Fault Source Research Articles

Comparison between the Hamiltonian Monte Carlo method and the Metropolis–Hastings method for coseismic fault model estimation

A rapid source fault estimation and quantitative assessment of the uncertainty of the estimated model can elucidate the occurrence mechanism of earthquakes and inform disaster damage mitigation. The Bayesian statistical method that addresses the posterior distribution of unknowns using the Markov chain Monte Carlo (MCMC) method is significant for uncertainty assessment. The Metropolis–Hastings method, especially the Random walk Metropolis–Hastings (RWMH), has many applications, including coseismic fault estimation. However, RWMH exhibits a trade-off between the transition distance and the acceptance ratio of parameter transition candidates and requires a long mixing time, particularly in solving high-dimensional problems. This necessitates a more efficient Bayesian method. In this study, we developed a fault estimation algorithm using the Hamiltonian Monte Carlo (HMC) method, which is considered more efficient than the other MCMC method, but its applicability has not been sufficiently validated to estimate the coseismic fault for the first time. HMC can conduct sampling more intelligently with the gradient information of the posterior distribution. We applied our algorithm to the 2016 Kumamoto earthquake (MJMA 7.3), and its sampling converged in 2 × 104 samples, including 1 × 103 burn-in samples. The estimated models satisfactorily accounted for the input data; the variance reduction was approximately 88%, and the estimated fault parameters and event magnitude were consistent with those reported in previous studies. HMC could acquire similar results using only 2% of the RWMH chains. Moreover, the power spectral density (PSD) of each model parameter's Markov chain showed this method exhibited a low correlation with the subsequent sample and a long transition distance between samples. These results indicate HMC has advantages in terms of chain length than RWMH, expecting a more efficient estimation for a high-dimensional problem that requires a long mixing time or a problem using nonlinear Green’s function, which has a large computational cost.Graphical

Benign-to-malignant transition in external short circuiting of lithium-ion batteries

External short circuiting (ESC) is a main source of battery faults. However, the ESC damage mechanism and its evolution process are unclear, resulting in difficulties in safety management. Here, we report the impact of different ESC durations on battery performance and divide the ESC process into four stages. The analysis reveals that there is a benign regime in which the ESC effect is comparable to nominal charge-discharge cycling. When ESC duration is close to a critical time, there is a benign-to-malignant transition. The critical time corresponds to the inflection point at the end of battery current curve, which reflects heating-induced membrane melting and contraction that distorts the jellyroll. The critical time surface under various conditions is established and the center temperatures of the critical time and battery completely failure are disclosed, paving the way for fault diagnosis and using “benign ESC” in a controlled fashion. • Benign-to-malignant evolution of battery ESC damage mechanism is revealed • Critical time to characterize the occurrence of malignant battery damage is identified • Equivalent influence correlation is established between benign SC and nominal cycling • Battery heating method based on controllable benign short circuit is proposed Chen et al. reveal the evolution of damage mechanism during battery external short circuit, pointing out that there is a benign-to-malignant transition. The critical time to characterize the battery malignant damage is identified. This research may open new possibilities for applying short circuit in a controlled fashion.

Impact of directional effect of strong ground motion on scenario-based earthquake hazards: preliminary results

Scenario-based earthquake hazards are useful for social planning and disaster mitigation. In this study, general attenuation properties of earthquake events are analysed empirically with respect to the direction of seismic rupture from the epicentre. The study is primarily focused on presenting a relationship between fault source characteristics and the most credible direction of any earthquake that occurs at that source. Since such a direction is not only a function of source but also is dependent on site parameters, several ground motion prediction equations are utilised in congregation with methods to evaluate site parameters. The method involves a graphical relationship between scenario spectral ordinates and polar coordinates to estimate the most credible direction for that scenario. An analysis illustrating the method is presented here for the Himalayan megathrust fault, the Main Boundary Thrust.

