Distribution Of Faults Research Articles

Formation mechanism of the small-angle X-type strike-slip faults in deep basin and its controlling on hydrocarbon accumulation: a case study from the Tabei Uplift, Tarim Basin, NW China

In the central Tarim Basin, numerous hydrocarbon deposits were found along ultra-deep strike-slip faults, and its evolving progress and formation mechanism are research hotspots. The Paleozoic small-angle X-type strike-slip fault in the Tabei Uplift is the research subject in this article. Based on high-precision three-dimensional seismic data, three structural deformation layers were revealed: the rift system, weak strike-slip deformation and salt tectonics in the deep structural layer (Sinian–Middle Cambrian), the strong strike-slip deformation and karst-dissolution structure in the middle structural layer (Upper Cambrian–Middle Ordovician), and echelon normal faults in the shallow structural layer (Upper Ordovician–Carboniferous). The formation and evolution of strike-slip faults is jointly controlled by the distribution pattern of basement rift and the activities of surrounding orogenic belts, which can be divided into three stages. In the Middle to Late Cambrian, the initial subduction of the Paleo-Asian and Proto-Tethyan oceans precipitated the emergence of two sets of small-angle X-type strike-slip faults, striking NW and NE above the grooves of Precambrian rifts, influenced by local weak compressive stress. Affected by the closure of peripheral paleo-ocean, strike-slip faults deformed considerably in the Middle–Late Ordovician and were reactivated in the Silurian–Carboniferous, forming en-echelon normal faults in the shallow layer. The layered deformation structure of the strike-slip faults significantly affects the accumulation of hydrocarbons. The differential hydrocarbon enrichment of faults in the Tabei Uplift is collectively influenced by the distribution of source rocks and the migration of oil and gas. The topographical features of the Tabei Uplift, along with the distribution of strike-slip faults across tectonic units, have rendered the NE direction the preferential pathway for hydrocarbon migration. Additionally, impacted by the development of en echelon faults, the NE-trending faults offer superior conditions for hydrocarbon preservation and charging condition, compared to the NW-trending faults.

Dead Zone Fault Detection Optimization Method for Few-Mode Fiber Links Based on Unexcited Coupled Higher-Order Modes

Dead Zone Fault Detection Optimization Method for Few-Mode Fiber Links Based on Unexcited Coupled Higher-Order Modes

Late Quaternary Surface Displacements on Accretionary Wedge Splay Faults in the Cascadia Subduction Zone: Implications for Megathrust Rupture

Because splay faults branch at a steep dip angle from the plate-boundary décollement in an accretionary wedge, their coseismic displacement can potentially result in larger tsunamis with distinct characteristics compared to megathrust-only fault ruptures, posing an enhanced hazard to coastal communities. Elsewhere, there is evidence of coseismic slip on splay faults during many of the largest subduction zone earthquakes, but our understanding of potentially active splay faults and their hazards at the Cascadia subduction zone remains limited. To identify the most recently active splay faults at Cascadia, we conduct stratigraphic and structural interpretations of near-surface deformation in the outer accretionary wedge for the ~400 km along-strike length of the landward vergence zone. We analyze recently acquired high-frequency sparker seismic data and crustal-scale multi-channel seismic data to examine the record of deformation in shallow slope basins and the upper ~1 km of the surrounding accreted sediments and to investigate linkages to deeper décollement structure. We present a new fault map for widest, most completely locked portion of Cascadia from 45 to 48°N latitude, which documents the distribution of faults that show clear evidence of recent late Quaternary activity. We find widespread evidence for active splay faulting up to 30 km landward of the deformation front, in what we define as the active domain, and diminished fault activity landward outside of this zone. The abundance of surface-deforming splay faults in the active outer wedge domain suggests Cascadia megathrust events may commonly host distributed shallow rupture on multiple splay faults located within 30 km of the deformation front.

