Earth and Planetary Science Letters最新文献

{"title":"Climate-change-induced seismicity: The recent onset of seasonal microseismicity at the Grandes Jorasses, Mont Blanc Massif, France/Italy","authors":"Verena Simon ,&nbsp;Toni Kraft ,&nbsp;Jean-Christophe Maréchal ,&nbsp;Agnès Helmstetter ,&nbsp;Tobias Diehl","doi":"10.1016/j.epsl.2025.119372","DOIUrl":"10.1016/j.epsl.2025.119372","url":null,"abstract":"<div><div>Modeling studies indicate that the geosphere can dynamically respond to climate change, increasing geological and geomorphological hazards. One such hazard is climate-driven seismicity due to hydrological changes, though observational evidence supporting this phenomenon remains scarce. We present the first dataset linking climate-change-induced snow/glacier melt to increased seismic hazard. Using a template-matching-enhanced catalog (2006–2022), we analyze the ongoing Grandes Jorasses Earthquake Sequence (GJES, Mont Blanc Massif, France/Italy; M_L≤3.1/M_W≤2.9), which exhibits a sudden onset of strong annual periodicity in fall 2015. Our relocations identify seismicity along a major fault zone outcropping in the Mont Blanc Tunnel, where runoff and isotope data suggest that inflow is dominated by young surface meltwater. Modeling meltwater infiltration with a 1D-hydraulic diffusion constrained by the S2M meteorological snowpack model confirms that most of the GJES seismicity can be meltwater-induced. Additionally, our statistical analysis reveals a migratory seismicity component, hosting the largest events. While initially triggered by seasonal meltwater, this component expands primarily via a tectonic mechanism affected by aseismic slip. We attribute the onset of increased and periodic seismicity in 2015 to intensified climate-change-driven heat waves affecting the Mont Blanc Massif's high-altitude cryosphere. Retreating permafrost and glaciers alter meltwater-infiltration pathways, inducing pore-pressure changes that trigger seismicity in new source areas. During peak meltwater-driven seismicity, the seismic hazard levels can rise by two orders of magnitude compared to pre-2015 levels. Our findings suggest that climate change can significantly elevate the local seismic hazard in alpine regions. This phenomenon may affect other glaciated areas globally, highlighting the need for improved seismic risk assessment for impacted alpine communities.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"666 ","pages":"Article 119372"},"PeriodicalIF":4.8,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonically induced changes in vent fluid compositions and metal concentrations at Main Endeavour Field, northeast Pacific Ocean","authors":"Guy N. Evans ,&nbsp;Zoe Krauss ,&nbsp;Marvin D. Lilley ,&nbsp;William E. Seyfried Jr. ,&nbsp;William S.D. Wilcock","doi":"10.1016/j.epsl.2025.119485","DOIUrl":"10.1016/j.epsl.2025.119485","url":null,"abstract":"<div><div>Seafloor hydrothermal vents are dynamic systems that respond to changes in magmatic heat fluxes, crustal permeability and connectivity, and mineral precipitation. However, the logistical challenges associated with marine science operations often preclude direct observation of these dynamics. Here, we utilize infrastructure of Ocean Network Canada’s NEPTUNE cabled observatory to compare time-series vent fluid samples with contemporaneous records of vent fluid temperature and ocean bottom seismicity at the Main Endeavour Field, northeast Pacific Ocean. We find that previously reported changes in vent fluid chemistry coincide with episodes of increased earthquake activity. Ratios of Mg to other fluid mobile elements are consistent with influx of a Mg- and sulfate-depleted fluid, which we attribute to active circulation of intermediate-temperature hydrothermal fluids within shallow seabed lavas. Concentrations of chalcophile transition metals and metalloids are strongly correlated and sensitive to vent fluid temperature, which we propose indicates differential precipitation/dissolution of sulfide minerals. Episodes of heightened microearthquake activity associated with changes in vent fluid chemistry and/or temperature are characterized by swarm-like bursts of relatively small magnitude, likely shallow-origin, earthquakes. Together, these data highlight the sensitivity of vent fluid temperature and chemistry to seismic activity that alters near-surface permeability and connectivity between seawater and various hydrothermal reservoirs.