Journal of Geophysical Research: Solid Earth最新文献

{"title":"Permeability of the Pāpaku Fault Within the Hikurangi Subduction Zone Determined From the Thermal Response to a Free Flowing Well Test","authors":"Roberto D. Clairmont,&nbsp;Patrick M. Fulton","doi":"10.1029/2024JB030965","DOIUrl":"10.1029/2024JB030965","url":null,"abstract":"<p>The paucity of in situ meso-scale permeability measurements within subduction zones makes it difficult to fully characterize hydrologic processes and conditions that influence fault zone behavior. In the Hikurangi subduction zone, where large shallow slow slips are observed, there are outstanding questions about the hydrologic influence splay faults have on fluid pressures along the megathrust. Here, by utilizing the borehole thermal response to a free-flowing well test, we estimate the permeability of the Pāpaku thrust fault, which extends from the Hikurangi décollement to the seafloor of the frontal accretionary wedge. The experiment is made possible by using a high-resolution temperature sensor array within the Te-Matakite subseafloor observatory near the northern Hikurangi Trough which is open to the Pāpaku fault ∼323 m below seafloor. The observatory was installed during International Ocean Discovery Program (IODP) Expedition 375 in 2018. After 5 years of recording, the wellhead was unsealed resulting in outflow indicative of overpressures within the fault. The observed temperature response to the outflow reflects flow velocities that constrain the Pāpaku fault zone permeability to <i>k</i> ≥ 1.9 × 10⁻¹⁴ m². The temporal evolution of flow, however, reveals that the connectivity of this permeable zone is bounded to several tens of meters of extent and not to the seafloor. These results suggest the Pāpaku fault and other splay faults within the Hikurangi margin may serve as conduits for localized fluid flow and pressure redistribution but may not have sufficient hydrologic connection to transmit fluid or sufficiently relieve fluid pressure from the décollement.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030965","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154043","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":"Hydrogen in the Earth's Outer Core From Density Measurements of Liquid Fe-H up to 102 GPa and 4,100 K","authors":"Suyu Fu,&nbsp;Kei Hirose,&nbsp;Shunpei Yokoo,&nbsp;Fumiya Sakai,&nbsp;Kenta Oka","doi":"10.1029/2025JB031934","DOIUrl":"10.1029/2025JB031934","url":null,"abstract":"<p>Among several candidate light elements in the Earth's core, hydrogen may be of particular importance due to its abundance in the universe and siderophile nature at high pressure and temperature (<i>P-T</i>) conditions. However, the hydrogen content in the core remains unclear due to the lack of reliable experimental constraints on the thermoelastic properties of Fe-H alloys. In this study, we report the density of liquid Fe-H alloys with various hydrogen contents up to 102 GPa and 4,100 K based on the measured X-ray diffraction diffuse signals using a diamond-anvil cell. Combined with previous measurements of the density of liquid pure Fe, we quantitatively evaluated the effect of hydrogen on the density of liquid Fe-H alloys at high <i>P-T</i> by using a thermoelastic model. Our results show that hydrogen could greatly decrease the density of liquid Fe-H alloys but weakly affects its isothermal bulk modulus and the Grüneisen parameter. Models show that liquid Fe with 0.83–0.90 wt% H in the outer core (the maximum value) along an expected geotherm could have densities and bulk sound velocities comparable with seismic observations after considering experimental uncertainties. Although these results indicate that hydrogen could be a major light element in the Earth's outer core, other light elements (Si, O, S, and C) might be further considered in future studies to better interpret geophysical, geochemical, and cosmochemical observations of our planet.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145140686","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":"Rift-Related Sedimentary Basin and Deeper-Seated Mafic Intrusions Modeled Beneath Thwaites Glacier, West Antarctica: Influence on Glacier Dynamics","authors":"Louise Borthwick,&nbsp;Atsuhiro Muto,&nbsp;Sridhar Anandakrishnan,&nbsp;Kirsty Tinto,&nbsp;Ronan Agnew,&nbsp;Alex Brisbourne,&nbsp;Rebecca Schlegel,&nbsp;Siobhan Killingbeck,&nbsp;Bernd Kulessa,&nbsp;Richard Alley,&nbsp;Amanda Willet,&nbsp;Sierra Melton","doi":"10.1029/2025JB031716","DOIUrl":"10.1029/2025JB031716","url":null,"abstract":"<p>Thwaites Glacier in West Antarctica has been identified as a route to destabilization of the whole West Antarctic Ice Sheet, potentially leading to several meters of sea-level rise. However, future evolution of Thwaites Glacier remains uncertain due to a lack of detailed knowledge about its basal boundary that will affect how its retreat proceeds. Here we aim to improve understanding of the basal boundary in the lower part of Thwaites Glacier by modeling the crustal structures that are related to the bed-type distribution and therefore influence the basal slip. We combine long-offset seismic, and gravity- and magnetic-anomaly data to model the crustal structures along two <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>120 km lines roughly parallel to ice flow. We find a sedimentary basin <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>40 km in length in the along-flow direction, with a maximum thickness of 1.7 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math> 0.2 km, and two mafic intrusions at 5–10 km depth that vary in maximum thickness between 3.8 and 8.6 km. The sedimentary basin and major mafic intrusions we modeled are likely related to the multi-stage tectonic evolution of the West Antarctic Rift System. Thwaites Glacier flows across a tectonic boundary within our study site, indicating it flows across tectonically formed structures. The varying geology and resulting variations in bed types demonstrate the influence of tectonics on Thwaites Glacier dynamics.