Search Results (222)

Fault slips induced by hydraulic fracturing are the primary mechanism of casing de-formation during deep shale gas development in Sichuan’s Luzhou Block, where de-formation rates reach 51% and severely compromise productivity. To address a critical gap in existing research on quantitative risk assessment systems, we developed a probabilistic model integrating pore pressure evolution dynamics with Monte Carlo simulations to quantify slip risks. The model incorporates key operational parameters (pumping pressure, rate, and duration) and geological factors (fault friction coefficient, strike/dip angles, and horizontal stress difference) validated through field data, showing >90% slip probability in 60% of deformed well intervals. The results demonstrate that prolonged high-intensity fracturing increases slip probability by 32% under 80–100 MPa pressure surges. Meanwhile, an increase in the friction coefficient from 0.40 to 0.80 reduces slip probability by 6.4% through elevated critical pore pressure. Fault geometry exhibits coupling effects: the risk of low-dip faults reaches its peak when strike parallels the maximum horizontal stress, whereas high-dip faults show a bimodal high-risk distribution at strike angles of 60–120°; here, the horizontal stress difference is directly proportional to the slip probability. We propose optimizing fracturing parameters, controlling operation duration, and avoiding high-risk fault geometries as mitigation strategies, providing a scientific foundation for enhancing the safety and efficiency of shale gas development. Full article

On 8 June 2025, the Mw 6.4 Paratebueno earthquake struck the eastern foothills of the Eastern Andes, Colombia. The event occurred near the Guaicáramo fault, along the eastern margin of the Eastern Cordillera fold-and-thrust belt. To investigate its rupture characteristics and tectonic implications, we utilized ALOS-2 and Sentinel-1 SAR data to derive coseismic deformation fields. Source geometry and slip distribution were inverted with the Okada dislocation model, and static Coulomb failure stress change were calculated to assess the triggering relationship with the 2023 Mw 6.2 Meta-Cundinamarca earthquake. The results reveal maximum line-of-sight displacements of 43 cm, 23 cm and 32 cm, respectively, caused by a northwest-dipping blind reverse fault (strike ~213°, dip 58°) with ~5 m maximum slip concentrated at depths of 8–12 km, without surface rupture. Combining geological and stratigraphic evidence, including regional structures and sedimentary cover thickness, this event implies a transition from a normal fault to reverse fault due to ongoing shortening of fold-and-thrust belt, consistent with a thick-skinned tectonic origin. Coulomb stress modeling suggests the 2023 event promoted the 2025 rupture, and the combined effect of the two events further increased stress on the southeastern Guaicáramo fault, implying elevated seismic hazard. Full article

Faults are the primary drivers of earthquakes and exert a strong control on rupture mechanisms, earthquake magnitude, and the spatial distribution of coseismic landslides (CLs). However, how CL spatial distribution patterns vary with faulting style remains poorly constrained. Here, we compiled a catalog of CLs associated with 18 global major earthquakes (M_W > 6.0) within continental regions since 1900 and explored the distribution patterns of CLs associated with the three major earthquake types: oblique-slip, dip-slip, and strike-slip. Our results reveal two distinct spatial distribution patterns of CLs: a hanging-wall distribution for oblique-slip and dip-slip earthquakes and a bell-shaped distribution for strike-slip earthquakes. The orientation of CLs is closely related to fault geometry and slip type. Specifically, in oblique-slip, strike-slip, and dip-slip earthquakes, CLs predominantly develop parallel, perpendicular, or perpendicular to the fault strike, respectively. In terms of slip rake, CLs are mainly aligned perpendicular, parallel, and parallel to the fault slip direction for oblique-slip, strike-slip, and dip-slip events, respectively. Importantly, the distribution patterns of CLs encode information about ground movement during an earthquake. While Peak Ground Acceleration (PGA) serves as an indicator of ground motion intensity, a comprehensive characterization of CLs—including their size and predominant movement direction—requires consideration of both the earthquake type and the local slope conditions. Full article