Coseismic Surface Deformation, Fault Modeling, and Coulomb Stress Changes of the March 2021 Thessaly, Greece, Earthquake Sequence Based on InSAR and GPS Data

Abstract In March 2021 three strong earthquakes with magnitudes (Mw) of 6.3, 6.0, and 5.2 occurred in Thessaly plain, Greece, on 3, 4, and 12 March, respectively. The modeling of all the three sources, by inversion of Interferometric Synthetic Aperture Radar and Global Positioning System data, indicates a northeast–southwest-trending extensional stress field with indications for northeast-dipping sources. The unmapped fault source of the first mainshock (Mw 6.3) is located approximately 6 km to the southwest of the known Larissa fault (LF). Moreover, the fault that was activated during the second mainshock (Mw 6.0) appears to be located more to the north, bordering the Titarisios river valley to the southwest, whereas the third mainshock (Mw 5.2) appears to be triggered at a fault segment located further to the northwest. The Coulomb stress analysis using the slip distributions of the three aforementioned mainshocks revealed a unilateral triggering of the second and third event toward the northwest, and explained the spatial development of the entire aftershock sequence. Furthermore, among the already known active faults in the broader area, only the LF was brought closer to failure as a result of the imparted stress changes.

Tsunami Early Warning System Based on Maritime Wireless Communication

Tsunami buoy, linked to satellite, is commonly used as a tsunami early warning system but has been discovered to have several drawbacks such as the need for approximately 5 minutes to issue an early warning for a tsunami after detecting the initial wave as well as its fragility. It was also reported that the twenty-two buoys placed in the Indonesian seas from 2012 to 2018 were damaged and missing. Therefore, this study proposes a new method for tsunami early warning by integrating ship-to-ship maritime wireless communication. It is important to note that vessels or fishing boats with over 30 GT have the ability to travel more than 100 nmi (approximately 180 km) from the shoreline and can be equipped with point-to-multipoint VHF radio communication. Meanwhile, smaller boats on the fishing ground located approximately 2-5 km from the shore can use a WiFi network to communicate like a wireless mesh while the existing terrestrial network can be used for the ship-to-shore communication between boats and land stations. This system is expected to provide significant benefits for a fishing town such as Pangandaran, West Java, Indonesia which is directly facing Java Megathrust in the Indian Ocean. Therefore, a tsunami numerical simulation was conducted in this study using Shallow Water Equation which involved a hypothetical tsunami simulated from the possible fault source which is approximately 250 km from the source. Moreover, the vessel’s location was assumed to be in line with the fishing ground while the arrival time of the tsunami was estimated from the model to be 22.5 minutes and compared to the relay time of the proposed system which was approximately 5.4 seconds. This is faster in terms of delay than the existing system which relays information through satellite at approximately 5 minutes in an ideal condition and also has the ability to reduce the need for tsunami buoys.

Feature optimization method for the localization technology on loose particles inside sealed electronic equipment

Existing localization technology on loose particles inside sealed electronic equipment focuses on the selection and parameter optimization of classification algorithms;the features in the specific region has not been considered. Targeting this problem, this paper shifts the research focus to features in the localization dataset and proposes a feature optimization method. First, for the missing values in the localization dataset, the numerical filling method using a variety of statistical functions or directly discarding them are compared to obtain the optimal missing value processing method. Second, different processing methods using z-score standardization, min–max standardization, and row normalization are compared to obtain the best standardization or normalization method. Third, statistic-based and model-based feature selection methods are sutdied and the Pearson correlation coefficient, p-value, and the feature importance of decision trees are used to quantitatively measure the feature performance. On this basis of this measurement, the multi-channel characteristics of the localization technology on loose particles are comprehensively considered, and a multi-channel weighted threshold feature selection method is designed. The feasibility of the new method is verified on the localization dataset. Finally, verification datasets, representing aerospace electronic modules and aerospace power supplies, are established to verify the practicability and universality of the feature optimization method. The results show that the plane and spatial localization accuracy achieved on the localization dataset increased from 87.01% and 83.67% to 95.23% and 95.51%, respectively, after feature optimization, and the plane and spatial localization accuracy achieved on the verification datasets increased from 84.51% and 80.64%% to 90.57% and 89.16%, respectively. This is the highest localization accuracy currently achieved in aerospace engineering. The current study is an important supplement to loose particle detection research and has important practical value for improving the reliability of aerospace systems. This method can also be applied to other localization research on fault sources and acoustic emission source based on machine learning.

