquake.展开更多
Using the moment tensor inversion method, we calculate the focal mechanisms of the aftershock sequence of the Ms=6.1 Lulong earthquake occurred on October 19, 1982 in Hebei Province. We found that the pressure axis in...Using the moment tensor inversion method, we calculate the focal mechanisms of the aftershock sequence of the Ms=6.1 Lulong earthquake occurred on October 19, 1982 in Hebei Province. We found that the pressure axis in Lulong basin is nearly in the east-west direction with an azimuth of N74°E. However, in the north of the basin the stress axis changes to N43°E; and in some places near the center of the basin it changes to the northwest that is almost perpendicular to the P axis obtained by us from those events around the basin. This feature illuminates that in Lulong earthquake sequence, the stress direction is different in different parts of crustal structure, which shows that the tectonic movement in Lulong region is complex. This is because that Lulong is located in the eastern part of Chinese mainland and is subject to the compression of Japanese Sea Basin driven by the Pacific Plate. On the other hand, nipped by the Yanshan and North China blocks, Lulong is obviously restricted by the block boundaries.展开更多
plane with the strike of 127°, the dip of 79° and the rake of 171°. The rupture process inversion result of MS=7.9 earthquake shows that the total rupture duration is about 37 s, the scalar moment tenso...plane with the strike of 127°, the dip of 79° and the rake of 171°. The rupture process inversion result of MS=7.9 earthquake shows that the total rupture duration is about 37 s, the scalar moment tensor is M0=0.97 × 1020 N·m. Rupture mainly occurred on the shallow area with 110 km long and 30 km wide, the location in which the rupture initiated is not where the main rupture took place, and the area with slip greater than 0.5 m basically lies within 35 km deep middle-crust under the earth surface. The maximum static slip is 3.6 m. There are two distinct areas with slip larger than 2.0 m. We noticed that when the rupture propagated towards northwest and closed to the area around the MS=7.3 hypocenter, the slip decreased rapidly, which may indicate that the rupture process was stopped by barriers. The consistence of spatial distribution of slip on the fault plane with the distribution of aftershocks also supports that the rupture is a heterogeneous process owing to the presence of barriers.展开更多
Ruichang-Yangxin earthquake is another moderate earthquake in Yangxin-Jiujiang area since 2005 Jiujiang-Ruichang M5.7 earthquake. In order to more understand the seismic activities in this area, we study the moment te...Ruichang-Yangxin earthquake is another moderate earthquake in Yangxin-Jiujiang area since 2005 Jiujiang-Ruichang M5.7 earthquake. In order to more understand the seismic activities in this area, we study the moment tensor solution and the seismogenic structure of the Ruichang-Yangxin earthquake. Precise earthquake relocation shows that the mainshock occurred on the southwestern part of the NE-trending fault and aftershocks are distributed not only along the NE-trending fault but also along its conjugated NW-trending fault. By comprehensive analysis on the earthquake distribution, characteristics of isoseismal curve, focal mechanism, and regional structure characteristics, it is inferred that this earthquake is caused by the NE-trending Tanlu fault. In addition, it has close relationship with the conjugated NW-trending fault as well. Many researches have shown that the junction area is the earthquake-prone area, and should be paid more attention to. And our study also proves this viewpoint.展开更多
Moment tensor inversion was carried out for small and moderate earthquakes with near-source broadband data recorded by a temporal small-aperture network consisting of three component accelerographs. Accelerograms were...Moment tensor inversion was carried out for small and moderate earthquakes with near-source broadband data recorded by a temporal small-aperture network consisting of three component accelerographs. Accelerograms were integrated twice to produce displacement seismograms and filtered by a Butterworth band-pass filter. Green's functions were calculated for a homogeneous semi-infinite elastic medium in the inversion. Direct P,S and converted SP phases were identified for the inversion with reference to the synthetic seismograms. Through the moment tensor inversion it is demonstrated that with very simple structure model and selected phases, one is able to retrieve the source mechanism and the seismic moment for small events, andthe source mechanism for moderate events. It is also demonstrated that the technique described in this studyis convenient for the determination of source mechanismal and stress state in dealing with numbers of small andmoderate earthquakes without detailed knowledge about the structure. As an application of the present technique, moment tensors of 15 aftershocks of the Ms 6. 1 earthquake occurred on April 18, 1985 in Luquan,Yunnan Province, China were retrieved. The inversion results show that these events can be reasonably modeled by a predominant double couple. It can be found from the distribution of principal stress axes and the average moment tensor that the pressure axis in this area lies horizontally in the NNW direction, which is consistent with the results obtained from previous studies. It implies that the occurrence of the Luquan earthquake sequence is tectonically related to the relative collision motion between the Indian and Eurasian Plates.展开更多
