Current Stress State Research Articles

Assessment of the Brittle–Ductile State of Major Injection and Confining Formations in the Alberta Basin

Subsurface interaction between critically stressed seismogenic faults and anthropogenic fluid injection activities has caused several earthquakes of concern over the last decade. Proactive detection of the reverse and strike-slip faults inherent in the Alberta Basin is difficult, while identification of faults likely to become seismogenic is even more challenging. We present a conceptual framework to evaluate the seismogenic potential of undetected faults, within the stratigraphic sequence of interest, during the site-selection stage of fluid injection projects. This method uses the geomechanical properties of formations present at sites of interest and their current state of stress to evaluate whether hosted faults are likely to be brittle or ductile since the hazard posed by faults in brittle-state formations is generally significantly higher than that of faults in ductile-state formations. We used data from approximately 3100 multi-stress triaxial tests to calculate the Mogi brittle–ductile state line for 51 major injection and confining formations in the Alberta Basin and in situ stress and pore pressure data from approximately 1200 diagnostic fracture-injection tests to assess the last-known brittle–ductile state of each formation. Analysis of these data shows that the major injection formations assessed in the Alberta Basin were in a ductile state, with some confining (caprock) formations in a brittle state at the time of the stress measurements. Once current site-specific in situ stress data are available, our method enables site-specific assessment of the current brittle–ductile state of geologic formations within the zone of influence of large-volume fluid-injection projects and an evaluation of the associated potential for fault seismogenesis.

Evaluation methods for surface compression stress measurements with unknown principle stress directions

The birefringent properties of glass can be well utilized for non-destructive testing of thermally tempered glass. The surface compression stress as well as the compression zone depth of thermally tempered glass is commonly measured with a scattered light polariscope. The measurement with scattered light polariscope provides information about stresses acting perpendicular to the measurement direction. Therefore, the measurement depends on the direction. In order to make a statement about the rough level of the prestress, a measurement in one direction can be sufficient, assuming an isotropic stress state and a relatively homogeneous distribution of the surface compression stress. However, in order to be able to make a more detailed statement about a non-isotropic stress state, measurements in up to four directions are necessary. Information about the direction of principal stresses and differences of principal stresses can then be evaluated. In the present work, it is investigated which deviations can be expected by measurements performed in only one direction or by measurements using up to four directions. For this purpose, five methods are introduced, which deviate in the assumptions made for the current stress state. The methods are compared using measurements on thermally tempered glass in a four-point bending test and on thermally tempered glass specimens without any external load.

The Virtual Fields Method to Indirectly Train Artificial Neural Networks for Implicit Constitutive Modelling

Artificial Neural Networks (ANNs) have the potential to provide a different approach to constitutive modelling, with the main advantage that these do not require to postulate a mathematical formulation or identify empirical parameters. Currently, the training of an ANN for implicit constitutive modelling mostly relies on paired data, usually stress-strain however, stress cannot be directly measured in a real experiment. As such, the training should be carried out indirectly using measurable variables from the experimental setting, such as displacements and the applied force. In the current work, displacements and global force data are used to indirectly train an ANN to predict the stress state of a material. An experimental test is recreated numerically in order to obtain displacement and global force data for different load distributions, i.e. obtaining synthetic data using a virtual experiment. The strain from the current and previous time increments are obtained from the corresponding displacements and used as inputs for the ANN to predict the current state of stress. Training is carried out without stress labels to compute the loss. Instead, the local and global equilibrium conditions, corresponding to the application of the Virtual Fields Method (VFM) to the physical model, are employed to compute the loss and update the network parameters, until the predicted stress state is accurate.