IoT Based Transmission Line Monitoring System

Electrical power is transmitted from the generation plants to end-users at distant locations through the transmission lines. These lines are exposed to various environmental conditions and faults may occur causing power interruption to end users, damage to the power system. The fault detection has been a main objective of power system engineers, in transmission and distribution systems. Identification of fault source is tedious task; fast fault detection can help to protect the equipment before any significant damage of the equipment. The exact fault dictation can help service man to remove persistent of the faults and type the faults occur regularly, thus reducing the occurrence of fault and minimize the time of power outages. The paper is intended to detect the of fault in transmission line using an NodeMCU and the same is transmitted to control center using IoT device.

Design and Development of Superimposed Directional Comparison Protection Scheme

To achieve the UK Net Zero future by 2050, National Grid needs to integrate significantly more renewable generation into the power grid. This increases the level of harmonics, reduces system inertia and adversely affects the fault level and the performance of existing protection relays. One solution to the protection problem is the use of new types of protection that use the change in the voltage and current caused by the fault, often referred to as a superimposed or incremental based protection technique. This paper describes how a superimposed directional comparison protection scheme performed when applied to a reduced section of the full UK National Grid network and relates this to the operating performance of traditional protection. Tests are performed using the simulators DIgSILENT and RelaySimTest configured with different source levels, fault types, fault locations and fault resistances. Results show the superimposed based protection scheme achieves faster fault detection and tripping than conventional protection and is capable of detecting higher resistive faults on networks where the source capacities vary from strong to weak.

Fault diagnosis and accommodation for multi-actuator faults of a fixed-wing unmanned aerial vehicle

This study proposes a system design scheme of fault detection, isolation, and accommodation algorithms for the actuator fault of a fixed-wing unmanned aerial vehicle (FW-UAV) by considering system nonlinearity, external disturbance, and multi-actuator faults. The fault diagnosis scheme consists of a comprehensive observer and a bank of fault isolation estimators designed based on the actuator of the FW-UAV. In the diagnosis module, the system model is transformed into two systems by introducing a transformation matrix, so that both the actuator faults and the system disturbance are separated. Then, the concept of equivalent output injection is applied to construct a comprehensive observer to detect the actuator fault and estimate the unknown system disturbance. In the isolation estimation module, a set of sliding mode observers (SMOs) is constructed to isolate the multi-actuator faults, which reveals the fault source precisely. The stability analysis of the proposed SMOs was derived from the solution of linear matrix inequalities. In the event of a fault, the fault estimation provided by the fault diagnosis solution is used to accommodate the fault effects, while maintaining good attitude control and position tracking performance of the FW-UAV. The effectiveness of the proposed scheme is verified by the simulation model of de Havilland DHC-2 ‘Beaver’ aircraft in different fault cases.

Quantitative Evaluation of Coseismic Deformations Induced by Seismogenic Faulting in Mining Exploration Area During the 2018 Xingwen and 2019 Changning Earthquakes, Sichuan, China

