Characteristic Slip Research Articles

Morphotectonic analysis of strike-slip faults in the Sayan-Tuva Upland (North Mongolia and South Siberia): Age and displacement rates

The Sayan-Tuva Upland is the northernmost positive relief of Central Asia, associated with the India-Asia collision. It formed on the boundary of the Siberian Craton in late Miocene-early Pliocene time and is characterized by uplift and shear displacement of lithospheric blocks. In this study, we answer the question of how deformation is distributed within the Sayan-Tuva Upland and what are the rates and age of horizontal displacements. Using morphotectonic and palaeoseismological analyses, we have calculated the displacement rates and onset of activation of three faults: Erzin-Agardag, Sayan-Tuva and Kaakhem, which are fragments of large strike-slip fault systems that cut across the entire Sayan-Tuva Upland. For the Erzin-Agardag Fault, the rate of left-lateral displacement is 0.7–1.4 mm/yr and the age of strike-slip reactivation is estimated to be 2.1–1.1 Ma. For the Sayan-Tuva and Kaakhem faults, the minimum horizontal displacement rates are 0.9 ± 0.1 and 0.6 ± 0.1 mm/yr, and the maximum ages of the onset of strike-slip displacements are 2.4 Ma and 5 Ma, respectively. We propose that 1.1–2.1 Ma ago there was a kinematic change that activated left-lateral strike-slip faults, leading to the formation of the modern kinematic model, characterized by eastward movement of lithospheric blocks along inherited fault systems between the Hangay Dome and the Siberian Craton. Analysis of slip distribution and trenching across the Erzin-Agardag Fault allowed estimating the mean recurrence interval of the ∼ M7.8 earthquakes between 9.4 and 4.7 ka. The Erzin-Agardag Fault has produced multiple displacements with an amplitude of ∼ 6.6 m and follows a characteristic slip model.

Subduction Zone Geometry Modulates the Megathrust Earthquake Cycle: Magnitude, Recurrence, and Variability

AbstractMegathrust geometric properties exhibit some of the strongest correlations with maximum earthquake magnitude in global surveys of large subduction zone earthquakes, but the mechanisms through which fault geometry influences subduction earthquake cycle dynamics remain unresolved. Here, we develop 39 models of sequences of earthquakes and aseismic slip (SEAS) on variably‐dipping planar and variably‐curved nonplanar megathrusts using the volumetric, high‐order accurate code tandem to account for fault curvature. We vary the dip, downdip curvature and width of the seismogenic zone to examine how slab geometry mechanically influences megathrust seismic cycles, including the size, variability, and interevent timing of earthquakes. Dip and curvature control characteristic slip styles primarily through their influence on seismogenic zone width: wider seismogenic zones allow shallowly‐dipping megathrusts to host larger earthquakes than steeply‐dipping ones. Under elevated pore pressure and less strongly velocity‐weakening friction, all modeled fault geometries host uniform periodic ruptures. In contrast, shallowly‐dipping and sharply‐curved megathrusts host multi‐period supercycles of slow‐to‐fast, small‐to‐large slip events under higher effective stresses and more strongly velocity‐weakening friction. We discuss how subduction zones' maximum earthquake magnitudes may be primarily controlled by the dip and dimensions of the seismogenic zone, while second‐order effects from structurally‐derived mechanical heterogeneity modulate the recurrence frequency and timing of these events. Our results suggest that enhanced co‐ and interseismic strength and stress variability along the megathrust, such as induced near areas of high or heterogeneous fault curvature, limits how frequently large ruptures occur and may explain curved faults' tendency to host more frequent, smaller earthquakes than flat faults.

