Journal of Geophysical Research: Solid Earth最新文献

{"title":"Spontaneous Initiation and Evolution of Polygonal Fault Systems During the Early Burial of Sediments in 3D Numerical Models","authors":"A. I. Chemenda, G. Ballas, A. Gay","doi":"10.1029/2025JB031506","DOIUrl":"https://doi.org/10.1029/2025JB031506","url":null,"abstract":"<p>Polygonal Fault Systems (PFS) or networks were generated in 3D finite-difference models within the upper (active) layer of two-layer model. The driving force of this process results from a progressive diagenetically induced volumetric contraction (porosity reduction) of the active layer during its burial. This contraction causes extensional strains, reduces horizontal compressive stresses, and increases deviatoric stresses, leading to elastoplastic yielding and strain-softening of the material in this layer. At a certain point, the initially homogeneous material loses stability resulting in deformation bifurcation and localization within narrow deformation bands (incipient faults). The material undergoes progressive failure within the bands, accompanied by the accumulation of the normal-sense displacement along the faults and the evolution of the fault system, with some faults dying and others forming. The fault architecture characterized in the models by depth-dependent fault density and pattern, is remarkably similar to the natural PFS, both buried and exhumed. The fault spacing (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>S</mi>\u0000 </mrow>\u0000 <annotation> $S$</annotation>\u0000 </semantics></math>) in the models scales with the active layer thickness (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>T</mi>\u0000 </mrow>\u0000 <annotation> $T$</annotation>\u0000 </semantics></math>) and increases as shear coupling (τ<sub>0</sub>) between the active and substratum layers decreases. The maximum throw <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>δ</mi>\u0000 </mrow>\u0000 <annotation> $delta $</annotation>\u0000 </semantics></math> along the faults linearly scales with <i>T</i> and increases with the volume or porosity reduction <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>ϕ</mi>\u0000 </mrow>\u0000 <annotation> ${Delta }phi $</annotation>\u0000 </semantics></math>. Under the chosen model parameters, the typical <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>δ</mi>\u0000 <mo>/</mo>\u0000 <mi>T</mi>\u0000 </mrow>\u0000 <annotation> $delta /T$</annotation>\u0000 </semantics></math> ratio of 0.045 for natural PFS, was obtained in the models for <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>ϕ</mi>\u0000 <mo>≈</mo>\u0000 <mn>7</mn>\u0000 <mo>%</mo>\u0000 </mrow>\u0000 <annotation> ${Delta }phi mathit{approx }7mathit{%}$</","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031506","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Low-Angle Boundaries in Amphibole and Their Implications for Accommodating Grain Boundary Sliding in Naturally Deformed Amphibolite","authors":"Jianhua Liu,&nbsp;Shuyun Cao,&nbsp;Xuemei Cheng,&nbsp;Lefan Zhan,&nbsp;Shuting Wang","doi":"10.1029/2024JB031080","DOIUrl":"https://doi.org/10.1029/2024JB031080","url":null,"abstract":"<p>The deformation and interaction of amphibole grains are crucial for comprehending the rheological behavior and physical properties of middle to lower crust. However, the mechanisms of strain accommodation and grain boundary processes in amphibolites are poorly studied. In this study, we analyzed a naturally deformed amphibolite from an exhumed continental strike-slip shear zone. The amphibole grains can be categorized into two distinct types: type I and type II, with the type II being embedded within type I. Type I amphibole grains exhibit typical plastic deformation behavior, distinguished by the presence of discernible dislocation arrays and formation of subgrains. In contrast, type II amphibole grains predominantly display microfractures in the middle of grains and voids occur in their elongated tails. Meanwhile, we identified three types of low-angle boundaries in amphibole grains with varying microstructural and nanoscale characteristics. Our findings indicate that low-angle boundaries in minerals are not exclusively associated with crystal-plastic deformation. Furthermore, the deformation characteristics in type II amphibole grains are related to grain boundary sliding (GBS) process. To relieve stress concentration during grain boundary sliding in type II amphibole grains, two accommodation mechanisms are proposed: (a) Grain boundary diffusion with elimination of grain boundary irregularities. (b) Intragranular deformation of adjacent grains through either a brittle or a ductile process. Our findings hold significant implications for understanding the stress concentration and accommodation during deformation process in amphibolite.