Change In Strike Research Articles

Efficacy and mechanism of enhanced Sb(V) removal from textile wastewater using ferric flocs in aerobic biological treatment

Antimony contamination from textile industries has been a global environmental concern and the existing treatment technologies could not reduce Sb(V) to meet the discharge standards. To overcome this shortcoming, ferric flocs were introduced to expedite the biological process for enhanced Sb(V) removal in wastewater treatment plant (WWTP). For this purpose, a series of laboratorial-scale sequential batch reactor activated sludge processes (SBRs) were applied for Sb(V) removal with varied reactor conditions and the transformation of Fe and Sb in SBR system was investigated. Results showed a significant improvement in Sb(V) removal and the 20 mg L−1 d−1 iron ions dosage and iron loss rate was found to be only 15.2%. The influent Sb(V) concentration ranging 153–612 μg L−1 was reduced to below 50 μg L−1, and the maximum Sb(V) removal rate of the enhanced system reached about 94.3%. Furthermore, it exhibited high stability of Sb(V) removal in the face of antimonate load, Fe strike and matrix change of wastewater. Sludge total Sb determination and capacity calculation revealed decreasing in Sb adsorption capacity and desorption without fresh Fe dosage. While sludge morphology analysis demonstrated the aging and crystallization of iron hydroxides. These results verify the distinct effects of fresh iron addition and iron aging on Sb(V) removal. High-throughput gene pyrosequencing results showed that the iron addition changed microbial mechanisms and effect Fe oxidized bacterial quantity, indicating Sb(V) immobilization achieved by microbial synergistic iron oxidation. The present study successfully established a simple and efficient method for Sb(V) removal during biological treatment, and the modification of biological process by iron supplement could provide insights for real textile wastewater treatment.

The Impact of the Bohemian Spur on the Cooling and Exhumation Pattern of the Eastern Alpine Wedge of the European Alps

AbstractFold and thrust belt architecture may be influenced by basement geometry of the downgoing plate. This influence is notoriously difficult to assess due to a common lack of subsurface constraints and low resolution of exhumation estimates in space and time. The Bohemian Spur is a basement high at the transition from the Alps to the Carpathians. It coincides with narrowing of the foreland basin and an orogen‐scale change of strike. Its location in one of the best‐studied orogens in the world makes it an ideal case for understanding how basement topography influences fold and thrust belt tectonics. However, since thermochronological studies were mainly focused on the core of the Alps, timing and amount of exhumation remain poorly constrained in these peripheral parts of the orogen. We present new apatite (U‐Th)/He and fission track data from the wedge above the Bohemian Spur. Thermally reset ages monitor a so far un(der)appreciated phase of prominent Late Oligocene to Miocene cooling, associated with crustal thickening, uplift and erosion during wedge propagation. Pronounced exhumation on the order of 3–4.5 km can be related to basement steps beneath the advancing wedge. The spur acted as a buttress for foreland‐propagating thrusting, pinning deformation and nucleating antiformal stacking and duplexing and thus exhumation above it. We illustrate how along‐ and across‐strike changes of sub‐detachment topography impact wedge propagation and control fold and thrust belt geometries. The buttressing effect accounts for most of the exhumation, while deep‐seated slab dynamics are of subordinate importance for wedge uplift.

Seismic cycle controlled by subduction geometry: novel 3-D quasi-dynamic model of Central Chile megathrust

SUMMARY Subduction earthquakes show complex spatial and temporal rupture patterns, exhibiting events of varied sizes, which rupture distinct or overlapping fault segments. Elucidating first-order controlling conditions of rupture segmentation and return periods of large earthquakes is therefore critical for seismic and tsunami hazard estimations. The Chilean subduction zone frequently hosts several Mw > 8 earthquakes, with heterogeneous recurrence rates and locations. Here, we implement 3-D quasi-dynamic rate and state frictional models to investigate the role of plate interface geometry on the distribution of interseismic coupling and coseismic ruptures in Central Chile. First, we develop synthetic-parametric models that show how dip and strike variations may increase the probabilities to produce partial seismic barriers, which tend to avoid the production of large earthquake ruptures and modulate rupture lengths. Then, we simulate the subduction seismic cycle processes on Central Chile (25°S–38°S), imposing depth-dependent frictional properties on a realistic non-planar 3-D subduction interface geometry. Similar to results obtained for synthetic-parametric models, after 5000 yr of simulation, regions with abrupt dip or strike changes increase the probabilities of stopping coseismic propagation of simulated Mw 8.0–9.0 earthquakes. Our simulated earthquake sequences on the Central Chile subduction zone delimit rupture areas that match geometrical interface features and historical earthquakes, results that point to the crucial role of fault interface geometry on seismic cycle segmentation along strike.

