Stress Field Research Articles

Permeability Enhancement Induced by Fracture Shear Dilation During Close-Range Coal Seam Mining

The advance of the working face in coal seams alters the local stress field and may give rise to fractures in the vicinity of the excavation. In this study, a constitutive model in which damage is defined as a function of volumetric strain was established and utilized in a numerical model to prognosticate the fracture development around the excavation. The predicted fractures that emerged in the overlying rock mass were found to exhibit hybrid characteristics. A permeability model was also constructed, taking into account both tension- and shear-induced fracture development. The permeability increase of the upper adjacent coal seam is most notable within 40 m from the goaf boundary. As the working face progresses, the permeability of the upper adjacent coal seam is further enhanced while that of the lower adjacent coal seam remains unaffected. The permeability at the goaf boundary is high and reaches its maximum at the rear of the working face, indicating that for the permeability change, the effect of shear-induced dilation plays a more crucial role than that of pressure-dependent compaction. This study can be used to guide the design of coal seam methane drainage for the mining of closely spaced coal seams.

Benchmarking numerical simulation of induced fault slip with semi-analytical solutions

AbstractPore pressure fluctuation in subsurface reservoirs and its resulting mechanical response can cause fault reactivation. Numerical simulation of such induced seismicity is important to develop reliable seismic hazard and risk assessments. However, modeling of fault reactivation is quite challenging, especially in the case of displaced faults, i.e., faults with non-zero offset. In this paper, we perform a systematic benchmarking study to validate two recently developed numerical methods for fault slip simulation. Reference solutions are based on a semi-analytical approach that makes use of inclusion theory and Cauchy-type singular integral equations. The two numerical methods both use finite volume discretizations, but they employ different approaches to represent faults. One of them uses a conformal discrete fault model (DFM) while the other employs an embedded (non-conformal) fault model. The semi-analytical test cases cover a vertical frictionless fault, and inclined displaced faults with constant friction and slip-weakening friction. It was found that both numerical methods accurately represent pre-slip stress fields caused by pore pressure changes. Moreover, they also successfully cope with a vertical frictionless fault. However, for the case with an inclined displaced fault with a constant friction coefficient, the embedded method can not converge for the post-slip phase, whereas the DFM successfully coped with both constant and slip-weakening friction coefficients. In its current implementation, the DFM is therefore the model of choice when accurate simulation of local faulted systems is required.

Stress Field and Crack Pattern Interpretation by Deep Learning in a 2D Solid

ABSTRACTA nonlinear variational auto‐encoder (NLVAE) is developed to reconstruct the plane strain stress field in a solid with embedded cracks subjected to uniaxial tension, uniaxial compression, and shear loading paths. Latent features are sampled from a skew‐normal distribution, which allows encoding marked variations of the features of the stress field across the load steps. The NLVAE is trained and tested based upon stress maps generated with the finite element method (FEM) with cohesive zone elements (CZEs). The NLVAE successfully captures stress concentrations that develop across the loading steps as a result of crack propagation, especially when enhanced disentanglement is emphasized during training. Some latent variables consistently emerge as significant across various microstructure descriptors and loading paths. Correlations observed between the evolution of fabric descriptors and that of their significant stress latent features indicate that the NLVAE can capture important microstructure transitions during the loading process. Crack connectivity, crack eccentricity, and the distribution of zones of highly connected opened cracks versus zones with no cracks are the fabric descriptors that best explain the sequences of latent features that are the most important for the reconstruction of the stress field. Notably, the distributional shape, tail behavior, and symmetry of microstructure descriptor distributions have more influence on the stress field than basic measures of central tendency and spread.

Extension of a 3D Geological Entity Modeling Method for Discontinuous Deformation Analysis