The Central Mindoro Fault (CMF) is a major active oblique, sinistral strike-slip fault within the Philippine archipelago that accommodates the oblique convergence between the Philippine Sea Plate (PSP) and the Sunda Plate (SP). This study focused on assessing the spatial distribution of relative uplift rates along the CMF by calculating multiple geomorphic indices (elongation ratio, volume-to-area-ratio, valley floor width-to-height ratio, hypsometric integral, and normalized steepness index) and interpreting these values in the context of any along-strike variations in geology and climate, as well as the context of the CMF’s kinematics. We observed 2 characteristics of spatial distributions of relative uplift rates: (1) at least 20–30 km-long high uplift rate sections in the northwestern end of the CMF-bound mountain range (CMF segment I), and (2) at most, CMF-wide moderate to high uplift rates. This trend matches the geomorphic-based cumulative fault offset measurements distribution, possibly indicating consistent kinematics and an overall nearly-uniform stress-field since at least the Pleistocene. Based on the spatial distribution of areas with high relative uplift rates highlighted by this study, future efforts to assess the CMF’s seismogenic capability should focus on segments I and III. Full article

On 8 September 2023, an Mw 6.8 earthquake struck the High Atlas Mountains in western Morocco, where the tectonic regime has been poorly investigated due to its remoteness and weaker seismicity compared to the northern plate boundary. In this study, we combine the measurements from the Interferometric Synthetic Aperture Radar images and the seismic data to invert the coseismic slip model of the 2023 Morocco earthquake. The results show a predominantly reverse slip motion with a minor left-lateral strike slip. The rupture process lasts about 15 s and reaches the maximum of its seismic moment release rate at about 5 s. The coseismic slip is mainly distributed in a depth range of ~20–30 km, with the ~1.4 m maximum coseismic slip at a depth of ~25 km. The Coulomb stress change suggests a significant stress loading effect on surrounding faults. The high-angle transpressive rupture kinematics of the 2023 Morocco earthquake reveal steep oblique–reverse faulting of the Tizi n’Test fault within the western High Atlas Mountains. The slight left-lateral strike slip and focal depth anomaly of this event are largely attributed to differential crustal shortening and the rejuvenation of early rift structures inherited from the Mesozoic complex evolution. Full article

The precise characterization of surface rupture zones and associated co-seismic displacement fields from large earthquakes provides critical insights into seismic rupture mechanisms, earthquake dynamics, and hazard assessments. Stereo-photogrammetric digital elevation models (DEMs), produced from high-resolution satellite stereo imagery, offer reliable global datasets that are suitable for the detailed extraction and quantification of vertical co-seismic displacements. In this study, we utilized pre- and post-event WorldView-2 stereo images of the 2024 Ms7.1 Wushi earthquake in Xinjiang to generate DEMs with a spatial resolution of 0.5 m and corresponding terrain point clouds with an average density of approximately 4 points/m². Subsequently, we applied the Iterative Closest Point (ICP) algorithm to perform differencing analysis on these datasets. Special care was taken to reduce influences from terrain changes such as vegetation growth and anthropogenic structures. Ultimately, by maintaining sufficient spatial detail, we obtained a three-dimensional co-seismic displacement field with a resolution of 15 m within grid cells measuring 30 m near the fault trace. The results indicate a clear vertical displacement distribution pattern along the causative sinistral–thrust fault, exhibiting alternating uplift and subsidence zones that follow a characteristic “high-in-center and low-at-ends” profile, along with localized peak displacement clusters. Vertical displacements range from approximately 0.2 to 1.4 m, with a maximum displacement of ~1.46 m located in the piedmont region north of the Qialemati River, near the transition between alluvial fan deposits and bedrock. Horizontal displacement components in the east-west and north-south directions are negligible, consistent with focal mechanism solutions and surface rupture observations from field investigations. The successful extraction of this high-resolution vertical displacement field validates the efficacy of satellite-based high-resolution stereo-imaging methods for overcoming the limitations of GNSS and InSAR techniques in characterizing near-field surface displacements associated with earthquake ruptures. Moreover, this dataset provides robust constraints for investigating fault-slip mechanisms within near-surface geological contexts. Full article