Fault Geometry and Late Quaternary Kinematics Along the Tieluzi Fault: Implications for Tectonic Deformation and Eastward Expansion of the Tibetan Plateau, China

AbstractThe Tieluzi Fault is the largest structure in the East Qinling Mountains, and is considered to be the easternmost continuation of the Altyn Tagh‐Haiyuan‐Qinling Fault System (AHQFS) that allows the eastward extrusion of the Tibetan Plateau and South China Block. We studied the fault geometry and kinematics of the Tieluzi Fault using field investigations, detailed interpretations of high‐resolution satellite imagery and digital elevation models, and late Quaternary dating methods. Paleoseismic investigations indicate that the most recent earthquake along the Tieluzi Fault occurred before 1,500–1,300 cal. BP. Geological and geomorphological observations show that segments west of Lushi County are more active than those to the east. The spatial variations in tectonic activity along the Tieluzi Fault are interpreted to be related to four possible mechanisms: strike change, discontinuity, intersection, and branch. The late Quaternary left‐lateral slip rate is determined to be 0.9 ± 0.1 mm/yr on the Tieluzi Fault. The prominent left‐lateral faulting along the Tieluzi Fault suggests that most of the left‐lateral displacement along the eastern AHQFS has been accommodated by the Tieluzi Fault, which forms the most frontier of the eastward expansion of the Tibetan Plateau. Furthermore, we suggest that the left‐lateral faulting in the East Qinling Mountains is a response to relative eastward motion of the South China block pushed by the Tibetan Plateau with respect to the North China Plain Block. Also, our results indicate that the Tibetan Plateau has undergone a stepwise eastward expansion.

3D mineral prospectivity modeling in the Sanshandao goldfield, China using the convolutional neural network with attention mechanism

Mineralization distribution is spatially heterogeneous and jointly controlled by multiple ore-controlling factors. Given this ubiquitous feature, we integrated the attention mechanism of the Convolutional Block Attention Module (CBAM), which contains both channel and spatial attention modules, into a convolutional neural network (CNN) to develop a more robust 3D mineral prospectivity modeling (MPM) approach. A network interpretive algorithm (DeepLIFT) was conducted to the CNN deconstruction to evaluate whether the key ore-controlling information is read. The Sanshandao goldfield in China, with significant fault controls on gold mineralization distribution, was selected as a case study to verify the proposed method. In this case, we generated the 5-channel images by projecting five ore-related fault features to feed into CNN. The optimal prospectivity model of CNN + CBAM was subsequently yielded by a gradient-based optimization of stochastic objective functions and an optimized regularization cross-entropy loss function. By decomposing the constructed model and the vanilla CNN model, we observed the CNN + CBAM has lower feature scores of fault distance and larger scores of fault geometry (e.g., dip and undulation) at Xiling, Haiyu, and Xinli than CNN. These segments occur significant fault strike or dip changes that have influenced mineralization spatial continuity, which is well consistent with the expert knowledge of metallogeny in the Sanshandao goldfield. This means that the CBAM has induced the CNN to focus on key ore-controlling features from complex exploration data, which is likely to improve the model’s prediction ability. The prospectivity results of CNN + CBAM and other comparison shallow machine learning methods (e.g., random forest) revealed that the CNN + CBAM model produced more reliable results, as evidenced by (1) being highly consistent with known mineralization, (2) having the highest AUC values and success rate, and (3) accurately predicting deep voxels that have been explored by drill holes. Thus, the proposed CNN + CBAM method, with a remarkable capacity for emphasizing critical ore-associated features, is recommended for application in deep 3D MPM. Six possible mineralization sites in the Sanshandao field were identified based on the CNN + CBAM prospective data, which may aid future gold exploration.