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystallographic Texture, Structure, and Stress Transmission in Nugget Sandstone Examined With X-Ray Tomography and Diffraction Microscopy","authors":"Ryan C. Hurley,&nbsp;Ye Tian,&nbsp;Mohmad M. Thakur,&nbsp;Jun-Sang Park,&nbsp;Peter Kenesei,&nbsp;Hemant Sharma,&nbsp;Adyota Gupta,&nbsp;Kwangmin Lee","doi":"10.1029/2025JB031690","DOIUrl":"https://doi.org/10.1029/2025JB031690","url":null,"abstract":"<p>Subsurface processes in sandstones are controlled by porosity, permeability, and deformation mechanisms, all of which are controlled by a complex interplay of crystallographic rock texture, structure, and micromechanics. Texture, structure, and micromechanics have historically been studied using optical and electron microscopy of thin-sections. We employed a new combination of in situ X-ray tomography and ray diffraction microscopy to study crystallographic texture, structure, and grain stresses in 3D. We examined these features in a sample of Nugget sandstone, a sandstone constituting hydrocarbon reservoirs across the American West. Our aims are threefold. First, we demonstrate the utility of X-ray diffraction microscopy probes for revealing texture, structure, and stress transmission in 3D. Second, we apply these techniques to Nugget sandstone and discuss findings in the context of prior work. Third, we study grain stress tensor evolution during mechanical compression to examine whether their heterogeneity and orientation evolution reflect that of inter-particle forces in granular materials. Our results show: (a) larger grains featured higher intra-granular misorientations, possibly from an increased prevalence of cements; (b) pores closed parallel to the loading direction and opened normal to loading; (c) grain stresses featured heterogeneity and orientations similar to inter-particle forces in non-cohesive granular materials; (d) grains featured compressive stresses in the loading direction and tensile stresses orthogonal to the loading direction, the latter resisting sample dilation and grain separation. Our work demonstrates the first known application of multi-modal X-ray tomography and diffraction microscopy to sandstone, providing new 3D insight into the nature of quartz cement and stress evolution.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Edifice Slope, Failure Surface Geometry, and Magma Intrusion Depth on the Development of Flank Instability at Volcanoes","authors":"J. Gonzalez-Santana,&nbsp;C. Wauthier,&nbsp;S. Tung,&nbsp;T. Masterlark","doi":"10.1029/2024JB030627","DOIUrl":"https://doi.org/10.1029/2024JB030627","url":null,"abstract":"<p>Magmatism is a known driver of flank instability at volcanoes where flank slip has been observed. Studies of instability at Kı̄lauea, Piton de la Fournaise, and Etna imply that long-term flank motion likely requires the presence of a layer accommodating the sliding, and a force, such as magma intrusion, that promotes slip. We present a parametric study using 2D Finite Element Models, to assess how edifice slope, failure surface geometry, edifice asymmetry, and intrusion depth affect the potential for development of flank instability at volcanoes. We quantify whether the tested conditions would favor flank slip based on the Coulomb Stress Changes (CSCs) associated with endmember scenarios and showcase the expected surface displacements for each scenario, to highlight their deviations from half-space models. Development of favored instability is more likely when dike intrusions span an edifice with shallower-dipping failure surfaces, or detachment faults, regardless of edifice steepness. Another favorable scenario occurs in steep edifices with steeply-dipping failure surfaces when the intrusion is beneath the edifice. The same is observed when introducing asymmetry on the opposing flank to simulate buttressing. We also find that neglecting topography yields smaller amplitude displacements with longer wavelengths, and these differences are greater the steeper the volcanic edifice. This topographical effect is more important when modeling horizontal displacements and stress changes induced by shallower intrusions.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030627","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laboratory Insights on Hydraulic Fracture Closure and Stress Measurement","authors":"Zhi Ye,&nbsp;Ahmad Ghassemi","doi":"10.1029/2024JB029854","DOIUrl":"https://doi.org/10.1029/2024JB029854","url":null,"abstract":"<p>Reliable knowledge of the magnitudes and orientations of in situ stress is essential for scientific and engineering activities in the subsurface, particularly in energy and storage applications. A common technique for determining the minimum principal stress (S₃) is to interpret the fracture closure pressure from the pressure decline transient during the shut-in phase of hydraulic fracturing. However, existing methods for interpreting fracture closure pressure often yield inconsistent results, leading to significant uncertainties in determining the minimum principal stress. To address this issue, we conducted a series of controlled laboratory injection/fall-off experiments on various rock types using different injection fluids to demonstrate the physical processes of fracture closure. Our results indicate that fracture closure follows a three-stage process, with the onset of mechanical closure during Stage 2 providing the most reliable estimate of S₃. Building on these findings, we propose using the early deviation on dP/dG versus <i>G</i> plot, corresponding to the beginning of Stage 2, for fracture closure analysis, as it consistently yields reliable stress estimates in both laboratory and field-scale hydraulic fracturing stress measurements. Additionally, our laboratory results suggest that the instantaneous shut-in pressure (ISIP) method could provide reasonable but higher-bound estimates of the minimum principal stress, indicating the potential value of integrating fracture closure pressure and ISIP for more accurate stress measurements. This study not only clarifies fracture closure analysis for stress determination but also offers a comprehensive understanding of the physics governing fracture closure during the shut-in phase of hydraulic fracturing operations.