In this study,we propose a new method to determine full moment tensor solution for induced seismicity.This method generalizes the full waveform matching algorithm we have developed to determine the double-couple(DC)fo...In this study,we propose a new method to determine full moment tensor solution for induced seismicity.This method generalizes the full waveform matching algorithm we have developed to determine the double-couple(DC)focal mechanism based on the neighbourhood algorithm.One major difference between the new method and the former one is that we adopt a new misfit function to constrain the candidate moment tensor solutions with respect to a reference DC solution in addition to other misfit terms characterizing the waveform matching.Through synthetic tests using a real passive seismic survey geometry,the results show the new constraint can help better recover the DC components of inverted moment tensors.We further investigate how errors in the velocity model and source location affect the moment tensor solution.The synthetic test results indicate that the constrained inversion is robust in recovering both the DC and non-DC components.We also test the proposed method on several real induced events in an oil/gas field in Oman using the same observation system as synthetic tests.While it is found that the full moment tensor solutions without using the DC constraints have much larger non-DC components than solutions with the DC constraints,both solutions are able to fit the observed waveforms at similar levels.The synthetic and real test results suggest the proposed DC constrained inversion method can reliably retrieve full moment tensor solutions for the induced seismicity.展开更多
We investigate the accuracy and robustness of moment tensor(MT)and stress inversion solutions derived from acoustic emissions(AEs)during the laboratory fracturing of prismatic Barre granite specimens.Pre-cut flaws in ...We investigate the accuracy and robustness of moment tensor(MT)and stress inversion solutions derived from acoustic emissions(AEs)during the laboratory fracturing of prismatic Barre granite specimens.Pre-cut flaws in the specimens introduce a complex stress field,resulting in a spatial and temporal variation of focal mechanisms.Specifically,we consider two experimental setups:(1)where the rock is loaded in compression to generate primarily shear-type fractures and(2)where the material is loaded in indirect tension to generate predominantly tensile-type fractures.In each test,we first decompose AE moment tensors into double-couple(DC)and non-DC terms and then derive unambiguous normal and slip vectors using k-means clustering and an unstructured damped stress inversion algorithm.We explore temporal and spatial distributions of DC and non-DC events at different loading levels.The majority of the DC and the tensile non-DC events cluster around the pre-cut flaws,where macro-cracks later develop.Results of stress inversion are verified against the stress field from finite element(FE)modeling.A good agreement is found between the experimentally derived and numerically simulated stress orientations.To the best of the authors’knowledge,this work presents the first case where stress inversion methodologies are validated by numerical simulations at laboratory scale and under highly heterogeneous stress distributions.展开更多
基金supported by the National Natural Science dation Foun-of China(Grant Number 42272204)Key Laboratory of Coal sources Re-Exploration and Comprehensive Utilization,Ministry of Natural Resources,Canada(SMDZ-KF2024-4)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2024JCCXDC06)supported in part by open fund project of State Key Laboratory for Fine Exploration and Intelligent Development of Coal Research(SKLCRSM23KFA04)。
文摘This paper proposed a moment tensor regression prediction technology based on ResNet for microseismic events.Taking the great advantages of deep networks in classification and regression tasks,it can realize the great potential of fast and accurate inversion of microseismic moment tensors after the network trained.This ResNet-based moment tensor prediction technology,whose input is raw recordings,does not require the extraction of data features in advance.First,we tested the network using synthetic data and performed a quantitative assessment of the errors.The results demonstrate that the network exhibits high accuracy and efficiency during the prediction phase.Next,we tested the network using real microseismic data and compared the results with those from traditional inversion methods.The error in the results was relatively small compared to traditional methods.However,the network operates more efficiently without requiring manual intervention,making it highly valuable for near-real-time monitoring applications.