Seismic Performance of Steel-Reinforced High Strength Concrete Joints Considering Bond Slip Effect

This study presents a solution for push-out failure for the staged bond-slip constitutive relationship between the structural steel and high strength concrete, taking into account the concrete strength grade, anchoring length, and stirrup ratio. The critical point coordinates for different stages are determined by the tests of 14 steel-reinforced high strength concrete (SRHSC) specimens. It is observed that with the increase in the concrete strength grade and anchorage length, the ultimate load of the specimens increased significantly, but the influence on the residual bond strength was not significant. The effect of the stirring ratio was mainly manifested in a slight increase in the initial bond strength. The formula for calculating SRHSC characteristic bond strength and characteristic slip value is established, and the bond-slip constitutive relation of SRHSC is proposed based on the tests. The material constitutive model considering the effect of bond-slip is implanted into the software in the case of the ABAQUS finite element platform. The material is applied to the numerical simulation analysis of the SRHSC exterior joints. The rationality and accuracy of the new material are verified by comparing the simulation results with the test results.

Cyclic behavior of rubber-coated stud-UHPC shear connectors exposed to reversed cyclic loadings

Steel-ultra-high performance concrete (UHPC) composite structures that could maximize the benefits of two materials have gained ground in bridge structures for accelerating construction speed and reducing self-weight. However, the shear stiffness of ordinary stud connectors (OSCs) in UHPC might exceed the actual demand, leading to the insufficient deformation capacity of OSCs. Therefore, the flexible rubber-coated stud connectors (FRSCs) were developed to replace the OSCs for improving the ductility of shear connectors. The shear performance of FRSCs in UHPC subjected to reversed cyclic loadings has been not understood, which limits its application in the practical construction. The cyclic behavior of FRSCs was examined through modified push-pull test specimens, and the static loading tests were carried out to determine the characteristic slip capacity and shear strength. Numerical models were established to reveal the damage process and failure mechanism of FRSCs and employed to conduct detailed parametric studies. The results demonstrated the FRSCs exhibited high ductility and large energy absorption capacity than OSCs and possessed sufficient shear bearing capacity, indicating their potential application in steel-UHPC composite systems. Increasing the height and thickness of rubber sleeve could enhance the slip capacity of FRSCs under monotonic loadings, while having no effect on the cyclic ductility. Finally, an empirical equation was developed to accurately predict the FRSC shear strength.

Temporal evolution of shear-induced dilatancy of rock fractures: controls from surface roughness and normal stress

SUMMARY Understanding the shear-induced dilatancy of rock fractures is important for assessing the permeability evolution and seismic hazard in shale and geothermal reservoirs. The displacement dependence of fracture dilation has been well studied, while the influence of slip velocity is poorly constrained. In this study, we combined displacement- and velocity-dependent aperture models to reproduce the transient shear-induced dilatancy of fractures in sandstone in 16 normal stress unloading tests. Our results show that the combined aperture model can describe the transient fracture aperture evolution during accelerating slip induced by normal stress unloading better than the model dependent only on slip displacement. Slip velocity could enhance the aperture increase on smoother fractures at lower normal stresses and higher slip velocities. Both the dilation factor and characteristic slip distance decrease with increasing normal stress and surface roughness, signifying reduced contribution of slip velocity to transient shear-induced dilatancy at higher normal stresses and surface roughness. The dilation angle increases with the increase of surface roughness, and this increase diminishes at higher normal stresses primarily attributable to more severe asperity wear. These findings highlight the importance of slip velocity in controlling the transient evolution of aperture and permeability of a rock fracture. Our study also provides constraints on the constitutive parameters in the combined aperture model for describing transient shear-induced fracture dilatancy. We suggest that it is crucial to incorporate the velocity-dependent aperture model to simulate the nonlinear evolution of fracture aperture in future analytical and numerical models involving coupled hydromechanical processes in geoenergy systems.