Analysis of Tokyo 2020 Olympic modern pentathlon equestrian jumping results

Modern Pentathlon (MP) includes an equestrian Jumping discipline, with horses drawn blindly by unfamiliar riders. At the Tokyo 2020 Olympic Summer Games, concerns regarding inadequate horsemanship generated adverse publicity for MP. Conventional stadium Jumping in Tokyo provided an opportunity for comparison of the two closest Olympic equestrian Jumping disciplines. The objectives of this study were to complete an objective analysis of the Tokyo MP riding phases, and to test the hypothesis that MP riding faults in women's and men's Tokyo competitions combined were more frequent than in the Individual Jumping Qualifier (JQ). Types of faults for Tokyo MP (n = 71 riders) and JQ (n = 73 riders) were tabulated from published official results and detailed observation of online videos of each competition. Fault distributions were compared using Chi-square analysis (significance at P < .05). MP riders had more jumping faults (15.4 %) than JQ (7.8 %, P < .0001). Both MP and JQ riders had more faults at oxers (17.1 %, P < .0001 and 9.7 %, P = .0171, respectively) than verticals (14.5 % and 6.2 %). JQ (9.8 %, P = .0093) but not MP (15.7 %, p = .5166) riders had more faults in the second half of the course compared to the first half (5.7 % and 15.0 %, respectively). Double clear rounds (no jumping or time faults) were 4.9 times more likely in JQ (34.2 %) than in MP (6.9 %: P < .0001). Proposed solutions to decrease MP fault frequency include lower maximum fence heights, fewer jumping efforts, and a more liberal re-ride policy.

Influence of faults on late-stage migration of methane-rich gas in a major unconventional hydrocarbon accumulation: Montney Formation, western Canada

Faults are thought to act as barriers or conduits for intraformational hydrocarbon migration within unconventional low-permeability hydrocarbon accumulations. However, well-documented studies substantiating this phenomenon at the regional-scale are scarce. Here, we use an extensive molecular and isotopic dataset for produced-gas samples (n = 562) from the Montney unconventional hydrocarbon accumulation of northeast British Columbia to show that regional-scale secondary migration of methane-rich gas was significantly influenced by the distribution and orientation of faults. Cross-plots using iC4/nC4, δ13C ethane and δ13C propane exhibit single coherent distributions, suggesting that the C2+ components of most of these gases share interrelated histories of generation, maturation and primary migration. Conversely, cross-plots using gas dryness and δ13C methane against other selected gas parameters demonstrate geographic differentiation, with samples from the southeastern part of the study area generally exhibiting elevated molecular concentration and isotopic enrichment of methane compared to the samples from the northwestern part of the study area. The compositional and isotopic enrichment of methane in the southeastern samples signify significant late-stage secondary migration of highly mature methane-rich gas from deeper zones to shallower zones, and mixing with in-situ hydrocarbon fluids of lower thermal maturity. Previous structural mapping documents the presence of numerous subsurface thrust-faults related to the Cordilleran orogeny in the northwestern area, while these features are entirely absent in the southeastern area. Consequently, we conclude that thrust-faults, with accompanying clay-rich gouges, formed effective en-echelon barriers to the late-stage secondary migration of methane-rich gas in the northwestern area and prevented substantial mixing of hydrocarbon fluids.

Spatial distribution of near-fault landslides along Litang fault zones, eastern Tibetan Plateau

Active fault zones are areas impacted by intense tectonic activity, where geohazards such as landslides occur and their distribution characteristics vary across segments. Using the Litang fault zone in the eastern Tibetan Plateau as an example, this study cataloged landslides within a 10 km range on both sides of the fault zone. The Litang fault zone was divided into four sections based on landform characteristics and the spatial distribution of active faults. A comprehensive analysis was conducted on the relationship between landslide distribution and topography, lithology, and active faults in different sections. Additionally, the study employed a random forest model to compare landslide susceptibility between the whole-region and its sub-regions. The results show that lithology and topography significantly influence the distribution of landslide types. The Upper Triassic sandstone, Slate exhibit more debris flows in areas with slopes ranging from 5° to 35°, while slopes >35° in the Upper Triassic sandstone, Slate are prone to unstable slopes. Rock avalanche occur in Upper Triassic sandstone, Slate, and Quaternary sand and gravel. Active faults play a key role in control ling landslides distribution through distance, hanging wall, locked segment, and direction effects. The number of landslides is positively correlated with the activity of faults. Additionally, the dip angle and motion characteristics of faults have significant influence on the distribution of landslides. The results of landslide susceptibility evaluation show that sub-region models have higher accuracy than the whole-region model. This study provides a new method for exploring the spatial distribution of landslides and can provide scientific reference for reducing landslide disasters in active fault zones.

