Journal of Geophysical Research: Solid Earth最新文献

{"title":"Dynamic Rupture Modeling of Large Earthquake Scenarios at the Hellenic Arc Toward Physics-Based Seismic and Tsunami Hazard Assessment","authors":"Sara Aniko Wirp, Alice-Agnes Gabriel, Thomas Ulrich, Stefano Lorito","doi":"10.1029/2024JB029320","DOIUrl":"10.1029/2024JB029320","url":null,"abstract":"<p>The Mediterranean Hellenic Arc subduction zone (HASZ) has generated several <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>W</mi>\u0000 </msub>\u0000 <mo>≥</mo>\u0000 </mrow>\u0000 <annotation> ${mathrm{M}}_{W}ge $</annotation>\u0000 </semantics></math>8 earthquakes and tsunamis. Seismic-probabilistic tsunami hazard assessment typically utilizes uniform or stochastic earthquake models, which may not represent dynamic rupture and tsunami generation complexity. We present an ensemble of ten 3D dynamic rupture earthquake scenarios for the HASZ, utilizing a realistic slab geometry. Our simplest models use uniform along-arc pre-stresses or a single circular initial stress asperity. We then introduce progressively more complex models varying initial shear stress along-arc, multiple asperities based on scale-dependent critical slip weakening distance, and a most complex model blending all aforementioned heterogeneities. Thereby, regional initial conditions are constrained without relying on detailed geodetic locking models. Varying epicentral locations in the simplest, homogeneous model leads to different rupture speeds and moment magnitudes. We observe dynamic fault slip penetrating the shallow slip-strengthening region and affecting seafloor uplift. Off-fault plastic deformation can double vertical seafloor uplift. A single-asperity model generates a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>W</mi>\u0000 </msub>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${mathrm{M}}_{W}sim $</annotation>\u0000 </semantics></math>8 scenario resembling the 1303 Crete earthquake. Using along-strike varying initial stresses results in <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>W</mi>\u0000 </msub>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${mathrm{M}}_{W}sim $</annotation>\u0000 </semantics></math>8.0–8.5 dynamic rupture scenarios with diverse slip rates and uplift patterns. The model with the most heterogeneous initial conditions yields a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>W</mi>\u0000 </msub>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${mathrm{M}}_{W}sim $</annotation>\u0000 </semantics></math>7.5 scenario. Dynamic rupture complexity in prestress and fracture energy tends to lower earthquake magnitude but enhances tsunami","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029320","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566211","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":"Exploring the Dynamic Interactions Between the Southern San Andreas Fault and a Normal Fault Under the Salton Sea","authors":"Luis Iván Bazán Flores,&nbsp;Christodoulos Kyriakopoulos,&nbsp;David D. Oglesby,&nbsp;Aron J. Meltzner,&nbsp;Thomas K. Rockwell,&nbsp;John M. Fletcher,&nbsp;Daniel Brothers","doi":"10.1029/2023JB028621","DOIUrl":"10.1029/2023JB028621","url":null,"abstract":"<p>We investigate the dynamic interactions between the Southern San Andreas Fault (SSAF) and a proximal normal fault (NF) beneath the Salton Sea in southern California. The NF, positioned near the SSAF terminus at Bombay Beach, exhibits 11–15 displacement events across 14 stratigraphic sequences, with a range of 0.2–1.4 m of vertical offset since ∼2–3 ka. Notably, four of these events may align temporally with SSAF earthquakes, raising questions about the possible interplay between the two faults. Utilizing dynamic rupture models, we analyze the coseismic interactions between the SSAF and NF, addressing under what conditions the SSAF induces slip on the NF. Our findings reveal that a suite of SSAF ruptures, particularly those propagating from north to south, can trigger slip on the normal fault and replicate observed vertical offsets. If the SSAF extends beneath the Salton Sea, earthquakes originating south of the NF intersection are less likely to trigger normal fault slip, although we cannot exclude this possibility. Some SSAF ruptures do not trigger discernible slip on the NF, rendering such events undetectable in the stratigraphic record. Our research contributes toward discussions regarding the seismic hazard in southern California, shedding light on the interplay between the SSAF and NF.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566210","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":"Dʺ Structures Beneath the East China Sea Resolved by P-Wave Slowness Anomalies","authors":"Jiewen Li,&nbsp;Dongdong Tian,&nbsp;Daoyuan Sun,&nbsp;Ping Tong","doi":"10.1029/2024JB029584","DOIUrl":"https://doi.org/10.1029/2024JB029584","url":null,"abstract":"<p>The Dʺ layer, defined as 200–400 km in the lowermost mantle, is a thermal and chemical boundary layer between the solid silicate mantle and the liquid outer core. Deciphering the detailed structures of the Dʺ region is essential for unlocking the thermal and chemical states in the deep Earth. Here, we precisely measure the slowness and back-azimuth of the direct P-waves by beamforming based on the <i>F</i>-trace stack at the KZ Array in Kazakhstan, to investigate the detailed Dʺ structures beneath the East China Sea. The P-wave slowness for rays turning beneath the East China Sea exhibits a significant anomaly as a function of the P-wave turning depth. Strong correlations between slowness and back-azimuth anomalies for rays from different directions suggest a tilted Moho, with a tilting direction of ∼103° and a dip angle of ∼15°, beneath the KZ Array, further supported by radial receiver functions. After correcting for the slowness anomalies caused by the tilted Moho and heterogeneities outside the Dʺ layer, we construct a series of <i>Vp</i> Dʺ models to fit the remaining slowness anomalies for rays sampling the East China Sea. We obtain the best Dʺ model with a height of 360 km, a maximum <i>δVp</i> of +1.4%, a Dʺ discontinuity thickness of 120 km, and an 80-km low-velocity layer at the base of the mantle by minimizing residuals between the predicted and observed slowness anomalies. Combining the sharpness of the Dʺ discontinuity imaged here with mineralogical analysis suggests a Fe-enriched region in a cold subduction environment beneath the East China Sea.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573988","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":"Seismic Image of the Central to Southern Andean Subduction Zone Through Finite-Frequency Tomography","authors":"Y. Kondo,&nbsp;M. Obayashi,&nbsp;H. Sugioka,&nbsp;H. Shiobara,&nbsp;A. Ito,&nbsp;M. Shinohara,&nbsp;H. Iwamori,&nbsp;M. Kinoshita,&nbsp;M. Miller,&nbsp;C. Tassara,&nbsp;J. Ojeda","doi":"10.1029/2024JB028844","DOIUrl":"https://doi.org/10.1029/2024JB028844","url":null,"abstract":"<p>This study presents new seismic imaging of the Andean subduction zone through P-wave hybrid finite-frequency and ray-theoretical tomography. We measured both differential and absolute traveltimes using broadband seismic waveforms from stations in an array of ocean-bottom seismographs near the Chile Triple Junction (CTJ) and stations within 30° of the array. These data were combined with the global traveltime data set to obtain a global P-wave velocity structure with a focus on central to southern South America. The new tomographic image showed the Nazca slab geometry as a continuous fast anomaly, which is consistent with seismic activity and prior slab models. Furthermore, two notable structures were observed: a broad extension of the fast anomaly beneath the Nazca slab at 26–35°S and a slow anomaly east of the CTJ. The checkerboard resolution and recovery tests confirmed the reliability of these large-scale features. The fast anomaly, isolated from the Nazca slab, was interpreted as a relic Nazca slab segment based on its strong amplitude and spatial coincidence with the current Pampean and past Payenia flat slab segments. The slow anomaly near the CTJ was consistent with the previously inferred extent of the Patagonian slab window. Moreover, the active adakitic volcanoes are aligned with the southern edge of the anomaly, and the plateau basalts are located within the anomaly. Our model showed that the slow anomaly extended to a depth of up to 250 km, suggesting a depth limit that the asthenospheric window can influence.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561543","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":"Crustal Deformation and Seismic Velocity Perturbations in the Alto Tiberina Fault Zone (Northern Apennines, Italy)","authors":"C. Almagro Vidal,&nbsp;L. Zaccarelli,&nbsp;F. Pintori,&nbsp;E. Serpelloni","doi":"10.1029/2024JB029023","DOIUrl":"https://doi.org/10.1029/2024JB029023","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Crustal perturbations related to seismic activity can generally be observed with the occurrence of a large magnitude event. For less energetic seismic sequences though, the associated transient crustal variations are questionably measurable, and their observation gets easily obscured by relatively stronger perturbations such as the ones related to hydrological processes. In this study we reveal the significant role that terrestrial water-storage variations play in governing temporal crustal changes in the tectonically active Northern Apennines of Italy, and discuss the potential of accounting for its correction in order to monitor the relatively weaker transient perturbations caused by local seismic swarms. This area is characterized by an extensive level of low-energetic seismic activity, typically clustered in time and space, of which three main seismic swarms outstand during the 12 year period of study (2010–2021). Our analysis compares independent observations and processing methods of Global Navigation Satellite System measurements and ambient seismic noise recordings. We adopt a multivariate statistical approach to discriminate between independent sources of ground deformation, and seismic noise cross-correlation analysis to monitor relative seismic-velocity variations. The result shows how the perturbation effects produced by variations in total water content are dominant in both time series of ground deformations and seismic-velocity variations. After correcting for the water-related variation effects, our monitoring results reveal perturbations in the crustal properties whose activation time and depth range correlate with the occurrences of the seismic swarms.