Analysis of the inherent adaptability of basic truss and frame modules by means of an extended method of influence matrices

New approaches and technologies are needed to counter the effects of climate change and mitigate the depletion of material resources. A possible solution are adaptive load-bearing structures, i.e., structures that are equipped with sensors, actuators and control units, enabling the structure to optimise its current stress state. This requires new research regarding the overall structural design of material- and emission-efficient adaptive structures. Existing approaches employ sensitivity matrices or optimality criteria in optimization formulations to design adaptive load bearing structures and discuss the quality of the design based on the results. This paper presents the method of actuation influence matrices, which are a type of sensitivity matrix that can be used quantify the inherent adaptability of a structure. The aim is to develop an intuitive design method for adaptive structures. After a brief derivation of the influence matrices, the methodology is illustrated using three basic bracing systems – a truss, a frame and a diagonally braced frame – as example, demonstrating the relationship between structural topology and inherent adaptability. While the assessment of an adaptive structure’s quality depends on the specific use case and control objective, it is proposed that truss systems are good candidates for adaptive structures due to their inherent adaptability.

A dynamic bounding surface plasticity damage model for rocks subjected to high strain rates and confinements

A dynamic bounding surface plasticity damage model is developed for rocks with the consideration of high strain rates and confinements. This is achieved through adopting the strength surface of Holmquist-Johnson-Cook (HJC model)/ Johnson-Holmquist-ceramic (JH2 model) model as bounding surface, and employing the critical state concept for brittle-ductile transition. In addition, a simple continuum damage evolution law is taken for strength degradation and a simple vertical mapping rule is adopted to link current stress state with its corresponding strength state. A series of hardening rules that account for both plasticity and strain rate, and damage evolution law, etc., are proposed within the framework of consistent condition of dynamic model. A ‘S’ shape dynamic increase factor (DIF) function is adopted to consider the strain-rate effect of dynamic loadings, which aims to adjust the size of bounding surface with the consideration of radial enhancement. The proposed model is validated through modeling conventional triaxial compression tests under different confining pressures, dynamic triaxial tests, and Split Hopkinson Pressure Bar (SHPB) tests with various strain rates. Good agreement between modeling results and experimental data indicates that dynamic characteristics of rock, including rate and confinements dependency, are captured well by the proposed model. The proposed model is then implemented into a commercial software, GDEM, to simulate the stress wave propagation problem. Simulation results by the proposed model and two benchmark models are compared, which further validate the capability and applied potential of the proposed model.

A simple stress correction method for explicit integration algorithm of elastoplastic constitutive models and its application to advanced anisotropic S-CLAY1 model

The stress correction, which prevents stresses drifting from the yield surface, is a key step in the explicit scheme for integrating elastoplastic constitutive models in finite element analyses. In this paper, a simple, robust, and efficient stress correction method is proposed for improving the well-established explicit modified Euler scheme of Sloan et al. (2001). The method subtly proposes a single correction coefficient assuming that the stress components are proportional to the corrected stress components on the yield surface. The expression of the correction coefficient can be explicitly determined with the current stress state and the yield function, which allows the correction procedure to be easily and conveniently accomplished through multiplying the stress components by a single coefficient without resorting to the Newton iteration algorithm. The proposed method is applied to develop a user defined material (UMAT) subroutine for the advanced anisotropic elastoplastic model S-CLAY1 (Wheeler et al. 2003), which is subsequently used to simulate triaxial tests, the collapse of a rigid smooth square footing and a natural ground under embankment loading. The comparisons with other stress correction methods, the exact results from MATLAB, and the field measured values demonstrate the stability, robust, efficiency and validity of the proposed method.