Fault slip behavior and segmentation revealed by geomorphic offset clusters: An example from the middle Riganpei Co fault, central Tibet

High-resolution topographic datasets are useful for revealing offset features of fault geomorphology and are thus important for reconstructing the evolution history of faults. The Riganpei Co fault, located in the central Tibetan Plateau, is an important active fault on the northern boundary of the Bangong-Nujiang suture zone. In this study, WorldView-2 stereo images were used to generate high-resolution topographic data in a 1 km range on both flanks of the middle section of the Riganpei Co fault. We interpreted the tectonic geomorphology along the fault, classified it into distinct units, and measured the horizontal displacement of each unit. Within approximately 70 km along the fault, we obtained 396 displacement measurements ranging from 0 to 60 m. Given the evident uneven distribution of displacement, the fault was divided into four segments. In each fault segment, the reconstructed slip distributions revealed a tendency of larger displacements in the center and smaller displacements toward the ends. The cumulative offset probability distribution (COPD) of displacements displays 4–5 offset clusters in the range of 0–30 m for each segment, suggesting that at least four large earthquakes ruptured this fault. The binned COPD demonstrated that there are differences in the displacement accumulation modes among these fault segments, where the middle segment follows a characteristic slip accumulation mode. Reconstructed cumulative slip profiles revealed a complex pattern of strong earthquake activities along the Riganpei Co fault.

Experimental and nonlinear-analytical studies of cross-laminated-timber concrete composite floors with interface shear resistance enhancement of plate-end

Cross-laminated-timber (CLT)-concrete composite system has drawn more attention as a new technology. This study investigated CLT-concrete composite (CCC) floor with shear resistance enhancement of plate-end experimentally and analytically. In order to obtain the shear performance of coach screw connectors, two groups of push-out tests were carried out. Based on the test results and failure modes, three characteristic slip moduli of the push-out specimen were calculated. Then, three groups of four-point bending tests were conducted to study the flexural behavior of CCC floor with different screw arrangements. One group of bending specimens was designed by shear resistance enhancement of plate-end and showed excellent performance in terms of bending stiffness and bearing capacity. Furthermore, the nonlinear analytical model for calculating the relative slip of composite floor was established, which took into account the stiffness reduction effect of the connectors. Finally, based on the generalized connection system model, the optimized γ-method for calculating effective bending stiffness was proposed, which considered the Interface slip modulus transformation. By comparing with the experiment results, the analytical methods presented in this study could predict interface relative slip and effective bending stiffness of composite floor well, which provided important references for the design of CCC floor.

Prediction of inter-granular crack initiation susceptibility in post irradiated grade 300 steels

Grade 300 austenitic steel components are subjected to irradiation-assisted stress corrosion cracking hazard, in the context of nuclear pressurized water reactor operation. In this paper, it is assumed that inter-granular cracking susceptibility primarily depends on sub grain plasticity mechanisms, controlling the slip band thickness and spacing achieved for a plastic strain level imposed. A computational model evaluating the related grain-boundary stress evolutions is developed and evaluated, using actual post-irradiation observations. In practice, we calculate a quantitative damage susceptibility factor R depending on the characteristic local slip band arrangements and the grain to grain misorientation. The statistical R evolutions obtained are consistent with the strain localization and related intergranular crack susceptibility trends, under corresponding irradiation and deformation conditions.

Development of novel shear connectors for cold-formed steel concrete composite beams

The usage of cold-formed steel members as a primary structural element has increased drastically, paving the way for developing cold-formed steel-concrete composite members. The shear connectors are key elements to provide the composite action between steel and concrete. The research on suitable shear connectors for cold-formed steel-concrete composite members has been widely investigated. This study evaluates the behavior of three novel shear connectors. The proposed shear connectors were anchored without welding, making them suitable for light gauge sections by reducing the formation of residual stresses and geometrical imperfections. The first two shear connectors (trapezoidal and hexagonal) were anchored using self-tapping screws. The third one, the prefabricated shear connector, was incorporated by adopting suitable modifications in the beam without external connecting arrangements. The behaviour of connectors was assessed by conducting push-out tests as per Eurocode 4. The shear capacity, characteristic slip, initial stiffness, load-slip relationship, ductility, and energy absorption capacity of the connectors were analysed and presented. It is observed that the prefabricated shear connector has recorded the highest shear capacity and energy absorbing capacity among the proposed connectors.