Enrichment model and major controlling factors of below-source tight oil in Lower Cretaceous Fuyu reservoirs in northern Songliao Basin, NE China

Based on the geochemical, seismic, logging and drilling data, the Fuyu reservoirs of the Lower Cretaceous Quantou Formation in northern Songliao Basin are systematically studied in terms of the geological characteristics, the tight oil enrichment model and its major controlling factors. First, the Quantou Formation is overlaid by high-quality source rocks of the Upper Cretaceous Qingshankou Formation, with the development of nose structure around sag and the broad and continuous distribution of sand bodies. The reservoirs are tight on the whole. Second, the configuration of multiple elements, such as high-quality source rocks, reservoir rocks, fault, overpressure and structure, controls the tight oil enrichment in the Fuyu reservoirs. The source-reservoir combination controls the tight oil distribution pattern. The pressure difference between source and reservoir drives the charging of tight oil. The fault-sandbody transport system determines the migration and accumulation of oil and gas. The positive structure is the favorable place for tight oil enrichment, and the fault-horst zone is the key part of syncline area for tight oil exploration. Third, based on the source-reservoir relationship, transport mode, accumulation dynamics and other elements, three tight oil enrichment models are recognized in the Fuyu reservoirs: (1) vertical or lateral migration of hydrocarbon from source rocks to adjacent reservoir rocks, that is, driven by overpressure, hydrocarbon generated is migrated vertically or laterally to and accumulates in the adjacent reservoir rocks; (2) transport of hydrocarbon through faults between separated source and reservoirs, that is, driven by overpressure, hydrocarbon migrates downward through faults to the sandbodies that are separated from the source rocks; and (3) migration of hydrocarbon through faults and sandbodies between separated source and reservoirs, that is, driven by overpressure, hydrocarbon migrates downwards through faults to the reservoir rocks that are separated from the source rocks, and then migrates laterally through sandbodies. Fourth, the differences in oil source conditions, charging drive, fault distribution, sandbody and reservoir physical properties cause the differential enrichment of tight oil in the Fuyu reservoirs. Comprehensive analysis suggests that the Fuyu reservoir in the Qijia–Gulong Sag has good conditions for tight oil enrichment and has been less explored, and it is an important new zone for tight oil exploration in the future.

Three‐Dimensional Density Distribution and Seismic Activity along the Guxiang–Tongmai Segment of the Jiali Fault, Tibet

AbstractThe Guxiang–Tongmai segment of the Jiali fault is situated northeast of the Namche Barwa Syntaxis in northeastern Tibet. It is one of the most active strike‐slip faults near the syntaxis and plays a pivotal role in the examination of seismic activity within the eastern Himalayan Syntaxis. New study in the research region has yielded a 1:200000 gravity dataset covering an area 1500 km2. Using wavelet transform multiscale decomposition, scratch analysis techniques, and 3D gravity inversion methods, gravity anomalies, fault distributions, and density structures were determined across various scales. Through the integration of our new gravity data with other geophysical and geological information, our findings demonstrate substantial variations in the overall crustal density within the region, with the fault distribution closely linked to these density fluctuations. Disparities in stratigraphic density are important causes of variations in the capacity of geological formations to endure regional tectonic stress. Earthquakes are predominantly concentrated within the density transition zone and are primarily situated in regions of elevated density. The hanging wall stress within the Guxiang–Tongmai segment of the Jiali fault exhibits a notable concentration, marked by pronounced anisotropy, and is positioned within the density differential zone, which is prone to earthquakes.

Earthquake supercycles and fault interaction over the past 32 ka in the Lake Ebinur area, Xinjiang, China

Earthquake prediction and disaster assessment in tectonically active regions require a continuous and complete regional seismic archive, which is commonly difficult to obtain, especially for prehistoric records. Here, high-resolution analysis of the sedimentary sequence from Lake Ebinur in Xinjiang revealed a detailed history of environment evolution since 32 ka ago. Both the Cl content and ultrafine proportion revealed the changing climate: the climate was relatively dry with low lake-water volumes from 32 to 12 ka, while the climate became warmer and wetter since 12 ka. In addition, eight earthquakes were identified by comprehensive analysis of grain size and geochemical element proxies, showing more than two seismic supercycles, with gaps of ∼10.4 ka; these gaps are much larger than those inferred previously (∼4–7 ka). Notably, these seismic events exhibited a pattern of mutual transmittance between the BoA and Jinghenan faults. Such fault interaction can occur in the Lake Ebinur area because it is dominated by weak lithosphere in which strain is easily accumulated and released; the interaction can also be attributed to the unique spatial distribution and immature nature of both faults. Combined with trenching investigations, our high-resolution analysis of lacustrine sediments can reveal a complete history of tectonic activity, which can efficiently serve regional earthquake prediction and disaster assessment.