In the period between December 2018 and July 2019, a series of earthquakes (EQs), including the 16 December 2018 Ms 5.7 Xingwen mainshock and the 17 June 2019 Ms 6.0 Changning mainshock, struck the Changning shale gas exploration field in the southern margin of the Sichuan Basin. The Xingwen and Changning EQs both occurred on concealed faults, which led to hundreds of casualties, and affected a total of over 160 thousand people in southern Sichuan. The aftershock sequences following the Xingwen and Changning EQs were clustered in the vicinity of the Jianwu syncline and Changning anticline, respectively, and occurred mostly at depths of 3–7 km. In this study, coseismic surface deformation measurements obtained through differential interferometric synthetic aperture radar (D-InSAR) data were used to identify the faulting geometries and distributions. The coseismic deformation maps have maximum line-of-sight (LOS) displacements of ∼4.53 cm on the northwest side of the Xingwen EQ source fault and ∼7.84 cm on the southwest side of the Changning EQ source fault. The calculated static Coulomb stress changes indicated that most aftershocks occurred in increasing stress zones following the mainshock ruptures. From the InSAR deformation field, a complicated concealed seismogenic doublet fault was inferred, which predominately exhibited left-lateral strike-slip motion during the Xingwen and Changning EQs. The footwall ramp of the basement fault reactivated first, and resulted in the Xingwen EQ and concentrating stresses beneath the Changning anticline, which induced the Changning EQ half a year later. Compared with previous studies, we proposed that the fault network was lubricated by water that was injected during shale gas exploration, facilitating the occurrence of the Xingwen and Changning EQs. Such work evaluated the coseismic deformations of the Xingwen and Changning EQs, and derived the regional faulting distribution from aftershock sequences. It could provide useful information for monitoring and analyzing seismic activity around the hinge zones of folds in mining exploration areas, which contributes to effective risk assessment of disasters associated with seismic geo-environments.

Identification of voltage sag source based on Improved GRA

Abstract Accurate identification of fault source causing voltage sag is of great significance to the governance and further research of voltage sag. In this paper, a voltage sag source identification method based on improved grey correlation analysis (GRA) is proposed. In view of the deficiency that the traditional GRA only considers the similarity, the proposed method considers the geometric area and slope of sequence into the calculation of correlation coefficient, so that the improved GRA has attributes of both sequence similarity and data closeness. Eight features are extracted from six common types of sag waveforms to form standard and test sequence; The improved GRA is used to calculate the correlation degree between the test and standard sequences, then the identification of sag source can be realized. Simulation model is built in MATLAB. Results show that this proposed method can effectively identify the voltage sag source. Compared with the traditional GRA, this method has higher identification accuracy and stronger identification ability.

Scenario-based tsunami hazard assessment for the coast of Vietnam from the \(109^{o}\) Meridian fault zone

Located on the continental shelf and stretching approximately 1,000 km along the Central and Southern Central coasts of Vietnam, the 109o Meridian Fault system has long been recognized as seismically active. Empirical evidence of the seismic, volcanic, and submarine landslide activities also suggests that this fault might be capable of originating near-field tsunamis, which can harm the Vietnamese coastal zone. This paper investigates the possibility of the near-field tsunamis from the 109o Meridian Fault and their impact on the Vietnamese coasts. Location and segmentation of the 109o Meridian fault were determined using seismological, geophysical data, and geomorphologic evidence. The fault’s seismotectonic and geodynamic characteristics were used to model the tsunami source. The COMCOT model was used for simulating three worst-case tsunami scenarios excited by earthquakes with Mw = 8.0 originated in two different segments of the 109o Meridian Fault source. The relationship between tsunami wave height and the source-to-coast travel time is investigated in detail at the virtual sea-level stations distributed along the Vietnamese coastline. The simulation results are presented in the deep-ocean tsunami amplitude maps for the entire East Vietnam Sea region and the coastal tsunami amplitude maps for the Vietnamese coasts. The simulation results show the highest tsunami hazards concentrated along the Central and Southern Central Vietnam coastal zones (from Quang Nam province to Ba Ria-Vung Tau province), with the highest tsunami waves not exceeding 4 m observed off-shore the Quang Ngai, Phu Yen and Ninh Thuan provinces. The shortest tsunami travel time from the source to the Southern Central coast is 35 minutes. Due to its strike-slip mechanism, there is a low possibility of the 109o Meridian fault generating earthquake-triggered tsunamis. Moreover, even if they occurred, the near-field tsunamis generated from the 109o Meridian fault source can hardly cause severe damage and losses for the coastal zones of Vietnam, as shown by the simulation results. Nevertheless, the worst-case scenarios simulation results provide the highest risk that the near-field tsunamis from the 109o Meridian fault source might affect the Vietnamese coasts, which is helpful for the national tsunami warning and response purpose.

