Journal of Geophysical Research: Solid Earth最新文献_第4页

Toward Back-Projection Earthquake Rupture Imaging With Ocean Bottom Distributed Acoustic Sensing 海底分布声传感反演地震破裂成像研究

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-19 DOI: 10.1029/2025JB031483

Yuqing Xie, Jean-Paul Ampuero, Martijn van den Ende, Alister Trabattoni, Marie Baillet, Diane Rivet

{"title":"Toward Back-Projection Earthquake Rupture Imaging With Ocean Bottom Distributed Acoustic Sensing","authors":"Yuqing Xie, Jean-Paul Ampuero, Martijn van den Ende, Alister Trabattoni, Marie Baillet, Diane Rivet","doi":"10.1029/2025JB031483","DOIUrl":"https://doi.org/10.1029/2025JB031483","url":null,"abstract":"Distributed acoustic sensing (DAS) along seafloor fiber optic cables offers high-density, wide-aperture, real-time seismic data near subduction earthquakes, at a lower cost than conventional cabled ocean bottom seismic networks. It is thus a very promising approach to develop offshore observatories for hazard monitoring and mitigation and for fundamental research on earthquake processes. Here, we introduce a method for earthquake rupture imaging by back-projection of DAS data, taking full advantage of the data characteristics to achieve high resolution and accuracy. To develop and test the method, we use DAS data recorded along submarine telecom cables in Chile. The approach includes pre-processing steps, such as spatial integration and sediment time corrections, that greatly improve the back-projection performance. Our analysis of recordings of small earthquakes that can be considered as point sources demonstrates high accuracy in localizing seismic sources, with a resolution ranging from 2 to 5 km within a “high-resolution and high-robustness zone” around the cable. We demonstrate the ability of the method to image large ruptures by applying it to simulated waveforms of a magnitude seven earthquake, constructed by superposition of multiple empirical Green's functions. We find that strong coda waves do not compromise the precise detection and location of sub-sources. Our method could enhance early warning systems and offer high-resolution observations crucial for studying fault mechanics.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031483","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144869570","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}

引用次数: 0

Imaging Localized Slip-Induced Frictional Heating During Laboratory Earthquakes Using Magnetic Microscopy 用磁显微镜成像实验室地震中局部滑移引起的摩擦加热

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-18 DOI: 10.1029/2025JB031286

Zheng Gong, Roger R. Fu, Daniel Ortega-Arroyo, Hoagy O’Ghaffari, Matěj Peč, Valère R. Lambert

{"title":"Imaging Localized Slip-Induced Frictional Heating During Laboratory Earthquakes Using Magnetic Microscopy","authors":"Zheng Gong, Roger R. Fu, Daniel Ortega-Arroyo, Hoagy O’Ghaffari, Matěj Peč, Valère R. Lambert","doi":"10.1029/2025JB031286","DOIUrl":"https://doi.org/10.1029/2025JB031286","url":null,"abstract":"Slip-induced heating is crucial for understanding fault mechanics and energy partitioning during earthquakes. The strongest heating occurs in a thin, millimeter to sub-millimeter-scale zone, which poses a challenge for existing geothermometers because they lack spatial resolution or are limited to specific rock compositions. Here, we utilize the recently developed quantum diamond microscope (QDM) to resolve thermal demagnetization at micrometer resolution around experimentally produced slip zones, thereby quantifying the near-field slip-induced temperature excursion. This new technique also enables us to observe ∼300 μm-scale along-fault heterogeneities in heating intensity, highlighting the role of localized stress and deformation in guiding frictional evolution. A simple 1-dimensional heat diffusion model can simultaneously satisfy the temperature estimates from QDM, far-field thermocouple measurements, and microstructural observations of localized melting. This model constrains the thermal energy density during slip to be 52–65 kJ/m2 during our laboratory earthquakes, which accounts for 52%–75% of the total energy budget. We also estimate that the average friction coefficient during rapid slip is 0.2–0.3, suggesting significant weakening during slip. Our results provide new insights into the role of localized heating during earthquake-like failure and illuminate the role of thermal weakening mechanisms at pressures corresponding to the base of the seismogenic crust.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144861822","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}

引用次数: 0

Inferring Long-Term Geocenter Motion From Low-Degree Gravity Field 从低度重力场推断长期地心运动

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-17 DOI: 10.1029/2024JB030327

Yufeng Nie, Jianli Chen, Dongju Peng, Jin Li

{"title":"Inferring Long-Term Geocenter Motion From Low-Degree Gravity Field","authors":"Yufeng Nie, Jianli Chen, Dongju Peng, Jin Li","doi":"10.1029/2024JB030327","DOIUrl":"https://doi.org/10.1029/2024JB030327","url":null,"abstract":"Accurate determination of geocenter motion is essential not only for establishing a stable terrestrial reference frame, but also for deriving a complete picture of large-scale global mass redistribution in the Earth system. For geophysical applications, reliable geocenter motions can be inferred from time-variable gravity fields provided by the Gravity Recovery and Climate Experiment (GRACE) since 2002, but it is more challenging for the pre-GRACE era where only low-degree gravity fields are available from the Satellite Laser Ranging (SLR). In addition, geocenter motion estimates derived from SLR using the direct method lack the trend in a linear reference frame and are therefore generally not suitable for studying mass change rates. In this study, we derive the geocenter motion from low-degree gravity fields up to degree and order 5 after properly addressing signal leakage. Using the leakage-corrected land mass patterns combined with corresponding ocean mass fingerprints, we generate geocenter motion estimates and compare them with those derived from GRACE, geophysical models, and the SLR direct method between 2002 and 2020. The trends in our estimates are consistent with GRACE and models, with differences below 0.1∼0.2 mm/yr depending on the quality of the gravity field models, while the SLR direct estimates yield opposite trends, leading to significantly underestimated global ocean mass change rates. Our study provides the first promising solution to derive long-term geocenter motion rates from low-degree gravity fields, which can be used to track large-scale mass change back to the 1990s.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030327","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144861930","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}

引用次数: 0

Stress Heterogeneities Governed by Fault Structure and Stress Transfer: The 2016–2017 Central Italy Seismic Sequence 断裂结构和应力传递控制的应力非均质性：2016-2017年意大利中部地震序列

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-16 DOI: 10.1029/2024JB029763

Patricia Martínez-Garzón, Men-Andrin Meier, Cristiano Collettini, Federica Lanza, Georg Dresen

{"title":"Stress Heterogeneities Governed by Fault Structure and Stress Transfer: The 2016–2017 Central Italy Seismic Sequence","authors":"Patricia Martínez-Garzón, Men-Andrin Meier, Cristiano Collettini, Federica Lanza, Georg Dresen","doi":"10.1029/2024JB029763","DOIUrl":"https://doi.org/10.1029/2024JB029763","url":null,"abstract":"We analyze the evolution of stress parameters from the 2016–2017 central Italy seismic sequence taking advantage of ∼13,747 robust focal mechanisms from a deep learning catalog. The density of the catalog allows us to invert focal mechanisms over distances of a few km and different time periods. We inferred a number of stress-related parameters, including the fault plane variability, the orientation of principal stress axes and maximum horizontal stress, the relative magnitudes of principal stresses and the variability of the principal stress orientations with respect to the median. From the uniform regional stress field consistent with the extension of the Apennine Belt, we observe local stress heterogeneities that are driven by the structural features and the coseismic stress history. A variation of the principal stress magnitudes and regimes from pure normal faulting toward transtension with depth is observed. Stress differences at the 1–10 km wavelength are observed between each side of two of the main regional fault structures. The reported stress results suggest a partial mechanical coupling and a strong interaction between the shallow normal faults and the detachment horizon at depth. Furthermore, distinct trends are observed in the stress parameters after the largest mainshocks, and before the MW 6.5 Norcia mainshock, potentially indicating the high shear stress still available in well oriented faults after the MW 6.0 Amatrice earthquake. Our analysis holds implications toward (a) constraining stress magnitudes, (b) illuminating the interaction between the shallow normal faults and detachment horizons, and (c) tracking stress evolution during seismic sequence.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029763","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144858589","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}

引用次数: 0

Paleomagnetic Evidence for a Late Permian Qaidam-North China Connection, and the Cryptic Final Mesozoic Intra-Asian Suture 晚二叠世柴达木-华北连接的古地磁证据与末中生代亚洲内隐缝

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-14 DOI: 10.1029/2025JB031123

Teng Wang, Yanan Zhou, Douwe J. J. van Hinsbergen, Jiaopeng Sun, Xin Cheng, Ruiyang Chai, Shihua Xu, Pengfei Wang, Hanning Wu

{"title":"Paleomagnetic Evidence for a Late Permian Qaidam-North China Connection, and the Cryptic Final Mesozoic Intra-Asian Suture","authors":"Teng Wang, Yanan Zhou, Douwe J. J. van Hinsbergen, Jiaopeng Sun, Xin Cheng, Ruiyang Chai, Shihua Xu, Pengfei Wang, Hanning Wu","doi":"10.1029/2025JB031123","DOIUrl":"https://doi.org/10.1029/2025JB031123","url":null,"abstract":"Paleomagnetic data have long shown that the final assembly of eastern Eurasia occurred in the latest Jurassic, after the North China Block moved 1,000 s of km toward Eurasia throughout the late Paleozoic and Mesozoic. This was accommodated along the Solonker and Mongol-Okhotsk subduction zones whose sutures are well documented in (inner) Mongolia. During this time, one or more plate boundaries must have existed west of China to connect the (inner) Mongolian suture with the Paleotethyan plate boundaries. Paradoxically, no candidate Mesozoic plate boundary is known between North China and Eurasia to its west, in northern Tibet, the Tarim Basin, or the Tien Shan region. In this study, we show paleomagnetic pole from Upper Permian (255.7 ± 3.8 Ma) red beds from the Qaidam Block of northern Tibet, adjacent to the Tarim Basin, with positive fold test and corrected for inclination shallowing, with D = 348.7° ± 2.3°, I = 47° ± 2.5°, λ = 77.6°N, ɸ = 332.8°E, A95 = 2.1°, K = 24.7, N = 199. These data reveal that Qaidam Block's paleolatitude was indistinguishable from that expected if it was part of North China but must have undergone ∼21° ± 2° (>2,300 ± 220 km) paleolatitudinal motion relative to Eurasia since late Permian time. This suggests that the missing plate boundary (or boundaries), in the form of a transform or a subduction zone, must be sought around or within the Tarim Basin. This may form a starting point in a search for the cryptic, last intra-Asian suture(s) and calls for systematic regional restoration of circum-Tarim tectonic history.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144833257","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}

引用次数: 0

Development of 1D Hybrid Hydromechanical Models for Real-Time Forecasting of Induced Seismicity Rate 实时预测诱发地震活动性的一维混合流体力学模型的建立

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-14 DOI: 10.1029/2025JB031592

V. Clasen Repollés, A. P. Rinaldi, F. Ciardo, L. Passarelli, D. Karvounis, S. Wiemer

{"title":"Development of 1D Hybrid Hydromechanical Models for Real-Time Forecasting of Induced Seismicity Rate","authors":"V. Clasen Repollés, A. P. Rinaldi, F. Ciardo, L. Passarelli, D. Karvounis, S. Wiemer","doi":"10.1029/2025JB031592","DOIUrl":"https://doi.org/10.1029/2025JB031592","url":null,"abstract":"Hydraulic stimulations play an important role in Enhanced Geothermal Systems (EGS) by increasing the permeability of the host rock and facilitating more efficient fluid circulation and heat extraction. However, fluid injection operations are unavoidably accompanied by induced earthquakes. Adaptive Traffic Light Systems (ATLS) have been proposed as seismic risk mitigation tools for EGS stimulations. An ATLS scheme aims to provide real-time, adaptive, and time-dependent probabilistic seismic forecasts by leveraging the latest available data during ongoing industrial operations. Critical to ATLS are numerical models capable of robustly forecasting the temporal evolution of induced seismicity, while properly accounting for uncertainties. In this work, we present two classes of 1D hybrid hydromechanical models for real-time forecasting of induced earthquakes. We retrospectively apply these models to data sets from hydraulic stimulations performed at four different spatial scales: Grimsel Test Site (2017), Bedretto Underground Laboratory for Geoenergy and Geosciences (2022), Utah FORGE (2022), and Basel Deep Heat Mining project (2006). We compare the models' forecasting performance and real-time applicability. We found that a nonlinear pressure solution that accounts for both reversible and irreversible permeability changes, coupled with an analytical probability density-based approach to simulate seismicity, is more suitable for industrial-scale applications. A stochastic approach that explicitly simulates seismicity, albeit simplified and improved for computational efficiency, exhibits greater variability in performance and remains computationally expensive for industrial-scale cases involving large seismic data sets and high spatial resolution requirements.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031592","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144833258","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}

引用次数: 0

Microstructural Evolution of Carrara Marble During Semi-Brittle Deformation 半脆性变形过程中卡拉拉大理岩的显微组织演化

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-13 DOI: 10.1029/2024JB030914

Tongzhang Qu, Nicolas Brantut, David Wallis, Christopher Harbord

{"title":"Microstructural Evolution of Carrara Marble During Semi-Brittle Deformation","authors":"Tongzhang Qu, Nicolas Brantut, David Wallis, Christopher Harbord","doi":"10.1029/2024JB030914","DOIUrl":"https://doi.org/10.1029/2024JB030914","url":null,"abstract":"Fifteen marble samples were subjected to semi-brittle deformation through triaxial compression experiments, reaching axial strains of about 0.5%, 1.0%, 2.0%, 4.0%, or 7.5% at temperatures of 20°C, 200°C, or 350°C, under a confining pressure of 400 MPa. Deformation twins, lattice curvature, and intragranular microfractures in the samples were quantitatively characterized using forescattered electron images and electron backscatter diffraction. Microstructural analyses revealed that twins accommodate most of the shortening during the first 2% strain, whereas lattice curvature associated with geometrically necessary dislocations predominantly develops with more strain. Intragranular fracture intensity exhibits an almost linear correlation with strain during the first 2% strain but increases more gradually with strain thereafter. The mechanical data indicate a strong decrease of yield stress with temperature increasing between 20°C and 200°C, consistent with the temperature dependence of the critical resolved shear stress for dislocation glide. The post-yield strain hardening is likely caused by progressively increasing intensity of interactions among dislocations and between dislocations and twin boundaries. Based on the microstructural data and interpreted hardening mechanisms, we propose a phenomenological model, with state variables representing microstructural elements that hinder dislocation glide, as a step toward development of a microphysical constitutive model of semi-brittle deformation.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030914","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144833061","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}

引用次数: 0

Inclination Divergence of Paleomagnetic Data Caused by Tectonic Strain in Cretaceous Redbeds From the Lhasa Terrane (Tibetan Plateau): Insights From AMS, hf-AIR, and CPO Analyses 青藏高原拉萨地体白垩系红层构造应变引起的古地磁资料倾斜偏离：来自AMS、hf-AIR和CPO分析的启示

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-11 DOI: 10.1029/2024JB030655

Hongliang Lu, Baochun Huang, Qian Zhao, Zhiyu Yi, Josep M. Parés

{"title":"Inclination Divergence of Paleomagnetic Data Caused by Tectonic Strain in Cretaceous Redbeds From the Lhasa Terrane (Tibetan Plateau): Insights From AMS, hf-AIR, and CPO Analyses","authors":"Hongliang Lu, Baochun Huang, Qian Zhao, Zhiyu Yi, Josep M. Parés","doi":"10.1029/2024JB030655","DOIUrl":"https://doi.org/10.1029/2024JB030655","url":null,"abstract":"Paleomagnetic data from the Lhasa Terrane have been commonly utilized to constrain the paleo-position and shape of the southern margin of Asia prior to the India-Asia collision. However, there has been an ongoing debate regarding the reliability of the paleomagnetic data derived from Upper Cretaceous sedimentary rocks in the Lhasa Terrane. Here, we employ combined anisotropy of magnetic susceptibility (AMS), high-field anisotropy of isothermal remanent magnetization (hf-AIR), and crystal preferred orientation (CPO) measurements on the redbeds of the Shexing Formation. Regardless of the structure displayed by the AMS, the hf-AIR demonstrates a weak cleavage to deformational magnetic fabric, with minimum axes corresponding roughly with the c-axis of hematite in the bedding plane. Consequently, we argue that the inclination divergence observed between the two limbs of anticlines in the Late Cretaceous paleomagnetic data from the Lhasa Terrane is attributable to the rotation of hematite under weak post-depositional tectonic strain. We caution against using Upper Cretaceous redbeds from the Lhasa Terrane for paleogeographic reconstruction without an efficient correction of tectonic strain. Furthermore, we propose the adoption of anisotropy of magnetic remanence as a more suitable alternative to AMS for assessing the reliability of paleomagnetic data in sedimentary rocks.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144814970","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}

引用次数: 0

Waveform Effects on Shear Wave Splitting Near Fault Zones 断裂带附近横波分裂的波形效应

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-11 DOI: 10.1029/2025JB031656

J. Hua, V. Schulte-Pelkum, T. W. Becker, B. He, H. Zhu

{"title":"Waveform Effects on Shear Wave Splitting Near Fault Zones","authors":"J. Hua, V. Schulte-Pelkum, T. W. Becker, B. He, H. Zhu","doi":"10.1029/2025JB031656","DOIUrl":"https://doi.org/10.1029/2025JB031656","url":null,"abstract":"Shear wave splitting of teleseismic core phases such as SKS is commonly used to constrain mantle seismic anisotropy, a proxy for convective deformation. In plate boundaries, sharp lateral variations of splitting measurements near transform faults are often linked to deformation within a lithospheric shear zone below, but potential seismic waveform effects from heterogeneous structure on small scales may influence the interpretation. Here, we explore possible finite frequency effects on shear wave splitting near fault zones in a fully three-dimensional anisotropic setting. We find that shear zones wider than <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>80 km, a scale set by the Fresnel zone, can be clearly detected, but narrower zones are less distinguishable. Near the edge of the shear zone, the combined effect of anisotropy and scattering generates false splitting measurements with large delay times and fast axis orientation approaching the back-azimuth, a bias which can only be identified when records from different back-azimuths are analyzed together. This substantiates that back-azimuthal variations of splitting can arise not just from vertical layering but also lateral changes of anisotropic media. We also test the effects of shear zone edge geometry, epicentral distance, filtering frequency, crustal thickness, and sediment cover. Our study delineates the ability of shear wave splitting to resolve and investigate fault zones, and emphasizes the importance of good azimuthal coverage to correctly interpret observed anisotropy. Based on revisiting previous shear wave splitting and lithospheric deformation studies, we infer that many crustal fault zones are underlain by lithospheric shear zones at least 20 km wide.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB031656","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144814972","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}

引用次数: 0

Structure of the Ecuadorian Upper Plate From a Joint Seismic-Gravity Inversion 从地震-重力联合反演厄瓜多尔上板块结构

IF 4.1 2区地球科学

Journal of Geophysical Research: Solid Earth Pub Date : 2025-08-10 DOI: 10.1029/2024JB030667

Andrew Birkey, Colton Lynner, Chengping Chai, Monica Maceira

{"title":"Structure of the Ecuadorian Upper Plate From a Joint Seismic-Gravity Inversion","authors":"Andrew Birkey, Colton Lynner, Chengping Chai, Monica Maceira","doi":"10.1029/2024JB030667","DOIUrl":"https://doi.org/10.1029/2024JB030667","url":null,"abstract":"The Ecuadorian portion of the South American subduction zone presents an interesting case study in the structure and complex evolution of an upper plate. There are outstanding questions about its tectonic history, composition, and magmatic processes. While previous studies have employed ambient noise tomography to image the Ecuadorian upper plate, surface wave inversions alone often lack sensitivity at relevant shallow depths. This limitation can be overcome with an independent, complementary data set, such as gravity. We have jointly inverted Rayleigh wave phase velocities and Bouguer gravity anomalies to provide a more detailed seismic velocity model of the Ecuadorian upper plate. Our joint inversion has yielded several key improvements from previous models. First, we observe much shallower slow velocities beneath major basins (the Manabí, Progreso, and Gulf of Guayaquil), better aligning with expected basin structure. Second, we identify a high-velocity block beneath the entire forearc, corresponding to the Piñon Terrane, with velocities suggesting the presence of ultramafic material. Third, we highlight a new narrow swath of slow velocities beneath the Ecuadorian Andes, which closely follows the active volcanoes along the Eastern Cordillera. The extent of these slow velocities coincides with the termination of active arc volcanism and the predicted location of the subducted Carnegie Ridge. The predicted compositions for the mid to lower crust in the region preclude a purely compositional explanation for these velocities, suggesting that some level of partial melt is necessary.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 8","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030667","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144811372","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}

引用次数: 0