Shear Wave Velocity Applications in Geomechanics with Focus on Risk Assessment in Carbon Capture and Storage Projects

Shear wave velocity (Vs) has significant applications in geoengineering investigations. With the ongoing rise in carbon capture and storage (CCS) initiatives, the role of Vs in monitoring the CO2 sequestration sites is escalating. Although many studies have been conducted to assess CCS-induced risks, no inclusive research has been conducted integrating those investigations. This study strives to collate and integrate the applications of Vs in geoscience with an emphasis on CCS risk assessment. Based on this research, major CCS-induced risks were detected: induced seismicity, caprock failure, groundwater contamination, fault reactivation, and reservoir deformation. These risks were inclusively described, and the mathematical formulations incorporating the Vs parameter in risk analysis were elaborated. It was concluded that Vs applications can be further extended in monitoring CO2 plume migration, optimizing CO2 injection pressures, preventing shallow water contamination, and predicting CCS-induced seismic events. All these applications require fully coupled hydromechanical analysis based on poroelasticity theory. Hence, various factors including pore pressure, in situ stresses, faults distribution, and poroelastic parameters must be carefully determined before the CO2 injection phase. The mathematical formulations presented in the present study are quite applicable for granting the safety and long-term success of subsurface carbon sequestration.

Unveiling the transtensional geodynamics of Cenozoic depocenter changes in the Andaman sea: Seismic evidence for the existence of the East Sagaing Fault and the Andaman Basin Central Fault Zone in the Tanintharyi region

The Andaman Sea, situated at the highly oblique convergent boundary of the Indian and the Sunda Plates in the eastern Indian Ocean, has been shaped by transtensional geodynamics throughout the Cenozoic and has given rise to the formation of fault systems in the Andaman back-arc region. Out of these faults, the Sagaing Fault system exists as the active transform boundary between the Burmese and Eurasian Plates. The East Sagaing Fault, which runs through the Gulf of Martaban in the Andaman Sea, is a critical component of this Sagaing Fault system in fostering the transtensional regime and contributing to the opening of the Andaman Sea as a pull-apart basin. In contrast, the Andaman Basin Central Fault Zone, previously misinterpreted as the South Sagaing Fault, is an inactive fault system that experienced deformation until the Middle Miocene and is currently concealed beneath the East Andaman Basin. This temporal disparity in the Andaman Basin Central Fault Zone and East Sagaing Fault activity patterns has led to uncertainty regarding their existence within the Tanintharyi region of the Andaman Sea. To address this uncertainty, 2D and 3D seismic data interpretations were used to explore the distribution of faults, including the presence and extent of these two faults in the Tanintharyi region. Through a comparative analysis of the structural characteristics of the East Sagaing Fault in the northern part, and the Andaman Basin Central Fault Zone in the southern part of the Andaman Sea, this study presents compelling evidence confirming the existence of both faults in the Tanintharyi region with their structural implications. The innovative discoveries in this article contribute to a deeper understanding of Cenozoic depocenter changes in the Tanintharyi region, substantiating the significance of these two faults in transtensional geodynamics and allowing for a comprehensive examination of geodynamic evolution in the Andaman Sea region.

Reliability evaluation of flexible manufacturing systems based on three-layer index system with time-varying weights

With the development of industrial manufacturing, flexible manufacturing system provides an effective way to improve the machining quality and efficiency, as well as reduce the manufacturing cost. Fflexible manufacturing system reliability has been one focus of recent studies. But a systematic, effective and executable reliability evaluation method has not yet proposed in existing researches. This work firstly presented a three-layer index system for flexible manufacturing system reliability evaluation, which is composed of the whole layer indexes, subsystem layer indexes and equipment layer indexes determined by system composition and running features analysis. Time-varying weights of each layer are calculated through the modelling of the reliability and reliability importance based on the classical two-state failure hypothesis. Then, considering multi-state failure modes of elements, a fuzzy evaluation model of flexible manufacturing system reliability is established based on fault grading and statistics, considering grade and number distributions of faults within a certain statistical period. Moreover, through a simulation case of a box-parts finishing flexible manufacturing system, the influence of failure rates and service time on the index weights distribution is firstly revealed, which can provide theoretical basis for the improvement of flexible manufacturing system reliability; then the effectiveness of the proposed method is verified through the comparison of results obtained by the previous model based on two-state failure and the proposed model based on multi-state failure.

