Journal of Geophysical Research: Solid Earth最新文献

{"title":"Earthquake Nucleation and Slip Behavior Altered by Stochastic Normal Stress Heterogeneity","authors":"Meng Li, Andre Niemeijer, Ylona van Dinther","doi":"10.1029/2024jb029857","DOIUrl":"https://doi.org/10.1029/2024jb029857","url":null,"abstract":"In recent laboratory experiments, varying nucleation locations of accelerating slip with changing nucleation lengths were observed. Spatial variations in effective normal stress, due to the controlling influence on fault strength and fracture energy, play an important role. We quantitatively explain how spatially heterogeneous effective normal stresses affect earthquake nucleation and slip behavior. We simulate a meter-scale laboratory experiment in a numerical earthquake sequence model with stochastically variable normal stresses. We identify five regimes of earthquake nucleation and slip behaviors, controlled by the ratio of the heterogeneity wavelength <span data-altimg=\"/cms/asset/b1590383-a5e1-40b4-9214-18ab5b261c8c/jgrb57087-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"269\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb57087-math-0001.png\"><mjx-semantics><mjx-mrow data-semantic-children=\"1\" data-semantic-content=\"0,2\" data-semantic- data-semantic-role=\"leftright\" data-semantic-speech=\"left parenthesis lamda right parenthesis\" data-semantic-type=\"fenced\"><mjx-mo data-semantic- data-semantic-operator=\"fenced\" data-semantic-parent=\"3\" data-semantic-role=\"open\" data-semantic-type=\"fence\" style=\"margin-left: 0.056em; margin-right: 0.056em;\"><mjx-c></mjx-c></mjx-mo><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-parent=\"3\" data-semantic-role=\"greekletter\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi><mjx-mo data-semantic- data-semantic-operator=\"fenced\" data-semantic-parent=\"3\" data-semantic-role=\"close\" data-semantic-type=\"fence\" style=\"margin-left: 0.056em; margin-right: 0.056em;\"><mjx-c></mjx-c></mjx-mo></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb57087:jgrb57087-math-0001\" display=\"inline\" location=\"graphic/jgrb57087-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow data-semantic-=\"\" data-semantic-children=\"1\" data-semantic-content=\"0,2\" data-semantic-role=\"leftright\" data-semantic-speech=\"left parenthesis lamda right parenthesis\" data-semantic-type=\"fenced\"><mo data-semantic-=\"\" data-semantic-operator=\"fenced\" data-semantic-parent=\"3\" data-semantic-role=\"open\" data-semantic-type=\"fence\" stretchy=\"false\">(</mo><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic-parent=\"3\" data-semantic-role=\"greekletter\" data-semantic-type=\"identifier\">λ</mi><mo data-semantic-=\"\" data-semantic-operator=\"fenced\" data-semantic-parent=\"3\" data-semantic-role=\"close\" data-semantic-type=\"fence\" stretchy=\"false\">)</mo></mrow>$(lambda )$</annotation></semantics></math></mjx-assistive-mml></mjx-container> to the nucleation length <span data-altimg=\"/cms/asset/dad13513-83f0-4228-b9f7-a9","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"8 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887177","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":"Late Cretaceous Ophiolite Emplacement and Cenozoic Collisional Tectonics in the Northeastern Arabian Plate: Insights From New Broadband Magnetotelluric Data","authors":"B. A. Cherkose, H. Saibi, K. Al Bloushi, M. Y. Ali, A. Fowler, M. Smirnov","doi":"10.1029/2024jb028744","DOIUrl":"https://doi.org/10.1029/2024jb028744","url":null,"abstract":"The Late Cretaceous obduction of the Semail Ophiolite onto the rifted passive Arabian margin and the Cenozoic collisional tectonics with the final closure of the Neo-Tethys Ocean, are major contributors to the present-day crustal architecture of the northern United Arab Emirates (UAE). We acquired the first 3D grid magnetotelluric observations from 73 stations in the northern UAE in order to image deep crustal electrical structures associated with the two significant compressional episodes. Inversion of the broadband magnetotelluric data reveals the subsurface geometry of the high-resistivity ophiolite blocks, the underlying conductive thrust sheet (Haybi-Hawasina nappe), a “wedge-shaped” conductive foreland basin flanking the Hajar mountain ranges, and at depth, a high-resistivity structure associated with a fold-thrust belt adjacent to the allochthonous units, or Proterozoic crystalline basement. The ophiolite along the eastern coast (from cities Khor Fakkan to Fujairah) is more than 20 km thick and dips eastward. Across the Wadi Ham fault, the resistive ophiolite lies against less resistive materials that may represent Bani Hamid metamorphic rocks. The thin-skinned thrust sheets of the proximal-distal Tethyan sedimentary units (Haybi-Hawasina complexes) exhibit low resistivity in the Dibba zone. In contrast to its gently east-dipping geometry in the Dibba zone, the conductive Haybi-Hawasina structure in the southern portion of the study area appears nearly vertically (>20 km) beneath the dense Khor Fakkan and Aswad ophiolite blocks. This result suggests extensive deformation of the thrust sheets beneath the southerly dense ophiolite blocks.