On 18 December 2023, a M_w 6.2 earthquake occurred in close proximity to Jishishan County, located on the northeastern edge of the Qinghai–Tibet Plateau. The event struck the structural intersection of the Haiyuan fault, Lajishan fault, and West Qinling fault, providing empirical evidence for investigating the crustal compression mechanisms associated with the northeastward expansion of the Qinghai–Tibet Plateau. In this study, we successfully acquired a high-resolution coseismic deformation field of the earthquake by employing interferometric synthetic aperture radar (InSAR) technology. This was accomplished through the analysis of image data obtained from both the ascending and descending orbits of the Sentinel-1A satellite, as well as from the ascending orbit of the ALOS-2 satellite. Our findings indicate that the coseismic deformation is predominantly localized around the Lajishan fault zone, without leading to the development of a surface rupture zone. The maximum deformations recorded from the Sentinel-1A ascending and descending datasets are 7.5 cm and 7.7 cm, respectively, while the maximum deformation observed from the ALOS-2 ascending data reaches 10 cm. Geodetic inversion confirms that the seismogenic structure is a northeast-dipping thrust fault. The geometric parameters indicate a strike of 313° and a dip angle of 50°. The slip distribution model reveals that the rupture depth predominantly ranges between 5.7 and 15 km, with a maximum displacement of 0.47 m occurring at a depth of 9.6 km. By integrating the coseismic slip distribution and aftershock relocation, this study comprehensively elucidates the stress coupling mechanism between the mainshock and its subsequent aftershock sequence. Quantitative analysis indicates that aftershocks are primarily located within the stress enhancement zone, with an increase in stress ranging from 0.12 to 0.30 bar. It is crucial to highlight that the structural units, including the western segment of the northern margin fault of West Qinling, the eastern segment of the Daotanghe fault, the eastern segment of the Linxia fault, and both the northern and southern segment of Lajishan fault, exhibit characteristics indicative of continuous stress loading. This observation suggests a potential risk for fractures in these areas. Full article

Field surveys focused on detailed mapping and measurements of coseismic surface ruptures along the causative fault of the 6 February 2023, Mw 7.8 Kahramanmaraş earthquake. The aim was filling gaps in the previously available surface-faulting trace, validating the accuracy of data obtained from remote sensing, refining fault offset estimates, and gaining a deeper understanding of both the local and overall patterns of the main rupture strands. Measurements and observations confirm dominating sinistral strike-slip movement. An integrated and comprehensive slip distribution curve shows peaks reaching over 700 cm, highlighting the near-fault expressing up to 70% of the deep net offset. In general, the slip distribution curve shows a strong correlation with the larger north-eastern deformation of the geodetic far field dislocation field and major deep slip patches. The overall rupture trace is generally straight and narrow with significant geometric complexities at a local scale. This results in transtensional and transpressional secondary structures, as multi-strand positive and negative tectonic flowers, hosting different patterns of the mole-tracks at the outcrop scale. The comprehensive and detailed field survey allowed characterizing the structural framework and geometric complexity of the surface faulting, ensuring accurate offset measurements and the reliable interpretation of both morphological and geometric features. Full article

The 6 February 2023 M_W 7.8 and M_W 7.6 earthquakes in southeastern Türkiye ruptured more than 400 km of the East Anatolian Fault Zone (EAFZ), producing one of the most destructive seismic sequences in recent history. Here, we integrate InSAR data, a new GNSS velocity field, and small-magnitude earthquakes to investigate the coseismic deformation, rupture geometry, and interseismic strain accumulation along the EAFZ. Using elastic dislocation modeling with a variable-strike, multi-segment fault geometry, we constrain the slip distribution of the mainshocks, showing improved fits to the surface displacement compared to the planar fault model. The M_W 7.8 event ruptured a number of fault segments over ~300 km, while the M_W 7.6 event activated a more localized fault system with a peak slip exceeding 15 m. We also model two moderate events (M_W 5.6 in 2020 and M_W 5.3 in 2022) along the southwestern part of the Pütürge segment—an area not ruptured during the 2020 or 2023 sequences. GNSS-derived strain-rate and locking depth estimates reveal strong interseismic coupling and significant strain accumulation in this region, suggesting the potential for a future large earthquake (M_W 6.6–7.1). Similarly, the Hatay region, at the southwestern termination of the 2023 rupture, shows a persistent strain accumulation and complex fault interactions involving the Dead Sea Fault and the Cyprus Arc. Our results demonstrate the importance of combining remote sensing and geodetic data to constrain fault kinematics, evaluate rupture segmentation, and assess the seismic hazard in tectonically active regions. Targeted monitoring at rupture terminations—such as the Pütürge and Hatay sectors—may be crucial for anticipating future large-magnitude earthquakes. Full article

