Pub Date : 2025-11-07DOI: 10.1016/j.pepi.2025.107467
Mohammad Raeesi , Aram Fathian , Ali Misaghi , Cristiano Tolomei
The June 21, 2022, Khost earthquake in southeastern Afghanistan impacted a rural area housing multiple inadequately constructed towns and villages. Reports indicated over 3600 injuries and a minimum of 1163 fatalities. Historical records did not document any significant seismic events in the area prior to this incident. To examine the rupture process of the earthquake, we conducted multiple analyses using teleseismic and InSAR data, employing separate and joint slip inversion. Given that the 2022 earthquake only slightly ruptured the near-surface crust, the results imply that significantly larger earthquakes might occur again in the same location. The main stress was released as an impulsive rupture that lasted only two to three seconds.
{"title":"Source characteristics of the June 21, 2022 (Mw 6.1) Khost earthquake, Afghanistan","authors":"Mohammad Raeesi , Aram Fathian , Ali Misaghi , Cristiano Tolomei","doi":"10.1016/j.pepi.2025.107467","DOIUrl":"10.1016/j.pepi.2025.107467","url":null,"abstract":"<div><div>The June 21, 2022, Khost earthquake in southeastern Afghanistan impacted a rural area housing multiple inadequately constructed towns and villages. Reports indicated over 3600 injuries and a minimum of 1163 fatalities. Historical records did not document any significant seismic events in the area prior to this incident. To examine the rupture process of the earthquake, we conducted multiple analyses using teleseismic and InSAR data, employing separate and joint slip inversion. Given that the 2022 earthquake only slightly ruptured the near-surface crust, the results imply that significantly larger earthquakes might occur again in the same location. The main stress was released as an impulsive rupture that lasted only two to three seconds.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"369 ","pages":"Article 107467"},"PeriodicalIF":1.9,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-06DOI: 10.1016/j.pepi.2025.107465
Junjun Zhou , Bo Han , Andreas Junge , Xiangyun Hu , Tiaojie Xiao , Zhidan Long , Ningbo Bai
A three-dimensional (3D) magnetotelluric (MT) inversion framework for arbitrarily anisotropic media has been developed. This method integrates efficient forward modeling with Gauss-Newton (GN) minimization, utilizing an implicit formulation for sensitivity calculations. The forward problem is discretized using the edge-based finite element (FE) method, where a real-valued linear system, derived from the original complex-valued system, is solved with a direct-iterative hybrid solver to enhance computational efficiency. To address the storage and computational challenges posed by large, dense matrices during inversion, the preconditioned conjugate gradient (PCG) algorithm is employed for model updates. A horizontal anisotropic model is used to evaluate various inversion scenarios, including isotropic, principal axial anisotropic, and more complex anisotropic cases. The influence of inversion parameters on the data is analyzed, and the recoverability of these parameters is thoroughly investigated. Furthermore, the anisotropic inversion algorithm is applied to a complex model that includes both anisotropic and isotropic blocks to evaluate the algorithm's reliability. Finally, the inversion method is tested on the USArray MT dataset, demonstrating its robustness and effectiveness.