Spatial orientations of hydraulically conductive shear natural fractures for an arbitrary stress state: An analytical study of governing geomechanical factors

Hydraulic conductivity of natural shear fractures is considered with regard to the current stress state of fractured rocks. The paper focuses on spatial orientations of hydraulically conductive shear fractures existing in naturally fractured fluid saturated rocks. The concept of critically stressed fractures is used for the analysis. The paper presents an algorithm and analytical solution that can be used to obtain all possible spatial orientations of critically stressed fractures for an arbitrary stress tensor. The proposed solution is explicit, providing functionality to predict the spatial orientations of hydraulically conductive fractures for rocks subjected to arbitrary stresses. The results obtained from the presented methodology can be directly used to deal with results of geomechanical modeling of naturally fractured reservoirs development. Several analyses of applying the obtained solution in practice are presented in the paper: spatial orientations of critically stressed fractures are obtained for cases of different gradual changes in stress tensor components under specific conditions, providing an understanding of the main tendencies in these spatial orientations. According to the obtained results, spatial orientations of critically stressed fractures tend to be related to directions of principal stresses, while magnitudes of principal stresses govern the shapes of zones containing poles to critically stressed fractures at stereonets. The influence of the following major geomechanical factors standing for hydraulic conductivity of natural fractures is studied: magnitudes and directions of principal stresses, friction coefficient of rock. Stereonets are used to visualize the changes in spatial orientations of hydraulically conductive fractures, caused by alteration of stress state of the rock.

Home Working Stress in the COVID-19 Crisis Era: HRM's Response From Job Support, Work-Family Balance, and Psychological Relief.

This article explores the workplace stresses faced by home working (HW) employees in the COVID-19 outbreak; what strategies human resource manager (HRM) may deal with the present circumstances. We refer to the views and perceptions of HRM and review the current state of stress faced by home-based workers and their responses through the lens of HRM. (1) The types as eustress, acute stress, and chronic stress and the stressors as work, family, and psychological were analyzed. (2) HW brought more adverse effects caused by work-related stress than benefits. (3) HRM can provide stress mitigation from job support, work-family balance, and psychological relief. By focusing on those employees who are most vulnerable to pandemic fatigue and work-related stress, HRM can build better organizations for all employees. HRM practices may consider measures related to job itself, family, or psychology to reduce the stress of HW under the COVID-19 crisis.

Tay creep: a multi-mechanism model for rate-dependent deformation of soils

Constitutive models constructed within the combined framework of kinematic hardening and bounding surface plasticity have proved to be successful in describing the rate-independent deformation of soils under non-monotonic histories of stress or strain. Most soils show some rate-dependence of their deformation characteristics, and it is important for the constitutive models to be able to reproduce rate- or time-dependent patterns of response. This paper explores a constitutive modelling approach that combines multiple viscoplastic mechanisms contributing to the overall rate-sensitive deformation of a soil. A simple viscoplastic extension of an inviscid kinematic hardening model incorporates two viscoplastic mechanisms applying an overstress formulation to a ‘consolidation surface’ and a ‘recent stress history surface’. Depending on the current stress state and the relative ‘strength’ of the two mechanisms, the viscoplastic mechanisms may collaborate or compete with each other. This modelling approach is shown to be able to reproduce many observed patterns of rate-dependent response of soils.