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"80 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887174","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 Effects of Characteristic Weakening Distance on Earthquake Nucleation Styles in Fully Dynamic Seismic Cycle Simulations","authors":"Peng Zhai, Yihe Huang","doi":"10.1029/2024jb029719","DOIUrl":"https://doi.org/10.1029/2024jb029719","url":null,"abstract":"Earthquake nucleation is a crucial preparation process of the following coseismic rupture propagation. Under the framework of rate-and-state friction (RSF), it was found that the ratios of <span data-altimg=\"/cms/asset/33684ac5-3d1c-4a31-a249-ac443d836530/jgrb57070-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"332\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb57070-math-0001.png\"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-role=\"latinletter\" data-semantic-speech=\"a\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb57070:jgrb57070-math-0001\" display=\"inline\" location=\"graphic/jgrb57070-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic-role=\"latinletter\" data-semantic-speech=\"a\" data-semantic-type=\"identifier\">a</mi></mrow>$a$</annotation></semantics></math></mjx-assistive-mml></mjx-container> to <span data-altimg=\"/cms/asset/ae9b157a-a54a-4784-baa8-3c863bed4ffa/jgrb57070-math-0002.png\"></span><mjx-container ctxtmenu_counter=\"333\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb57070-math-0002.png\"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic- data-semantic-role=\"latinletter\" data-semantic-speech=\"b\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb57070:jgrb57070-math-0002\" display=\"inline\" location=\"graphic/jgrb57070-math-0002.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"italic\" data-semantic-role=\"latinletter\" data-semantic-speech=\"b\" data-semantic-type=\"identifier\">b</mi></mrow>$b$</annotation></semantics></math></mjx-assistive-mml></mjx-container> parameters control whether earthquakes nucleate as an expanding crack or with a fixed length prior to the dynamic instability. However, the characteristic weakening distance <span data-altimg=\"/cms/asset/0bf8e495-f2ef-4116-824a-3c684d8db3ea/jgrb57070-math-0003.png\"></span><mjx-container ctxtmenu_counter=\"334\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb57070-math-0003.png\"><mjx-semantics><mjx-mrow><mjx-msub data-seman","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"25 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880123","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":"Bayesian Preprocessing for Palaeomagnetic Sediment Records Using a Flexible Lock-In Function Approach","authors":"L. Bohsung, M. Schanner, M. Korte, M. Holschneider","doi":"10.1029/2024jb029936","DOIUrl":"https://doi.org/10.1029/2024jb029936","url":null,"abstract":"Geomagnetic field models covering past millennia rely on two main data sources: archaeomagnetic data, that provide snapshots of the geomagnetic field at specific locations, and sediment records, that deliver time series of the geomagnetic field from individual cores. The limited temporal and spatial global coverage with archaeomagnetic data necessitates use of sediment data, especially when models go further back in time. However, the accurate preprocessing and interpretation of sediment data is crucial. Unlike archaeomagnetic data, sediment data does not provide absolute values for intensities and declinations; instead, it represents relative variations. The detrital remanent magnetization (DRM) of sediment records is influenced by various depositional (dDRM) effects that can result in inclination shallowing, as well as post-depositional (pDRM) processes that cause a delayed and smoothed signal. To address the distortion associated with the pDRM effects, a novel class of flexible parameterized lock-in functions has been proposed. These lock-in functions involve four parameters, which are estimated using a Bayesian modeling technique and archaeomagnetic data. By extending the space of hyperparameters to include the calibration factor for intensities, the declination offsets and the inclination shallowing factor, we present a fully Bayesian preprocessing method for sediment records in form of a Python package, called <i>sedprep</i>. By applying the estimated parameters to the raw sediment data <i>sedprep</i> is able to provide a calibrated and preprocessed palaeomagnetic record.