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"666 ","pages":"Article 119485"},"PeriodicalIF":4.8,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology constrains the diffusivity of Ti in quartz and crystallization timescales of high-silica magmas in the Searchlight Magmatic System (NV, USA)","authors":"Ayla S. Pamukçu ,&nbsp;Sarah M. Hickernell ,&nbsp;Michael P. Eddy ,&nbsp;Blair Schoene ,&nbsp;Travis Steiner-Leach","doi":"10.1016/j.epsl.2025.119437","DOIUrl":"10.1016/j.epsl.2025.119437","url":null,"abstract":"<div><div>Many methods and mineral phases have been used to estimate crystallization timescales of high-silica magmas (≥68 wt. % SiO₂), which source some of the most impactful volcanic eruptions on Earth and are a significant component of Earth’s continental crust. Results from these efforts vary widely (10¹-10⁶ a), with a particularly large disparity between results from zircon geochronology and quartz geospeedometry. Quartz is widespread in high-silica magmas, and Ti-in-quartz diffusion chronometry is a commonly applied geospeedometer. However, recent work re-examining the diffusivity of Ti in quartz has introduced substantial uncertainty into our understanding of this parameter, and estimates of the diffusivity now vary by many orders of magnitude for the same temperature. This has all but eliminated the utility of this technique until this discrepancy can be resolved. In this work, we leverage field relations, geochronology, geobarometry, geochemistry, heat loss models, and crystal growth rates to establish limits on the crystallization timescales and conditions of high-silica extrusive (rhyolite) and intrusive (leucogranite) magmas in the Searchlight Magmatic System (NV, USA), which is comprised of the tectonically tilted Searchlight pluton and coeval Highland Range volcanics. We use these limits to critically assess Ti-in-quartz diffusion laws and constrain the diffusivity of Ti in quartz in this system. We conclude that only the fastest Ti-in-quartz diffusion laws produce timescales consistent with other geological constraints and that the crystallization times of the high-silica magmas were substantially shorter (rhyolite: &lt;10 ka, leucogranite: ≤51 ka) than the mushes (150-200 ka) from which they were segregated.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"666 ","pages":"Article 119437"},"PeriodicalIF":4.8,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of mass-independent Mo isotope anomalies in natural and industrially processed samples. Proof of concept for uranium provenance in nuclear forensics","authors":"Caroline Fitoussi ,&nbsp;Eric Pili ,&nbsp;Elsa Yobregat ,&nbsp;Mathieu Touboul ,&nbsp;Cécile Gardin","doi":"10.1016/j.epsl.2025.119459","DOIUrl":"10.1016/j.epsl.2025.119459","url":null,"abstract":"<div><div>Mass-independent isotope fractionation (MIF) has only been documented for a limited number of heavy elements (such as Hg, Tl and U) and has thus received limited attention for intermediate mass elements such as Mo. Conversely, mass-dependent isotope fractionation (MDF) of various isotope systems has become one of the most common tools in geochemistry as a means of deciphering processes that have shaped our planet. MDF signatures have provided fruitful insights by establishing a correspondence between a given process and specific isotope ratios. However, they are hampered by some limitations, notably because several processes can yield the same isotope signature or because superimposed effects can complicate interpretations. In this study, we identified Mo isotope mass-independent signatures resulting from, first, nuclear field shift effects, and second, fissiogenic isotopic anomalies in natural samples of uranium ores, as well as in industrially produced uranium ore concentrates. Furthermore, most MDF signatures yield residual anomalies after correction of instrumental mass bias using an exponential law, leading to a third signature (though an apparent MIF). The three types of mass-independent signatures were successfully deconvoluted and result in a powerful tracer that is shown to discriminate the origin of several ore deposits, from studying the isotope composition of uranium ores or uranium concentrates. These isotope effects discovered in natural uranium ores are produced by generic geochemical processes that have been described in many other environments. Thus, the identification of these effects opens the possibility of extending the search for mass-independent isotope signatures in natural samples with numerous isotope tracers in a broad number of applications such as environmental geochemistry or nuclear forensics.