{"title":"Effective gauss-newton inversion for 3D magnetotelluric data with arbitrarily anisotropic conductivities","authors":"Junjun Zhou , Bo Han , Andreas Junge , Xiangyun Hu , Tiaojie Xiao , Zhidan Long , Ningbo Bai","doi":"10.1016/j.pepi.2025.107465","DOIUrl":"10.1016/j.pepi.2025.107465","url":null,"abstract":"<div><div>A three-dimensional (3D) magnetotelluric (MT) inversion framework for arbitrarily anisotropic media has been developed. This method integrates efficient forward modeling with Gauss-Newton (GN) minimization, utilizing an implicit formulation for sensitivity calculations. The forward problem is discretized using the edge-based finite element (FE) method, where a real-valued linear system, derived from the original complex-valued system, is solved with a direct-iterative hybrid solver to enhance computational efficiency. To address the storage and computational challenges posed by large, dense matrices during inversion, the preconditioned conjugate gradient (PCG) algorithm is employed for model updates. A horizontal anisotropic model is used to evaluate various inversion scenarios, including isotropic, principal axial anisotropic, and more complex anisotropic cases. The influence of inversion parameters on the data is analyzed, and the recoverability of these parameters is thoroughly investigated. Furthermore, the anisotropic inversion algorithm is applied to a complex model that includes both anisotropic and isotropic blocks to evaluate the algorithm's reliability. Finally, the inversion method is tested on the USArray MT dataset, demonstrating its robustness and effectiveness.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"369 ","pages":"Article 107465"},"PeriodicalIF":1.9,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-04DOI: 10.1016/j.pepi.2025.107468
Kotaro Tarumi, Kazunori Yoshizawa
Lateral structural variations in the upper mantle generate azimuthal dependence in receiver functions (RFs) based on incoming directions of body waves. Although these azimuthal variations in RFs have not been considered in earlier studies of RF inversions, they provide a means to image localized changes in upper mantle interfaces. In this study, we incorporate azimuth-dependent RFs into a joint Bayesian inversion with multimode surface waves, applying this approach to major permanent broadband stations in Australia. The resulting models reveal dependence on event directions, and by identifying P-to-S conversion depths, we constructed a localized map of conversion points, reflecting local lateral variations of upper mantle discontinuities beneath each station. At the CTAO station in northeastern Australia, the lithosphere thickens rapidly northwestward, from 70 km to 120-130 km depth, corresponding to the tectonic boundary with the western cratonic region. At stations in western and central Australia, lithospheric thickness also varies laterally within the stable cratons, though these changes are more gradual than those in northeastern Australia. In addition to the lithosphere–asthenosphere boundary (LAB), both mid-lithospheric discontinuities (MLDs) and X-discontinuities (X-Ds) are observed in the local 1-D profiles. The X-Ds, characterized by seismic velocity jumps below the LAB, are found at multiple depths around 170, 220, 260, and 310 km, depending on location, accompanying the weakened radial anisotropy across these depths. The multiple MLDs are also identified in the cratonic regions, showing substantial variations in their seismological properties, including both positive or negative S-velocity jumps, which vary with location and depth. Our approach, incorporating azimuth-dependent RFs, enables the detection of localized changes in the upper mantle discontinuities and associated elastic properties, providing new insights into the complex layering of the upper mantle.
{"title":"Detecting rapid lateral changes of upper mantle discontinuities using azimuth-dependent P-wave receiver functions and multimode surface waves","authors":"Kotaro Tarumi, Kazunori Yoshizawa","doi":"10.1016/j.pepi.2025.107468","DOIUrl":"10.1016/j.pepi.2025.107468","url":null,"abstract":"<div><div>Lateral structural variations in the upper mantle generate azimuthal dependence in receiver functions (RFs) based on incoming directions of body waves. Although these azimuthal variations in RFs have not been considered in earlier studies of RF inversions, they provide a means to image localized changes in upper mantle interfaces. In this study, we incorporate azimuth-dependent RFs into a joint Bayesian inversion with multimode surface waves, applying this approach to major permanent broadband stations in Australia. The resulting models reveal dependence on event directions, and by identifying P-to-S conversion depths, we constructed a localized map of conversion points, reflecting local lateral variations of upper mantle discontinuities beneath each station. At the CTAO station in northeastern Australia, the lithosphere thickens rapidly northwestward, from 70 km to 120-130 km depth, corresponding to the tectonic boundary with the western cratonic region. At stations in western and central Australia, lithospheric thickness also varies laterally within the stable cratons, though these changes are more gradual