Bond Behavior of WAAM Reinforcements in Comparison to Conventional Steel Reinforcements

Additive manufacturing is becoming increasingly important in the construction industry. Wire arc additive manufacturing (WAAM) can be integrated into the selective paste intrusion (SPI) to enable the simultaneous printing of reinforced concrete. The bond behavior of a WAAM reinforcement was investigated with pull-out tests and compared to alternative reinforcement types to analyze the stress transfer between the different components. In the first step, the surface of all the reinforcement types was recorded using a laser-based line scan measuring system. This permits the evaluation of the surface parameters, such as the surface roughness Rq, or the related rib area fR. The WAAM reinforcement showed a bond behavior in the pull-out tests that was comparable to a reinforcing steel bar. Both the bond stresses achieved, and the occurring scatter of the measurement results at the characteristic slip values were almost the same. Even without existing transverse ribs, the WAAM reinforcement reached maximum bond stresses similar to the reinforcing steel. An evaluation of the surface roughness revealed a linear relationship with the maximum bond stress achieved with a logarithmic scaling of Rq. The bond work Wτ, which is a measure of the system stiffness, showed that WAAM reinforcements and reinforcing steel bars have approximately similar behavior.

Coseismic deformation of the 1976Ms 7.3 Chaldiran earthquake in eastern Turkey measured by satellite imagery, in comparison with field measurements

SUMMARYLarge continental earthquakes are infrequent, but they are important for understanding active tectonics. Many pre-1990, magnitude greater than 7 earthquakes have not been well documented due to a lack of data. The declassification of KeyHole (KH) imagery provides opportunities for investigating those historical events. In this study, we present new geodetic observations of surface deformation from the 1976 November 24 Ms 7.3 Chaldiran earthquake in eastern Turkey. We use various historical KH imagery and modern Pleiades stereo imagery to determine the coseismic deformation, providing new constraints on the 1976 rupture. Based on the image measurements, we resolve the coseismic slip at depth. The inverted slip from a simple elastic dislocation model, ∼4.0 m at shallow depth of the Hidirmentes segment, is larger than the surface displacement, around 3 m from previous field surveys, suggesting that the coseismic deformation is a combination of slip on the primary fault with 30 ± 16 per cent off-fault deformation. We also measure cumulative offsets at two sites with well-preserved features, and find a constant ratio of horizontal to vertical offsets throughout the past few earthquake cycles. Both the observed constant slip ratio in this study and offset clusters from previous field measurements support that the Chaldiran fault exhibits a characteristic slip behaviour in the late Quaternary. By combining all the geodetic and geological observations in the broader region, we also present a brief analysis of the slip rate of the Chaldiran fault.

Experimental and Numerical Investigation of the Shear Performance of PSCC Shear Connectors with Poured UHPC

Assembled steel-composite bridges generally use stud connectors to achieve the connection between the deck slab and the steel main girders. However, the commonly-used cluster studs weaken the integrity of the precast deck slabs and are not conducive to reducing the size of the precast deck slabs. Based on the excellent mechanical performance of UHPC, a precast steel-concrete composite bridge system consisting of precast bridge deck slabs, bonding cavities, and steel girders was proposed in this study. The system was named PSCC (Precast Steel-Concrete Connectors). To verify the applicability of PSCC connectors in engineering, push-out tests and finite element analysis were carried out in this paper to investigate the shear performance and influence parameters of PSCC connectors. The results showed that compared with the full bonding at the steel-UHPC interface, the shear bearing capacity of the specimens with 30% debonded area rate (the ratio of defect area to total interface area) and the shear bearing capacity of the specimens with 60% debonded area rate decreased by 0.35% and 9.74%, the elastic stiffness decreased by 14.86% and 21.72%, and the elastic-plastic stiffness decreased by 1.6% and 12.8%, respectively. When the steel-UHPC percentage of debonded area is less than 30%, the shear resistance of PSCC connectors is affected very little. However, when the steel-UHPC percentage of debonded area is 60%, the shear resistance of PSCC connectors is greatly affected. Therefore, adequate filling of the UHPC connection layer should be ensured in the project. In addition, the PSCC connectors have excellent ductility, their characteristic slip value Su is much higher than the EC4 specification of 6 mm, and they have better shear performance than conventionally installed stud connectors. According to the results of the parametric analysis, it was found that the failure mode of the PSCC connectors was shear reinforcement fracture when the area ratio of shear reinforcement to stud was less than 1.55, under the premise of the same material strength. On the contrary, the failure mode of PSCC connections was stud fracture. When the transverse spacing of both studs and shear reinforcement is 4d, the PSCC connectors can maintain a high ultimate load capacity while reducing the amount of UHPC in the bonding cavity. Therefore, 4d was chosen as the best spacing for both studs and shear reinforcement.