AbstractWith the development of 3D discontinuous deformation analysis (DDA) in precise stress fields and crack propagation problems, it has also demonstrated outstanding capabilities in solving continuous–discontinuous problems. However, currently, 3D DDA modeling primarily focuses on generating rock joint networks and developing 3D cutting algorithms. Correspondingly, 3D geological modeling methods are not yet mature, and establishing 3D models often demands substantial time. The lack of supporting preprocessing modeling methods and corresponding visual operation interfaces significantly hampers the development of 3D DDA. This method builds upon advanced research achievements in unmanned aerial vehicle oblique photography, 3D reconstruction, 3D cutting, computer graphics, and visualization program design. This research establishes a 3D geological entity modeling method for 3D DDA and constructs a comprehensive program using relevant C++ libraries and C language interfaces. In this method, a 3D geological model that incorporates geological elements such as strata and faults is initially established using non‐uniform rational B‐splines (NURBSs) surfaces as the boundary of the solid model. Subsequently, finite element meshing is applied, followed by corresponding topology transformation, resulting in a 3D block system model suitable for 3D DDA calculation. To cater for diverse application scenarios, continuous–discontinuous models integrated with subblocks and models of arbitrary polyhedra can be established. The proposed method has been validated through several typical modeling examples, showing its ability to rapidly and generate 3D high‐precision geological reality models suitable for 3D DDA calculations. Additionally, some techniques used in this method can be extended for modeling other numerical simulation methods, warranting further research.

Statistical and source characterization of the 2023 Kahramanmaraş Türkiye earthquake sequence

AbstractWe studied seismic features of the 2023 Kahramanmaraş Türkiye earthquake sequence by analyzing the spatiotemporal behavior of the b- and -p values and source characteristics of the mainshocks. We complemented our study by determining the regional stress field. The b-values in the region varied from 0.45 to 1.15. We observed a slight b-value decrease (Δb≈0.2) months before the two mainshocks. Our results exhibited complex b-value patterns on the fault planes and regular aftershock productivity rates (1.14 < p < 1.25). We compare static stress drop estimates derived from effective fault dimensions to those of finite-fault dimensions. Total effective stress drops (the sum of the stress drops of all fault segments) for the earthquake doublet were almost identical (~ 2.05 MPa), while those from finite-fault dimensions are somewhat lower (0.35 and 0.96 MPa). Based on a complete stress drop case, effective seismic efficiency was 0.65 and 0.43 for both mainshocks. The amount of partial stress drop was used to discriminate between different stress drop models. No clear model is discerned for the first mainshock, but a partial or even complete stress drop, assuming finite-fault dimensions, is supported by our measurements. Stress drop estimations derived from spectral analysis (25.46 and 34.39 MPa) agreed with global studies but larger than finite and effective fault estimates. Stress inversion results indicated that in the fault segments where the mainshocks occurred, the orientation of principal axes was consistent with a strike-slip regime. Conversely, the normal-faulting regime dominates adjacent areas of the main fault system.

Modeling Challenges and Limitation Principles of Reissner’s Mixed Approaches to Laminates

Displacement-based formulations for composite structures are directly linked to the functional called the Principle of Virtual Displacements and present the minimum number of independent modeled fields, which are the displacements. However, these models usually provide an inadequate approximation of the transverse stress fields and suffer from pathological numerical problems. These issues have been addressed with the introduction of mixed variational formulations where independent stress fields are included in the definition of the corresponding functionals. Particularly effective and widely used are Reissner’s mixed variational theorem and Hellinger–Reissner Principle. Both Reissner’s mixed variational theorem and Hellinger–Reissner principle allow the a priori enforcing of the interlaminar equilibrium because of the axiomatic modeling of the transverse stresses. However, these functionals are different and present their own challenges. Under certain circumstances, Reissner’s Mixed Variational Theorem was shown to produce thickness oscillations of the displacements and transverse stresses. It was not clear if Hellinger-Reissner Principle had similar properties. It is shown that both functionals may present numerical oscillations. Moreover, the reconstructed displacement and stress fields are actually identical between Reissner’s Mixed Variational Theorem and Hellinger-Reissner Principle if the orders of the in-plane stresses of the Hellinger–Reissner Prinicple case are sufficiently large. In other words, a Hellinger–Reissner Principle/Reissner’s Mixed Variational Theorem Limitation Principle is shown to exist in addition to the well-studied limitation principle between Hellinger–Reissner principle and principle of virtual displacements.

Application of machine learning for ‘what if?’ stress analysis

Analysis of stresses in components of even modestly complex geometries often require the use of finite element analysis (FEA). For testing a large number of design options quickly, FEA can be time consuming and provides more accuracy than required. In this project, a machine learning-based system is developed to provide quick and approximate solutions to stress analysis problems in parametrised compressor disc geometries. Simple mechanics problems were completed preliminarily to test the practicality of machine learning approaches for this application. This included applying instance selection by the [Formula: see text]-medoids algorithm to a 2D FEA problem. A parametrised compressor disc geometry was designed and defined by eight dimensions. Stress fields were produced from two superimposed loading schemes: the rotational body force and the force exerted on the disc by the blades 495,338 samples of training data were collected from 4374 FEA simulations. Four networks were trained to predict stresses caused by each loading scheme in order to produce stress fields. The best network was of the structure 9/20/20/2 and used normalised training data. For the geometry tested, it predicted stresses with a root-mean-square error of 1.51%. The code took 0.7 s to run in total, from start-up to completion of a stress plot. The importance of the inputs in the training data set were scored with a feature selection algorithm to aid further optimisation of the system. The low computation time makes this system suitable for the early stages in a design process.

