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| Open AccessDislocation interactions in olivine control postseismic creep of the upper mantle
Models of the viscosity evolution of mantle rocks are central to analyses of postseismic deformation but constraints on underlying physical processes are lacking. Here, the authors present measurements of microscale stress heterogeneity in olivine suggesting that long-range dislocation interactions contribute to viscosity evolution.
- David Wallis
- , Lars N. Hansen
- & Ricardo A. Lebensohn
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Article
| Open AccessOn the use of plume models to estimate the flux in volcanic gas plumes
Monitoring the flux of gas from volcanoes is a fundamental component of volcano monitoring programs and is used as a basis for eruption forecasting. Here, the authors present a new method using video images of volcanic gas plumes to measure the speed of convective structures and to estimate volcanic fluxes.
- Julia Woitischek
- , Nicola Mingotti
- & Andrew W. Woods
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Article
| Open AccessExperimental evidence for hydrogen incorporation into Earth’s core
Based on diamond-anvil cell experiments and cutting-edge secondary ion mass spectrometry analyses, the authors here show that hydrogen may be an important constituent in the Earth’s core and also in the metallic cores of any terrestrial planet or moon having a mass in excess of 10% of the Earth.
- Shoh Tagawa
- , Naoya Sakamoto
- & Hisayoshi Yurimoto
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Article
| Open AccessSegregated oceanic crust trapped at the bottom mantle transition zone revealed from ambient noise interferometry
By combining ambient noise interferometry with mineral physics modeling, this work sheds new light on mantle transition zone physics. Their findings provide new evidence of segregated oceanic crust subducted and trapped within the mantle transition zone, implying complex mantle circulation modes.
- Jikun Feng
- , Huajian Yao
- & Zhu Mao
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Article
| Open AccessFluid pressurisation and earthquake propagation in the Hikurangi subduction zone
Laboratory experiments reproducing earthquake slip in non cohesive fault rocks under fluid pressurised conditions are challenging. Thanks to these experiments, the authors show that earthquake slip occurring in tsunamigenic subduction zone faults is controlled by dilatancy and pressurisation processes.
- S. Aretusini
- , F. Meneghini
- & G. Di Toro
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| Open AccessRapid heat discharge during deep-sea eruptions generates megaplumes and disperses tephra
A novel model for submarine tephra dispersal by hydrothermal megaplumes is proposed. The energy flux inferred from our model aligns with megaplume observations, and suggests that the catastrophic release of hot crustal fluids, as opposed to lava heating, is responsible for megaplume generation.
- Samuel S. Pegler
- & David J. Ferguson
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Article
| Open AccessHow deep ocean-land coupling controls the generation of secondary microseism Love waves
The authors here study the origin of seismic Love waves induced by ocean waves. The study finds Love waves to originate along steep bathymetry and underlying geological interfaces, particularly sedimentary basins, yielding spatio-temporal information about ocean-land coupling in deep water.
- Florian Le Pape
- , David Craig
- & Christopher J. Bean
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Article
| Open AccessGlobal influence of mantle temperature and plate thickness on intraplate volcanism
Here, the authors compile a global geochemical database of Neogene-Quaternary intraplate volcanism. By comparing the distribution and composition of these rocks with tomographic models they show that intraplate volcanism can be used to constrain upper-mantle structure at the time of eruption.
- P. W. Ball
- , N. J. White
- & S. N. Stephenson
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Article
| Open AccessA reconciled solution of Meltwater Pulse 1A sources using sea-level fingerprinting
Meltwater Pulse 1A was the most rapid global sea-level rise event during the last deglaciation, but the source of the freshwater causing this rise is debated. Here, the authors use a data-driven inversion approach to show that the North American and Eurasian Ice Sheets were the dominant contributors.
- Yucheng Lin
- , Fiona D. Hibbert
- & Sarah L. Bradley
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Article
| Open AccessFault zone heterogeneities explain depth-dependent pattern and evolution of slow earthquakes in Cascadia
Here, the authors combine the geological and seismological constraints of the Cascadia Subduction Zone and develop a 3D rate and state friction model. By considering depth-dependent variations of differential pore pressure following a simple linear profile, the model reproduces the full spectrum of the observed ETS complexity.
- Yingdi Luo
- & Zhen Liu
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Article
| Open AccessFormation of large low shear velocity provinces through the decomposition of oxidized mantle
Dense Fe3+-rich bridgmanite can explain the seismic features of Large Low Shear Velocity Provinces, as it can form large-scale thermochemical piles in the deep mantle that remain stable throughout Earth’s history.
- Wenzhong Wang
- , Jiachao Liu
- & Zhongqing Wu
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Article
| Open AccessGround deformation reveals the scale-invariant conduit dynamics driving explosive basaltic eruptions
Here, the authors use 20 years of ground deformation data from Stromboli and correlate this data with eruptive records. They find that duration and amplitude of the inflation trend scales with eruption magnitude, indicating that explosive dynamics obeys the same (scale-invariant) conduit process.
- M. Ripepe
- , G. Lacanna
- & D. Delle Donne
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Article
| Open AccessThe Hindu Kush slab break-off as revealed by deep structure and crustal deformation
Here, the authors document active slab break-off and the crustal response during continental collision under the Hindu Kush, a rarely observed process since it happens over geologically short time spans.
- Sofia-Katerina Kufner
- , Najibullah Kakar
- & Bernd Schurr
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Article
| Open AccessCaribbean plate tilted and actively dragged eastwards by low-viscosity asthenospheric flow
Here, the authors follow a new approach using analytic solutions for Poiseuille-Couette channel flow to compute asthenospheric viscosities under the Caribbean. Active asthenospheric flow observed under the Caribbean contradicts the traditional view that the asthenosphere is only a passive lubricating layer for Earth’s tectonic plates.
- Yi-Wei Chen
- , Lorenzo Colli
- & Hejun Zhu
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Article
| Open AccessConstraining maximum event magnitude during injection-triggered seismicity
Recently triggered seismic events such as the Pohang earthquake have exceeded predictions of average energy releases by a factor of 1000. A new framework is proposed to define maximum event magnitudes as a function of pre-existing critical stresses and fluid injection volume.
- Ziyan Li
- , Derek Elsworth
- & M. W. McClure
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Article
| Open AccessThe stability of subducted glaucophane with the Earth’s secular cooling
Along the cold subduction geotherm, glaucophane remains stable down to pressure and temperature (P–T) conditions of ca. 240 km depth, whereas under the warm subduction geotherm, it dehydrates and breaks down into pyroxenes and silica between ca. 50 and 100 km depths.
- Yoonah Bang
- , Huijeong Hwang
- & Yongjae Lee
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Article
| Open AccessReal-time determination of earthquake focal mechanism via deep learning
The authors here present a deep learning method to determine the source focal mechanism of earthquakes in realtime. They trained their network with approximately 800k synthetic samples and managed to successfully estimate the focal mechanism of four 2019 Ridgecrest earthquakes with magnitudes larger than Mw 5.4.
- Wenhuan Kuang
- , Congcong Yuan
- & Jie Zhang
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Article
| Open AccessCaldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands
The authors here present geodetic and seismic data for a complete eruptive cycle (2005-2018) for Sierra Negra volcano, Galapagos Island. The data shows the largest pre-eruptive inflation (6.5 m) and rates of seismicity ever observed before a basaltic eruption and provides a rare illustration of caldera resurgence mechanisms.
- Andrew F. Bell
- , Peter C. La Femina
- & Michael J. Stock
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Article
| Open AccessMelting of subducted sediments reconciles geophysical images of subduction zones
Here, the authors identify that magnetotelluric conductive anomalies commonly observed on the trenchward-side of volcanic arcs in subduction zones can be explained by subducted sediments. High-pressure experiments show that these sediment melts will react with the overlying mantle wedge to produce electrically conductive phlogopite pyroxenites.
- M. W. Förster
- & K. Selway
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| Open AccessA role for subducted albite in the water cycle and alkalinity of subduction fluids
Albite is one of the major constituents in the Earth’s crust. Here, the authors report that under hydrous cold subduction conditions, albite undergoes breakdown into hydrated smectite and other phases, which release alkaline fluids into the mantle wedge.
- Gil Chan Hwang
- , Huijeong Hwang
- & Yongjae Lee
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Article
| Open AccessNo mafic layer in 80 km thick Tibetan crust
Crustal doubling in Tibet and the Himalayas by underthrusting of the Indian plate is thought to require the presence of a mafic layer above the Moho. Here, the authors present seismic data which shows that the middle Lhasa Terrane has very low velocity (Vp < 6.7 km/s) throughout the 80 km thick crust, which they suggest is predominantly felsic in composition.
- Gaochun Wang
- , Hans Thybo
- & Irina M. Artemieva
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Article
| Open AccessProbing complex geophysical geometries with chattering dust
Chattering dust, or chemically reactive grains of sucrose containing pockets of pressurized carbon dioxide, are used in this experimental approach to study rock fractures. The chattering dust emits acoustic shocks that can be monitored and illuminates fracture geometry.
- Laura J. Pyrak-Nolte
- , William Braverman
- & David D. Nolte
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Article
| Open AccessInitial effective stress controls the nature of earthquakes
The authors show that seismogenic faults can be activated by stress perturbations by all possible modes of slip independently of the frictional properties. They demonstrate, that the nature of seismicity is mostly governed by the initial stress level along the faults.
- François X. Passelègue
- , Michelle Almakari
- & Marie Violay
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Article
| Open AccessReconstructing the electrical structure of dust storms from locally observed electric field data
Electrification is naturally generated in dust storms but its structures remain largely unknown. Here, the authors present an inversion model to reconstruct such structures based on the locally observed electric field data, showing that dust storms exhibit a three-dimensional mosaic charge pattern.
- Huan Zhang
- & You-He Zhou
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Article
| Open AccessFault valving and pore pressure evolution in simulations of earthquake sequences and aseismic slip
Coupling between fault zone fluid flow, permeability evolution, and elastic stress transfer produces fault valving and fluid-driven aseismic slip and pore pressure pulses. This model might explain late interseismic fault unlocking, slow slip, and rapid pressure transmission in induced seismicity.
- Weiqiang Zhu
- , Kali L. Allison
- & Yuyun Yang
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Article
| Open AccessStructural dynamics of basaltic melt at mantle conditions with implications for magma oceans and superplumes
Transport properties of melts in the deep Earth have dictated the evolution of the early Earth’s magma oceans and also govern many modern dynamic processes, such as plate tectonics. Here, the authors find there is a reversal in the trends of transport properties of basaltic melts at pressures near 50 GPa, with implications for the timescales of early Earth’s magma oceans.
- Arnab Majumdar
- , Min Wu
- & John S. Tse
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Article
| Open AccessSouth China Sea documents the transition from wide continental rift to continental break up
The transition from wide continental rift to continental break-up remains enigmatic. Here, the authors show that northern margin of the South China Sea records the transition between wide continental rift to a highly extended continental margin, with strikingly similar structures and metamorphic core complexes to those described from the North American Cordillera and the Aegean.
- Hongdan Deng
- , Jianye Ren
- & Pan Luo
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Article
| Open AccessSeafloor evidence for pre-shield volcanism above the Tristan da Cunha mantle plume
Here, the authors combine bathymetry and sediment echosound data to present a submarine, volcanic map of the Tristan de la Cunha region. They find that the youngest volcanic expression of the Tristan de la Cunha mantle plume is currently located to the (south-) west of the island.
- Wolfram H. Geissler
- , Paul Wintersteller
- & Wilfried Jokat
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Article
| Open AccessMantle flow distribution beneath the California margin
Although the surface deformation of tectonic plate boundaries is well determined by geological and geodetic measurements, the pattern of flow below the lithosphere remains poorly constrained. Here, the author finds that major earthquakes in California have occurred above the regions of current plastic strain accumulation in the mantle.
- Sylvain Barbot
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Article
| Open AccessAn exponential build-up in seismic energy suggests a months-long nucleation of slow slip in Cascadia
Using machine learning algorithms, the authors here identify slow slip precursors in the Cascadia subduction zone to last for months - which in turn argues for a much better predictability of slow slip rupture.
- Claudia Hulbert
- , Bertrand Rouet-Leduc
- & Paul A. Johnson
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Article
| Open AccessDiscovery of flat seismic reflections in the mantle beneath the young Juan de Fuca Plate
Applying seismic imaging methods on ocean bottom hydrophone data, the authors here describe a horizontal, flat lithosphere base plus lithosphere-asthenosphere boundary beneath the young (0.51 to 2.67 Ma) Juan de Fuca plate.
- Yanfang Qin
- , Satish C. Singh
- & W. Roger Buck
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Article
| Open AccessElectronic correlations and transport in iron at Earth’s core conditions
The heat and electrical conductivity of Earth’s core matter represent key input quantities for geophysical models of the Earth’s core evolution and geodynamo. Here, the authors show how the scattering due to interactions between electrons has a relatively weak impact on the electrical and thermal conductivities of iron at core conditions.
- L. V. Pourovskii
- , J. Mravlje
- & D. Alfè
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Article
| Open AccessCascadia low frequency earthquakes at the base of an overpressured subduction shear zone
Regions of the subducting oceanic crust are often considered to be overpressured, owing to fluid trapped beneath an impermeable seal along the overlying inter-plate boundary. Here, the authors show that slow slip earthquakes at the Cascadia subduction zone occur immediately below a 6-10 km-thick shear zone, in which slab-derived fluids are likely trapped at near-lithostatic pore pressures.
- Andrew J. Calvert
- , Michael G. Bostock
- & Martyn J. Unsworth
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Article
| Open AccessLarge-scale mass wasting in the western Indian Ocean constrains onset of East African rifting
The authors describe a huge submarine landslide deposit offshore Tanzania and highlight that large and potentially tsunamigenic landslide events are associated with plateau uplift and continental rifting in East Africa.