Experimental Study on Multi-Domain Fault Features of AUV with Weak Thruster Fault

As the most important device of an Autonomous Underwater Vehicle (AUV), thrusters are one of the main sources of fault. If the thruster fault can be diagnosed in the early stage, it would give more time to guarantee the safety of an AUV. Fault feature extraction is the premise of fault diagnosis. The traditional feature calculation methods extract fault features from one domain. These methods work well in the case of high fault severity, but poorly in the case of weak fault severity. In addition, for weak faults, the fault features extracted by the traditional methods may not meet the monotonic relationship with fault severity and cannot be used in fault severity identification. Aiming at these problems, through experimental data analysis, this paper excludes the features that do not meet the law from the 52 selectable fault features in the time domain, frequency domain and time-frequency domain. Aiming at the problem that there is no useful feature in the frequency domain, a new feature calculation method is proposed, and the order of magnitude of the available feature is given, which provides concise and accurate information for subsequent fault feature fusion and fault severity identification.

Identification Method of Evolution Patterns of Favorable Oil and Gas Channels at Source Fault Configuration and Its Application

Favorable oil and gas channels during fault activity and cease episodes were determined to understand oil and gas distribution in reservoirs of “lower generation, upper accumulation”-type near faults in petroliferous basins through identifying and coupling conduit systems and hydrocarbon expulsion distribution during these periods, respectively. It was used to establish a method to identify the evolution patterns of favorable oil–gas charging positions at source fault configurations, which was applied to understand the evolution of favorable oil and gas channels in the middle and lower Es-3 sub-member in the southwest of the Jiuzhou fault. The results show that the conduit pattern in the Es-3 sub-member is mainly distributed in the center, west, and east of the F1 fault and the eastern part of the F7 fault in the southwest of the Jiuzhou fault. The conduit to non-conduit pattern is mainly distributed in the middle and center of the F7 fault. The non-conduit to conduit pattern is mainly distributed in the west and east of the F1 fault and the east of the F7 fault. The non-conduit is mainly distributed in the middle and east of the F7 fault. The conduit pattern and conduit to non-conduit pattern in the middle and lower Es-3 sub-member are favorable for hydrocarbon migration and accumulation. It is consistent with the oil and gas discovered in the middle and lower Es-3 sub-member near the southwest of the Jiuzhou fault, indicating that this method is feasible to identify the favorable oil and gas channels at source fault configurations.

Bearing Fault Classification Using Statistical Features And Machine Learning Approach

<p>Bearing degradation is the most common source of faults in machines. In this context, this work presents a monitoring scheme to diagnose bearing faults using machine learning approach. In this approach classification of healthy and faulty conditions of the bearing is carried out using artificial neural network (ANN). A set of statistical features are extracted from the acquired vibration signals. The decision tree technique is used to select significant features out of all statistical extracted features. The selected features were classified using different classifiers. Based on the various classifier results obtained, the ANN classifier achieve the maximum classification accuracy which is recommended for online monitoring and fault diagnosis of the bearing in various machines.</p>

Predictive Simulation for Surface Fault Occurrence Using High-Performance Computing

Numerical simulations based on continuum mechanics are promising methods for the estimation of surface fault displacements. We developed a parallel finite element method program to perform such simulations and applied the program to reproduce the 2016 Kumamoto earthquake, where surface rupture was observed. We constructed an analysis model of the 5 × 5 × 1 km domain, including primary and secondary faults, and inputted the slip distribution of the primary fault, which was obtained through inversion analysis and the elastic theory of dislocation. The simulated slips on the surface were in good agreement with the observations. We then conducted a predictive simulation by inputting the slip distributions of the primary fault, which were determined using a strong ground motion prediction method for an earthquake with a specified source fault. In this simulation, no surface slip was induced in the sub-faults. A large surface slip area must be established near a sub-fault to induce the occurrence of a slip on the surface.