The formation and deformation of the Neogene Pannonian Basin: a structural overview

The Pannonian Basin is a continental back-arc basin. Palaeomagnetics defined three terranes: Alcapa (Alps–Carapathians–Pannonian), Tisza–Dacia and Dinarides, rotated counterclockwise, clockwise and counterclockwise, respectively, in the Early and Middle Miocene. The timings and the extent of rotations suggest the terranes experienced differential internal rotations. Metamorphic core complexes occur along the margins and an internal part of the Pannonian Basin. Metamorphic core complexes display extension parallel then perpendicular to the margins. Low-temperature thermochronology defined that synrift exhumation occurred c. 18–16 Ma, coeval with map-view rotations. Microtectonic measurements evidenced superimposed fault patterns. When combined with palaeomagnetics, these patterns simplify to north–south compression throughout Late Paleogene–Middle Miocene. Complications result from rotating blocks deforming under this external stress field. Interpretation of seismic reflection data suggest that synrift phase was characterized by two perpendicular extensions. When rotations are considered, these resolve in east–west stretching. Strike-slip faulting during the Late Miocene accommodated differential movement of terranes pulled eastwards by slab roll-back along the Carpathians. Several inversions affect Late Miocene–Recent sediments. These are most intense and earliest in the SW Pannonian Basin, but also propagate into the internal parts. Rotational indentation of Adria into the Southern Alps–Western Dinarides is the main cause for inversion. Neotectonics reflect this inversion, that is enhanced by eastwards escaping Eastern Alps.

Optimization method for predicting coal reservoir fractures in the Laochang area of Eastern Yunnan using paleotectonic stress inversion

IntroductionCoal reservoir fractures serve as critical storage spaces and migration pathways for coalbed methane (CBM), significantly influencing CBM enrichment. The characteristics of coal reservoir fracture development can be obtained using traditional simulation methods, but these still have shortcomings. This work presents an optimization approach for the traditional method.MethodsThis study introduces an optimization approach for traditional methods with two novel contributions. This study integrates the simulation of tectonic stress fields with fracture prediction, using surface sandstone fractures as constraints to reconstruct the paleostress field of the coal seam, while also accounting for the influence of coal thickness on fracture development to calculate fracture density.ResultsThe predicted fracture density results were validated against measured values from the Bailongshan mine and Xiongdong coal mine with a relative error of approximately 12%, suggesting a reasonable degree of reliability.DiscussionBased on the results of the fracture simulation predictions, it is believed that the coal seam fracture density in the study area is mostly 10–20 lines/m and that the sweet spot for CBM development is located in the Yuwang block.

Numerical Study on the Determination of Crack Initiation Angle, Stress Field and Stress Triaxiality at Crack Tip in a Cracked Beam of Functionally Graded Material

Numerical Study on the Determination of Crack Initiation Angle, Stress Field and Stress Triaxiality at Crack Tip in a Cracked Beam of Functionally Graded Material

Experimental and numerical studies of the open hole tensile strength of drilled‐ and molded‐hole unidirectional laminates

AbstractIn this paper, we created a new molded‐hole process to manufacture holes instead of drilling in unidirectional (UD) carbon fiber reinforced plastics avoid fiber discontinuity. Several open hole tensile (OHT) tests were carried out on specimens with Cross ply (CP) and Quasi‐isotropic (QI) stacking sequence with drilled holes and molded holes. At the same time, we established finite element analysis (FEA) models of drilled‐hole laminate and molded‐hole laminate to characterize the stress field around the hole. The numerical analysis results reveals that the max principal strain distribution around the molded hole has much higher coincidence with fiber axial direction than that in drilled‐hole laminate. Moreover, the OHT strength results of QI specimens indicate that the plates with molded holes were more 50% higher than those with drilled holes. This process will provide reference for molded UD CFRP structure holes. And the numerical model can help engineering designer make OHT strength prediction.Highlights A new molded‐hole process for unidirectional prepreg was created. Molded‐hole specimens have higher open hole tensile strength than drilled‐hole pieces. The simulation results were close to the experimental results.