Fault structure and slip mechanics of the 2022 Mw 6.7 Menyuan earthquake revealed by coseismic rupture observations

Large and shallow strike-slip earthquakes produce striking ground ruptures, damaging roads and infrastructure but providing great opportunities for examining the fault's structure. After the 2022 Mw 6.7 Menyuan earthquake, we observed abundant surface fractures by a combination of optical remote sensing, radar offset and unmanned aerial vehicle measurements. These fractures reveal a complex fault structure including apparent bending geometries and bifurcating branches, which are essential to understanding the mechanisms of faulting. In this paper, we used triangular dislocations to construct the fault geometry that reflected the distribution of measured strike changes but avoided unexcepted discontinuities and overlaps where the fault bent. The modeled fault geometry revealed an extensional releasing bend which was responsible for the southward branching of the fault rupture at its western edge. Our results also demonstrated the potential to explain the occurrence of aftershock clusters and to infer their fault geometries through the correlation analysis of the aftershock distribution and the slip induced stress field. The triangular dislocation model also enabled the calculation of the fault plane roughness and its spatial variation which directly controlled the fault slip magnitude and rupture termination. These analyses reveal an unprecedented level of detail of the fault structure and slip mechanics and, to some extent, offer insights into the physical processes and structural properties of crustal faults in the Earth's shallow crust.

Slip localization on multiple fault splays accommodating distributed deformation across normal fault complexities

Deformation across structural complexities such as along-strike fault bends may be accommodated by distributed faulting, with multiple fault splays working to transfer the deformation between two principal fault segments. In these contexts, an unsolved question is whether fault activity is equally distributed through time, with multiple fault splays recording the same earthquakes, or it is instead localized in time and space across the distributed faults, with earthquakes being clustered on specific fault splays. To answer this question, we studied the distributed deformation across a structural complexity of the Mt. Marine fault (Central Apennines, Italy), where multiple fault splays accommodate the deformation throughout the change in strike of the fault. Our multidisciplinary (remote sensing analysis, geomorphological-geological mapping, geophysical and paleoseismological surveys) study identified five principal synthetic and antithetic fault splays arranged over an across-strike distance of 500 m, all of which showing evidence of multiple surface-rupturing events during the Late Pleistocene-Holocene. The fault splays exhibit different and variable activity rates, suggesting that fault activity is localized on specific fault splays through space and time. Nonetheless, our results suggest that multiple fault splays can rupture simultaneously during large earthquakes. Our findings have strong implications on fault-based seismic hazard assessments, as they imply that data collected on one splay may not be representative of the behaviour of the entire fault. This can potentially bias seismic hazard calculations.

Ecological assessment of the world's first shaft hydropower plant

Efforts to increase the share of renewable energies and to reduce the negative ecological impacts of hydropower use are driving the development of novel hydropower technologies. Innovative hydropower concepts and turbine types should cause less fish damage and be more ‘eco-friendly’ than conventional hydropower plants. In this study, extensive ecological monitoring at the world's first innovative shaft hydropower plant (SHPP) was carried out. The monitoring included the assessment of the corridor usage of downstream moving fish, turbine-related fish injuries and mortality, as well as changes in aquatic community and habitat associated with hydropower plant construction in a before-after comparison. A large proportion of downstream moving fish was not prevented from turbine passage by the installed physical barrier, resulting in mortality rates up to 44% that can be similar to those at conventional Kaplan turbines. Strike and pressure changes (decompression rate up to 377 kPa/s) during turbine passage were identified as a major cause of mortality. In addition, significant differences in the aquatic community and abiotic habitat characteristics between upstream and downstream sides of the dam could be detected, indicating an interruption of the river continuum. The findings of this study indicate that the theoretical advantages of the SHPP concept of optimal fish protection from turbine passage and a low disruption of the serial continuity could not be realized in practice. Further research is needed to optimize this concept to better prevent fish from turbine entrainment, improve bypass efficiency and reduce the effects of the disruption of serial continuity.