Paleoseismology of the Ganos segment; the western extend of the North Anatolian Fault (Turkey)

The Ganos fault that ruptured on 9 August 1912 (Mw: 7.4) is the westernmost inland segment of the North Anatolian fault (NAF). Here, the Ganos fault is bounded at its two tips with offshore faults segments, in the Sea of Marmara to the east and the Gulf of Saros to the west in the North Aegean Trough. Therefore, the paleoseismology of the 45-km-long inland fault is of importance to the seismic hazard analysis related to offshore active faults and in particular for the seismic gap in the Marmara Region. Earlier studies have established an earthquake chronology for the western and eastern inland tips of the Ganos fault. Here, we extend the paleoseismic studies toward the central segment. Three trenches at Yörgüç have revealed evidence for two faulting events, possibly post-1669 CE ±30 years, which can be correlated to the 1659 or 1766, and the 1912 historical earthquakes. At Yeniköy, we determined an offset of 46 ± 1 m and 47 ± 1 m on a stream channel and a ridge-crest, respectively. In two trenches we determined two faulting events for the last 1000 years and seven events for the last 3500 years. In trench T5, the base of the displaced stream channel provides a calibrated date of 829?591 BCE. Using the 46 ± 1 m right-lateral displacement, we calculate a slip rate of 16.9 ± 0.7 mm/year for the last 2732 ± 119 years. A combined analysis with earlier paleoseismic studies on the Ganos fault suggests that the historical earthquakes of 1912, 1766b or 1659, 1354 or 1343a, and 1063 ruptured the entire inland fault section. In such a case, the recurrence interval for this section of the NAF corresponds to 283 ± 81 years. Combining earlier estimations, we suggest an average slip rate of 17.1 ± 0.9 mm/year for the last 2700 years and observe a characteristic slip behavior of 4.5 to 5 m per event for this section of the North Anatolian plate boundary fault.

The evolution of rock friction is more sensitive to slip than elapsed time, even at near-zero slip rates

Nearly all frictional interfaces strengthen as the logarithm of time when sliding at ultra-low speeds. Observations of also logarithmic-in-time growth of interfacial contact area under such conditions have led to constitutive models that assume that this frictional strengthening results from purely time-dependent, and slip-insensitive, contact-area growth. The main laboratory support for such strengthening has traditionally been derived from increases in friction during "load-point hold" experiments, wherein a sliding interface is allowed to gradually self-relax down to subnanometric slip rates. In contrast, following step decreases in the shear loading rate, friction is widely reported to increase over a characteristic slip scale, independent of the magnitude of the slip-rate decrease-a signature of slip-dependent strengthening. To investigate this apparent contradiction, we subjected granite samples to a series of step decreases in shear rate of up to 3.5 orders of magnitude and load-point holds of up to 10,000 s, such that both protocols accessed the phenomenological regime traditionally inferred to demonstrate time-dependent frictional strengthening. When modeling the resultant data, which probe interfacial slip rates ranging from 3 .[Formula: see text]. to less than [Formula: see text], we found that constitutive models where low slip-rate friction evolution mimics log-time contact-area growth require parameters that differ by orders of magnitude across the different experiments. In contrast, an alternative constitutive model, in which friction evolves only with interfacial slip, fits most of the data well with nearly identical parameters. This leads to the surprising conclusion that frictional strengthening is dominantly slip-dependent, even at subnanometric slip rates.