基金the Graduate Innovation Program of China University of Mining and Technology,the Fundamental Research Funds for the Central Universities(Grant No.2023WLKXJ017)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX23_2776)the Shandong Energy Group(Grant No.SNKJ2022BJ03-R28)。
文摘In this study,we employed Bayesian inversion coupled with the summation-by-parts and simultaneousapproximation-term(SBP-SAT)forward simulation method to elucidate the mechanisms behind mininginduced seismic events caused by fault slip and their potential effects on rockbursts.Through Bayesian inversion,it is determined that the sources near fault FQ14 have a significant shear component.Additionally,we analyzed the stress and displacement fields of high-energy events,along with the hypocenter distribution of aftershocks,which aided in identifying the slip direction of the critically stressed fault FQ14.We also performed forward modeling to capture the complex dynamics of fault slip under varying friction laws and shear fracture modes.The selection of specific friction laws for fault slip models was based on their ability to accurately replicate observed slip behavior under various external loading conditions,thereby enhancing the applicability of our findings.Our results suggest that the slip behavior of fault FQ14 can be effectively understood by comparing different scenarios.
基金Universitas Negeri Surabaya,Universitas Sebelas Maret,and Universitas Syiah Kuala for providing research grants for the Indonesian Collaborative Research(RKI)scheme。
文摘The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor(CMT)automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas.Gisola software was used to estimate the CMT solution by selecting the velocity model that best suited the local and regional geological conditions in Indonesia and the surrounding areas.The data used in this study were earthquakes with magnitudes of 5.4 to 8.0.High-quality,real-time broadband seismographic data were provided by the International Federation of Digital Seismograph Networks Web Services(FDSNWS)and the European Integrated Data Archive(EIDA)Federation in Indonesia and the surrounding areas.Furthermore,the inversion process and filter adjustment were carried out on the seismographic data to obtain good CMT solutions.The CMT solutions from Gisola provided good-quality solutions,in which all earthquake data had A-level quality(high quality,with good variant reduction).The Gisola CMT solution was justified with the Global CMT(GCMT)solution by using the Kagan angle value,with an average of approximately 11.2°.This result suggested that the CMT solution generated from Gisola was trustworthy and reliable.The Gisola CMT solution was typically available within approximately 15 minutes after an earthquake occurred.Once it met the quality requirement,it was automatically published on the internet.The catalog of local and regional earthquake records obtained through this technology holds great promise for improving the current understanding of regional seismic activity and ongoing tectonic processes.The accurate and real-time CMT solution generated by implementing the Gisola algorithm consisted of moment tensors and moment magnitudes,which provided invaluable insights into earthquakes occurring in Indonesia and the surrounding areas.
基金No.09FE3007 of Institute of Geophysics,China Earthquake Administration
文摘A Mw6.4 earthquake occurred in L＇Aquila, central Italy at 1：32：42 （UTC）, April 6, 2009. We quickly obtained the moment tensor solution of the earthquake by inverting the P waveforms of broadband recordings from the global seismographic network （GSN） stations using the quick technique of moment tensor inversion, and further inferred that the nodal plane of strike 132°, dip 53° and rake -103° is the seismogenic fault.
基金funding support from the National Natural Science Foundation of China(Grant No.42177143 and 51809221)the Science Foundation for Distinguished Young Scholars of Sichuan Province,China(Grant No.2020JDJQ0011).