A Comprehensive Investigation of the Relationship between Fractures and Oil Production in a Giant Fractured Carbonate Field

This study examines the connections between various fracture indicators and production data with an example from one of the giant fields in the Middle East producing complex fractured carbonate lithologies. The field under study hosts two reservoirs with a long development and production history, including carbonates from the Asmari and Bangestan Formations. A fracture intensity map was generated based on the interpretation of image logs from 28 wells drilled within the field. Mud loss data were collected and mapped based on the geostatistical Gaussian Random Function Simulation (GRFS) algorithm. Maximum curvature maps were generated based on Asmari structural surface maps. Comparing the results shows a good agreement between the curvature map, fault distribution model, mud loss map, fracture intensity map, and productivity index. The results of image log interpretations led to the identification of four classes of open fractures, including major open fractures, medium open fractures, minor open fractures, and hairline fractures. Using the azimuth and dip data of the four fracture sets mentioned above, the fracture intensity log was generated as a continuous log for each well with available image log data. For this purpose, the fracture intensity log and a continuous fracture network (CFN) model were generated. The continuous fracture network model was used to generate a 3D discrete fracture network (DFN) for the Asmari Formation. Finally, a 3D upscaled model of fracture dip and azimuth, fracture porosity, fracture permeability, fracture length, fracture aperture, and the sigma parameter (the connectivity index between matrix and fracture) were obtained. The results of this study can illuminate the modeling of intricate reservoirs and the associated production challenges, providing insights not only during the initial production phase but also in the application of advanced oil recovery methods, such as thermal recovery.

Interaction between magmatism and polygonal faults revealed by three-dimensional seismic data in the Zhongjiannan Basin, South China Sea

The features of magmatism and polygonal faults are unveiled through a comprehensive analysis of high-resolution and reprocessed three-dimensional (3D) seismic data covering 1200 km2 in the Zhongjiannan Basin, South China Sea. These structures influence the hydrocarbons formation and migration, and the interaction between them is significant for hydrocarbon exploration. We identified magmatic bodies, including eight volcanoes, fifty sills, and a single igneous diapir, are mainly developed in three stages: 27.9–23 Ma (between T70 and T60), around 11.6 Ma (T40), and after 5.3 Ma (T30). The polygonal faults, characterized by linear, polygonal, and radial configurations, are extensively distributed within Miocene and Quaternary sediments. In the platform, polygonal faults manifest linear or polygonal attributes, while in the basin floor, they show a polygonal shape. Particularly, above volcanoes and the igneous diapir, the polygonal faults exhibit radial configurations. However, among volcanoes, few polygonal faults are discerned based on the coherence attribute slice. The controlling factors influencing the distribution of polygonal faults are the lithological disparity, temperature, and pressure. Radial fault formation is promoted by volcanoes and igneous diapir through differential compaction. The resultant vertical pathways formed by volcanoes and overlying radial faults play a crucial role in adjusting pressure differentials or water discharges. Consequently, these pathways disrupt the requisite conditions for the formation of polygonal faults among volcanoes. In the basin floor, magma intrusion occurs along the planes of polygonal faults, giving rise to inclined, spoon-shaped, and bowl-shaped sills. As weak zones, polygonal faults worked as connectors for sills at different depths. Hence, pre-existing polygonal faults are considered pathways facilitating magma migration from the lower Miocene to Pliocene strata, ultimately contributing to sill formation in shallow sediments. This study advances our understanding of the intricate interaction between polygonal faults and magmatism within sedimentary basins.