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031716","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145140688","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":"Magnetotellurics Point to Serpentinization as a Potential Source of Hydrogen in the Bulqizë Ophiolite","authors":"Yan Yao,&nbsp;Frédéric-Victor Donzé,&nbsp;Mathieu Persem,&nbsp;Laurent Truche,&nbsp;Bardhyl Muceku,&nbsp;Stéphane Garambois,&nbsp;Ivan Vujevic,&nbsp;Nicolas Lefeuvre,&nbsp;Edmond Goskolli","doi":"10.1029/2025JB031898","DOIUrl":"10.1029/2025JB031898","url":null,"abstract":"<p>Hydrogen was first detected in the Bulqizë ophiolite massif (Albania) in 1992, and its origin remains uncertain, with hypotheses ranging from active serpentinization to the release of trapped, fossil H₂. To constrain the thickness of the ophiolite layer—a key parameter for evaluating hydrogen generation—we conducted a magnetotelluric survey using recording stations located both within and outside the massif. Data processing and subsequent 1D and 2D electrical resistivity models reveal a heterogeneous resistivity distribution, indicating a potential transition from unaltered to progressively serpentinized rocks. The ophiolite thickness is estimated at approximately 6,000 m, and thermal gradients suggest that temperatures may exceed 100°C at depth. These findings imply that regional water inputs could facilitate serpentinization and contribute to hydrogen production, providing important constraints on the geochemical processes occurring within the ophiolite.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031898","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145140693","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":"Mode of Continental Thinning and Breakup Along the North Iberian-Armorican Conjugate Margins in the Bay of Biscay","authors":"Asier Madarieta-Txurruka,&nbsp;Antonio Pedrera,&nbsp;Jesús Galindo-Zaldívar,&nbsp;Ferran Estrada,&nbsp;Jesús García-Senz,&nbsp;Gemma Ercilla","doi":"10.1029/2025JB031754","DOIUrl":"https://doi.org/10.1029/2025JB031754","url":null,"abstract":"<p>Continental breakup involves multiple extension styles; each linked to unique structural and sedimentary processes. High-angle, low-angle, listric and antilistric normal faults develop at different stages and positions during rifting. The Bay of Biscay and its margins, a prototypical example of magma-poor rifted margins during Jurassic-Cretaceous, offer insights into the development and interaction of these faults related to lithospheric rheology. To this end, a margin-to-margin crustal scale cross-section is constructed and sequentially restored from a detailed review of available geological and seismic data and gravity and magnetic modeling. The first rifting phase was controlled by high-angle normal faults affecting the strong upper levels of the crust, pre-thinned during the previous Permian-Triassic rifting. These faults rotated and converged at depth, forming a continent-dipping detachment in the weaker middle crust, enabling crustal breakup and mantle exhumation in the pre-thinned sector, and developing the supradetachment Asturias Basin. Partial melting during Permian-Triassic rifting strengthened the lower crust, enhancing crust-mantle coupling during the second rifting phase. During mantle exhumation, weak serpentinized peridotites facilitated the formation of antilistric faults, coinciding with an abrupt increase in extension rates. Subsequently, the rates of extension began to decrease, culminating in the upwelling of the asthenosphere to form a proto-oceanic ridge before the spreading cessation. Finally, the North-Iberian Margin underwent a moderate inversion during the Alpine contraction. These results shed light on the influence of prior tectonic events, interactions between normal fault systems, and their link to lithospheric rheology during rifting, with implications for other magma-poor rifted margins.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031754","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135563","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":"EBSD-Based Calibration of Differential Stress From Experimentally Deformed Black Hills Quartzite Using the Perimeter-Area Fractal Dimension","authors":"Scott E. Johnson,&nbsp;Won Joon Song,&nbsp;Erik K. Anderson,&nbsp;Christopher C. Gerbi,&nbsp;Senthil S. Vel,&nbsp;David J. Prior,&nbsp;Michael Stipp","doi":"10.1029/2024JB030866","DOIUrl":"https://doi.org/10.1029/2024JB030866","url":null,"abstract":"&lt;p&gt;Microstructures that preserve quantitative information about deformation conditions during viscous flow of crystalline materials are rare, the most common example being the dynamically recrystallized grain or subgrain size to infer differential stress. There are many instances in which identification of recrystallized grains or subgrains is challenging. Thus, another microstructural attribute that relates to differential stress would be useful. We use electron backscatter diffraction (EBSD) data from experimentally deformed Black Hills quartzite to show that the perimeter-area fractal dimension of quartz aggregates (the slope of the log-log relationship between perimeter and diameter), which we term the grain boundary dimension (&lt;i&gt;GBD&lt;/i&gt;), strongly correlates with differential stress (&lt;i&gt;σ&lt;/i&gt;) in rocks deformed by dislocation creep. Unlike traditional methods for estimating differential stress, the &lt;i&gt;GBD&lt;/i&gt; method does not require identification of recrystallized grains or subgrains. Analysis of 9 samples yields both power-law and logarithmic calibrations (&lt;i&gt;σ&lt;/i&gt; in MPa) &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;G&lt;/mi&gt;\u0000 &lt;mi&gt;B&lt;/mi&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.691&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.098&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;σ&lt;/mi&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.105&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.031&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $GBD=left(0.691pm 0.098right)times {sigma }^{left(0.105pm 0.031right)}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;G&lt;/mi&gt;\u0000 &lt;mi&gt;B&lt;/mi&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.267&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.081&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;mi&gt;log&lt;/mi&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mi&gt;σ&lt;/mi&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.59&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.16&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $GBD=left(0.267pm 0.081right)times log left(sigma right)+left(0.59pm 0.16right)$&lt;/annotation&gt;\u0000 ","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135559","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":"Tracing Fluid-Rock Interactions and Migration Pathways in Shallow Megathrust Shear Zones Through Rock Magnetic Analysis","authors":"Claudio Robustelli Test,&nbsp;Dario Bilardello,&nbsp;Elena Zanella,&nbsp;Stefano Ghignone,&nbsp;Luca Pellegrino,&nbsp;Enzo Ferrara,&nbsp;Andrea Festa,&nbsp;Francesca Remitti","doi":"10.1029/2025JB031374","DOIUrl":"10.1029/2025JB031374","url":null,"abstract":"<p>Megathrust shear zones are the main fluid transport pathways during the seismic cycle and play a key role in controlling physicochemical alteration. Defining fluid-rock interaction in wall rocks provides evidence for unraveling the hydrogeology of shear zones and their link to active fluid circulation. We analyzed the variation in concentration, grain size and assemblages of magnetic minerals in the wall rocks of a shallow megathrust (the Sestola Vidiciatico shear zone) where no evidence of high-frictional heating has been recorded. The Sestola Vidiciatico shear zone preserves evidence of active fluid circulation and stress-switch during the last brittle phases of the Early to Middle Miocene subduction of the Adriatic plate beneath the frontal prism of the European plate. Magnetic properties indicate low bulk heat transfer during the seismic cycle. Changes in magnetic mineral concentrations highlight iron depletion from clay minerals and dissolution of iron-oxides for interaction with exotic fluids during the coseismic phase. The relative distribution of Fe-oxides and goethite suggests migration of Fe-enriched fluids along fractures during the coseismic/postseismic phase, followed by precipitation for interaction with local fluids. Subsequent alteration and weathering of magnetic minerals, accompanied by the formation of hematite and maghemite, are related to partial oxidation during the interseismic phase. Heterogeneity in magnetic mineral distribution supports active fluid circulation during repeated seismic events and/or exhumation. Rock magnetic characterization of wall rocks in exhumed megathrust represents a promising tool to better understand the role of fluid migration and redox conditions during seismic cycles in subduction zones.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 9","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031374","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145133901","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":"Seismicity From Modern Magmatic Activity Beneath Taupō Volcano, Aotearoa New Zealand","authors":"Eleanor R. H. Mestel,&nbsp;Finnigan Illsley-Kemp,&nbsp;Martha K. Savage,&nbsp;Colin J. N. Wilson,&nbsp;Bubs Smith,&nbsp;Sigrún Hreinsdóttir","doi":"10.1029/2025JB031644","DOIUrl":"10.1029/2025JB031644","url":null,"abstract":"<p>Taupō is an active caldera volcano lying beneath Lake Taupō in the central North Island, Aotearoa New Zealand. It last erupted <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>1,800 years ago, and today has background seismicity interspersed with unrest episodes, most recently in 2019 and 2022–2023. It presents challenges in monitoring due to the lake and consequent limited control on volcano-related earthquake locations. Using national seismometer network data and 13 temporary broadband seismometers, we detected and located earthquakes near Taupō between October 2019 and September 2022. We refined the locations with relative relocation, and calculated magnitudes along with selected focal mechanisms. Seismicity beneath the northern part of the lake was related to the volcano's magmatic system: seismicity rates increased during the unrest and varied focal mechanisms demonstrate a lack of tectonic control. An