文摘One of the major factors inhibiting the construction of deep underground projects is the risk posed by rockbursts.A study was conducted on the access tunnel of the Shuangjiangkou hydropower station to determine the evolutionary mechanism of microfractures within the surrounding rock mass during rockburst development and develop a rockburst warning model.The study area was chosen through the combination of field studies with an analysis of the spatial and temporal distribution of microseismic(MS)events.The moment tensor inversion method was adopted to study rockburst mechanism,and a dynamic Bayesian network(DBN)was applied to investigating the sensitivity of MS source parameters for rockburst warnings.A MS multivariable rockburst warning model was proposed and validated using two case studies.The results indicate that fractures in the surrounding rock mass during the development of strain-structure rockbursts initially show shear failure and are then followed by tensile failure.The effectiveness of the DBN-based rockburst warning model was demonstrated using self-validation and K-fold cross-validation.Moment magnitude and source radius are the most sensitive factors based on an investigation of the influence on the parent and child nodes in the model,which can serve as important standards for rockburst warnings.The proposed rockburst warning model was found to be effective when applied to two actual projects.
基金Financial support for this work is provided by the National Natural Science Foundation of China (no.51474208)the National Key Research and Development Program of China (2016YFC0600904)+1 种基金a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)The fnancial support provided by China Scholarship Council (CSC,Grant no.201606420013)
文摘In this study,the moment tensor of transversely isotropic shale was analyzed using a discrete element method-acoustic emission model(DEM-AE model).Firstly,the failure modes of the shale obtained from the acoustic emission(AE) events and physical experiments were compared.Secondly,the relationships between AE events and seismic magnitudes,and AE events and the resulting cracks were analyzed.Finally,a moment tensor T-k chart describing the seismic source was introduced to demonstrate the differences in the transversely isotropic shale.The results showed that,for different anisotropy angles,a linear logarithmic relationship existed between the cumulative AE events and the seismic magnitude in the concentration area of the AE events.A normal distribution was observed for the number of AE events as the seismic magnitude changed from small to large.The moment tensor T-k chart indicated that the number and proportion of linear tension cracks in the shale were highest.When θ = 30°,the peak seismic magnitude was at a minimum.The average seismic magnitude in the concentration area of the AE events was also relatively small.Points close to the U=-1/3V line and the number of cracks included in a single AE event were at a minimum,and the corresponding peak stress also reached its lowest level.In contrast,when θ=90°,all related parameters were contrary to the above θ = 30° case.The DEM-AE model and the moment tensor T-k chart are suitable for analyzing the distribution of shale cracks appearing during the loading process.This study can provide constructive references for future research on the fracturing treatment of shale.
文摘Moment tensor inversion was carried out to myert the source mechanism and source time function of the Ms=7.6November 6. 1988, Lancang-Gengma. Yunnan Province, Chin4 earthquake. Waveforms of long-period bodywaves recorded by China Digital Seismograph Network (CDSN) were used in the inversion. The inverted resultshows one nodal plane of right-lateral strike-slip faulting and another of left-lateral strike-slip faulting and a simplesource time function of a duration of about 15 s and scalar seismic moment of 6.4x 102oN-N-m From the geologicaldata and tectonic settings and also from field observations and epicentral distribution of aftershocks, the nodalplane striking in the azimuth of 313° is preferred as the fault plane. The pressure axis lies almost horizontally innorth-south direction.
基金Project(2017YFC1503103)supported by the National Key Research and Development Plan of ChinaProjects(51774064,51974055,41941018)supported by the National Natural Science Foundation of China+1 种基金Project(DUT20GJ216)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(51627804)supported by the Special-Funded Program on National Key Scientific Instruments and Equipment Development,China。
文摘Dongjiahe Coal Mine belongs to the Carboniferous Permian coal field which has a high degree of karst and fissure development.This paper takes the working face of Dongjiahe Coal Mine as an example;through the microseismic(MS)monitoring system arranged on the working face,the moment tensor theory was used to invert the focal mechanism solution of the anomalous area of the floor MS event;combining the numerical simulation and field data,the underlying floor faults were identified by the stress inversion method.The results show that:1)Moment tensors were decomposed into three components and the main type of rupture in this area is mixed failure according to the relative criterion;2)The hidden fault belongs to the reversed fault,its dip angle is approximately 70°,and the rupture length is 21 m determined by the inversion method of the initial dynamic polarity and stress in the focal mechanism;3)The failure process of the fault is divided into three stages by numerical simulation method combined with the temporal and spatial distribution of MS events.The results can provide a reference for early warning and evaluation of similar coal mine water inrush risks.