This paper addresses the issues of sensor failures and actuator faults in mining tracked mobile vehicles (TMVs) operating in harsh environments by proposing a global fixed-time fault-tolerant control strategy based on a hierarchical unknown input observer structure. First, a kinematic and dynamic model of the TMV is established considering side slip and track slip, and its linear parameter-varying (LPV) model is constructed through parameter-dependent linearization. Then, a distributed structure consisting of four collaborating low-dimensional observers is designed, including a state observer, a disturbance observer, a position sensor fault observer, and a wheel speed sensor fault observer, and the fixed-time convergence of the closed-loop system is proven. Additionally, by equivalently treating actuator faults as power losses, an observer capable of identifying and compensating for motor efficiency losses is designed. Finally, an adaptive fault-tolerant control law is proposed by combining nominal control, disturbance compensation, and sliding mode switching terms, achieving global fixed-time stability and fault tolerance. Experimental results demonstrate that the proposed control system maintains excellent trajectory tracking performance even in the presence of sensor faults and actuator power losses, with tracking errors less than 0.1 m. Full article

The distribution of in situ stress fields in reservoirs is critical for the accurate exploration and efficient exploitation of hydrocarbon resources, especially in deep, fault-developed strata where tectonic activities significantly complicate stress field patterns. To clarify the perturbation effects of faults on in situ stress fields in deep reservoirs, this study combines dynamic–static parameter conversion models derived from laboratory experiments (acoustic emission Kaiser effect and triaxial compression tests) with a coupled “continuous matrix–discontinuous fault” numerical framework implemented in FLAC^3D6.0. Focusing on the BKQ Formation reservoir in the MH area, China, we developed a multivariate regression-based inversion model integrating gravitational and bidirectional tectonic stress fields, validated against field measurements with errors of −2.96% to 9.07%. The key findings of this study include the following: (1) fault slip induces stress reductions up to 22.3 MPa near fault zones, with perturbation ranges quantified via exponential decay functions (184.91–317.74 m); (2) the “continuous matrix–discontinuous fault” coupling method resolves limitations of traditional continuum models by simulating fault slip through interface contact elements; and (3) stress redistribution exhibits NW-SE gradients, aligning with regional tectonic compression. These results provide quantitative guidelines for optimizing hydrocarbon development boundaries and hydraulic fracturing designs in faulted reservoirs. Full article

Aero-engine turbine vanes made from directionally solidified nickel-based superalloys often fail with crack formation from the external wall of cooling channels. Therefore, this study simulates the compressive load on the external wall of the vane and conducts a sequence of creep–fatigue evaluations at 980 °C to investigate the creep–fatigue damage mechanisms of a directionally solidified superalloy and to assess its life. It is found that at low strain ranges, creep damage is dominant, with creep cavities forming inside the specimen and fatigue sources mostly distributed in the specimen interior. As the strain range increases, the damage mechanism transitions from creep-dominated to creep–fatigue coupled damage, with cracks nucleating preferentially on the surface and exhibiting a characteristic of multiple fatigue sources. In the longitudinal (L) specimen, dislocations in multiple orientations of the {111}<110> slip system are activated simultaneously, interacting within the γ channels to form dislocation networks, and dislocations shear through the γ′ phase via antiphase boundary (APB) pairs. In the transverse (T) specimen, stacking intrinsic stacking faults (SISFs) accumulate within the limited {111}<112> slip systems, subsequently forming a dislocation slip band. The modified creep–fatigue life prediction model, incorporating strain energy dissipation and stress relaxation mechanisms, demonstrates an accurate fatigue life prediction under creep–fatigue coupling, with a prediction accuracy within an error band of 1.86 times. Full article