arcuate shape in the seismicity at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>6 km depth resulted from the interaction of the magmatic system with a caldera ring fault. The arcuate shape was visible in the background seismicity before the start of the 2022–2023 unrest episode but was particularly active during the first months of unrest, reflecting intrusive episodes into the rhyolitic magma reservoir. In contrast, earthquakes north of the lake, as well as around and beneath the southern part of the lake, demonstrated tectonic controls, with rift-aligned focal mechanisms and seismic swarms. Improvements that could be made to routine earthquake characterization at Taupō and allow detailed interpretation of activity in near-real-time include: a volcano-specific velocity model, a lower threshold to identify earthquakes, routine relative relocation, and enhanced seismic instrumentation.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 9","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031644","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145133835","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":"Crustal Structure of the Yunnan Region, China Revealed by Adjoint Tomography Based on Frequency-Dependent Traveltimes","authors":"Zhi Wei,&nbsp;Li Zhao,&nbsp;Hrvoje Tkalčić,&nbsp;Kaiyue Zheng,&nbsp;Yi Wang","doi":"10.1029/2024JB030719","DOIUrl":"10.1029/2024JB030719","url":null,"abstract":"<p>We conduct a high-resolution seismic tomography for the crustal P and S-wave velocities of Yunnan region in southwestern China. Waveforms recorded at 128 broadband stations from 131 regional earthquakes of moment magnitudes 3.9–5.5 occurring between 2009 and 2021 are used to obtain traveltime residuals by the cross-correlation between records and synthetics. Using the regional community velocity model SWChinaCVM-1.0 as the initial model, we carry out a three-stage iterative adjoint tomography, progressing from the longer period band of 50–20 s to shorter-period bands of 30–10 s and 30–5 s. The final model shows general consistency in the spatial patterns of P- and S-wave velocity anomalies. Widespread low-velocity anomalies with high-Vp/Vs ratios in the mid and lower crust in the region suggest that weak materials of the mid-lower crustal flow migrate through the channels formed by the deep mantle plume that led to the Emeishan Large Igneous Province. Localized velocity and Vp/Vs ratio anomalies also reveal that the Lijiang-Xiaojinhe Fault Zone appears to be confined in the upper crust, while the Anninghe-Zemuhe Fault Zone and the Xiaojiang Fault Zone are both whole-crust structures reaching the Moho interface. The Red River Fault Zone, a whole-crust fault, separates the Yangtze Craton to the northeast from the Indo-China Block to the southwest. The main fault zones, the decoupling between the crustal and uppermost mantle parts, and the widespread weak mid-lower crustal materials mutually interact, all contributing to the tectonic evolution of the entire region.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 9","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145103720","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":"Coupling 3D Geodynamics and Dynamic Rupture: Rheology and Stress Control on Strike-Slip Fault Evolution and Earthquake Dynamics","authors":"Anthony Jourdon,&nbsp;Jorge N. Hayek,&nbsp;Dave A. May,&nbsp;Alice-Agnes Gabriel","doi":"10.1029/2025JB031730","DOIUrl":"10.1029/2025JB031730","url":null,"abstract":"<p>Tectonic deformation shapes the Earth's surface, with strain localization resulting in the formation of shear zones and faults that accommodate significant tectonic displacement. Earthquake dynamic rupture models, which provide valuable insights into earthquake mechanics and seismic ground motions, rely on initial conditions such as pre-stress states and fault geometry. However, these are often inadequately constrained due to observational limitations. To address these challenges, we loosely couple 3D geodynamic models to 3D strike-slip dynamic rupture simulations, for the first time accounting for off-fault plastic deformation, providing a mechanically consistent framework for earthquake analysis. Our approach does not prescribe fault geometry but derives it from the underlying lithospheric rheology and tectonic evolution of the system, captured by long-term geodynamic modeling. We perform three long-term geodynamics models of a strike-slip system, each involving different continental crust rheology. We link these with 14 dynamic rupture models, in which we investigate the role of varying fracture energy and plastic strain energy dissipation in the dynamic rupture behavior. Our results highlight the important role of the brittle-ductile transition and indicate that the long-term 3D stress field, which is directly related to the rheology of the lithosphere, favors slip on fault segments better aligned with the regional plate motion. Fault bends and minor variations in the long-term 3D stress field can strongly affect rupture dynamics, providing a physical mechanism for arresting earthquake propagation. Our geodynamically informed earthquake models highlight the need for detailed 3D fault modeling across time scales for a comprehensive understanding of earthquake mechanics.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 9","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031730","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145103624","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}