基金financially supported by the National Natural Science Foundation of China(No.42272204)the National Key Research and Development Program of China(No.2018YFB0605503)the Fundamental Research Funds for the Central Universities(No.2021JCCXDC02)。
文摘To improve the accuracy of microseismic inversion,seismic anisotropy and moment tensor source should be carefully considered in the forward modelling stage.In this study,3D microseismic anisotropy wave forward modelling with a moment tensor source was proposed.The modelling was carried out based on a rotated-staggered-grid(RSG)scheme.In contrast to staggered-grids,the RSG scheme defines the velocity components and densities at the same grid,as do the stress components and elastic parameters.Therefore,the elastic moduli do not need to be interpolated.In addition,the detailed formulation and implementation of moment-tensor source loaded on the RSG was presented by equating the source to the stress increments.Meanwhile,the RSG-based 3D wave equation forward modelling was performed in parallel using compute unified device architecture(CUDA)programming on a graphics processing unit(GPU)to improve its efficiency.Numerical simulations including homogeneous and anisotropic models were carried out using the method proposed in this paper,and compared with other methods to prove the reliability of this method.Furthermore,the high efficiency of the proposed approach was evaluated.The results show that the computational efficiency of proposed method can be improved by about two orders of magnitude compared with traditional central processing unit(CPU)computing methods.It could not only help the analysis of microseismic full wavefield records,but also provide support for passive source inversion,including location and focal mechanism inversion,and velocities inversion.
文摘Moment tensor inversion for the focal mechanism of the 12 earthquakes of the Dongfang (Hainan) earthquakeswarm occurred from June to August 1992 with near-source broadband data recorded by a temporal small-aperturenetwork consisting of DCS-302 digital three-component accelerographs. The results inverted indicate that thepredominant components of sources of all these 12 earthqualles were shear dislocations. The principal pressureaxis and the principal tension axis are in NW-SE direction and in NE-SW direction, respectively, and their dips arealmost horizontal. It could infer that these earthquakes occurred within the same ambient stress field.
文摘Breakthrough point source model, extended earthquake source model is used to calculate more seismic source parameters in this paper. We express seismic source using higher degree moment tensors, to reduce a Iarge number terms originally presenting in higher degree moment tensor representation, Haskell rupture model is used. We in verted the source parameters of Mani earthquake in Tibet using broad-band body wave of 32 stations of Global Seismograph Network (GSN), the results show that it is a strike-slip fault, rupture direction is 75°, rupture duration is 19 s, the fault plan is φ=77°， δ5=88°, A=0°, the auxiliare plane is φ=347°, δ=90°, k=178°, and the fault dimension is 47 km×28 km. These results will give new quantitative data for earth dynamics and have practical meaning for seismic source tomography research.
文摘Using the technique of seismic moment tensor inversion, the source mechanisms of 10 earthquakes with Ms5.2that occurred in China from November 1996 to January 1998 were determined rapidly. The determined resultswere sent as 'Bulletins of Source Mechanism Parameters of Earthquakes' to the Seismic Regime Guards' Office,China Seismological Bureau, and the relevant provincial seismological bureaus. These bulletins have played rolein the fast response to large earthquakes.
基金The International 973 Programs (2001CB711005 and 2004DFA06000) the Special Program of China Earthquake Administration (2004BA601B)
文摘The moment tensor solutions of 51 small to moderate earthquakes occurred in the Capital Region in the year of 2004 are obtained by inverting the broadband waveform data. Accordingly, other source parameters, such as scalar seismic moments, moment magnitudes, double-couple （DC） components and compensated-linear-vector-dipole （CLVD） components, are determined as well as fault parameters and stress-axis parameters. The inverted results are evaluated by groups of numerical tests.