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561736","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":"Shear-Dominant Continental Rifting in Northern Ryukyu Revealed by Ambient Noise Tomography","authors":"Kai-Xun Chen,&nbsp;Ban-Yuan Kuo,&nbsp;Ting-Jun Lin,&nbsp;Pei-Ying Patty Lin,&nbsp;Yuancheng Gung,&nbsp;Eh Tan,&nbsp;Shuichi Kodaira,&nbsp;Yasushi Ishihara,&nbsp;Mamoru Nakamura,&nbsp;Ryuta Arai,&nbsp;Fang-Yi Lee,&nbsp;Shu-Huei Hung,&nbsp;Kate Huihsuan Chen,&nbsp;Ching-Ren Lin,&nbsp;Chau-Chang Wang","doi":"10.1029/2024JB029448","DOIUrl":"https://doi.org/10.1029/2024JB029448","url":null,"abstract":"<p>In this study, we reveal the deformational structure of the crust of the northern part of the Ryukyu Arc and Okinawa Trough using ambient noise tomography. Compared with southern Ryukyu, the northern segment exhibits a wide and shallow basin, a crust without localized thinning, slow extension rates, and highly arc-oblique, right-lateral retreat of the Ryukyu Arc. We present both isotropic and azimuthally anisotropic shear-wave velocity models using data recorded by an ocean-bottom seismometer array and nearby island stations. The isotropic model demonstrates a monotonic decrease in velocity from the backarc to the forearc, in accord with the accretionary-prism origin of the latter. The resolved azimuthal anisotropy exhibits arc-parallel and arc-perpendicular fast shear-wave polarization directions in the upper to mid-crust and the lower crust to uppermost mantle in much of the arc and backarc, respectively. We interpret the arc-parallel anisotropy as resulting from the anisotropic fabrics aligned by the vertical shearing imposed by the right-lateral motion of the Ryukyu Arc. The underlying arc-perpendicular anisotropy may be attributed to horizontal shearing driven by corner flow in the mantle wedge. We found arc-perpendicular anisotropy in the forearc upper crust, which may reflect crack alignment caused by the collision of the Amami Plateau. The oblique arc retreat and the resolved deformation fabrics in the arc and backarc together attest to the shear-dominant, transtensional nature of the northern Ryukyu continental rift system. Some of the features in northern Ryukyu may be better explained from the perspective of transtensional rifting.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029448","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561686","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":"Mitigation and Optimization of Induced Seismicity Using Physics-Based Forecasting","authors":"Ryley G. Hill,&nbsp;Matthew Weingarten,&nbsp;Cornelius Langenbruch,&nbsp;Yuri Fialko","doi":"10.1029/2024JB028759","DOIUrl":"https://doi.org/10.1029/2024JB028759","url":null,"abstract":"<p>Fluid injection can induce seismicity by altering stresses on pre-existing faults. Here, we investigate minimizing induced earthquake potential by optimizing injection operations in a physics-based forecasting framework. We built a 3D finite element model of the poroelastic crust for the Raton Basin, Central US, and used it to estimate time dependent Coulomb stress changes due to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>25 years of wastewater injection in the region. Our finite element model is complemented by a statistical analysis of the seismogenic index (SI), a proxy for critically stressed faults affected by variations in the pore pressure. Forecasts of seismicity rate from our hybrid physics-based statistical model suggest that induced seismicity in the Raton Basin, from 2001 to 2022, is still driven by wastewater injection despite declining injection rates since 2011. Our model suggests that pore pressure diffusion is the dominant cause of Coulomb stress changes at seismogenic depth, with poroelastic stress changes contributing about 5% to the driving force. Linear programming optimization for the Raton Basin reveals that it is feasible to reduce earthquake potential for a given amount of injected fluid (safety objective) or maximize fluid injection for a prescribed earthquake potential (economic objective). The optimization tends to spread out high-rate injectors and shift them to regions of lower SI. The framework has practical importance as a tool to manage injection rate per unit field area to reduce induced earthquake potential. Our optimization framework is both flexible and adaptable to mitigate induced earthquake potential in other regions and for other types of subsurface fluid injection.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB028759","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525297","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":"Lithospheric Structure and Strength Variations in Antarctica From Joint Modeling of Elevation, Geoid and Seismic Data","authors":"Fei Ji,&nbsp;Mingju Xu,&nbsp;Qiao Zhang,&nbsp;Xiaochun Liu,&nbsp;Xin Zhou","doi":"10.1029/2024JB029455","DOIUrl":"https://doi.org/10.1029/2024JB029455","url":null,"abstract":"<p>Antarctica is renowned for its ancient cratons, difficult-to-observe sutures and active continental rifts. Detailed lithospheric structure and strength estimates are crucial for understanding the potential distribution, long-term geological evolution, and deformation patterns of this continent. The lithospheric structure of the Antarctic continent is investigated based on joint