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"666 ","pages":"Article 119459"},"PeriodicalIF":4.8,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144230935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ghost plumes hidden beneath Earth’s continents","authors":"Simone Pilia ,&nbsp;Giampiero Iaffaldano ,&nbsp;D. Rhodri Davies ,&nbsp;Mohammad Ismaiel ,&nbsp;Paolo A. Sossi ,&nbsp;Scott Whattam ,&nbsp;Dapeng Zhao ,&nbsp;Hao Hu","doi":"10.1016/j.epsl.2025.119467","DOIUrl":"10.1016/j.epsl.2025.119467","url":null,"abstract":"<div><div>Mantle plumes are hot, buoyant upwellings that rise from Earth’s core-mantle-boundary (CMB) at ∼2890 km depth to the surface. As they ascend towards the lithosphere – our planet’s rigid outermost shell – decompression melting results in surface volcanism. In continental interiors, a thicker lithosphere restricts plume ascent and associated decompression melting. However, it remains uncertain whether limited continental volcanism implies few sub-continental mantle plumes. Here, we present inter-disciplinary evidence revealing the first clear example of an amagmatic “ghost” plume in eastern Oman – the Dani plume. Despite lacking present-day surface volcanism, this plume is robustly imaged using P- and S-wave arrival-time residuals from distant earthquakes, recorded by a dense regional seismic network. A positive thermal anomaly is further corroborated by a ∼14 depression of the 410-km discontinuity and a ∼20 km upward deflection of the 660-km discontinuity. The imaged low-velocity structure is overlain by positive present-day residual topography in a region enigmatically uplifted since the late Eocene (∼40 Ma). Our analyses of kinematic reconstructions demonstrate that asthenospheric flow associated with the Dani plume modified Indian-plate motion in the late Eocene, allowing us to bound the likely arrival time of this plume beneath the lithosphere. Besides offering an approach to identify hidden continental plumes, both at the present-day and via Earth’s geological record, our study suggests that CMB heat-flux estimates should be revised upwards, with implications for thermal and core evolution models.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"666 ","pages":"Article 119467"},"PeriodicalIF":4.8,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial scale dependence of fault physical parameters and its implications for the analysis of earthquake dynamics from the lab to fault systems","authors":"Davide Zaccagnino ,&nbsp;Oscar Bruno ,&nbsp;Carlo Doglioni","doi":"10.1016/j.epsl.2025.119481","DOIUrl":"10.1016/j.epsl.2025.119481","url":null,"abstract":"<div><div>An accurate assessment of seismic hazard requires a combination of earthquake physics and statistical analysis. Because of the limitations in the investigation of the seismogenic sources and of the short temporal intervals covered by earthquake catalogs, laboratory experiments have played a crucial role in improving our understanding of earthquake phenomena. However, differences exist between acoustic emissions in the lab, events in small, regulated systems (e.g., mines) and natural seismicity. One of the most pressing issues concerns the role of mechanical parameters and how they affect seismic activity across boundary conditions and spatial-temporal scales. Here, we focus on fault friction. There is evidence inferred from geodesy, computational simulations and seismological investigations that most large faults are weak and characterized by very low static friction coefficients which are inconsistent with those of smaller faults and laboratory experiments. We support the hypothesis that static friction decreases with fault size due to the presence of fabrics, roughness, structural asperities and network geometry. We also model its scaling behavior as dependent on a few physical properties (e.g., fault fractal dimension). Conversely, dynamic coefficients are not affected by the spatial scale. Mathematical derivations are based on the hypothesis that earthquake onset results from fracture instability controlled by the extremes of fault shear strength. We validate this using a simple model for earthquake occurrence rooted in fracture mechanics, which reproduces key features of major seismicity (i.e., interevent time distribution, clustering and frequency-size relationship).