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Discontinuous Galerkin Method for Simulating 3D Seismic Wave Propagation in Nonlinear Rock Models: Verification and Application to the Mw 7.8 2015 Gorkha, Nepal Earthquake","authors":"Zihua Niu,&nbsp;Alice-Agnes Gabriel,&nbsp;Sebastian Wolf,&nbsp;Thomas Ulrich,&nbsp;Vladimir Lyakhovsky,&nbsp;Heiner Igel","doi":"10.1029/2025JB031378","DOIUrl":"https://doi.org/10.1029/2025JB031378","url":null,"abstract":"<p>The nonlinear mechanical responses of rocks and soils to seismic waves play an important role in earthquake physics, influencing ground motion from source to site. Continuous geophysical monitoring, such as ambient noise interferometry, has revealed co-seismic wave speed reductions extending tens of kilometers from earthquake sources. However, the mechanisms governing these changes remain challenging to model, especially at regional scales. Using a nonlinear damage model constrained by laboratory experiments, we develop and apply an open-source 3D discontinuous Galerkin method to simulate regional co-seismic wave speed changes during the 2015 M_<i>w</i> 7.8 Gorkha earthquake. We find pronounced spatial variations of co-seismic wave speed reduction, ranging from &lt;0.01% to &gt;50%, particularly close to the source and within the Kathmandu Basin, while disagreement with observations remains. The most significant reduction occurs within the sedimentary basin and varies with basin depths, whereas wave speed reductions correlate with the fault slip distribution near the source. By comparing ground motions from simulations with elastic, viscoelastic, elastoplastic, and nonlinear damage rheologies, we demonstrate that the nonlinear damage model effectively captures low-frequency ground motion amplification due to strain-dependent wave speed reductions in soft sediments. We verify the accuracy of our approach through comparisons with analytical solutions and assess its scalability on high-performance computing systems. The model shows near-linear strong and weak scaling up to 2,048 nodes, enabling efficient large-scale simulations. Our findings provide a physics-based framework to quantify nonlinear earthquake effects and emphasize the importance of damage-induced wave speed variations for seismic hazard assessment and ground motion predictions.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031378","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Another Simple Test for the Presence of Multidomain Behavior During Paleointensity Experiments","authors":"Alexander W. Tully,&nbsp;Greig A. Paterson","doi":"10.1029/2025JB031608","DOIUrl":"https://doi.org/10.1029/2025JB031608","url":null,"abstract":"<p>Paleointensity measurements are vital for understanding the deep Earth and the evolution of the geomagnetic field, however, they suffer from non-ideal behavior that compromises the fidelity of the results. In an attempt to screen for non-ideal behavior in paleointensity experiments, selection criteria are used. One such non-ideal behavior is partial thermoremanent magnetization tails, which in the IZZI protocol result in a zig-zagging pattern on an Arai plot. While checks for these tails can be performed, these are not routinely used in experiments. We set out a new framework with which to create, develop, and re-assess selection criteria before applying it to our proposed new selection statistic, <i>Ziggie</i>, which is specific to detecting zig-zagging behavior. In creating <i>Ziggie</i>, we have attempted to define a criterion that is able to objectively and robustly identify the target behavior, consistently provide a quantifiable assessment of the target behavior, and is predominately sensitive to the target behavior while being free of undue influences. Other pre-existing statistics identifying Arai plot zig-zag, <i>Z</i>*, <i>IZZI_MD</i>, <i>β</i>, and <i>SCAT</i>, are also tested, but fail to meet all requirements. When a criterion of <i>Ziggie</i> ≤ 0.1 is applied to real IZZI data we find an overall improvement in the results and suggest the adoption of this criterion in future IZZI analysis.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031608","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Measurements on the Coefficient of Restitution of Colliding Irregular Volcanic Particles","authors":"Francesco Neglia,&nbsp;Emanuele Caruso,&nbsp;Fabio Dioguardi,&nbsp;Daniela Mele,&nbsp;Damiano Sarocchi,&nbsp;Roberto Sulpizio","doi":"10.1029/2024JB030445","DOIUrl":"https://doi.org/10.1029/2024JB030445","url":null,"abstract":"&lt;p&gt;Dense volcanic granular flows are polydisperse in terms of grain size and density, and their flow characteristics are mainly governed by particle-particle collisions and frictional forces acting at the boundaries. The parameter measuring the energy dissipation during the collisions is the coefficient of restitution (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $e$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;), which is proportional to the fraction of the original energy stored in the colliding particles that is restored to the same ones after the collision. &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $e$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is fundamental in computational fluid dynamics (CFD) numerical models to simulate multiphase