than those in northeastern Australia. In addition to the lithosphere–asthenosphere boundary (LAB), both mid-lithospheric discontinuities (MLDs) and X-discontinuities (X-Ds) are observed in the local 1-D profiles. The X-Ds, characterized by seismic velocity jumps below the LAB, are found at multiple depths around 170, 220, 260, and 310 km, depending on location, accompanying the weakened radial anisotropy across these depths. The multiple MLDs are also identified in the cratonic regions, showing substantial variations in their seismological properties, including both positive or negative S-velocity jumps, which vary with location and depth. Our approach, incorporating azimuth-dependent RFs, enables the detection of localized changes in the upper mantle discontinuities and associated elastic properties, providing new insights into the complex layering of the upper mantle.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"369 ","pages":"Article 107468"},"PeriodicalIF":1.9,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145468949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-03DOI: 10.1016/j.pepi.2025.107466
Benjamin T. Strozewski , Ojashvi Rautela , Johannes Buchen , Wolfgang Sturhahn , Takayuki Ishii , Itaru Ohira , Olivia Pardo , Jiyong Zhao , Thomas S. Toellner , Jennifer M. Jackson
Oxyhydroxide phases in the (Al,Fe)OOH–MgSiO2(OH) system may form within oceanic lithosphere and transport hydrogen in their crystal structures into the lowermost mantle via cold, subducted slabs. In this work, we present new measurements of the seismic wavespeeds of the dense oxyhydroxide (Al,Fe)-phase H (Al0.84FeMg0.02Si0.06OOH) to 100 GPa constrained by nuclear resonant inelastic X-ray scattering, incorporating previous constraints on the equation of state of this phase. At 300 K and pressure greater than 70 GPa, (Al,Fe)-phase H exhibits high P-wave speeds (lnV +12%) and low S-wave speeds (lnV −7%) relative to the preliminary reference Earth model (PREM). Experimentally determined sound velocities are incorporated into a model of a hydrous metabasalt including (Al,Fe)-phase H and compared with the seismic wavespeeds of pyrolitic mantle along appropriate adiabats. Hydrous metabasalt may reproduce an anti-correlation of negative shear wave velocity and positive bulk sound velocity at the upper edges of large, low velocity provinces when compared to pyrolitic mantle but has similar wavespeeds to PREM in this region. Hydrous metabasalt with conceivable concentrations of (Al,Fe)-phase H can be distinguished from PREM in V at mid-mantle depths (1100–1700 km) and in V at shallower depths (750–1000 km). Subducted hydrous metabasalt could contribute to scattering of seismic waves across the depth interval of the post-stishovite transition, which may be affected by the formation of (Al,Fe)-phase H.
{"title":"Sound velocities of (Al,Fe)-phase H and the seismic visibility of dense oxyhydroxides in Earth’s lower mantle","authors":"Benjamin T. Strozewski , Ojashvi Rautela , Johannes Buchen , Wolfgang Sturhahn , Takayuki Ishii , Itaru Ohira , Olivia Pardo , Jiyong Zhao , Thomas S. Toellner , Jennifer M. Jackson","doi":"10.1016/j.pepi.2025.107466","DOIUrl":"10.1016/j.pepi.2025.107466","url":null,"abstract":"<div><div>Oxyhydroxide phases in the (Al,Fe)OOH–MgSiO<sub>2</sub>(OH)<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> system may form within oceanic lithosphere and transport hydrogen in their crystal structures into the lowermost mantle via cold, subducted slabs. In this work, we present new measurements of the seismic wavespeeds of the dense oxyhydroxide (Al,Fe)-phase H (Al<sub>0.84</sub>Fe<span><math><msubsup><mrow></mrow><mrow><mn>0</mn><mo>.</mo><mn>07</mn></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msubsup></math></span>Mg<sub>0.02</sub>Si<sub>0.06</sub>OOH) to 100 GPa constrained by nuclear resonant inelastic X-ray scattering, incorporating previous constraints on the equation of state of this phase. At 300 K and pressure greater than 70 GPa, (Al,Fe)-phase H exhibits high P-wave speeds (<span><math><mi>δ</mi></math></span>lnV<span><math><msub><mrow></mrow><mrow><mi>P</mi></mrow></msub></math></span> <span><math><mo>></mo></math></span>+12%) and low S-wave speeds (<span><math><mi>δ</mi></math></span>lnV<span><math><msub><mrow></mrow><mrow><mi>S</mi></mrow></msub></math></span> <span><math><mo><</mo></math></span>−7%) relative to the preliminary reference Earth model (PREM). Experimentally determined sound velocities are incorporated into a model of a hydrous metabasalt including (Al,Fe)-phase H and compared with the seismic wavespeeds of pyrolitic mantle along appropriate adiabats. Hydrous metabasalt may reproduce an anti-correlation of negative shear wave velocity and positive bulk sound velocity at the upper edges of large, low velocity provinces when compared to pyrolitic mantle but has similar wavespeeds to PREM in this region. Hydrous metabasalt with conceivable concentrations of (Al,Fe)-phase H can be distinguished from PREM in V<span><math><msub><mrow></mrow><mrow><mi>S</mi></mrow></msub></math></span> at mid-mantle depths (1100–1700 km) and in V<span><math><msub><mrow></mrow><mrow><mi>P</mi></mrow></msub></math></span> at shallower depths (750–1000 km). Subducted hydrous metabasalt could contribute to scattering of seismic waves across the depth interval of the post-stishovite transition, which may be affected by the formation of (Al,Fe)-phase H.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"369 ","pages":"Article 107466"},"PeriodicalIF":1.9,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145520961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.pepi.2025.107460