</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"666 ","pages":"Article 119481"},"PeriodicalIF":4.8,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144221628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magma sources, crustal storage depths, and degassing of alkalic, CO2-rich magmas at Nyiragongo and Nyamulagira Volcanoes, Democratic Republic of the Congo","authors":"Lissie Connors ,&nbsp;Paul J. Wallace ,&nbsp;Kenneth W.W. Sims ,&nbsp;D. Matthew Sublett Jr. ,&nbsp;Robert J. Bodnar","doi":"10.1016/j.epsl.2025.119477","DOIUrl":"10.1016/j.epsl.2025.119477","url":null,"abstract":"<div><div>Nyiragongo and Nyamulagira are two of the most active volcanoes in the East African Rift System, producing some of the highest fluxes of volcanic CO₂ and SO₂ on Earth, yet pre-eruptive volatile constraints at these volcanoes remain sparse. Here, we report the geochemistry of melt inclusions (MI) from Mg-rich tephra erupted from flank cones of Nyamulagira and Nyiragongo. In our sample suite, CO₂ concentrations in bubble-corrected melt inclusions reach ∼1.3 and 0.9 wt% for Nyiragongo and Nyamulagira, respectively. Water concentrations are 0.8–1.6 wt% for primitive compositions and 0.2–0.4 wt% for more evolved compositions. Sulfur concentrations reach up to 3100 ppm at Nyiragongo and 2500 ppm at Nyamulagira. Major element ‘fingerprinting’ of MI shows that some tephra samples have MI with both Nyamulagira and Nyiragongo-type compositions, requiring mixing of olivine originally crystallized from multiple distinct magma types. Volatile solubility modeling yields a wide range of crystallization depths for more primitive magmas, with maximum values of ∼10–18 km, compared to &lt;5 km for more evolved magmas erupted at the Nyamulagira summit. Estimated CO₂ concentrations for primary melts based on final equilibration with a lherzolite residue at mantle depths are 6.0 ± 2.5 wt% for Nyiragongo and 4.4 ± 2.5 wt% for Nyamulagira. Major element and volatile data are consistent with magma generation in metasomatized lithospheric mantle domains (metasomes) of amphibole+clinopyroxene+lesser phlogopite, with high initial CO₂ sourced from carbonate phase(s). Degassing models of CO₂, H₂O, and S show that gas compositions at the two volcanoes can be explained by evolved magmas feeding summit lava lakes by a process of conduit convection and degassing.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"665 ","pages":"Article 119477"},"PeriodicalIF":4.8,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 dominance of coastal microseisms in the Indian Ocean","authors":"Sanjay S. Negi ,&nbsp;Dhananjai K. Pandey ,&nbsp;Lachit S. Ningthoujam ,&nbsp;Amit Kumar ,&nbsp;Nisha Nair ,&nbsp;P G Remya ,&nbsp;Vineet K. Gahalaut","doi":"10.1016/j.epsl.2025.119479","DOIUrl":"10.1016/j.epsl.2025.119479","url":null,"abstract":"<div><div>Strong microseisms in the Indian Ocean are generally attributed to the intense Southern Ocean processes. This conventional view, however, undermines the role of potential coastal reflections emanating from the adjoining landmasses. Here, we use an array of ocean bottom seismometers to investigate the role of coastal over Southern Ocean processes as triggering mechanisms for microseisms in the Indian Ocean. We apply polarization, power spectral density, correlation analysis along with numerical wave modelling and attenuation analysis to characterise microseisms and their potential sources. Contrary to the prevailing views, coastal reflections appear to dominate the strongest deep Southern Ocean seismic noise in the Indian Ocean. We attribute such anomalous behaviour to the propagation path effects. Interestingly, the strongest secondary microseisms are generated during the simultaneous development of cyclones in the opposite hemispheres. These findings have vital implications for the way we characterize and quantify the seismic noise in the closed ocean systems.