A Note of Reliability Analysis of SM-λ in Folded-Crossed Hypercube with Conditional Faults

The fault tolerance of an interconnection network of parallel and distributed systems can be evaluated by various topological parameters of its underlying graph [Formula: see text], with strong Menger edge connectivity being a vital parameter in this regard. A connected graph [Formula: see text] is called strongly Menger edge connected (SM-[Formula: see text]) if it connects any pair of vertices [Formula: see text] and [Formula: see text] with [Formula: see text] number of edge-disjoint paths. Under the uniform distribution of faults in a large interconnection network, it is improbable that each faulty edge incident to a vertex will occur simultaneously. Thus, [Formula: see text]-strongly Menger edge connected of order [Formula: see text] was introduced in 2018 by He et al. Here, [Formula: see text] is called as [Formula: see text]-strongly Menger edge connected of order [Formula: see text], if [Formula: see text] remains SM-[Formula: see text], where [Formula: see text] is an arbitrary edge set in a graph [Formula: see text] with [Formula: see text] and the minimum degree of the remaining graph [Formula: see text]. The largest [Formula: see text] keeping the property of [Formula: see text] being SM-[Formula: see text] is denoted as [Formula: see text]. Among variants of hypercube, the [Formula: see text]-dimensional folded-crossed hypercube [Formula: see text] attracts attention in recent years. In this paper, we focus on calculating the exact value of the maximum conditional edge-fault-tolerant number of order [Formula: see text] of [Formula: see text], [Formula: see text] for two integers [Formula: see text] and [Formula: see text].

Shallow structure and late quaternary slip rate of the Osaka Bay fault, western Japan

The Osaka Bay is situated at a seismically active region north of the Median Tectonic Line and east of Awaji Island in western Japan, known as part of the Kinki Triangle and the Niigata–Kobe Tectonic Zone. Dense distribution of active faults and high geodetic strain rates characterize the region, posing a major seismic hazard potential to the coastal and metropolitan areas of the Kansai region. To investigate the shallow structure and recent deformation history of active faults in the Osaka Bay, we acquired 15 high-resolution seismic profiles using a Mini-GI airgun and a Boomer as active sources, together with multi-beam bathymetry data across the Osaka Bay Fault. Our seismic sections image a ~ 0.1 to 3.7 km-wide asymmetric anticline forelimb above the Osaka Bay Fault at shallow depths, coupled with a ~ 2.6 km-wide syncline to the west, and a broad, ~ 11 km-wide syncline in the footwall to the east. The synclinal axial surface at shallow depths measured in this study ranges 75°–89°. We observe the vertical displacement of the Osaka Bay Fault increasing northwards along strike. The sediment thickness on the hanging wall, however, is variable, modified by non-tectonic processes such as by tidal currents, affecting the geometry of growth strata. The most recent deformation by the Osaka Bay Fault reaches to near the seafloor by active folding, with large vertical offsets of 8–14 m over the last ~ 11 ka, and 5–11 m over the last ~ 5 ka. By combining with previously reported borehole age data, the average uplift rate on the Osaka Bay Fault is estimated to be ~ 1.0 to 1.7 m/ka during the Latest Pleistocene to Holocene. The inferred slip of the Osaka Bay Fault during the Holocene is likely to account for > 5% of the regional geodetic strain accumulation within the Kinki Triangle. Further studies to evaluate the Holocene slip rates of regional faults are necessary to assess the seismic hazards and the internal strain budgets within the Kinki Triangle and the Niigata–Kobe Tectonic Zone.Graphical abstract

Application of wide-field electromagnetic method for favorable target optimization in the Heishan granite geothermal area of Yunnan Province

The Heishan geothermal area is positioned above the sole Yunnan–Tibet high-temperature geothermal belt, where huge geothermal energy resources are available. Utilizing the characteristics of large exploration depth, extensive coverage, and high precision of the wide-field electromagnetic method, four survey lines were deployed, totaling 29.8 km, to enable a comprehensive analysis of the granite structure and fault distribution. The results indicate that the rocks within the area can be vertically divided into a granite basement and a fractured layer. Moreover, three different zones of resistivity were identified: the granite basement zone has a resistivity range of 2500–20000 Ω m, whereas the compressional shear zone and the secondary fault zone have a resistivity range of 750–2500 Ω m, and the extensional fault zone and the main fault zone have resistivity values below 750 Ω m. The Heishan-Hejian fault and the fault zone formed during its right-lateral strike-slip process, as well as the controlled area of the Qianmaihe fault, are all favorable targets. Of these, the Qianmahe fault possesses a larger-scale heat-conducting and water-controlling structure. In addition, in the secondary fault-controlled area extending to the west, the zone between F2’ and F4 exhibits renewed tectonic activity, suggesting a greater potential for geothermal resources.