The Deformation Characteristics of the Zhuka Fault in Lancang River and Its Influence on the Geostress Field

The construction of infrastructure projects such as the Sichuan–Tibet Railway and western cascade hydropower stations has led to the increasing development of ultra-long and deeply buried tunnels in an environment characterized by highly active neotectonic movement, which affects the sustainable development of ecological civilization in Tibet. However, the effects of faults resulting from tectonic activity on the distribution of geostress fields have not been systematically studied. This research focuses on the development characteristics and basic type of the Zhuka fault near the RM hydropower station, aiming to analyze the phenomenon of geostress concentration in the study area. Field investigations have revealed significant high-geostress damage on the downstream slope of the lower dam site, situated on the hanging wall of the Zhuka fault. The results indicate a correlation between these high-geostress phenomena and the Zhuka fault, suggesting the concentration of geostress within a certain range on the hanging wall and outside of the fault zone. Stress concentration primarily depends on the characteristics of fault thrusting and fault morphology. The left-lateral strike-slip and thrusting process of the Zhuka fault, combined with NNW-directed tectonic compression stress and sudden changes in fault strike, contribute to geostress concentration within a specific range of the fault hanging wall. The observed high-geostress damage to the hard rock on the valley slope results from the combined effect of construction stress concentration and fourth-order valley incision stress concentration, which influences site selection for the RM hydropower station, thereby highlighting the role of geostress concentration outside the fault zone in engineering practice. This study provides valuable insights into geostress concentration and its implications for sustainable development in the Sichuan–Tibet region.

Effects of Body Weight Support in Running on Achilles Tendon Loading.

Achilles tendon (AT) tendinopathy is common in runners. Repetitive AT loading may play a role in etiology. Interventions such as body weight support (BWS) may reduce loading on the AT in running. Examine how ground reaction force, AT loading, foot strike and cadence variables change in running with BWS. Twenty-four healthy female runners free from injury were examined. Participants ran on an instrumented treadmill with and without BWS using a harness-based system at a standardized speed. The system has 4 elastic cords affixed to a harness that is attached to a frame-like structure. Kinematic data and kinetic data were used in a musculoskeletal model (18 segments and 16 degrees of freedom) to determine AT loading variables, foot strike angle and cadence. Paired t-tests were used to compare each variable between conditions. Ground reaction force was 9.0% lower with BWS (p<.05). Peak AT stress, force, and impulse were 9.4%, 11.7% and 14.8% lower when using BWS in running compared to no support (p<.05). Foot strike angle was similar (p<.05) despite cadence being reduced (p<.05). BWS may reduce AT loading and impulse variables during running. This may be important in the rehabilitation efforts.

Subsurface fracture characterization in a folded ultra-deep tight-gas sandstone reservoir: A case study from the Keshen gas field, Tarim Basin, China

In the Keshen gas field in the northern Tarim Basin, the main production interval is the ultra-deep (>6000 m), ultra-high pressure Lower Cretaceous Bashijiqike Formation. Understanding the characteristics and role of natural fractures in the reservoir is essential for efficient exploration and development. Data from borehole images (42 vertical wells) and cores (12 vertical wells) enabled a comprehensive characterization of fracture attributes, including mode, orientation, fill, density, and clustering as well as variations with respect to depth and structural position. Using image logs from 20 vertical wells and cores from 12 wells, we find that steeply dipping (>60°), E-W and N–S-striking fractures are the most common across the studied anticline. Fracture density is highest in the forelimb and near faults (2.85 fractures/m), compatible with fracture formation during folding and associated faulting. Fracture clusters 10+ m wide are also preferentially located within these structural zones and are spaced around 5–15 m apart. Fracture orientations, fill, and density varies with depth. We identify a depth transition horizon above and below which fracture characteristics, specially strike, dip, and resistivity change dramatically. We infer those changes are due to fold geometry, rheological differences associated with increasing pressure and temperature at extreme depths. We observe anhydrite-filled fractures located near the top of the formation, whose presence is associated with overlying evaporites. Vertical and lateral variations of fracture characteristics and distribution discovered in this reservoir may aid the interpretation and prediction of the fracture network in other ultra-deep sandstone reservoirs with a comparable setting or well performance.