Determination of Slip Factor between CNC-Cut Serrated Surfaces of S355J2 Grade Steel Plates

Structural joint configurations realized with serrated steel surfaces have started to be used in the construction fields to assemble the primary and the secondary structural members of civil engineering structures. The main advantages of these joint configurations rely on their flexibility to accommodate construction tolerances and their slip-resistant load-bearing mechanism against dynamic loading conditions. Therefore, it is important to reliably establish the characteristic value of the friction coefficient or in other words the slip factor between the serrated steel surfaces to design reliable slip-resistant connections. In this study, the characteristic slip factor between the CNC-cut serrated surfaces prepared from S355J2 grade steel plates is determined to investigate the impact of the CNC-cutting procedure on the slip-resistant load-bearing behaviour of steel-to-steel interfaces. Five experimental tests were performed according to EN1090-2, Annex G. The results are presented as the load-slip curves, variation of the bolt pre-tension load level, nominal and actual slip factors for the tested configuration of the CNC-cut serrated steel-to-steel interface.

Extension of Aseismic Slip Propagation Theory to Slow Earthquake Migration

AbstractNatural faults host various types of migrating slow earthquake phenomena, with migration speeds much lower than seismic wave speeds and different moment‐duration scaling from regular earthquakes. To advance the obtained quantitative understanding of the migration process and long duration of slow earthquakes, I study a chain reaction model in a population of brittle asperities based on a rate‐ and state‐dependent friction on a 3‐D subduction plate boundary. Simulation results show that the migration speed is quantitatively related to frictional properties by an analytical relation derived here. By assuming that local pore water in front of the migration drives rapid tremor reversal and is so local as to hold a constant stress drop, the application of the analytical solution to observational results suggests that (a) the temporal changes of observed migration speeds for the rapid tremor reversal could be explained by about 70% reduction of the effective normal stress; (b) effective normal stress for the deeper extension of seismogenic segment in the western part of Shikoku is about 1.5 times greater than that in the central part. Applying rupture time delay between slow earthquake asperities for the duration longer than regular earthquake, I also conclude that (c) the characteristic slip distance of rate‐and‐state friction for low‐frequency earthquakes is roughly between 30 µm and 30 mm; (d) the stress and strength drops of very low‐frequency earthquakes is much smaller than 1 MPa.

Constraining Paleoseismicity of the Wulashan Piedmont Fault on the Northern Margin of the Ordos Block From Fault Scarp Morphology

Fault scarps preserve important information about past earthquakes on a fault, and thus can be applied to investigate the fault slip histories and rupture patterns. In this study, the morphology of fault scarps was used to constrain the paleoseismicity of the Wulashan Piedmont Fault located on the northern margin of the Ordos Block based on high-resolution LiDAR topography. We constructed the vertical displacement distribution of the fault through measuring the heights of a large number of scarp profiles extracted on different geomorphic surfaces along the fault. Through statistical analysis of the dense collection of vertical displacement dataset, a total of seven paleoseismic events were identified which followed a characteristic slip pattern with an average slip of ∼1.0 m. We further detected slope breaks in the fault scarp morphology to quantify the number of paleoearthquakes that occurred on the scarps, and discriminated at least five individual surface-breaking events. Both the number and slip of paleoearthquakes recognized from the morphology of fault scarps were in good agreement with previous paleoseismic trenching records. Based on the empirical scaling relationship between moment magnitude and rupture parameters, a moment magnitude ofMw6.7–7.5 was determined for the paleoearthquakes occurred on the fault. With the fault slip rate derived by previous studies, we estimated an average recurrence interval of 1.3–1.8 kyr for the paleoseismic events, which is very close to the elapsed time since the most recent earthquake, indicating a high potential seismic hazard on the Wulashan Piedmont Fault.