Fault Source Model and Stress Changes of the 2021 Mw 7.4 Maduo Earthquake, China, Constrained by InSAR and GPS Measurements

ABSTRACTOn 22 May 2021, an Mw 7.4 earthquake struck Maduo, China, within the eastern Bayan Har block of the Tibetan plateau. The eastward-extruding Bayan Har block is marked by active seismicity along its boundary faults, including the 2008 Mw 7.9 Wenchuan earthquake, but large earthquakes within the block are relatively rare. Thus, the Maduo earthquake could provide useful information about crustal deformation of the Tibetan plateau. Early reports, shortly after the earthquake, have suggested a sinistral strike-slip fault rupture, but the fault geometry and slip distribution vary in these models due to the limited observational constraints. Here, we reconstructed a model of fault geometry and coseismic slip using Interferometric Synthetic Aperture Radar and Global Positioning System data. A nonplanar fault model was constructed based on pixel-offset images and the optimized dip angle. The along-strike variation of the dip angle is small, so a single optimized dip is used. Our results suggest that the Maduo earthquake ruptured ∼156 km on a northwest-striking major fault that dips 78°, and ∼24 km on a minor southeast-striking fault that dips 64°. Most fault slip occurred above 15 km depth, and released a moment of ∼1.65×1020 N·m. Using the resolved fault source model, we calculated the change of coulomb failure stress in the region and on the neighboring faults. The Maduo earthquake highlighted intrablock deformation in the Tibetan plateau whereas numerous lithospheric blocks extrude along major strike-slip faults.

Quality-Reliability Coupled Network Modeling and Importance Measure of Multi-Stage Manufacturing Systems via Network Controllability Analysis

The fluctuation of product quality is closely related to the degradation of the equipment in multi-stage manufacturing systems. This paper proposes a critical measure approach for a quality-reliability coupled network of multi-stage manufacturing systems via network controllability. The impact of component degradation will be transmitted, expanded, and accumulated in multiple manufacturing stages, leading to quality flaws or even shutdowns of the entire system. An important measurement method via controllability analysis is provided by quantifying the impact of attacking the quality-reliability coupled network. By quantifying the control ability of the fault source node on the key quality attribute node, the weakness that affects the processing accuracy of a production line is identified. Case studies of real production lines are applied to verify the effectiveness, and comparative results show the method can guide the quality-reliability improvement of manufacturing systems.

A novel underdetermined source number estimation for coupled vibration sources of mechanical fault based on variational mode decomposition

A novel underdetermined source number estimation for coupled vibration sources of mechanical fault based on variational mode decomposition

Three Mw ≥ 4.7 Earthquakes Within the Changning (China) Shale Gas Field Ruptured Shallow Faults Intersecting With Hydraulic Fracturing Wells

AbstractFrom 2017 to 2019, three destructive earthquakes (27 January 2017 Mw 4.7, 16 December 2018 Mw 5.2, and 3 January 2019 Mw 4.8) occurred in the Changning shale gas field in the southwest Sichuan Basin, China. Previous seismological studies attributed these events to hydraulic fracturing (HF), but were unable to identify the causative seismogenic faults and their slip behaviors. Here, we use Sentinel‐1 synthetic aperture radar data to measure surface deformation triggered by the three events and conduct geodetic inversions to characterize their rupture models. The resulting coseismic interferograms show prominent surface deformation with the maximum line‐of‐sight displacements of up to 4 cm. The inversion results show that all three earthquakes mainly ruptured sedimentary formations above the shale gas bed, in the upper 3 km of the crust, with slip magnitudes ranging from 8.5 to 15 cm, and stress drops ranging from ∼1.8 to ∼3.3 MPa. Their source faults intersect with horizontal HF wells, but do not root in the crystalline basement. Combined with the reported difficulty of increasing HF operation pressures prior to the three events, we argue that they were most likely induced by direct injection of pressurized fluids into the fault zones. Crustal deformation patterns inferred from regional topography and GPS velocities highlight that the Changning field is located within a triple junction region near the southeastern margin of the Tibetan Plateau with large deformation gradients; such conditions are not only favorable to the development of critically stressed faults, but also facilitate the occurrence of at least moderate magnitude earthquakes.