Ján Šimkanin
Changes in the geomagnetic field corresponding to the Earth’s inner core growth are numerically investigated. The Geodynamo is driven by thermochemical convection in the Earth’s outer core, with the codensity gradient serving as the primary driving force. Simulations begin with a small inner core (‘Past’), which progressively enlarges until reaching a stage where the inner core becomes dominant (‘Future’). During the ’Past’ stage, the Geodynamo model generates a multipolar geomagnetic field, which gradually transitions into a predominantly dipolar field as the inner core grows. These transitions are also accompanied by shifts between weak-field and strong-field dynamos and vice versa. The ratio of magnetic to kinetic energy emerges as a more reliable parameter for controlling the transition from multipolar to dipolar dynamos. The dipole component for a small inner core proves unstable, with frequent polarity reversals. As the inner core grows, the frequency of these reversals decreases until the ‘Present’ case, where polarity reversals cease entirely. It is important to note that during the ‘Past’, fluctuations in dipole polarity are observed even in a dipole-dominated magnetic field. In the ‘Future’ stage, representing a potential scenario for the Earth’s geomagnetic field, the hydromagnetic dynamo produces a dipole-dominated magnetic field without polarity reversals. However, if the Earth’s liquid outer core becomes exceedingly small, convection diminishes, causing the Geodynamo to fail. This leads to a slow decay of the magnetic field due to magnetic diffusion. During the ’Future’ stage, the emergence of subcritical dynamos is observed. It is important to note that the results of the present analysis are more strongly influenced by the supercriticality of the flow than by the inner core size, as the latter is determined by the selected solution parameters.
{"title":"Geomagnetic field and the growth of the Earth’s inner core: Past, present and future","authors":"Ján Šimkanin","doi":"10.1016/j.pepi.2025.107460","DOIUrl":"10.1016/j.pepi.2025.107460","url":null,"abstract":"<div><div>Changes in the geomagnetic field corresponding to the Earth’s inner core growth are numerically investigated. The Geodynamo is driven by thermochemical convection in the Earth’s outer core, with the codensity gradient serving as the primary driving force. Simulations begin with a small inner core (‘Past’), which progressively enlarges until reaching a stage where the inner core becomes dominant (‘Future’). During the ’Past’ stage, the Geodynamo model generates a multipolar geomagnetic field, which gradually transitions into a predominantly dipolar field as the inner core grows. These transitions are also accompanied by shifts between weak-field and strong-field dynamos and vice versa. The ratio of magnetic to kinetic energy emerges as a more reliable parameter for controlling the transition from multipolar to dipolar dynamos. The dipole component for a small inner core proves unstable, with frequent polarity reversals. As the inner core grows, the frequency of these reversals decreases until the ‘Present’ case, where polarity reversals cease entirely. It is important to note that during the ‘Past’, fluctuations in dipole polarity are observed even in a dipole-dominated magnetic field. In the ‘Future’ stage, representing a potential scenario for the Earth’s geomagnetic field, the hydromagnetic dynamo produces a dipole-dominated magnetic field without polarity reversals. However, if the Earth’s liquid outer core becomes exceedingly small, convection diminishes, causing the Geodynamo to fail. This leads to a slow decay of the magnetic field due to magnetic diffusion. During the ’Future’ stage, the emergence of subcritical dynamos is observed. It is important to note that the results of the present analysis are more strongly influenced by the supercriticality of the flow than by the inner core size, as the latter is determined by the selected solution parameters.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"368 ","pages":"Article 107460"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.pepi.2025.107459
Clemens Kloss
Studies of Earth’s magnetic field and its sources rely on accurate geomagnetic field models derived from ground and satellite-based magnetic data. During the field model estimation, data errors are usually assumed to be uncorrelated in time and independent of position. However, limitations in the field model parameterization, especially regarding ionospheric and magnetospheric fields, lead to data errors that are not only larger than the expected measurement noise but are also correlated in time and vary with position. As a result, the obtained model uncertainties are often underestimated, making it more challenging to evaluate the reliability of recovered signals in the field models.