文摘Two earthquakes of Ms=6.0 and Ms=6. 1 consecutively occurred on December 31, 1994 and January 10, 1995 in Beibuwan region, China. By using the generalized reflection-transmission coefficient matrix and the discrete slowness integration method in the calculation of Green's functions, we obtained the focal mechanisms of these earthquakes using long-period waveforms of regional body waves recorded by the China Digital Seismograph Network (CDSN) by means of moment tensor inversion method in frequency domain. The results inverted indicate that the focal mechanisms of these two earthquakes were similar to each other. Their principal compressional stresses are in NW-SE direction and principal tensional stresses are in NE-SW direction. It turns out that the occurrence of the two earthquakes was controlled by the same tectonic environment related to the collision of the Philippine Plate and the Eurasian Plates. On the other hand, the results imply that the stress field in the seismogenic region has a significant change after the Ms=6.0 earthquake. It may be proposed that the occurrence of the Ms=6. 1 earthquake could be related to the stress field adjustment caused by the Ms=6.0 earthquake.
基金National Natural Science Foundation of China(40234038)
文摘Using the moment tensor inversion method, we calculate the focal mechanisms of the aftershock sequence of the Ms=6.1 Lulong earthquake occurred on October 19, 1982 in Hebei Province. We found that the pressure axis in Lulong basin is nearly in the east-west direction with an azimuth of N74°E. However, in the north of the basin the stress axis changes to N43°E; and in some places near the center of the basin it changes to the northwest that is almost perpendicular to the P axis obtained by us from those events around the basin. This feature illuminates that in Lulong earthquake sequence, the stress direction is different in different parts of crustal structure, which shows that the tectonic movement in Lulong region is complex. This is because that Lulong is located in the eastern part of Chinese mainland and is subject to the compression of Japanese Sea Basin driven by the Pacific Plate. On the other hand, nipped by the Yanshan and North China blocks, Lulong is obviously restricted by the block boundaries.
基金The Specialized Funds for National Key Basic Study (G1998040704), the Dual Project of China Earthquake Admini-stration (9691309020301) and National Natural Science Foundation of China (46764010).
文摘plane with the strike of 127°, the dip of 79° and the rake of 171°. The rupture process inversion result of MS=7.9 earthquake shows that the total rupture duration is about 37 s, the scalar moment tensor is M0=0.97 × 1020 N·m. Rupture mainly occurred on the shallow area with 110 km long and 30 km wide, the location in which the rupture initiated is not where the main rupture took place, and the area with slip greater than 0.5 m basically lies within 35 km deep middle-crust under the earth surface. The maximum static slip is 3.6 m. There are two distinct areas with slip larger than 2.0 m. We noticed that when the rupture propagated towards northwest and closed to the area around the MS=7.3 hypocenter, the slip decreased rapidly, which may indicate that the rupture process was stopped by barriers. The consistence of spatial distribution of slip on the fault plane with the distribution of aftershocks also supports that the rupture is a heterogeneous process owing to the presence of barriers.
基金supported by the Director Foundation of Institute of Seismology, China Earthquake Adminstration(IS201102643)National Nature Science Foundation of China (No. 41004020)
文摘Ruichang-Yangxin earthquake is another moderate earthquake in Yangxin-Jiujiang area since 2005 Jiujiang-Ruichang M5.7 earthquake. In order to more understand the seismic activities in this area, we study the moment tensor solution and the seismogenic structure of the Ruichang-Yangxin earthquake. Precise earthquake relocation shows that the mainshock occurred on the southwestern part of the NE-trending fault and aftershocks are distributed not only along the NE-trending fault but also along its conjugated NW-trending fault. By comprehensive analysis on the earthquake distribution, characteristics of isoseismal curve, focal mechanism, and regional structure characteristics, it is inferred that this earthquake is caused by the NE-trending Tanlu fault. In addition, it has close relationship with the conjugated NW-trending fault as well. Many researches have shown that the junction area is the earthquake-prone area, and should be paid more attention to. And our study also proves this viewpoint.