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"7 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880239","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":"Paleomagnetic Imprints of Sulfate Reduction Pathways in Continental Shelf Sediments: Organoclastic Versus Anaerobic Oxidation of Methane","authors":"Yakar Zemach, Ron Shaar, Orit Sivan, Barak Herut, Orit Hyams-Kaphzan, Oded Katz, Andrew P. Roberts","doi":"10.1029/2024jb029611","DOIUrl":"https://doi.org/10.1029/2024jb029611","url":null,"abstract":"Marine continental shelf sediments with high deposition rates may provide useful archives of rapid geomagnetic secular variation as long as the primary magnetization is not altered substantially by diagenesis. To quantify the effects of sulfate (SO₄^2-) reduction, which is a dominant early diagenetic process in such sediments, on paleomagnetic recording, we analyzed four 6-m long sediment cores from the eastern Mediterranean shelf. Two cores did not reach the methanogenic zone and are characterized by continuous organoclastic sulfate reduction (OSR), while the other two have a distinctive shallow sulfate-methane transition zone (SMTZ). Age models based on 28 radiocarbon ages indicate steady deposition rates with spatially varying age spans, which suggest that different parts of the shelf stopped accumulating sediments at different times during the Holocene. The upper sediment column in all cores is dominated by detrital titanomagnetite and biogenic magnetite. OSR-affected sediments record continuous (titano) magnetite dissolution, which resulted in steady magnetic susceptibility and remanence decreases. For cores that reach the methanogenic zone, similar behavior is observed at or above the STMZ, but magnetic properties stabilize at greater depths. Paleomagnetic directions in these sediments are more coherent, with better agreement with geomagnetic models than sediments affected by OSR. We suggest that methane-rich sediments with a shallow SMTZ and high sedimentation rates can better preserve primary paleomagnetic signals than OSR-dominated sediments due to a lack of dissolved sulfide in the main methanogenic zone, and that a susceptibility decline with depth should be a warning sign for paleomagnetic studies.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"27 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880124","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":"Ferrous Iron (Fe+2) Released From Iron-Rich Chlorite as a Reductant for Unconformity-Related Uranium Mineralization: Insights From Reactive Fluid Flow Modeling","authors":"Mingqian Wu, Kunfeng Qiu, Jianwen Yang","doi":"10.1029/2024jb030063","DOIUrl":"https://doi.org/10.1029/2024jb030063","url":null,"abstract":"Debate continues over the reducing mechanisms for the formation of unconformity-related uranium (URU) deposits. This paper evaluates, for the first time, the potential of iron-rich chlorite as a reductant for uranium mineralization using reactive fluid flow modeling method. Our results confirm that Fe²⁺, released from the breakdown of iron-rich chlorite, can reduce aqueous hexavalent uranium to precipitate economically significant URU deposits similar in size and grade to those formed with CH₄ as the reducing agent. The resulting uranium mineralization tends to occur in the basement and below the downwelling parts of overlying basinal fluid circulation cells, where oxidizing basinal fluid percolates across the unconformity and reacts with upward flowing reducing basement brine. Therefore, the basinal fluid circulation pattern controlled by the permeability of the sandstone aquifer is critical in determining the formation and distribution of URU deposits. When the sandstone layer is more permeable, the simulated uranium deposits become larger in size, and vice versa. If the sandstone permeability is &lt;5 × 10⁻¹⁴ m², no obvious uranium deposits can be formed. In contrast, the permeability of fault zones does not have a significant effect on uranium mineralization, although it does affect fluid flow behaviors within the fault zone itself. We also demonstrate that fault zones do not appear to be a prerequisite for the formation of URU deposits when Fe⁺² serves as a reductant, which highlights important exploration implications. Uranium exploration should, in addition to continuing to target graphitic fault zones, also consider areas where faults and/or graphite units do not exist.