Arc Suppression Control With Adaptive Parameters of Active Grounding Device Considering Ground Fault Resistance Uncertainty

Active grounding device (AGD) is an effective device to eliminate grounding arcs and prevent disasters caused by ground faults in distribution networks. However, due to the uncertainty of the ground fault resistance, the traditional arc suppression control cannot guarantee the suppression effect and the control stability simultaneously under the fixed control parameters. In this paper, an arc suppression control method based on adaptive parameters is proposed. According to the dual-loop control model of the AGD connected to the fault distribution network, the relationship between the model input and the fault voltage is derived. Then in two extreme cases of the ground fault resistance, the suppression effect and the system stability are analyzed using the amplitude-frequency curve and the root locus, respectively. Further, a control method is proposed to make control parameters self-adaptive through the feedback information of the residual fault voltage. Finally, the effectiveness of the proposed control method is verified by the simulation model of MATLAB/Simulink and the low-voltage experiment of the prototype, which can realize arc suppression with high, low or dynamic resistance ground fault.

Current active fault distribution and slip rate along the middle section of the Jiali-Chayu fault from Sentinel-1 InSAR observations (2017–2022)

The Jiali-Chayu fault, situated on the eastern side of the eastern Himalayan syntaxis, is the southeastern margin of the large strike-slip fault zone of the Jiali Fault. The study of the distribution and activity within this fault zone is imperative for a comprehensive understanding of the tectonic movement patterns in the southeastern Tibetan Plateau. Previous studies have established that the kinematic characteristic of the Jiali-Chayu fault diverges significantly from that of other segments within the Jiali fault. Nonetheless, the current tectonic characteristics, including the slip sense, slip rate, and geometric deformation of this fault, are still not well resolved, leading to divergent interpretations regarding its contemporary activity intensity. This paper introduced an optimized time-series InSAR method with phase compensation designed for regions characterized by low coherence and exhibiting slow deformation. Using Sentinel-1 SAR data from both ascending and descending orbits spanning the period between 2017 and 2022, we successfully derived deformation rates for the middle part of the Jiali-Chayu fault at a spatial resolution of 150 m. The slip and dip rates of active faults are determined by considering the fault movement rates from two different observation angles, in conjunction with strike angle and the assumed dip angle of the fault. The results show that the deformation rates of the three branches are very different, with F2-1 and F2-2 exhibiting notable activity, while other areas exhibit relatively weaker activity. The strike-slip rates for F2-1 and F2-2 faults range between 3.6 and 5.3 mm/a and 3.05 to 5.13 mm/a, respectively, while their respective dip-slip rates fall within the range of 1.1–2.7 mm/a and 2.99–5.02 mm/a. In accordance with the fault slip directions, we classify the F2-1 fault as a sinistral (left-lateral) strike-slip fault and the F2-2 fault as a dextral (right-lateral) strike-slip fault. This study addresses a gap in remote sensing methods for detecting active fault activity in this region, providing a systematic foundation for identifying weak activity characteristics within the fault zone.Graphical

Seismic 3D full-horizon tracking based on a knowledge graph to represent the stratigraphic sequence relationship

Seismic 3D full-horizon tracking is a fundamental and crucial step in sequence analysis and reservoir modeling. Existing automatic full-horizon tracking approaches lack effective methods for representing the stratigraphic sequence relationships in seismic data. However, the inability to represent the stratigraphic sequence relationships fully and accurately makes it challenging to address discontinuous areas affected by faults and unconformities. To address this issue, we develop a knowledge graph representing the stratigraphic sequence relationship, which enables the simultaneous extraction of all horizon surfaces once the stratigraphic distribution of the seismic data is obtained. This method first generates horizon patches and calculates the fault attributes, followed by the construction of an initial knowledge graph that characterizes the overall distribution of horizon patches and faults. The initial knowledge graph comprises nodes and edges. The nodes represent horizon patches, and their attributes cover the geographical location information of the patches and faults. Simultaneously, the edges represent the relationship between the horizon patches, including the stratigraphic sequence relationship, and their attributes illustrate the potential for connecting these patches. Furthermore, we introduce a multilayer knowledge graph based on the point-set topology to fuse the nodes. This allows for the continuous merging of the horizon patches to obtain horizon surfaces across discontinuities with the constraints of fault attributes and stratigraphic sequence relationships in 3D space. Synthetic and field examples demonstrate that our approach can effectively represent stratigraphic sequence relationships and accurately track horizons located in discontinuous areas with faults and unconformities.