文摘Moment tensor inversion was carried out for small and moderate earthquakes with near-source broadband data recorded by a temporal small-aperture network consisting of three component accelerographs. Accelerograms were integrated twice to produce displacement seismograms and filtered by a Butterworth band-pass filter. Green's functions were calculated for a homogeneous semi-infinite elastic medium in the inversion. Direct P,S and converted SP phases were identified for the inversion with reference to the synthetic seismograms. Through the moment tensor inversion it is demonstrated that with very simple structure model and selected phases, one is able to retrieve the source mechanism and the seismic moment for small events, andthe source mechanism for moderate events. It is also demonstrated that the technique described in this studyis convenient for the determination of source mechanismal and stress state in dealing with numbers of small andmoderate earthquakes without detailed knowledge about the structure. As an application of the present technique, moment tensors of 15 aftershocks of the Ms 6. 1 earthquake occurred on April 18, 1985 in Luquan,Yunnan Province, China were retrieved. The inversion results show that these events can be reasonably modeled by a predominant double couple. It can be found from the distribution of principal stress axes and the average moment tensor that the pressure axis in this area lies horizontally in the NNW direction, which is consistent with the results obtained from previous studies. It implies that the occurrence of the Luquan earthquake sequence is tectonically related to the relative collision motion between the Indian and Eurasian Plates.
基金We want to thank the reviewers for their valuable comments about this manuscript.This study is funded by the National Science and Technology Major Project of China(No.2016ZX05023004)the National Natural Science Foundation of China(Nos.41804040 and 41861134009).
文摘In this study,we propose a new method to determine full moment tensor solution for induced seismicity.This method generalizes the full waveform matching algorithm we have developed to determine the double-couple(DC)focal mechanism based on the neighbourhood algorithm.One major difference between the new method and the former one is that we adopt a new misfit function to constrain the candidate moment tensor solutions with respect to a reference DC solution in addition to other misfit terms characterizing the waveform matching.Through synthetic tests using a real passive seismic survey geometry,the results show the new constraint can help better recover the DC components of inverted moment tensors.We further investigate how errors in the velocity model and source location affect the moment tensor solution.The synthetic test results indicate that the constrained inversion is robust in recovering both the DC and non-DC components.We also test the proposed method on several real induced events in an oil/gas field in Oman using the same observation system as synthetic tests.While it is found that the full moment tensor solutions without using the DC constraints have much larger non-DC components than solutions with the DC constraints,both solutions are able to fit the observed waveforms at similar levels.The synthetic and real test results suggest the proposed DC constrained inversion method can reliably retrieve full moment tensor solutions for the induced seismicity.
文摘We investigate the accuracy and robustness of moment tensor(MT)and stress inversion solutions derived from acoustic emissions(AEs)during the laboratory fracturing of prismatic Barre granite specimens.Pre-cut flaws in the specimens introduce a complex stress field,resulting in a spatial and temporal variation of focal mechanisms.Specifically,we consider two experimental setups:(1)where the rock is loaded in compression to generate primarily shear-type fractures and(2)where the material is loaded in indirect tension to generate predominantly tensile-type fractures.In each test,we first decompose AE moment tensors into double-couple(DC)and non-DC terms and then derive unambiguous normal and slip vectors using k-means clustering and an unstructured damped stress inversion algorithm.We explore temporal and spatial distributions of DC and non-DC events at different loading levels.The majority of the DC and the tensile non-DC events cluster around the pre-cut flaws,where macro-cracks later develop.Results of stress inversion are verified against the stress field from finite element(FE)modeling.A good agreement is found between the experimentally derived and numerically simulated stress orientations.To the best of the authors’knowledge,this work presents the first case where stress inversion methodologies are validated by numerical simulations at laboratory scale and under highly heterogeneous stress distributions.