granular flows because it is required to solve the particles motion and the particle-particle momentum exchange. The calculation of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $e$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; for irregular volcanic particles is an unsolved challenging problem, which is here addressed by colliding particles through a pendulum-type instrumental apparatus. &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $e$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; was calculated for volcanic particles with different density (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;ρ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $rho $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;), diameter (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;d&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $d$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and particles size ratio (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;d&lt;/mi&gt;\u0000 &lt;mtext&gt;ratio&lt;/mtext&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${d}_{text{ratio}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;), and the data were used to obtain linear relationships between &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $e$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and the investigated parameters. Afterward, a multicollinearity analysis and a multiple regression were applied to all data to adequately predict","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030445","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"14 Years of Slip on the Hikurangi Subduction Zone","authors":"Sylvain Michel,&nbsp;Romain Jolivet,&nbsp;Emilie Klein,&nbsp;Louise Maubant","doi":"10.1029/2024JB030865","DOIUrl":"https://doi.org/10.1029/2024JB030865","url":null,"abstract":"<p>Slow slip events (SSEs) on the Hikurangi subduction megathrust in New Zealand have been studied extensively. However, we lack a comprehensive and consistent catalog over a long time period since 2010. Recent studies have focused on short time periods and rarely provide a time dependent image of slip during SSEs, let alone between SSEs. In addition, the use of different methods, parametrizations and data sets does not allow to compare SSEs at different periods of time. Our study aims to model the spatio-temporal history of slip of the subduction, devoid of temporal smoothing, over the entire 2009–2023 time period based on GNSS time series. We combine an Independent Component Analysis decomposition with an inversion scheme to derive a history of accelerations and slowdowns of aseismic fault slip on the megathrust. We then combine a SSE detection procedure with an inter-SSE linear trend correction to reference this slip time series to the inter-SSE loading rate and build a catalog of 27 SSEs. We observe a change in the behavior of SSEs after the 2016 Kaikoura earthquake with respect to the pre-Kaikoura period, highlighted by changes in the slip frequency content. We finally evaluate using a Bayesian approach the subduction inter-SSE coupling map, the SSEs cumulative slip between 2009 and 2023, to constrain the distribution of locked regions over 14 years and conclude that moment deficit accumulates mostly under Wellington peninsula at a rate of 4.9 ± 0.5 10¹⁸ N.m/yr.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030865","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interseismic Megathrust Coupling at the Osa Peninsula, Costa Rica","authors":"Mason Perry,&nbsp;Cyril Muller,&nbsp;Marino Protti,&nbsp;Lujia Feng,&nbsp;Emma M. Hill","doi":"10.1029/2024JB030641","DOIUrl":"https://doi.org/10.1029/2024JB030641","url":null,"abstract":"<p>At the Osa Peninsula in southern Costa Rica, magnitude &gt;7 earthquakes have been generated along the Middle American trench in 1904, 1941, and 1983 following a ∼40-year recurrence interval, suggesting a rupture may be impending. However, regional interseismic coupling remains poorly constrained, largely due to sparse observations that are likely contaminated by aliasing effects of repeating shallow slow slip events (SSEs) that occur roughly every 4 years, but were only discovered recently. These SSEs, while likely reducing megathrust coupling near the trench, may load or trigger the next rupture of the 1983 asperity. Using new continuous Global Navigation Satellite System (GNSS) data from an updated and densified regional network, we derive inter-SSE rates of deformation and invert for slip deficit and megathrust coupling along the Middle American Trench, implementing block modeling to correct for the motion of the Panama microplate. We invert for slow slip and remove a time-averaged estimate of cumulative slow slip from our models. Our results indicate that the region of highest inter-SSE coupling (&gt;0.8) corresponds with the spatial extent of SSE slip. We also find that SSEs are sufficient to release nearly all the elastic strain accumulated over their 4-year recurrence interval in localized regions. Accounting for this, in the region immediately downdip of the slow slip patch—the same region thought to have ruptured in the 1983 <i>M</i>_w 7.4 event—we estimate an interseismic coupling ratio of ∼0.5–0.7 corresponding to ∼1.75–2 m of accumulated slip deficit since 1983, sufficient to generate a similar magnitude rupture in the future.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030641","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}