This study investigates the effect of including correlated data errors in field modeling. The approach involves building a stochastic data error model to treat correlated errors due to unmodeled magnetospheric fields within the CHAOS geomagnetic field modeling framework. The error model parameters are estimated using empirical covariances computed from vector residuals between the satellite magnetic observations made by the Swarm satellites and the CHAOS geomagnetic field model. Field modeling experiments are performed with and without including the data error covariances described in the stochastic error model.
The inclusion of data error covariances due to unmodeled magnetospheric fields leads to only small changes in the estimated internal field, but also a noticeable increase in model uncertainty for the sectoral coefficients. This highlights the significant impact of unmodeled magnetospheric fields and the importance of accurately defining data errors, including the covariances between observations, for interpreting the retrieved magnetic signals in geomagnetic field modeling.
{"title":"Accounting for correlated data errors in geomagnetic field modeling using Swarm magnetic observations","authors":"Clemens Kloss","doi":"10.1016/j.pepi.2025.107459","DOIUrl":"10.1016/j.pepi.2025.107459","url":null,"abstract":"<div><div>Studies of Earth’s magnetic field and its sources rely on accurate geomagnetic field models derived from ground and satellite-based magnetic data. During the field model estimation, data errors are usually assumed to be uncorrelated in time and independent of position. However, limitations in the field model parameterization, especially regarding ionospheric and magnetospheric fields, lead to data errors that are not only larger than the expected measurement noise but are also correlated in time and vary with position. As a result, the obtained model uncertainties are often underestimated, making it more challenging to evaluate the reliability of recovered signals in the field models.</div><div>This study investigates the effect of including correlated data errors in field modeling. The approach involves building a stochastic data error model to treat correlated errors due to unmodeled magnetospheric fields within the CHAOS geomagnetic field modeling framework. The error model parameters are estimated using empirical covariances computed from vector residuals between the satellite magnetic observations made by the <em>Swarm</em> satellites and the CHAOS geomagnetic field model. Field modeling experiments are performed with and without including the data error covariances described in the stochastic error model.</div><div>The inclusion of data error covariances due to unmodeled magnetospheric fields leads to only small changes in the estimated internal field, but also a noticeable increase in model uncertainty for the sectoral coefficients. This highlights the significant impact of unmodeled magnetospheric fields and the importance of accurately defining data errors, including the covariances between observations, for interpreting the retrieved magnetic signals in geomagnetic field modeling.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"368 ","pages":"Article 107459"},"PeriodicalIF":1.9,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-30DOI: 10.1016/j.pepi.2025.107463
Charles-Édouard Boukaré , Laura K. Schaefer , Hanika Rizo
To celebrate over 55 years of Physics of the Earth and Planetary Interiors providing a venue for communicating advancements in the chemical and dynamical processes that lead to planetary differentiation, we revisit Earth’s magma ocean in light of the seminal works of Ohtani (1983); Abe and Matsui (1986). Models of Earth’s formation suggest a hot initial state in which much of the planet’s interior was substantially, if not entirely, molten. The global-scale molten silicate mantle is referred to as a magma ocean. Because elements of the periodic table show different affinities for liquid, solid, and gaseous phases, the transition from a molten to a solid mantle provides a key window for early chemical differentiation, with profound implications for Earth’s long-term evolution. The magma ocean hypothesis has been extensively studied in the context of the Moon’s evolution. Major advances in our understanding of the lunar magma ocean have been enabled by experimental access to relevant petrological conditions. Pioneering studies by Ohtani (1983); Abe and Matsui (1986); Solomatov and Stevenson (1993c); Abe (1997) explored magma ocean processes in the context of the Earth, and although high-pressure data for Earth’s mantle were limited at the time, these studies correctly anticipated much of the physics now central to early Earth models. Recent developments, including analyses of short-lived isotopic systems, high pressure experiments using diamond anvil cells, and ab-initio calculations are now providing new constraints on models of Earth’s magma ocean. This review summarizes these recent advances and how they change our understanding of the Earth’s magma ocean evolution. We also discuss the current challenges in developing an interdisciplinary yet coherent picture of the Earth’s earliest evolutionary stages.