Archaean metamorphic basement reservoirs, characterized by the development of natural fractures, constitute the primary target for oil and gas exploration in the Bozhong Depression, Bohai Bay Basin, Eastern China. Based on analyses of geophysical image logs, cores, scanning electron microscopy (SEM), and laboratory measurements, tectonic fractures are identified as the dominant type of natural fracture. Their development is primarily controlled by lithology, weathering intensity, and faulting. Fractures preferentially develop in metamorphic rocks with low plastic mineral content and are positively correlated with weathering intensity. Fracture orientations are predominantly parallel or subparallel to fault strikes, while localized stress perturbations induced by faulting significantly increase fracture density. Open fractures, constituting more than 60% of the total reservoir porosity, serve as both primary storage spaces and dominant fluid flow conduits, fundamentally governing reservoir quality. Consequently, spatial heterogeneity in fracture distribution drives distinct vertical zonation within the reservoir. The lithological units are ranked by fracture development potential (in descending order): leptynite, migmatitic granite, gneiss, cataclasite, diorite-porphyrite, and diabase. Diabase represents the lower threshold for effective reservoir formation, whereas overlying lithologies may function as reservoirs under favorable conditions. The large-scale compressional orogeny during the Indosinian period marked the primary phase of tectonic fracture formation. Subsequent uplift and inversion during the Yanshanian period further modified and overlaid the Indosinian structures. These structures are characterized by strong strike-slip strain, resulting in a series of conjugate shear fractures. During the Himalayan period, preexisting fractures were primarily reactivated, significantly influencing fracture effectiveness. The development model of the fracture network system in the metamorphic basement reservoirs of the study area is determined by a coupling mechanism of dominant lithology and multiphase fracturing. The spatial network reservoir system, under the control of multistage structure and weathering, is key to the formation of large-scale effective reservoirs in the metamorphic basement. Full article

The spatial variation characteristics of near-fault velocity pulses lack in-depth understanding, and it is difficult to consider this feature in probabilistic seismic hazard analysis and the ground motion input for structural seismic analysis. Based on ground motion simulation, this study performs spatial characteristic analysis of velocity pulses. The Mw 6.58 strike-slip Imperial Valley and the Mw 6.8 dip-slip Northridge earthquakes are adopted as the cases, and the simulation method is validated by comparing synthetics with observations. The multi-component broadband ground motion fields are simulated, and the pulse parameters and the pulse area are extracted using the multi-component pulse identification method. The spatial characteristics of various pulse parameters are analyzed. The results show that for a single earthquake, the pulse period is a spatial variable related to source-to-site geometry, the pulse amplification factor has great spatial variation, and the orientation of the maximum pulse component is controlled by the radiation pattern. Finally, the influence of slip distribution on pulse is explored based on two earthquakes, in which the uniform slip, the random slip, and the hybrid slip are combined with different rupture directions. This study contributes to a more reasonable consideration of pulse-like ground motion in seismic risk assessment and earthquake response analysis. Full article

On 22 July 2020, an Mw 6.4 earthquake occurred in Nima County in the Qiangtang Terrane of the central Tibetan Plateau. This event, caused by normal faulting, remains controversial in terms of its rupture process and causative fault due to the complex tectonics of the region. In this study, we analyzed the coseismic and postseismic deformation using differential interferometric synthetic aperture radar (D-InSAR). The coseismic slip distribution was independently estimated through InSAR inversion and teleseismic waveform analysis, while the afterslip distribution was inferred from postseismic deformation. Coulomb stress failure analysis was conducted to assess the potential seismic hazard. Our results showed a maximum line-of-sight (LOS) coseismic deformation of about 29 cm away from the satellite, with quasi-vertical subsidence peaking at 35 cm. Four distinct deformation zones were observed in the quasi-east–west direction. Coseismic deformation and slip models based on InSAR and teleseismic data indicate that the Nima earthquake ruptured the West Yibu Chaka fault. The seismogenic fault had a strike of 26°, an eastward dip of 43°, and a rake of −87.28°, with rupture patches at depths of 3–13 km and a maximum slip of 1.1 m. Postseismic deformation showed cumulative LOS displacement of up to 0.05 m. Afterslip was concentrated in the up-dip and down-dip areas of the coseismic rupture zone, reaching a maximum of 0.11 m. Afterslip was also observed along the East Yibu Caka fault. Coulomb stress modeling indicates an increased seismic risk between the Yibu Caka fault and the Jiangai Zangbu fault, highlighting the vulnerability of the region to future seismic activity. Full article