Are Low‐Frequency Earthquake Moments Area‐ or Slip‐Limited? A Rock Record Examination

AbstractThe seismic moments observed for low‐frequency earthquakes (LFEs) vary over multiple orders of magnitude, even where the LFEs occur within families of similar events. Although this variability is typically interpreted to record a scale‐limited process at the LFE source, neither the slip per LFE nor the rupture area can be determined from seismological constraints. Here, we examine incrementally developed slickenfibers that have been proposed to record LFEs in exhumed subduction zones. These structures form through repeated, micron‐scale slip events across dilational irregularities in the fault plane, which are punctuated by cementation and sealing in the interstitial space. By statistically analyzing the geometry of inclusion trails delineating slip‐parallel mineral‐growth increments, we constrain the variability in slip per inferred LFE and test end‐member hypotheses regarding the controls on LFE moments. We find that that the slickenfibers exhibit characteristic slip increments, favoring a “slip‐limited” model that requires large variability in LFE rupture areas.

Superior strength-ductility synergy of layered aluminum under uniaxial tensile loading: The roles of local stress state and local strain state

A typical layered Al composed of alternating fine-grained layers (FLs) and coarse-grained layers (CLs), fabricated by hot pressing and hot rolling, exhibits a superior strength-ductility synergy under uniaxial tensile loading compared with monolithic Al. The mechanism behind the excellent mechanical properties was elucidated from the perspective of local stress state and local strain state. We found that the operative slip systems of CLs cannot be predicted by the classical Schmid factor, indicating a complex local stress state differing from global uniaxial tension. The so-called local multiaxial stress state, probably caused by the deformation incompatibility between constituent layers, was then proposed, and proved feasible for predicting the slip systems in CLs. On the other hand, the digital image correlation revealed that the strong strain partitioning leads to the transformation of local strain state on CLs from uniaxial to biaxial stretch despite under uniaxial tensile loading. Such the local strain state was incorporated into the Taylor ambiguity method, which can derive magnitudes of operative slip systems in the CLs grains with different orientations. The Taylor ambiguity results agreed well with the multiple microbands formation revealed by the quasi in-situ electron backscatter diffraction coupled with a novel misorientation mapping approach. The characteristic slip system activation and dislocation microbands governed by the local stress state and local strain state imply more latent hardening, hence enhancing the strain hardening capability of layered Al. Our work provides a new direction to achieve a superior strength-ductility synergy by designing local stress/strain and tailoring corresponding deformation mechanisms.

Block Tectonics Across Western Tibet and Multi‐Millennial Recurrence of Great Earthquakes on the Karakax Fault

AbstractFault slip rates are critical to quantify continental deformation. Those along the Karakax fault (northwestern Altyn Tagh Fault: ATF) have been debated, even though it is one of Tibet's most outstanding active faults. At Taersa, using LiDAR measurements of terrace and fan riser offsets (∼6 to ∼500 m) and10Be/26Al dating of alluvial surfaces (<210 ka), we obtain a late Quaternary slip rate of ∼2.5 ± 0.5 mm/yr. This doubles the ∼2.6 ± 0.5 mm/yr rate time span found to the east and west. We interpret the ∼150 km‐long, free‐faced rupture along the fault to be that of theM∼ 7.6 event felt in Hotan in 1882. Characteristic slip (∼6 m) during four large earthquakes since ∼10 ka implies a ∼2500 ± 500 years return time. A ∼3 mm/yr rate is consistent with the ∼80 km offset of the Karakax river since uplift of the West Kunlun range and sediment deposition in the Tarim foreland accelerated, ∼24 Ma ago. The faster slip rate (∼10.5 mm/yr) on the central ATF matches the sum of those along the reactivated West Tibetan terrane boundaries (Karakax and Longmu‐Gozha Co faults) at the Uzatagh triple junction (∼36°N, 83°E). The abrupt termination and altitude drop of the Karakorum range where the Longmu Co and Karakorum faults meet (Angmong junction), also reflect triple junction kinematics. Such localized changes account for the rise of the Karakorum and West Kunlun ranges and support lithospheric block tectonics rather than diffusely distributed deformation.