The SpannEnD project: 3-D stress prediction in the upper crust of Germany

Abstract. Assessment of the stability of deep geological repositories is a key task in the site selection process for high-level radioactive waste. Geomechanical stability is affected by endogenous and exogenous processes as well as by geotechnical operations. Stability prediction requires both an estimate of future stress changes as well as the initial, i.e. current stress state. However, data records on the current stress state in the upper crust are incomplete, sparse and spatially unevenly distributed. Therefore, geomechanical-numerical models are the only way to estimate the full stress tensor at locations where stress observations are not available. The main components of such a 3-D geomechanical model are the distribution of the elastic rock properties and rock density as well as stress data for the model calibration. The aim is to find the optimal initial and boundary conditions that result in a best-fit with respect to available stress data within the model volume. For this reason, the first open access database for stress magnitude data has been developed as an extension of the existing database on stress orientation data (world-stress-map.org). The new database contains 568 data records from Germany and surrounding areas, but only 15 % of these data records are of acceptable quality. Thus, only one reliable set of stress magnitude data is available for an area of 100×100 km2. Based on existing compilations of the crustal structure in and around Germany, data were merged into one model with the aim of estimating the 3-D stress state in Germany. Geomechanical models for stress estimation in Germany were created with varying geometrical and mechanical resolution. While the first model consists of four mechanical units and 1.3 million finite elements, the subsequent model consists of 12 units and 3.6 million finite elements. The results of the best-fit model with respect to the stress data reveal that there are regional differences when calculating the fracture potential, i.e. the distance to failure of intact rock as well as different values of slip tendency, which provides a measure of the reactivation potential of pre-existing faults. The observed variability of the modelled stress field can be used as a first-order assessment. Since model uncertainties are still high, the absolute values are not yet reliable. However, the model can be used to derive consistent initial and boundary conditions for models on a regional scale. Furthermore, it makes it possible to investigate the influence of the large-scale crustal structure on the overall stress pattern. The modelling workflow is set-up in a way that new information and higher resolution if needed can be implemented when more data are provided. This will improve the reliability of both, the model prediction on the large scale as well as the initial and boundary conditions for high-resolution regional models for selected areas during the site selection process.

An Open-Access Stress Magnitude Database for Germany

Abstract. The stress field in the Earth's crust plays a central role in the site-selection process for a deep geological repository for high-level nuclear waste. Site selection and construction planning must take into account several factors that are influenced by the stress state. These include the excavation damage zone, the hydraulic permeability of the host rock, the self-sealing capacity, the effects of seismic events and the possible reactivation of faults as migration pathways for fluids and radionuclides. Likewise, the initial stress state is of central importance for the long-term studies to prove site safety over 1 Ma. To obtain a continuous description of the current 3D stress state, 3D geomechanical numerical models are used. These models have to be calibrated with data on stress magnitudes to obtain robust predictions. One of the central goals of the SpannEnD project (Spannungsmodell Endlagerung Deutschland, http://www.spannend-projekt.de, last access: 31 October 2021) was to build the first comprehensive and publicly accessible stress magnitude database for Germany, including a quality ranking of the data compiled from different methods. This database is the logical extension of the database of the World Stress Map project, in which so far only information on stress orientations and the stress regime has been compiled systematically. We present this first compilation of stress magnitude data published and made available by Morawietz et al. (2020). The stress data density is generally low and heterogeneous, so that a model calibration at the scale of a site model is not possible. Therefore, the main objective of the SpannEnD project is to develop a 3D geomechanical numerical model for the whole of Germany. The resulting 3D stress field will provide the basis for regional and local models in a later phase of the site selection process. Details on this are presented in three complementary contributions in this symposium by Reiter et al., Röckel et al. and Ahlers et al. The new Geology Data Act (Geologie-Datengesetz) now allows access to considerably more data, which will be incorporated into an update of the database after assessment according to the defined quality criteria. This database extension will improve the reliability of the predictions of the geomechanical models on different spatial scales.

Some Aspects of the Current State of Prenatal Stress and the Role of Oxidative Stress in the Realization of Its Consequences

Some Aspects of the Current State of Prenatal Stress and the Role of Oxidative Stress in the Realization of Its Consequences