The impact of local muscle fatigue and foot strike techniques on kinematic features and plantar pressure distribution while walking

Although numerous studies have been performed, there are no clear findings providing a meaningful statement about how foot strike changes as a result of muscular fatigue. In studies on running fatigue, it is not possible to differentiate which kinematic or kinetic changes are a direct result of local muscle fatigue and varied speeds. This study aimed to investigate the effect of foot strike technique and localized muscle fatigue of the plantar and dorsal flexors on plantar pressure distribution and selected kinematic features of treadmill running. Twenty-six voluntary forefoot and rearfoot runners of similar age and body mass participated in the study. Each group completed two tests with a time interval of 3-7 days. The kinematic data was measured with the help of a three-dimensional measuring and analysis system while the volunteers ran on the treadmill. The fatigue protocol included an isometric maximal force test and an isokinetic endurance test. In order to check the differences, a variance analysis with repeated measurements was used. The strength values of the two groups of runners showed significant average differences in the plantar flexors in the endurance test and in the fatigue index for both the left and right legs. The results of the strength values are surprising because the plantar flexors of this group of runners should be well-trained due to the forefoot strike during regular running. In response to fatigue, the pressure maxima decreased under the exposed foot regions, i.e. under the forefoot at forefoot strike and under the heel at rearfoot strike. The two groups of runners differed in foot angle at foot-on with higher values measured in the forefoot runners. The larger foot angle of the forefoot runners improved shock absorption and can thus reduce the risk of injury.

Unraveling an enigmatic boundary along the Sunda-Banda volcanic arc

This study utilizes a range of complementary geological, geophysical, and geochemical data to analyze the structural, deformational, and compositional variations along the Sunda-Banda volcanic arc transitional zone from oceanic to continental subduction. The core component is a synthesis of three station-based anisotropy inferences and two 3-D shear wave velocity models in the crust and upper mantle, all of which are derived based on ∼5 years of broadband seismic data collected across eastern Indonesia. These seismic results are based on receiver functions, shear wave splitting, ambient noise tomography, and a new teleseismic surface wave tomography model. We observe distinct along-arc spatial variations in the shear wave velocity and anisotropic structure within the crust and mantle wedge above the subducting slab. An intriguing arc-perpendicular orientation is observed in crustal fabrics and mantle anisotropy consistently in central Flores, contrasting with the arc-parallel orientations on the western and eastern sides. The orientations correlate with the change in strike of the highest topography as well as the presence of ∼N-S aligned cinder cones in central Flores. The 3-D shear wave velocity model in the crust and uppermost mantle also presents a sharp structural change in central Flores that indicates a relatively thinner crust. At deeper depths, the newly imaged upper mantle structure exhibits along-arc variations, but the change across central Flores appears to be distributed more broadly and outlines a relatively slow mantle wedge beneath eastern Flores. These new observations roughly correlate with previously identified changes in volcanic geochemistry characteristics across central Flores. Our study links the surface topography, geology, and volcanism with subsurface crust and mantle structures, unraveling an enigmatic structural and/or compositional boundary along the Banda volcanic arc.

The Coupling of Stride Length and Foot Strike in Running.

Modifying stride length and/or foot strike in running results in mechanical alterations associated with injury risk. Stride length and foot strike have often been treated as independent factors that affect running mechanics, but there is evidence to suggest that they may be coupled. The purpose of this study was to determine if foot strike and stride length are coupled in running, and if so, can these variables be independently manipulated? Additionally, we sought to determine how independently and simultaneously manipulating stride length and foot strike influenced running kinematics and kinetics. Fifteen individuals ran over ground with stride lengths +/– 10 % of their preferred stride length while adopting both a fore/mid foot strike and rear foot strike pattern, as well as running with their self-selected stride length and foot strike when the opposite variable was controlled. Three-dimensional motion capture and force plate data were captured synchronously during the manipulated stride length x foot strike trials. The results indicate that foot strike and stride length are coupled, with shorter stride lengths being associated with a F/MFS and longer stride lengths being associated with a RFS pattern. Impact peak magnitude was primarily dependent on foot strike, with a F/MFS pattern reducing the magnitude of the impact peak force regardless of stride length. Peak vertical and horizontal ground reaction forces were found to be primarily dependent on stride length, with longer stride lengths resulting in increased vertical and horizontal ground reaction forces, regardless of foot strike. It is difficult, but possible, to independently manipulate stride length and foot strike. Clinicians should be aware of the coupled changes in stride length and foot strike.