Faulting by the 2023 great earthquakes of Türkiye and associated stress field and its effects on built environment

Abstract Background Faulting induced by earthquakes and its analysis are of great importance for areas with high probability of earthquakes. However, there has been no particularly effective methods to evaluate the damage and applicable solutions for recovery. In this paper, the damage from Türkiye earthquakes is investigated by authors, which has important theoretical significance and practical value. On 6 February, 2023, two successive earthquakes with magnitudes (Mw) of 7.8 (called Pazarcık earthquake) and 7.6 (Ekinözü earthquake) occurred in the south-eastern part of Türkiye. The total length of the surface ruptures was more than 500 km long and resulted in striations reflecting the sinistral faulting and extensive ground deformations. In this study, the authors present the outcomes of the investigations on the surface ruptures, their characteristics, stress field associated with both earthquakes, shear strength property of fault segments and the damaging effects on various structures and made some recommendations with the purpose of how to build structures in active fault zones and decrease the negative effects of faulting on structures. Results Besides summarizing the main characteristics of the world-shaking Kahramanmaraş earthquake doublet in southeast Türkiye in 2023, this study described the main features of the surface ruptures, their relation to the inferred crustal stresses in Türkiye, and the damaging effects on the major engineering structures. The observations and inferences are of great significance for understanding the causes of earthquakes and future seismic risk assessment. Various laboratory experiments were performed on the samples of fault gouge gathered from the sites of surface ruptures and these experimental results provided very valuable quantitative information on the constitutive models of the fault zones. The observations clearly showed that it is almost impossible to prevent damage on structures due to surface ruptures, if certain engineering principles such as increasing higher ductility, lowering gravitational center and/or the implementations of raft foundations are followed. Conclusions The stress state inferences obtained from the striation of the fault surface ruptures as well as from the focal plane solutions are expected to be useful to evaluate the regional stress state of the earthquake region. Assessments indicated that the stress states in Arabian plate and Anadolu platelet are different from each other. However, in-situ direct stress measurement techniques would be quite useful to validate the stress state inferred in this study. The laboratory experiments on samples gathered from the fault outcrops of the earthquakes using direct shear tests, stick-slip tests as well as conventional tensile, compressive and triaxial tests provided the quantitative values for the parameters of constitutive laws for fault zones, which can be utilized in the numerical simulation of earthquakes. If a fault break happens to be just passing underneath the structures, it is almost impossible for mankind to prevent the damage to structures. However, the authors made some recommendations to reduce the negative effects of fault ruptures on structures. These recommendations are such that the structures should be built as ductile and redundant structures with lower center of gravity and raft foundations. Dam construction should be on active faults should be avoided. If they are to be built for whatever reason, they should be of rock-fill type. As tubular structures and tunnels would be generally subjected forced displacement field, it is recommended to utilize flexible joints, segmented and enlargement to deal such displacement fields.

Innovative computational model for optimal deep coal mining under large-scale crustal stress conditions.

Understanding and controlling the ground stress in deep coalfield mining is crucial for ensuring mine safety and efficiency. This study aims to address two unresolved scientific issues in ground stress research: the selection of optimal excavation plans and the large-scale rapid acquisition of ground stress data. A novel computational model is proposed for key rock layer control under different crustal stress conditions. The model considers the complexity and uncertainty of ground stress distribution by simplifying the key rock strata into a fixed-fixed beam model and calculating their safety through mechanical methods. Introducing an innovative approach for acquiring large-scale stress fields using GPS data. By inverting large-scale strain fields in the coalfield area, combined with World Stress Map (WSM) and measured data, accurate stress fields are obtained. The proposed optimal excavation plan can be applied to various coalfield locations worldwide, providing a scientific basis for safe and efficient mining operations. Additionally, the innovative use of GPS data in obtaining large-scale stress fields offers a valuable tool for assessing ground stress variation.