Numerical modelling of the stress in the Pamir-Hindu Kush region

The current stress state of the Earth's crust in Central Asia depends entirely on the interaction of the Eurasian plate with the Indian and Arabian plates. Moreover, an essential role in this action is played by the subduction process in the Pamir-Hind Kush zone. In this region, deep earthquakes and anomalies in seismic velocities indicate subduction of the Indian Plate. To determine the effect of earthquakes on the stress state of the Earth's crust in Central Asia, we analyzed the hypocenters according to the available data over a hundred years. Taking the envelope of the hypocenters as the surface of the subducted indenter, we analyzed its penetration into the mantle. Instead of the pushing force of the indenter, the velocity of the Indian plate is taken into consideration. A model of the stresses is constructed on the equations of creeping motion of a viscous incompressible fluid. The stress variation in the Earth's crust and mantle was calculated as the stress difference before and after the earthquake. The mechanism of earthquakes is modelled by an introduction of equivalent volume forces in the equilibrium equations corresponding to a couple dipoles without a moment. The equations of creeping motion are numerically solved using boundary element methods. Numerical experiments with different physical model parameters for the Earth's crust and mantle were conducted. To introduce the negative buoyancy of the subducting plate, partial eclogitization of the rocks in the collision zone was assumed. As a result, a certain combination of stiffness and density was determined for the lithosphere and mantle, which explained the peculiarities of this region. The influence of crustal and mantle earthquakes in the Pamir-Hindu Kush region on the change in background stresses in Central Asia was analyzed which are not higher than 2–3%.

Heat Stress and Kidney Function in Farmworkers in the US: A Scoping Review

ABSTRACT Chronic kidney disease of unknown etiology (CKDu) has been well described in farmworkers in Latin America. Agricultural workers in the United States (US) are exposed to similar hot and humid working conditions, but CKDu in the US is under-described. This review aims to better understand the current literature describing the connection between heat stress and kidney function in farmworkers in the United States. Utilizing a scoping review methodology, we searched CINAHL, Embase, PubMed, and Web of Science databases to better understand the current state of the heat stress and kidney function research in farmworkers within the United States. In this review, 229 pieces of literature were screened. Ultimately, 4 articles were chosen to be included in the scoping review. Common themes within the articles were variations in study protocol lengths and type of heat stress measurement. Additionally, the majority of the work completed was quantitative to date, with only one study providing a critical social lens for analysis of CKDu in the United States. We found evidence that more work is needed within the US to understand the relationship between working in the heat and kidney function in agricultural and other workers who experience high heat conditions at work and are susceptible to the deleterious effects of working in said conditions.

Symptomatic discretization of small earthquake clusters reveals seismic coupling to 2017 Bodrum earthquake (Mw 6.6) in the Gulf of Gökova (SW corner of Turkey): Viscous-compliant seismogenesis over back-arc setting

In this study, the small relocated “same and/or similar size events” repeated in each observed cluster are deduced from temporal and spatial statistics of microseismicity. Microseismicity not exceeding Mw 5.0 that occurred in the years from 2010 to 2014 and were recorded by the network of the Turkish General Directorate of Disaster Affairs were investigated. In the Gulf of Gökova (SW corner of Turkey), the November 26, 2012 Bozburun mainshock (Mw 4.8) was evaluated with its small events, together with its accompanying aftershock sequences that occurred in three discrete areas (Bozburun, Ula, Bodrum) of the gulf: the May 16, 2013 Ula aftershock (Mw 4.6), the March 25, 2014 Bozburun aftershock (Mw 4.0), and the May 1, 2014 Bodrum aftershock (Mw 4.0). Statistical analysis was accomplished by subdividing temporal distribution of microseismicity and resorting to a number of temporal clusters that allowed the mainshock-aftershock sequence to be placed into subgroups, and thus resulted in five clusters of various sizes linked to spatial clusters. The successive occurrence and clustering of small events into distinct discrete domains in time and space allowed reliable constraints on the stress state of the study area and suggested an interaction of the clusters. The interacting clusters offered an opportunity to evaluate the seismic coupling to 2017 Bodrum earthquake (Mw 6.6) in the study area. Our portrayal of the clusters inferred from small relocated events provide an important contribution to Bozburun, Ula and Bodrum: (1) a symptomatic discretization that is “peaked-like statistical behaviors” of clusters of small relocated events through time and space is an anomalously conspicuous feature, (2) this feature proposes a process of the inevitable interaction and triggering of the discrete clusters, indicating transient acceleration of aseismic slip on surrounding, uncoupled sections of the study area, and (3) this process reveals an evidence of the viscous-compliant seismicity as a principal objective of the cluster interaction, and hence a matter of seismic coupling scenario of the clusters to 2017 Bodrum earthquake (Mw 6.6) in the study area. These conclusions highlight the importance of the seismic-aseismic slip partitioning, arresting and balancing in the co-seismic source regions of the seismically active extensional grabens in driving the large earthquakes near the future and the viscous-compliant seismogenesis over back-arc setting of the Gulf of Gökova that provides an opportunity to understand the seismic coupling processes and the current stress state of the study area. This study implicates for the extensional back-arc graben basins in the Aegean region and WSW-Turkey that require a knowledge of the linkage between upper mantle flow processes and shallow, thin crustal dynamics in the region.