为了庆祝超过55年的地球和行星内部物理学，提供了一个交流导致行星分化的化学和动力学过程进展的场所，我们根据大谷（1983）的开创性作品重新审视了地球的岩浆海洋；安倍和松井（1986）。地球形成的模型表明，在一个炎热的初始状态下，地球内部的大部分（如果不是全部的话）基本上是熔融的。全球范围的熔融硅酸盐地幔被称为岩浆海洋。由于元素周期表上的元素在液态、固态和气态阶段表现出不同的亲和力，从熔融地幔到固态地幔的转变为早期化学分化提供了一个关键窗口，对地球的长期演化具有深远的影响。岩浆海洋假说在月球演化的背景下得到了广泛的研究。我们对月球岩浆海洋的认识取得了重大进展，这是通过对相关岩石学条件的实验获得的。Ohtani（1983）的开创性研究；安倍和松井（1986）；Solomatov and Stevenson (1993c)；Abe（1997）在地球的背景下探索了岩浆海洋过程，尽管当时地幔的高压数据有限，但这些研究正确地预测了许多现在对早期地球模型至关重要的物理学。最近的发展，包括对短寿命同位素系统的分析，利用金刚石砧细胞进行的高压实验，以及从头算，现在为地球岩浆海洋的模型提供了新的限制。本文综述了这些最新进展，以及它们如何改变我们对地球岩浆海洋演化的认识。我们还讨论了目前在发展地球最早进化阶段的跨学科但连贯的图片所面临的挑战。
{"title":"The Earth’s magma ocean: Processes and current interpretations from an interdisciplinary perspective","authors":"Charles-Édouard Boukaré , Laura K. Schaefer , Hanika Rizo","doi":"10.1016/j.pepi.2025.107463","DOIUrl":"10.1016/j.pepi.2025.107463","url":null,"abstract":"<div><div>To celebrate over 55 years of Physics of the Earth and Planetary Interiors providing a venue for communicating advancements in the chemical and dynamical processes that lead to planetary differentiation, we revisit Earth’s magma ocean in light of the seminal works of Ohtani (1983); Abe and Matsui (1986). Models of Earth’s formation suggest a hot initial state in which much of the planet’s interior was substantially, if not entirely, molten. The global-scale molten silicate mantle is referred to as a magma ocean. Because elements of the periodic table show different affinities for liquid, solid, and gaseous phases, the transition from a molten to a solid mantle provides a key window for early chemical differentiation, with profound implications for Earth’s long-term evolution. The magma ocean hypothesis has been extensively studied in the context of the Moon’s evolution. Major advances in our understanding of the lunar magma ocean have been enabled by experimental access to relevant petrological conditions. Pioneering studies by Ohtani (1983); Abe and Matsui (1986); Solomatov and Stevenson (1993c); Abe (1997) explored magma ocean processes in the context of the Earth, and although high-pressure data for Earth’s mantle were limited at the time, these studies correctly anticipated much of the physics now central to early Earth models. Recent developments, including analyses of short-lived isotopic systems, high pressure experiments using diamond anvil cells, and ab-initio calculations are now providing new constraints on models of Earth’s magma ocean. This review summarizes these recent advances and how they change our understanding of the Earth’s magma ocean evolution. We also discuss the current challenges in developing an interdisciplinary yet coherent picture of the Earth’s earliest evolutionary stages.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"369 ","pages":"Article 107463"},"PeriodicalIF":1.9,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145468950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
MgO is the end-member of the primary constituents of the lower mantle, and identifying its crystal preferred orientation (CPO) developments or slip systems is key to understanding seismic observations and the dynamics of the lower mantle. To investigate the temperature dependence on CPO developments in MgO under high-pressure conditions corresponding to the lower mantle, we conducted large-strain deformation experiments using the rotational diamond anvil cell (rDAC) combined with synchrotron X-rays, achieving pressures up to 80 GPa and temperatures up to 973 K. Our results revealed that the CPO developments in MgO under large-strain deformation are temperature-dependent even at relatively low temperatures. The crystal plane parallel to the shear plane changed from the {110} plane to the {100} plane with increasing temperature and pressure. Based on our experimental results, we constructed a temperature-pressure map that shows the CPO variation of MgO. The temperature-pressure map obtained in this study provides essential foundational information for advancing our understanding of rheology in the lower mantle.
{"title":"Temperature and pressure dependence on slip systems in MgO: Insights from large-strain deformation experiments using the rotational diamond anvil cell","authors":"Keiya Ishimori , Shintaro Azuma , Kentaro Uesugi , Masahiro Yasutake , Keishi Okazaki , Bunrin Natsui , Eranga Gyanath Jayawickrama , Kenji Ohta","doi":"10.1016/j.pepi.2025.107461","DOIUrl":"10.1016/j.pepi.2025.107461","url":null,"abstract":"<div><div>MgO is the end-member of the primary constituents of the lower mantle, and identifying its crystal preferred orientation (CPO) developments or slip systems is key to understanding seismic observations and the dynamics of the lower mantle. To investigate the temperature dependence on CPO developments in MgO under high-pressure conditions corresponding to the lower mantle, we conducted large-strain deformation experiments using the rotational diamond anvil cell (rDAC) combined with synchrotron X-rays, achieving pressures up to 80 GPa and temperatures up to 973 K. Our results revealed that the CPO developments in MgO under large-strain deformation are temperature-dependent even at relatively low temperatures. The crystal plane parallel to the shear plane changed from the {110} plane to the {100} plane with increasing temperature and pressure. Based on our experimental results, we constructed a temperature-pressure map that shows the CPO variation of MgO. The temperature-pressure map obtained in this study provides essential foundational information for advancing our understanding of rheology in the lower mantle.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"369 ","pages":"Article 107461"},"PeriodicalIF":1.9,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a simple linear equation to calculate the degree of melting of the mantle using the major element composition of basalts. We constructed a model based on compiled results from high-pressure mantle melting experiments. We used a model selection approach to objectively select the optimal equation from many potential models, based on statistical criteria. We found that the degree of mantle melting () can be predicted with a simple equation that uses only the concentrations of three major elements, which are , FeO (total iron as FeO), and MgO (wt.%), as follows:
The model allows us to calculate the degree of melting of the uppermost upper mantle (spinel lherzolite and harzburgite), under both anhydrous and hydrous conditions. The equation yields the equilibrium degree of melting in the case of batch melting, and the weighted-mean degree of melting of accumulated melt in the case of fractional melting. We also describe the petrological and thermodynamic implications of the equation. The degrees of melting of natural basalts are calculated as examples of the application of the equation.
{"title":"A simple linear regression model for calculating the degree of melting of the upper mantle using the major element composition of basalts","authors":"Kenta Ueki , Satoru Haraguchi , Atsushi Nakao , Hikaru Iwamori","doi":"10.1016/j.pepi.2025.107464","DOIUrl":"10.1016/j.pepi.2025.107464","url":null,"abstract":"<div><div>We present a simple linear equation to calculate the degree of melting of the mantle using the major element composition of basalts. We constructed a model based on compiled results from high-pressure mantle melting experiments. We used a model selection approach to objectively select the optimal equation from many potential models, based on statistical criteria. We found that the degree of mantle melting (<span><math><mi>F</mi></math></span>) can be predicted with a simple equation that uses only the concentrations of three major elements, which are <span><math><msub><mrow><mi>SiO</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, FeO<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span> (total iron as FeO), and MgO (wt.%), as follows:</div><div><span><math><mrow><mi>F</mi><mrow><mo>(</mo><mi>wt</mi><mo>.</mo><mtext>%</mtext><mo>)</mo></mrow><mo>=</mo><mn>4</mn><mo>.</mo><mn>020</mn><mo>×</mo><msub><mrow><mi>SiO</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><mn>5</mn><mo>.</mo><mn>109</mn><mo>×</mo><msup><mrow><mi>FeO</mi></mrow><mrow><mo>∗</mo></mrow></msup><mo>+</mo><mn>1</mn><mo>.</mo><mn>436</mn><mo>×</mo><mi>MgO</mi><mo>−</mo><mn>244</mn><mo>.</mo><mn>924</mn><mo>.