Controls on crustal seismicity segmentation on a local scale in the Southern Central Andes

The Argentine Andes between 34° and 36°S comprise a region that lies immediately south of the transition from the Chilean-Pampean flat-slab to a normal subduction segment. Several key changes take part through this area, such as a westward shift of the magmatic arc front, the end of Paleozoic outcrops of the Frontal Cordillera denoting a decline in exhumation, the change in strike of the orogenic belt, and a ∼2 km decrease in maximum and mean topography. We assess the associated segmentation of the deformation by studying the local seismicity. By analyzing one year of seismological data obtained from a local network, we found a significant shift in the low magnitude (M < 3) crustal seismicity pattern at ∼34.8°S. To the north, most events occur along the topographic front. In contrast, to the south, no events are observed in the frontal region but are instead located closer to the Andean axis. In addition, we used gravity data to determine elastic thickness in the region to compare crustal seismic activity with the pattern of crustal rigidity. We discuss this and other geological, tectonic, and climatic factors as possible controls on seismicity segmentation. We do not find a controlling role by neither elastic thickness nor precipitation patterns. Instead, we propose a thermal contrast due to the volcanic arc's geometry, and differing stress transfer from the subducting slab owing to mantle wedge heterogeneities, as the main active controls on the seismicity distribution; modulated by a passive control by pre-Andean rheological features of the crust.

Geomechanical Modeling and Inversion Analysis of the in-situ Stress Field in Deep Marine Shale Formations: A Case Study of the Longmaxi Formation, Dingshan Area, China

Based on the comprehensive analysis of wellbore characteristics in a deep shale gas field, the in-situ stress state of the shale reservoir was assessed in this study for the Longmaxi formation in the Dingshan area, Southwestern China. The data obtained from hydraulic fracturing, drilling-induced fractures, and in-situ core testing were used to determine the magnitude and direction of the maximum principal horizontal stress in five wells. Besides, hydraulic fracturing and cross-multipole array acoustic logging (XMAC) were employed to determine the vertical variation of the in-situ stress. Based on the logging interpretation and mechanical test results, the spatial distribution of rock mechanical parameters in the Dingshan area was assessed by the amplitude variation versus offset (AVO) seismic inversion. A 3D heterogeneous mechanical inversion model was realized via the ANSYS and CATIA3D finite element software packages, providing the area in-situ stress field simulation. The depth, fault strike, and position change effects on the main stress, horizontal stress difference, and horizontal stress difference coefficient were numerically simulated. The results show that the maximum principal stress azimuth was mainly concentrated in the NE20°-NE80° sector. Moreover, the development zone of natural fractures was related to the area with the highest principal stress differences. The maximum principal stress variation in the study area was mainly in the compressive range from −135 to −45 MPa, gradually increasing from east to west and south to north. The stress type mainly depended on the depth, fault strike, and rock mechanical parameters, while the stress difference and stress difference coefficient near the fault structure were relatively small. This study’s findings are considered instrumental in improving the borehole stability, determining the casing setting point, and optimizing the well location in deep shale reservoirs with similar geological conditions.

The Sensitivity of Tsunami Impact to Earthquake Source Parameters and Manning Friction in High-Resolution Inundation Simulations