Particle breakage evolution of coral sand using triaxial compression tests

Particle breakage continuously changes the grading of granular materials and has a significant effect on their mechanical behaviors. Revealing the evolution pattern of particle breakage is valuable for development and validation of constitutive models for crushable materials. A series of parallel triaxial compression tests along the same loading paths but stopped at different axial strains were conducted on two coral sands with different particle sizes under drained and undrained conditions. The tested specimens were carefully sieved to investigate the intermediate accumulation of particle breakage during the loading process. The test results showed that under both drained and undrained conditions, particle breakage increases continuously with increasing axial strain but exhibits different accumulating patterns, and higher confining pressures lead to greater particle breakage. Based on the test results, the correlations between particle breakage and the stress state as well as the input energy were examined. The results demonstrated that either the stress state or input energy alone is inadequate for describing the intermediate process of particle breakage evolution. Then, based on experimental observation, a path-dependent model was proposed for particle breakage evolution, which was formulated in an incremental form and reasonably considers the effects of the past breakage history and current stress state on the breakage rate. The path-dependent model successfully reproduced the development of particle breakage during undrained triaxial compression using the parameters calibrated from the drained tests, preliminarily demonstrating its effectiveness for different stress paths.

A Geomechanical Evaluation of Fault Reactivation Using Analytical Methods and Numerical Simulation

One of the main problems related to mature oilfields is the decreased pore pressure due to hydrocarbon production. Therefore, to maintain the production rate of a reservoir, the lost pressure must be compensated. A very traditional method to increase the pressure is to inject natural gas into the reservoir. This technique is widely used in SW Iranian reservoirs because of the readily available supply of this type of gas. Reactivation of pre-existing faults and inducing new fractures into the reservoir and cap rock are some of the potential risks regarding gas injection. In this article, using data such as well logs, pore pressure estimates, and rock mechanical test results, the geomechanical simulation of the Asmari reservoir in the Gachsaran oilfield, SW Iran has been carried out. For this purpose, the current stress field was determined using elastic moduli of reservoir rocks and formation integrity test (FIT) results. Then, by applying analytical methods such as Mohr diagrams and slip tendency, the reactivation possibility of four faults in the field was analyzed, and the maximum sustainable pore pressures were estimated. In the next step, numerical simulations were conducted using ABAQUS software to investigate the injected gas flow path, leakage potential through the cap rock, possible fault reactivation due to gas injection, and shear stress build-up and plastic strain development in different parts of the reservoir. Results of Mohr diagrams and slip tendency showed that all the faults are stable in the current stress state, and fault F2 has the potential to sustain a maximum pore pressure of 55 MPa in the field. On the other hand, fault F3 has the proper conditions (i.e., strike and dip referring to σHmax orientation) for reactivation. Results of numerical simulations suggested that an injection pressure of 30 MPa would not induce any new fracture or fault slip within 5 years of injection. In this period, the injected gas plume moves upward through the damage zone and reaches the shallower parts of the cap rock. It was also shown that by applying an injection pressure of 60 MPa, slip would occur on fault F4 after 10 days of injection.