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"665 ","pages":"Article 119479"},"PeriodicalIF":4.8,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near full locking on the shallow megathrust of the central Cascadia subduction zone revealed by GNSS-Acoustic","authors":"John B. DeSanto ,&nbsp;David A. Schmidt ,&nbsp;Mark Zumberge ,&nbsp;Glenn Sasagawa ,&nbsp;C. David Chadwell","doi":"10.1016/j.epsl.2025.119463","DOIUrl":"10.1016/j.epsl.2025.119463","url":null,"abstract":"<div><div>The Cascadia subduction zone represents a seismic hazard to the Pacific Northwest region of North America, yet the state of fault locking near the deformation front, which could cause a devastating tsunami upon rupturing, remains poorly understood due to limited offshore observations along the subduction zone. In this study, we present the first seafloor geodetic measurements of the horizontal deformation rates on the accretionary prism from an array of four GNSS-Acoustic sites surveyed since 2016. These GNSS-Acoustic sites, despite resting on the North American plate, show velocities that are a significant fraction of the subducting Juan de Fuca plate velocity. In contrast, the continuous GNSS stations along the Oregon coast are moving at velocities &lt;1 cm/yr relative to the North American Plate. Locking models constrained by these offshore velocities show that the subduction zone interface near the deformation front must be nearly locked offshore Oregon. To satisfy both the onshore and offshore geodetic observations, the locked zone must be relatively narrow and only minimal aseismic creep is permissible at the deformation front. These results suggest that appreciable elastic strain has accumulated near the deformation front, which elevates the potential for tsunamigenesis along this portion of the subduction zone.</div></div><div><h3>Plain Text Abstract</h3><div>There is a large earthquake hazard in the region offshore British Columbia, Washington state, Oregon, and Northern California associated with the Cascadia subduction zone, where the Juan de Fuca oceanic plate subducts beneath the North American continental plate. The lack of seafloor observations of plate movement limits our understanding of the hazard, particularly where a future earthquake could rupture up to the seafloor and cause a large tsunami. We present seafloor measurements using Global Navigation Satellite System (GNSS) and acoustic ranging data collected offshore Oregon from 2016–2022 that show that the seafloor is moving at horizontal rates comparable with the subducting Juan de Fuca plate. This suggests that a future earthquake offshore Oregon is capable of rupturing up to the seafloor and causing a devastating tsunami.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"665 ","pages":"Article 119463"},"PeriodicalIF":4.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144194530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shear wave splitting reveals east-west variations in Subducted Indian plate morphology beneath Southern Tibetan Plateau","authors":"Shitan Nie ,&nbsp;Xiaobo Tian ,&nbsp;Yun Chen ,&nbsp;Xiaofeng Liang ,&nbsp;Chenglong Wu","doi":"10.1016/j.epsl.2025.119468","DOIUrl":"10.1016/j.epsl.2025.119468","url":null,"abstract":"<div><div>The subduction of the Indian plate beneath the Tibetan Plateau drives key geodynamic processes, yet east-west variations in slab morphology remain poorly resolved. Seismic anisotropy, measured by teleseismic shear wave splitting (SWS), provides critical insights into mantle deformation linked to subduction geometry. Using a new east-west-oriented broadband seismic array (Tibet-30 N) in the southern Lhasa terrane, we analysed 639 SWS measurements and 527 null results. Our study reveals pronounced lateral variations in fast polarization directions (0°–60°) and splitting times (0–0.9 s). Delayed SKS arrivals (∼2 s) and null splitting near the Yadong–Gulu rift (YGR) suggest asthenospheric upwelling through a slab tear, consistent with low upper-mantle velocities. East of the YGR, large splitting times (0.9 s) and NNE fast directions align with flat subduction, while steep subduction west of the YGR induces vertical mantle flow and reduced anisotropy. Step-like changes in splitting parameters across north‒south-trending rifts imply segmented subduction angles: steep between the Tangra Yum Co and Pumqu–Xianza rifts, transitioning to flat eastward. Integrating previous SWS observations, we propose a model where tearing of the Indian slab beneath rifts facilitates asthenospheric upwelling, while lateral mantle flow reflects slab geometry. Our results highlight east-west variations in Indian plate subduction—flat in eastern and western Tibetan plateau and steep centrally—controlled by slab tearing and mantle dynamics.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"665 ","pages":"Article 119468"},"PeriodicalIF":4.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144189743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}