modeling of elevation and geoid data with the incorporation of seismic data and thermal constraints. Moreover, these results are used to infer the yield strength envelopes across Antarctica. The laterally variable lithospheric strength is finally generated by vertically integrating the above envelopes. Our results show that the variations in the depth of the lithosphere-asthenosphere boundary (LAB) are analogous to the variations in the integrated lithospheric strength; these parameters vary from 60 to 220 km and from 0.5 × 10¹³ Pa m to 4.5 × 10¹³ Pa m, respectively. Several regions of East Antarctica exhibit thick and strong lithospheric mantle, suggesting the presence of scattered cratonic blocks. In contrast, a thin and weak lithosphere is observed in the tectonically active West Antarctica and East Antarctic orogenic belts. Generally, our new LAB model correlates well with previous estimates, but there is a significant inconsistency beneath the Gamburtsev Subglacial Mountains, where a shallow LAB (∼120 km), high Moho temperature, and low strength (&lt;1.0 × 10¹³ Pa m) are estimated. We speculate that this anomaly may be similar to the thinned lithosphere in Dronning Maud Land and reflects the removal of the mantle lithosphere during or after the orogenesis associated with the assembly of the Gondwana supercontinent.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525683","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":"Numerical Simulation on the Electrical Conductivity of Ternary Mixtures Containing NaCl Solution, Quartz, and Smectite","authors":"K. Aoyama,&nbsp;T. Hashimoto","doi":"10.1029/2024JB029063","DOIUrl":"https://doi.org/10.1029/2024JB029063","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>While the electrical conductivity of smectite-rich rocks is high, previous studies have only partially revealed its dependence on temperature, salinity, and porosity. This knowledge gap mainly arises from challenges in controlling various experimental conditions when measuring the conductivity of real smectite-bearing rock samples and quantifying the smectite content. To mimic conductivity measurements under ideal conditions, this study aimed to develop a simulator capable of accurately configuring the conditions to predict the direct-current conductivity of saturated rocks composed of an aqueous NaCl solution, quartz, and smectite under various temperatures (20°C–200°C), salinities (10⁻⁴–5 mol kg⁻¹), porosities (0–1), and smectite fractions (0–1). The simulator reproduced the experimental conductivity measurements from drilled core samples by giving the anisotropy of those components' distribution. In addition, simulations with randomly assigned components revealed that when rocks contain abundant smectite, the bulk conductivity partially decreases with increasing NaCl solution's salinity or volume fraction. These negative slopes were approximated using empirical equations derived from previous studies. Percolation analysis further revealed that when the components are randomly assigned, conductive paths begin to form between the ends of the modeled sample once the sum of the volume fraction of bulk pore and smectite reaches 0.1.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029063","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525684","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":"Structure and Non-Ideal Mixing of Fe-Ni-S Liquid at High Temperature and Pressure and Its Implication for the Earth's Outer Core Composition","authors":"Sajin Satyal,&nbsp;Jianwei Wang","doi":"10.1029/2024JB029436","DOIUrl":"https://doi.org/10.1029/2024JB029436","url":null,"abstract":"<p>The effect of light elements (LEs) such as sulfur on the physical properties of liquid iron-nickel alloy under the earth's outer core conditions is critical for understanding the core composition and dynamics. First-principles molecular dynamics simulations were employed to model Fe-Ni-S liquid with S concentrations in the range of (0–25) atomic percent (at%) at 4050 K and (0–33.33) at% at 5530 K and pressures relevant to the core-mantle boundary (CMB) and inner core boundary (ICB), respectively. The thermodynamic mixing properties of Fe-Ni-S liquid were calculated, showing that the excess volume for Fe-Ni-S alloys deviates negatively from ideal mixing by −0.33% at 12.5 at% S at the CMB and −0.35% at 17 at% S at the ICB. Similarly, the excess enthalpy negatively deviated from the ideal mixing by −3.4 kJ/mole and −13 kJ/mole at the similar S concentrations at CMB and ICB, respectively, indicating non-ideal mixing throughout the outer core. Similar behaviors are observed for isothermal bulk modulus (<i>K</i>_T) and seismic velocity. The short- and intermediate-range structures were analyzed and used to explain the non-ideal mixing behaviors. The results suggest that extrapolations using ideal mixing underestimates the sound velocity by ∼0.14 km/s near CMB and ∼0.10 km/s near ICB, which is significant for constraining the core composition. If S is the only LE, the density at 10–12 wt% S matches the preliminary reference earth model (PREM). The seismic velocity at 12–15 wt% S matches PREM. These results suggest the presence of other LEs in the outer core.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525468","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}