Stress State of Uzbekistan’s Seismically Active Areas

The current stress state of the Earth’s crust in the territory of Uzbekistan was studied by cataclastic analysis of displacements along fault sets for the collected catalog of earthquake focal mechanisms (EFM), compiled from the data of different authors. Two stages of stress field reconstruction are implemented at different levels of area detail of averaging parameters and for different magnitude hierarchies of the analyzed earthquakes. Azimuths and dip angles of principal stresses axes, Lode–Nadai coefficient values, geodynamic type of stress state, relative (normalized to the cohesion strength of the rock massif) normalized values of the maximum shear stress and effective pressure are determined for different areas of the studied territory. As a result of natural stress reconstructions based on the focal mechanisms of earthquakes with magnitudes M ≤ 4.5 and M ≥ 5, differences in the parameters of the stressed state were revealed. It has been suggested that the hierarchy of magnitude levels of the considered earthquakes reflects the stressed state of various deep layers of the crust. It is shown that strong earthquakes gravitate to zones of reduced effective pressure. On this basis, segments of active faults have been identified in the territory of eastern Uzbekistan, which are considered zones of potentially increased seismic hazard.

Anelastic strain recovery in situ stress measurement method and its application prospect in underground mines

Current stress state data are important in underground mine construction, analysis the of tunnel stability, the forecasting of coal and gas rock bursts in underground mines. At present, the hollow inclusion gauge is primarily used for in situ stress measurement in underground mines. However, the sensors of these gauges often fail to fully adhere to the borehole wall, which can reduce the reliability of the measurement results. In this study, the anelastic strain recovery (ASR) in situ stress measurement method based on oriented cores is introduced. The effectiveness of this technique is analyzed by comparing the test results with those obtained by the hydraulic fracturing method. In addition, the reliability of the ASR method is evaluated by repeatability testing. The ASR results indicate a horizontal minimum principal stress error of less than 10% compared with those obtained by the hydraulic fracturing method. The repeatability test results show good consistency in the in situ stress measurement results of two back-to-back test samples. The ASR method is a safe and highly efficient technique that is not limited by the depth and measurement environment. Therefore, it is expected to have broad application for underground mine in situ stress measurement.

Imaging the Tectonic Grain of the Northern Cordillera Orogen Using Transportable Array Receiver Functions

AbstractAzimuthal variations in receiver function conversions can image lithospheric structural contrasts and anisotropic fabrics that together compose tectonic grain. We apply this method to data from EarthScope Transportable Array in Alaska and additional stations across the northern Cordillera. The best-resolved quantities are the strike and depth of dipping fabric contrasts or interfaces. We find a strong geographic gradient in such anomalies, with large amplitudes extending inboard from the present-day subduction margin, the Aleutian arc, and an influence of flat-slab subduction of the Yakutat microplate north of the Denali fault. An east–west band across interior Alaska shows low-amplitude crustal anomalies. Anomaly amplitudes correlate with structural intensity (density of aligned geological elements), but are the highest in areas of strong Cenozoic deformation, raising the question of an influence of current stress state. Imaged subsurface strikes show alignment with surface structures. We see concentric strikes around arc volcanoes implying dipping magmatic structures and fabric into the middle crust. Regions with present-day weaker deformation show lower anomaly amplitudes but structurally aligned strikes, suggesting pre-Cenozoic fabrics may have been overprinted or otherwise modified. We observe general coherence of the signal across the brittle-plastic transition. Imaged crustal fabrics are aligned with major faults and shear zones, whereas intrafault blocks show imaged strikes both parallel to and at high angles to major block-bounding faults. High-angle strikes are subparallel to neotectonic deformation, seismicity, fault lineaments, and prominent metallogenic belts, possibly due to overprinting and/or co-evolution with fault-parallel fabrics. We suggest that the underlying tectonic grain in the northern Cordillera is broadly distributed rather than strongly localized. Receiver functions thus reveal key information about the nature and continuity of tectonic fabrics at depth and can provide unique insights into the deformation history and distribution of regional strain in complex orogenic belts.