Analytical solution of surrounding rock stress and plastic zone of rectangular roadway under non-uniform stress field

The shape and extent of the plastic zone can effectively reflect the degree of deformation and failure of the surrounding rock. By applying complex variable functions and the theory of elasticity, a mechanical model for the surrounding rock of a rectangular roadway is established. The analytical solution for the stress in the surrounding rock of a rectangular roadway under a non-uniform stress field is derived, and the spatial stress distribution pattern in the surrounding rock of the rectangular roadway is obtained. Furthermore, using the Mohr-Coulomb criterion, the boundary equation of the plastic zone in the surrounding rock of a rectangular roadway is derived, and the morphological characteristics of the plastic zone are obtained. The results indicate that the plastic zones on both sides of the rectangular roadway are arc-shaped. The asymmetry of the stress environment has a significant impact on the plastic zones in the roof and floor of the rectangular roadway, causing the shape of the plastic zones to resemble a “petal” pattern. The lateral pressure coefficient and the height-to-width ratio have a significant impact on the stress distribution and the morphological characteristics of the plastic zone in the surrounding rock of the rectangular roadway. By validating the computational accuracy of the analytical solution through numerical simulations and conducting an engineering applicability analysis based on a coal mine roadway, it has been demonstrated that the analytical calculation method is both rational and possesses good engineering applicability. This provides reliable theoretical guidance for the design calculations and construction planning of similar roadway projects.

Designing optimized geometry and fiber orientation of composites for dynamic tension via artificial intelligence

Machine learning is quickly becoming an invaluable tool for examining large databases to find patterns and predictions based on similar parameters tested in previous studies. A natural application of this subset of artificial intelligence revolves around material data sets where tests are repeated for basic studies (e.g. tension, compression, bending, or shear) and extrapolating the data for tests not yet considered. Dynamic testing and validation with machine learning is examined here, as a significant time and cost is required for understanding larger-sized specimens (cm scale and larger) especially when the samples are composite materials in tension. This is due in part to the challenges involved in ensuring failure at the region of interests for an anisotropic material and minimizing the number of repeated tests. In this study, the data sets were generated artificially via finite element analysis with failure, and a machine learning code applied to infer the shape of the tensile test coupon knowing only the failure and stress field. Then the algorithm was run to generate a library of ideal coupon geometries based on ply angle and area location of failure within the test specimen. The result is a highly efficient prediction algorithm that can create the ideal specimen shape for tensile testing at speeds orders of magnitude faster than comparable finite element codes.

IGA Approximations of Elastic Interfaces and their Defects in an Elastic Medium with Couple Stress

AbstractThe objective of this work is to develop and implement a computational algorithm for calculating stress and couple-stress fields induced by bulk and interfacial line defects such as dislocations and generalized disclinations within phase/grain boundaries. The thermodynamic driving forces on line and planar defects, responsible for coupled plasticity and interface motion, fully coupled to stress, couple-stress and applied boundary conditions are also computed. A continuum approach for small deformations is considered following the formulation outlined in Acharya and Fressengeas (Continuum mechanics of the interaction of phase boundaries and dislocations in solids. In: Differential Geometry and Continuum Mechanics, pages 123–165, 2015), extended herein in the thermodynamics to accommodate physically necessary ingredients that arose in the modeling in Zhang and Acharya (J Mech Phys Solids 119:188–223, 2018), Zhang et al. (J Mech Phys Solids 114:258–302, 2018). Constitutive relations are derived from kinematics, balance laws and from the use of the second law of thermodynamics in global form. One of the challenges presented by this approach is the inclusion of couple stresses, Toupin (Arch Rational Mech Anal 17(2):85–112, 1964), and the consequent treatment of 4th order systems arising from the equations of balances of linear and angular momentum. In order to deal with these equations, the classical FEM approach is replaced by iso-geometric analysis (IGA), as proposed by Hughes et al. (Comput Methods Appl Mech Eng 194(39):4135–4195, 2005). Results on stress and couple stress fields of the various defects involved are computed. Further, the coupling of the dislocation density with the eigenwall allows for the capturing of the shear parallel to the grain boundary, which has been observed experimentally and through molecular dynamics.

A method for predicting thermal expansion coefficients of carbon fiber/epoxy composites with void defects

AbstractTo predict the coefficient of thermal expansion (CTE) of carbon fiber/epoxy resin composites with void defects comprehensively and accurately, a comprehensive study is carried out by integrating experiment, analytical model (ANM), and finite element model (FEM). The experiments on composites are conducted combining with Micro‐CT to provide geometric parameters and verification for ANM and FEM. An ANM considering void defects is established based on the Chamis model to investigate the influence of porosity, temperature and the ratio of modulus of the constituents of composites. A FEM is established to verify the ANM and reveal the mechanisms of the influence of void defects. The results show that the proposed ANM has high agreement with FEM and experiment. The longitudinal CTE decreases by 61.94% as the porosity increases from 0% to 20% at 60°C, and the same change of porosity results in a 15.62% decrease at 180°C. The transverse CTE is less susceptible to changes in porosity, showing reductions of 2.32% at 60°C and 3.33% at 180°C.Highlights An innovative model is proposed to predict CTE considering void defects. The glass transition temperature Tg of the resin has a significant effect on CTE. Void defects change the homogeneity of the original stress field of the matrix. The reduction of the longitudinal CTE caused by void defects is more significant.