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"8 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874477","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":"Seismicity and Present-Day Crustal Deformation in the Southern Puna Plateau","authors":"Sankha Subhra Mahanti, Eric Kiser, Susan Beck, Amanda Hughes","doi":"10.1029/2024jb028918","DOIUrl":"https://doi.org/10.1029/2024jb028918","url":null,"abstract":"The Southern Puna plateau in the central Andes has a complicated tectonic history that includes episodes of distributed shortening and extension, lithospheric delamination, uplift and Quaternary backarc volcanism. In this study, the upper crustal structure and present-day deformation in this area is investigated using a new regional earthquake catalog derived with a deep-learning-based phase picker. Results show abundant strike-slip seismicity at shallow depths in the eastern Southern Puna plateau that reveals active fault systems in the area and indicates N-S extension/E-W compression that changes orientation and relative magnitude from north to south. A broad zone of seismic quiescence in the western plateau may indicate a zone of upper crustal decoupling from large-scale deformation. The region separating the western and eastern plateau exhibits a complex stress field that can be related to the boundary of east/west oriented middle-to-lower crustal flow in the main volcanic arc. Southeast of the plateau in the Sierras Pampeanas, crustal seismicity deepens and is dominated by conjugate reverse faulting structures associated with the direction of plate convergence. Vp and Vs seismic velocity models of the upper crust obtained through local earthquake tomography with the improved seismic catalog show low-velocity anomalies near intermontane basins, except in the Antofagasta basin where a high-velocity anomaly possibly represents shallow intrusive component of Quaternary basaltic volcanism. Below the Cerro Galan caldera, an upper crustal 10-day long earthquake swarm is observed which may indicate local stress perturbations from fluids at the top of the crustal magmatic system that feeds this volcano.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"275 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142869971","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":"Dislocation Creep of Diopside Aggregates Under Unsaturated Hydrous Conditions at a Confining Pressure of 300 MPa","authors":"Jianfeng Li, Maoshuang Song, Hao Wang, Guinan Zhang, Shenghua Mei, Xiaodong Zheng, Xiaoning Wang, Zhexuan Jiang","doi":"10.1029/2024jb029472","DOIUrl":"https://doi.org/10.1029/2024jb029472","url":null,"abstract":"To understand the dislocation creep behavior of clinopyroxene in the upper mantle, hot-pressed diopside aggregates without predrying treatment were triaxially deformed under water-unsaturated conditions at a confining pressure of 300 MPa, temperatures of 1323–1523 K, and strain rates of 10⁻⁶–10⁻⁴ s⁻¹, using a Paterson gas-medium apparatus. Fourier transform infrared measurements of the water contents of the samples before and after deformation revealed that water diffusion loss occurred during the deformation process. A simple diffusion model based on Fick's law was established to predict the variation in the water content with respect to time during deformation. Fitting the mechanical data with a power flow law yielded a stress exponent <i>n</i> of 4.3 ± 0.3, an activation energy <i>Q</i> of 427 ± 31 kJ/mol and a water content exponent <i>r</i> of 1.2 ± 0.2 for the dislocation creep of the diopside aggregates under water-unsaturated conditions. When the flow law was extrapolated to anhydrous and water-saturated conditions, the calculated flow strengths of the diopside aggregates were generally in agreement with the strengths determined directly by deformation experiments, but there also existed contribution from grain boundary water under water-saturated conditions. The results of our study indicate that the strength of diopside or upper mantle clinopyroxene is comparable to the strength of olivine under anhydrous conditions but weaker than that of olivine under water-saturated conditions in the dislocation creep regime. Therefore, diopside might dominate the rheological behavior in some clinopyroxene-enriched and hydrous regions of the upper mantle.