In seismically active regions with variable dominant focal mechanisms, there is considerable tsunami inundation height uncertainty. Basic earthquake source parameters such as dip, strike, and rake affect significantly the tsunamigenic potential and the tsunami directivity. Tsunami inundation is also sensitive to other properties such as bottom friction. Despite their importance, sensitivity to these basic parameters is surprisingly sparsely studied in literature. We perform suites of systematic parameter searches to investigate the sensitivity of inundation at the towns of Catania and Siracusa on Sicily to changes both in the earthquake source parameters and the Manning friction. The inundation is modelled using the Tsunami-HySEA shallow water code on a system of nested topo-bathymetric grids with a finest spatial resolution of 10 m. This GPU-based model, with significant HPC resources, allows us to perform large numbers of high-resolution tsunami simulations. We analyze the variability of different hydrodynamic parameters due to large earthquakes with uniform slip at different locations, focal depth, and different source parameters. We consider sources both near the coastline, in which significant near-shore co-seismic deformation occurs, and offshore, where near-shore co-seismic deformation is negligible. For distant offshore earthquake sources, we see systematic and intuitive changes in the inundation with changes in strike, dip, rake, and depth. For near-shore sources, the dependency is far more complicated and co-determined by both the source mechanisms and the coastal morphology. The sensitivity studies provide directions on how to resolve the source discretization to optimize the number of sources in Probabilistic Tsunami Hazard Analysis, and they demonstrate a need for a far finer discretization of local sources than for more distant sources. For a small number of earthquake sources, we study systematically the inundation as a function of the Manning coefficient. The sensitivity of the inundation to this parameter varies greatly for different earthquake sources and topo-bathymetry at the coastline of interest. The friction greatly affects the velocities and momentum flux and to a lesser but still significant extent the inundation distance from the coastline. An understanding of all these dependencies is needed to better quantify the hazard when source complexity increases.

Coseismic fault model of the 2017 MW 6.5 Jiuzhaigou earthquake and implications for the regional fault slip pattern

On August 8, 2017, an MW 6.5 earthquake occurred in Jiuzhaigou County, Sichuan Province, China, on the eastern margin of the Qinghai–Tibet Plateau. This study investigates the coseismic deformation field and fault model with ascending and descending Sentinel-1 synthetic aperture radar (SAR) images, aftershock distribution, and elastic half-space dislocation model. The regional fault slip pattern is then quantitatively examined using the boundary element method. The results show that the ascending and descending interferometric synthetic aperture radar (InSAR) coseismic deformation fields display an overall NNW–SSE trend, with more significant deformation on the southwest side of the fault. The coseismic fault geometry is divided into NW and SE sub-faults with strikes of 162.1° and 149.3°, respectively. The coseismic fault slip is dominated by a left-lateral strike-slip movement with an average rake of −2.31°, mainly occurring at a depth of 0–13.04 km with a shape of an approximately inverted triangle. The fault slip features two peak slip zones, with a maximum of 1.39 m. The total seismic moment is 6.34 × 1018 N·m (MW 6.47). The boundary element calculation quantitatively indicates that the regional fault slip pattern may be mainly attributable to the changing strike and dip. The strike changes from NNW–SSE to nearly NS direction, and the dip gradually decreases from the Jiuzhaigou earthquake fault in the north to the Huya fault in the south. With these characteristics, the Huya and the Jiuzhaigou earthquake faults form the eastern boundary of the Minshan uplift zone and accommodate the accumulated deformation.

The effect of along-strike variation in dip on rupture propagation on strike-slip faults

AbstractStrike-slip faults can be nonplanar in both their strike and dip dimensions. While a large body of work has investigated the effects of changes in strike on earthquake rupture and arrest, no previous studies have investigated the role of along-strike variations in dip on strike-slip ruptures. Here, I use the three-dimensional finite-element method to conduct dynamic simulations of ruptures on strike-slip faults with linear surface traces and changes in dip along strike. I experiment with the amount of dip change as well as the abruptness of that change under a variety of initial stress conditions. In all of my initial stress cases, I find that a change in dip along strike can cause rupture to stop, and that larger dip changes over shorter distances are more likely to do so. This is largely due to the change in strike at depth that inherently comes from changing the dip; the majority of these behaviors are a result of the rupture front being forced to change direction mid-rupture. While some dip-slip movement does occur on the nonvertical parts of the model fault, it does not have a significant effect on rupture extent. However, linear-surface-trace, nonvertical-dip faults do produce different surface slip, stress, and ground motion patterns compared to corresponding nonlinear-strike, vertical-dip faults. Together, my results show that changes in dip along strike-slip faults do considerably impact the rupture process, suggesting that this type of geometrical complexity should be considered in rupture forecasts and hazard assessments.

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower