Journal of Geophysical Research: Solid Earth最新文献

{"title":"Characterizing Shallow Attenuation and Microearthquake Source Parameters Using a Downhole DAS Array at the Cape Modern Geothermal Field","authors":"Hilary Chang,&nbsp;Nori Nakata,&nbsp;Rachel E. Abercrombie,&nbsp;Sireesh Dadi,&nbsp;Aleksei Titov","doi":"10.1029/2026JB034276","DOIUrl":"10.1029/2026JB034276","url":null,"abstract":"<p>Earthquake source parameters are crucial for assessing seismic hazard and understanding earthquake source physics. However, source parameter estimation is challenging for small earthquakes because they suffer notorious trade-offs with shallow attenuation. Borehole Distributed Acoustic Sensing (DAS) uses fiber-optic cables to provide unprecedented spatial resolution for attenuation analysis and a closer recording of the earthquake source. In this study, we use DAS in a vertical well in the Cape Modern geothermal field, near Milford, Utah, to characterize shallow attenuation and estimate source parameters of microearthquakes <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mn>0</mn>\u0000 <mo>&lt;</mo>\u0000 <mi>M</mi>\u0000 <mo>&lt;</mo>\u0000 <mn>1.7</mn>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(0&lt; M&lt; 1.7)$</annotation>\u0000 </semantics></math> that occurred during a stimulation. We directly correct the DAS instrument response and directional sensitivity. We use along-depth spectral ratios to obtain a high-resolution Quality Factor (<i>Q</i>) profile for P waves in the top 2,500 m. We find low <i>Q</i> at the near surface, and that attenuation primarily decreases with depth, with less dependence on rock types, consistent with previous studies in California and Switzerland. We use a single-spectral approach to estimate corner frequency, source radius, slip, magnitude, and spectral stress drop over the limited magnitude range. The spectral stress drops do not show magnitude dependence, while their variability might relate to fault heterogeneity or rupture variability. The DAS response-correction is channel-dependent and can introduce biases in source parameters. We reduce potential biases by using channels with similar responses and checking measurement consistency. We use the Empirical Green's Function for two event pairs to benchmark the results. This work shows the potential of using DAS for understanding crustal attenuation and characterizing microearthquakes.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB034276","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895259","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":"Fully Contained Laboratory Earthquakes: The Effect of Asperity Aspect Ratio and Free Surfaces","authors":"Sara B. L. Cebry,&nbsp;Jun Young Song,&nbsp;Gregory C. McLaskey","doi":"10.1029/2025JB033548","DOIUrl":"10.1029/2025JB033548","url":null,"abstract":"<p>Corner frequency (<i>f</i>_<i>c</i>) and seismic moment (<i>M</i>_<i>0</i>) are key parameters derived from seismic signals that are used to characterize earthquake stress drop, rupture area, and slip. These parameters are also affected by fault geometry and boundary conditions. However, the systematic study of these effects in laboratory settings has been challenging. This study presents laboratory earthquake experiments that examine how rupture dynamics are influenced by (a) the aspect ratio of rectangular PMMA velocity-weakening (VW) asperities surrounded by the Teflon velocity-strengthening (VS) patches, and (b) whether the sides of a VW asperity are confined with VS patches or are free surfaces. We found that increasing confinement by reducing free surfaces or increasing the VW asperity aspect ratio stabilizes fault slip, so that higher normal stress is required to transition from aseismic to seismic slip. Increased confinement and high aspect ratios also reduced <i>M</i>_<i>0</i> and increased <i>f</i>_<i>c</i>, both of which were determined from the radiated seismic waves. <i>M</i>_<i>0</i> and <i>f</i>_<i>c</i> were primarily controlled by the shorter dimension of the VW asperity. Analysis of high-frequency acoustic emission signals revealed that ruptures on high-aspect-ratio VW asperities propagated more unidirectionally, whereas ruptures on square VW asperities were more complex. Further, the high-aspect-ratio asperities were more likely to be eroded by surrounding VS regions while low-aspect-ratio asperities were more likely to rupture into the VS surroundings. These results demonstrate that both the confinement from surrounding stable areas and the geometry of the seismogenic patch can affect rupture nucleation, propagation, and seismic source characteristics.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895261","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":"Imaging Submarine Fault Zones Using Reflected S-waves Extracted by Ambient Noise Interferometry From Distributed Acoustic Sensing","authors":"Zhufeng Lu,&nbsp;Xiaodong Yang,&nbsp;Heng Zhang,&nbsp;Liwei Wang,&nbsp;Xinghan Liu,&nbsp;Yao Luo,&nbsp;Fan Zhang,&nbsp;Jian Lin,&nbsp;Jianhua Geng,&nbsp;Jizhong Yang","doi":"10.1029/2025JB033370","DOIUrl":"10.1029/2025JB033370","url":null,"abstract":"<p>The northern margin of South China Sea has experienced strong tectonic deformation since the Late Mesozoic, and formed a complex fault network. Along this margin, previous studies have mainly imaged offshore faults in the Shantou region at &gt;30 m water depth. However, the precise fault location and geometry at &lt;30 m water depth (nearshore) are poorly resolved due to lack of geophysical observations, preventing a better assessment of marine geohazards. Here, we retrieve high-resolution zero-offset S-wave reflections from interferometric autocorrelation of ambient noise recorded by Distributed Acoustic Sensing (DAS) along a 29-km submarine cable deployed in the nearshore. The meter-scale reflections delineate stratigraphic boundaries, fault structures, and potential magmatic intrusions, where fault locations are validated by independent constraints including a 2D shear-wave velocity model, spurious energy in the cross-correlation functions, and earthquake wavefield analyses. We precisely locate the nearshore extension of the Changle-Nan'ao Fault and resolve an ∼8-km-wide graben bounded by the Nanpeng Island Outer Fault and a newly mapped fault, beneath the graben the igneous intrusion is identified, indicating strong tectonic and magmatic interaction. This structurally weakened zone has localized extension which may contribute to seafloor instability. By using DAS ambient noise autocorrelation, we successfully retrieved geologically interpretable reflections, demonstrating the potential of using existing fiber-optic cables to provide cost-effective, high-resolution structural constraints in complex tectonic settings.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895212","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":"Probability and Recurrence of Maximum Magnitude Based on Stochastic Modeling of Internal Fault Geometry","authors":"Vincent Roche,&nbsp;Mirko van der Baan,&nbsp;John Walsh,&nbsp;Tom Manzocchi","doi":"10.1029/2025JB032073","DOIUrl":"10.1029/2025JB032073","url":null,"abstract":"<p>The recognition that relay zones along faults can act as barriers to earthquake propagation implies that rupture size may not be random and earthquakes are constrained by fault geometry. Resolution and observational biases can, however, complicate the integration of actual fault zone geometries into deterministic modeling strategies, thereby negatively impacting earthquake magnitude assessment. This paper describes a statistical modeling strategy as an alternative. The chosen method relies on a stochastic approach combining quantitative fault zone characteristics with a kinematic model linking realistic fault segmentation with expected rupture termination. A sensitivity analysis highlights the effect of fault geometry on rupture sizes, including an increase in the probability of large ruptures, and corresponding changes in the earthquake magnitude-frequency distribution and associated <i>b</i>-values, with decreasing degrees of segmentation and increasing fault maturity. Three case studies confirm these effects for the Yushu-Ganzi-Xianshuihe fault system, the North Anatolian fault system, and hydraulic fracturing in Ohio. For each case, simulations show first-order agreement with documented seismicity, including observed magnitude-frequency distributions, and support the notion that fault characteristics such as relay zone size and internal segmentation are structural controls determining earthquake <i>b</i>-values and maximum magnitudes. These findings suggest that the incorporation of more realistic fault zone geometries and their impact on rupture cascading could improve seismic risk assessment across various regions.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB032073","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895258","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":"Pn-Wave Tomography Using Deep-Learning-Based Phase Picking Reveals Fine-Scale Structure of the Uppermost Mantle Beneath the Southwestern United States","authors":"Hua Kong,&nbsp;Yan Lü,&nbsp;Juan Li,&nbsp;Zhuowei Xiao,&nbsp;Lian-Feng Zhao,&nbsp;Lijun Liu","doi":"10.1029/2026JB034108","DOIUrl":"10.1029/2026JB034108","url":null,"abstract":"<p>The southwestern United States, with its intense tectonic activity and dense seismic networks, serves as a natural laboratory for studying crust-mantle material exchange and energy transfer. In recent years, the rapid growth of seismic observational data and the development of deep learning-based automatic phase-picking techniques have provided new opportunities for high-resolution seismic imaging research. This study utilized the Seis-PickNet phase-picking model to expand the Pn-wave travel-time database for the southwestern United States. Based on the newly picked travel times, the study constructed a high-resolution model of the uppermost mantle velocity structure and anisotropy structure in the region. The inversion results show that the spatial distribution of active tectonic units in the area corresponds well to significant low-velocity anomalies and strong anisotropic features in the uppermost mantle. Furthermore, the study reveals independent thermal upwelling conduits in the uppermost mantle beneath volcanic fields along the margins of the Colorado Plateau, including the Black Rock Desert Volcanic Field, the Uinkaret Volcanic Field, and the San Francisco Volcanic Field. Additionally, the results support the existence of ancient Farallon slab subduction remnants beneath the central Great Basin. This research not only deepens the understanding of mantle dynamics and complex subsurface structures in the region but also highlights the critical role of deep learning-driven phase-picking technology in enhancing the quality of seismic tomography.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895260","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 Velocity of Chlorite Under High Pressure and Temperature and Implications for the Lesser Antilles Subduction Zone","authors":"Nicholas Backhouse,Andrew Thomson,John Brodholt,Rostislav Hrubiak,Wilson Crichton,Ming Hao,Emmanuel A. Codillo,Anne Pommier,Michael J. Walter","doi":"10.1029/2025jb032997","DOIUrl":"https://doi.org/10.1029/2025jb032997","url":null,"abstract":"Abstract Chlorite is thought to be one of the major water‐carrying phases in subduction zones, both within the slab and in the mantle wedge. Its presence has previously been linked to common seismological observations at subduction zones, including P and S wave anisotropy as well as high V P / V S ratios (&gt;1.8) in the mantle wedge. However, at present, there are very few high pressure and temperature measurements of the seismic velocity of chlorite at subduction zone conditions, hampering accurate seismological interpretations. This study presents seismic velocities and PVT equation of state measurements of two natural monomineralic chlorite schists, at conditions extending up to ∼5 GPa and 773K. One major finding is the anomalously high V P / V S ratio of these samples, which increase &gt;3 at 5 GPa and 773 K. This result suggests that only a small amount of chlorite (&lt;10%) is required in mantle peridotite assemblages to reproduce the observed V P / V S anomalies &gt;1.8, such as those in the Lesser Antilles subduction zone, and that regions with high V P / V S are not necessarily diagnostic of a free fluid.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"17 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Impact of Double Subduction on Plate Velocity and Euler Pole Shifts: Insights From Spherical Subduction Models","authors":"Zonglin Guo,Adam F. Holt,Derya Gürer","doi":"10.1029/2026jb034505","DOIUrl":"https://doi.org/10.1029/2026jb034505","url":null,"abstract":"Abstract Same‐dip double subduction (SDDS), in which two parallel slabs dip in the same direction, has been linked to accelerated plate motion in both modern and ancient convergent systems, such as the Late Cretaceous Africa–Eurasia system. Yet a systematic framework for quantifying how SDDS alters plate kinematics in a large‐scale spherical geometry is lacking. Here, we use 3‐D spherical geodynamic models to investigate plate velocity changes and corresponding Euler pole shifts caused by the insertion of a second (rear) subduction zone. Across a wide range of rheological and geometric parameters, SDDS consistently increases the velocity of the subducting plate, especially behind the rear trench, redirects subducting‐plate motion toward the rear slab, and produces pronounced Euler pole shifts of up to 33 (∼3,600 km). We complement the numerical models with a torque‐balance analysis, which shows that these dramatic plate velocity changes arise from two primary effects: (a) additional slab pull exerted by the added slab and (b) a reduction in the effective subducting‐plate area contributing to basal‐drag resistance. This plate‐area reduction is the dominant contributor to Euler pole displacement, with enhanced slab pull providing a secondary but reinforcing effect. We characterize the impact of an extensive set of model parameters: plate and mantle rheology primarily modify velocity magnitudes, while geometric factors that modify plate and trench geometry govern the relative velocity differences (e.g., Euler pole shifts) between the single‐ and double‐subduction geometries. Our spherical subduction modeling provides a generalized geodynamic framework for interpreting plate‐motion reorganizations associated with intra‐oceanic subduction initiation and termination.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"35 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932983","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":"Pore‐Scale Mechanism of Anomalous Saturation Dependence for Induced Polarization: Insights From Desiccation Experiments and Pore‐Network Modeling","authors":"Siyuan Qiang,Xiaoqing Shi,André Revil,Alexis Maineult","doi":"10.1029/2026jb034086","DOIUrl":"https://doi.org/10.1029/2026jb034086","url":null,"abstract":"Abstract The complex conductivity method, also known as spectral induced polarization (SIP), is widely used in hydrogeophysical investigations. Power‐law functions with positive exponents between the in‐phase/quadrature components of complex conductivity and water saturation are key petrophysical relationships to interpret field data. However, laboratory and field tests frequently report anomalous observations in which quadrature conductivity (alternatively the normalized chargeability) increases with decreasing saturation. A mechanistic explanation for this phenomenon in terms of electrical double layer polarization theory has been lacking so far. Here, we investigate the pore scale mechanism of this anomalous behavior through laboratory desiccation experiments and numerical simulations. A pore‐network modeling framework that explicitly accounts for water‐solid interfacial effects on complex conductivity is established. The results show that the non‐monotonic dependence of quadrature conductivity on saturation is governed by two mechanisms: (i) the persistence or attenuation of polarization on water‐solid interfaces associated with different pore water configurations (scenarios with or without water film retention) and (ii) preferential drainage of larger pores during desiccation. These findings provide a water‐solid interface‐based physical explanation for the anomalous quadrature conductivity behavior, and offer a mechanistic basis for interpreting geoelectrical data in partially saturated media like soils and rocks.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"141 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932950","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":"3D Absorption and 2D Scattering Attenuation of the Kashmir “Seismic Gap” in NW Himalaya","authors":"Dibyajyoti Chaudhuri,Amarjeet Kumar,Supriyo Mitra,Sunil Kumar Wanchoo,Keith Priestley","doi":"10.1029/2026jb034313","DOIUrl":"https://doi.org/10.1029/2026jb034313","url":null,"abstract":"Abstract The Kashmir “seismic gap” in NW Himalaya has accumulated sufficient elastic strain to cause a great earthquake. Constraining the lateral and depth‐dependent variations in seismic attenuation across this region is essential for ground‐shaking estimation from earthquakes. Recently acquired waveform data from precisely‐located‐local earthquakes are used to compute: (a) 3D S‐wave attenuation using coda‐normalization; (b) 3D intrinsic absorption using coda quality‐factor; and (c) 2D scattering from peak delay‐time measurements. Our results, interpreted in light of the structure and seismicity, reveal frequency‐dependent variations in attenuation, controlled by the crustal structure, lithology, geometry of major thrusts and active faults. High attenuation/absorption characterize the sedimentary/meta‐sedimentary rocks of the Sub‐Himalaya and the Lesser Himalayan Duplex in the Kishtwar Window (KW). Enhanced attenuation and scattering within the KW and its surroundings are attributed to concentrated seismicity associated with the frontal ramp of the Main Himalayan Thrust (MHT). In contrast, the reentrants of the Main Frontal Thrust and Reasi Thrust, representing surface expressions of MHT lateral‐ramp, exhibit relatively low attenuation/absorption. This is possibly due to shallowing of the underthrust Indian crust across the lateral ramp. The Higher Himalayan crystallines show low attenuation and weak scattering. The Kashmir Valley shows lateral contrasts in attenuation/absorption, indicating varying sedimentary thicknesses. The MHT demarcates the contrast between the high absorption/attenuation Himalayan Wedge above and the low absorption/attenuation underthrusting Indian crust below. The Indian upper‐crust shows high attenuation in patches, possibly related to fluids from metamorphic dehydration reactions or inherited heterogeneity.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"138 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895266","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":"Segmented Crust of Southeastern Iran Reveals Complex Dynamics of the Zagros–Makran Transition: Insights From Ambient Noise Full-Waveform Inversion","authors":"Yanji Lyu,&nbsp;Shiva Arvin,&nbsp;Ling Chen,&nbsp;Morteza Talebian,&nbsp;Haiqiang Lan,&nbsp;Xueyang Bao,&nbsp;Xu Wang,&nbsp;Yifan Gao,&nbsp;Zimu Wu,&nbsp;José Badal,&nbsp;Bo Wan,&nbsp;Yang Chu,&nbsp;Yang Shen","doi":"10.1029/2025JB033196","DOIUrl":"10.1029/2025JB033196","url":null,"abstract":"<p>Southeastern Iran represents a key tectonic transition between the Zagros continental collision belt and the Makran oceanic subduction zone, providing an important natural setting to investigate how crustal structure and slab geometry vary across a collision–subduction boundary. Using a newly acquired seismic data set and an ambient noise full-waveform inversion method, we obtain a high-resolution 3D shear-wave (S-wave) velocity model for the crust and uppermost mantle down to 60 km depth. The obtained velocity structure is highly heterogeneous and exhibits pronounced segmentation. Makran is characterized by low-angle (∼8°–10°) oceanic subduction, while Zagros is dominated by pronounced collision-related crustal thickening and prominent low-velocity shear zones. The deepest Moho reaches ∼55 km depth beneath the Urumieh Dokhtar Magmatic Arc (UDMA), while the thinnest crust of ∼35 km (including sediments) is observed near Coastal Makran. Extremely thick, low-velocity sedimentary packages are imaged beneath the Makran accretionary wedge (∼20 km) and the Zagros fold-thrust belt (∼15 km). A mid-crustal high-velocity anomaly observed beneath the southern UDMA indicates solidified magmatic rocks. Another high-velocity anomaly beneath the Jaz Murian basin is interpreted as remnant oceanic lithosphere. A prominent lateral velocity contrast in the lower crust and uppermost mantle at the Zagros–Makran boundary, along with a diffuse zone in the middle-upper crust, indicates depth-dependent segmentation across this transition. These new constraints on slab geometry and crustal architecture refine our knowledge of the evolution of the Arabia–Iran convergent margin.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148895254","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}