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"92 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874473","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":"Experimental Evidence for Reaction-Induced Weakening of (Carbonated) Serpentinite Fault Gouges","authors":"L. Eberhard, A. R. Niemeijer, O. Plümper","doi":"10.1029/2024jb029887","DOIUrl":"https://doi.org/10.1029/2024jb029887","url":null,"abstract":"The seismic potential of faults depends on the local mineralogy and can change upon mineral reactions. We conducted friction experiments on serpentinite, carbonate and carbonated serpentinite fault gouges at temperatures from 400°C to 630°C, under 100 MPa effective normal stress and fluid saturated conditions. Pure serpentinite fault gouges exhibited unstable slip with significant strain-hardening. Carbonate-bearing serpentinite fault gouges showed stable sliding at temperatures &lt;500°C, but displayed unstable stick-slip behavior and strong strain weakening at temperatures ≥500°C. Microstructural analyses revealed localization and the formation of olivine and pyroxene from devolatilization reactions at temperatures ≥500°C. The degree of devolatilization increased near major slip planes and was enhanced by higher temperature and carbonate content, as shown by three-dimensional micro-computer tomography analyses. Nano-scale transmission electron microscopy analyses revealed the absence of hydrous and carbonate phases along major slip planes. We attribute the strong weakening and unstable slip behavior in carbonated serpentinite fault gouges to the formation of nano-sized anhydrous phases of olivine and pyroxene along the slip plane. Our results indicate that serpentinized fault zones may experience seismic event nucleation at temperatures approaching the thermodynamic stability limit of serpentine. This suggests that the absence of seismic events cannot exclusively be attributed to serpentinization. The formation of carbonates, through replacive and additive carbonation, can explain aseismic deformation in transform faults, but at elevated temperatures, devolatilization reactions in carbonated serpentinites cause strong localization and strain weakening, accompanied by laboratory seismicity.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"125 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874475","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":"Revisiting Slip Deficit Rates and Its Insights Into Large and Slow Earthquakes at the Nankai Subduction Zone","authors":"Raymundo Plata-Martinez,&nbsp;Takeshi Iinuma,&nbsp;Fumiaki Tomita,&nbsp;Yasuyuki Nakamura,&nbsp;Takuya Nishimura,&nbsp;Takane Hori","doi":"10.1029/2023JB027942","DOIUrl":"10.1029/2023JB027942","url":null,"abstract":"<p>The Nankai subduction zone presents significant seismic and tsunami risks, given its historical earthquakes exceeding magnitude 8 and the expectations of similar future events. Slow earthquakes, common at the shallow and deep plate interface, result from different frictional properties linked to interplate slip deficit accumulation. This study estimates slip deficit rates at the Nankai subduction zone using land and ocean-bottom geodetic data. Previous estimates encountered limitations, often smoothing slip deficits, omitting observational error differences between ocean-floor and land data, and relying on homogeneous structure models. To address these issues, we employ a novel trans-dimensional reversible jump Markov Chain Monte Carlo algorithm. This approach dynamically adjusts slip parameters, accommodating data resolution and producing a flexible slip distribution without predetermined spatial constraints. Additionally, it automatically weights data for observational errors and integrates elastic Green functions from a 3D structure of the Nankai region. Our results provide a finer, heterogeneous slip distribution, improving estimates in inland regions. However, limitations remain offshore in areas with sparse data. We revised the spatial distribution of Nankai slow earthquakes and confirmed a good agreement with intermediate slip deficit rates, identifying coupled and uncoupled regions. High slip deficit rates align with rupture areas of historic large earthquakes. Slow earthquakes occur at frictionally weak plate interfaces, and shallow slow earthquakes may result from subducting relief heterogeneities with important pore fluid pressure effects. We introduce an updated distribution of slip deficit rates for the Nankai subduction zone, considering observed slip deficit rates and the fast and slow earthquake occurrence.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JB027942","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857724","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}