</mo></mrow></math></span></div><div>The model allows us to calculate the degree of melting of the uppermost upper mantle (spinel lherzolite and harzburgite), under both anhydrous and hydrous conditions. The equation yields the equilibrium degree of melting in the case of batch melting, and the weighted-mean degree of melting of accumulated melt in the case of fractional melting. We also describe the petrological and thermodynamic implications of the equation. The degrees of melting of natural basalts are calculated as examples of the application of the equation.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"368 ","pages":"Article 107464"},"PeriodicalIF":1.9,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-18DOI: 10.1016/j.pepi.2025.107462
Zhiwei Zhang , Feng Long , Chaoliang Wang , Weiming Wang , Di Wang , Qian Lu , Chuntao Liang
The 17 June 2019 Changning MS 6.0 earthquake occurred half a year after the 2018 Xingwen MS 5.7 earthquake in the Sichuan Basin, China. Even though the two earthquakes are only 15 km apart, their focal mechanism solutions are different. The stress regime is critical to revealing the mechanisms of moderate earthquakes in the industrial mining region. In this study, we used the CAP full waveform method to calculate the focal mechanism solution, relocated the aftershocks using a hybrid multi-stage method, and further discussed the stress trigger relationship of the two events. The results show that the seismogenic structure of the Changning earthquake is related to the Shuanghe anticline and Baixiangyan-Shizitan anticline and their associated faults, while the Xingwen earthquake may occur on the hidden fault between the Changning anticline and the Jianwu syncline. The azimuth of the maximum principal compressive stress (S1) is NEE in the Changning area and NWW in the Xingwen area, The S1 direction in the Changning area is inconsistent with the stress field (NW) in southeast Sichuan, the perturbation of the local stress field reveals that the influence of long-term salt injection in the Changning area is more obvious than that of short-term hydraulic fracturing in the Xingwen area. Moreover, the Xingwen MS 5.7 earthquake may play a triggering role in the Changning MS 6.0 earthquake via static stress transfer.
{"title":"Probing the seismogenic mechanisms of the Changning MS 6.0 and Xingwen MS 5.7 earthquakes in the Sichuan Basin, China","authors":"Zhiwei Zhang , Feng Long , Chaoliang Wang , Weiming Wang , Di Wang , Qian Lu , Chuntao Liang","doi":"10.1016/j.pepi.2025.107462","DOIUrl":"10.1016/j.pepi.2025.107462","url":null,"abstract":"<div><div>The 17 June 2019 Changning <em>M</em><sub>S</sub> 6.0 earthquake occurred half a year after the 2018 Xingwen <em>M</em><sub>S</sub> 5.7 earthquake in the Sichuan Basin, China. Even though the two earthquakes are only 15 km apart, their focal mechanism solutions are different. The stress regime is critical to revealing the mechanisms of moderate earthquakes in the industrial mining region. In this study, we used the CAP full waveform method to calculate the focal mechanism solution, relocated the aftershocks using a hybrid multi-stage method, and further discussed the stress trigger relationship of the two events. The results show that the seismogenic structure of the Changning earthquake is related to the Shuanghe anticline and Baixiangyan-Shizitan anticline and their associated faults, while the Xingwen earthquake may occur on the hidden fault between the Changning anticline and the Jianwu syncline. The azimuth of the maximum principal compressive stress (S<sub>1</sub>) is NEE in the Changning area and NWW in the Xingwen area, The S<sub>1</sub> direction in the Changning area is inconsistent with the stress field (NW) in southeast Sichuan, the perturbation of the local stress field reveals that the influence of long-term salt injection in the Changning area is more obvious than that of short-term hydraulic fracturing in the Xingwen area. Moreover, the Xingwen <em>M</em><sub>S</sub> 5.7 earthquake may play a triggering role in the Changning <em>M</em><sub>S</sub> 6.0 earthquake via static stress transfer.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"368 ","pages":"Article 107462"},"PeriodicalIF":1.9,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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