Stress state and strength of welded joints with V-shaped elements

It has been established that in the vicinity of V-shaped elements with a sharp apex, the stress field has a singularity of type σ→∞, which requires the use of the concept of “stress intensity factor” in strength calculations. This need arose due to different dimensions of the SIF and fracture toughness. Special criteria for the destruction of structures with V-shaped stress concentrators have been developed, which include, as special cases, the criteria of classical mechanics and the criteria of fracture mechanics. An experimental test of the proposed criteria and calculation methods was carried out. The information obtained is useful for analyzing welded joints on main pipelines and other equipment.

Analytical study on plastic loosening zone of weak surrounding rocks tunnel in high cold areas

AbstractThe analysis of plastic loosening zone of tunnels with cold condition, high in situ stress, and weak stratum is the key scientific problem of tunnel construction in cold areas. Based on the unified strength theory and considering the coupling effect of high in situ stress and low‐temperature field, the analytical model of the plastic loosening zone of tunnel surrounding rocks was proposed, and the influence laws of physical parameters (initial ground stress, freezing temperature, excavation radius, and intermediate principal stress) was explored. The results illustrate that: (1) with the coupling of low temperature and stress fields, the in‐situ stress has a more significant effect on the radius of the plastic loosening zone of the tunnel surrounding rocks, showing a nonlinear correlation. When the in situ stress is small, the influence of the temperature field on the radius of the plastic loosening zone is more obvious. (2) The radius of the plastic loosening zone of the tunnel surrounding rocks increases synchronously with the excavation radius and gradually decreases with the increase of the intermediate principal stress. (3) The greater the temperature difference in the low‐temperature field, the tunnel stability has a more significant response to the intermediate principal stress and is positively correlated with the coefficient of the intermediate principal stress. (4) In the actual project, the proposed model can well describe the mechanical behavior and deformation characteristics of tunnel surrounding rocks in low‐temperature environment, showing applicability. The research results are expected to provide a theoretical basis for the study of tunnel stability in cold areas.

Glacial Hydro-Isostatic Adjustment at Mid-Ocean Ridges

Summary Recent studies have suggested a link between ice age sea level fluctuations and variations in magma production and crustal faulting along mid-ocean ridges based on the detection of Milankovitch cycle frequencies in topography off several ridges. These fluctuations have also been connected to variability in hydrothermal metal fluxes near ridges. Ice age sea level calculations have shown that the sea level change across glacial cycles will be characterized by significant geographic variability, that is, departures from eustasy, due to the gravitational, deformation and rotational effects of the glacial isostatic adjustment (GIA) process. Using a state-of-the-art GIA simulation that incorporates 3-D variations in Earth viscoelastic structure, including plate boundaries, and updated constraints on the magnitude and geometry of ice mass fluctuations, we predict global sea level changes from Last Glacial Maximum (LGM, 26 ka) to present and from the Penultimate Glacial Maximum (PGM, 143 ka) to the Last Interglacial (LIG, 128 ka). We focus on the results along three ridges: the Mid-Atlantic Ridge, Juan de Fuca Ridge and East Pacific Rise, which are examples of slow, intermediate and fast spreading ridges, respectively. Sea level change across the Mid-Atlantic Ridge shows the greatest variability, ranging from a sea level fall greater than 200 m in Iceland to a maximum rise of ∼150 m in the South Atlantic, with significant non-monotonicity north of the Equator as the ridge weaves across the field of sea level changes. We also calculate changes in crustal normal stress from LGM to present-day across the Mid-Atlantic and Juan de Fuca Ridges and the East Pacific Rise. These results indicate that the contribution from ice mass changes to the crustal stress field can be significant well away from the location of ancient ice complexes. We conclude that any exploration of the hypothesized links to magma production and crustal faulting must consider both ocean and ice loading effects and, more generally, the profound geographic variability of the GIA process.