- Vittorio Maselli
- , David Iacopini
- & Dick Kroon
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Article
| Open AccessLimited and localized magmatism in the Central Atlantic Magmatic Province
The Central Atlantic Magmatic Province is the most aerially extensive magmatic event in Earth’s history, yet few constraints exist on the volumes of intrusions at depth. Here, the authors find limited intrusive volumes beneath the South Georgia Rift, consistent with modest potential mantle temperatures (<1500 °C) related to syn-rift decompression melting.
- R. E. Marzen
- , D. J. Shillington
- & S. H. Harder
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Article
| Open AccessRapid geomagnetic changes inferred from Earth observations and numerical simulations
The authors here use numerical simulations combined with a time-dependent model of Earth’s magnetic field spanning the last 100 kyrs. They identify field directional changes to be 10 times faster than previously thought.
- Christopher J. Davies
- & Catherine G. Constable
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Article
| Open AccessAutomated design of a convolutional neural network with multi-scale filters for cost-efficient seismic data classification
The authors present an automated design approach to propose a new neural network architecture for seismic data analysis. The new architecture classifies multiple seismic reflection datasets at extremely low computational cost compared with conventional architectures for image classification.
- Zhi Geng
- & Yanfei Wang
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Article
| Open AccessUnderstanding rate effects in injection-induced earthquakes
- Maryam Alghannam
- & Ruben Juanes
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Article
| Open AccessThe influence of the brittle-ductile transition zone on aftershock and foreshock occurrence
Earth surface continues to slip after large earthquakes at a slow velocity for a period of a year or more. In this study, the authors show how such slow slip before and after large earthquakes relates to the interaction of the brittle zone of the fault with the ductile zone at greater depth.
- Giuseppe Petrillo
- , Eugenio Lippiello
- & Alberto Rosso
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Article
| Open AccessVictoria continental microplate dynamics controlled by the lithospheric strength distribution of the East African Rift
One of the largest continental microplates on Earth is situated in the center of the East African Rift System, and oddly, the Victoria microplate rotates counterclockwise with respect to the neighboring African tectonic plate. Here, the authors' modelling results suggest that Victoria microplate rotation is caused by edge-driven lithospheric processes related to the specific geometry of rheologically weak and strong regions.
- Anne Glerum
- , Sascha Brune
- & Manfred R. Strecker
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Article
| Open AccessFour-dimensional surface motions of the Slumgullion landslide and quantification of hydrometeorological forcing
Landslides are damaging natural hazards and can often lead to unexpected casualties and property damage. Here, the authors conduct geodetic and hydrological data analyses of the Slumgullion landslide, Colorado, and quantify the mass movement to find it fits a power-law flow theory and responds to hydroclimatic variability.
- Xie Hu
- , Roland Bürgmann
- & Eric J. Fielding
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Matters Arising
| Open AccessEvidence for simple volcanic rifting not complex subduction initiation in the Laxmi Basin
Recently, Pandey et al proposed relict subduction initiation occurred along a passive margin in the northwest Indian Ocean. Here, Clift et al question the evidence for subduction initiation, suggesting that simpler rifting-related processes can more simply explain the available data for the Laxmi Basin.
- Peter D. Clift
- , Gérôme Calvès
- & Tara N. Jonell
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Matters Arising
| Open AccessReply to ‘Evidence for simple volcanic rifting not complex subduction initiation in the Laxmi Basin’
Recently, Pandey et al. proposed relict subduction initiation occurred along a passive margin in the northwest Indian Ocean, however, Clift et al. questioned their evidence for subduction initiation, suggesting that simpler rifting-related processes could more simply explain the available data. Here, Pandey et al. reply to Clift et al.’s comment, and argue that geochemical and isotope data for Laxmi basin lavas distinctly imply relict subduction initiation.
- Dhananjai K. Pandey
- , Anju Pandey
- & Scott A. Whattam
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Article
| Open AccessGeophysical imaging of ophiolite structure in the United Arab Emirates
The Semail ophiolite provides evidence for geological processes that form oceanic crust, however, its deep structure remains debated. Here, the authors use geophysical imaging to determine that the ophiolite is bound by a thrust fault in the west, and a normal fault in the east, bounding a rapidly subsiding basin, implying the ophiolite may not be rooted in the Gulf of Oman crust.
- M. Y. Ali
- , A. B. Watts
- & T. Ambrose
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Article
| Open AccessCausal mechanism of injection-induced earthquakes through the Mw 5.5 Pohang earthquake case study
The authors here suggest a causal mechanism for injection-induced earthquakes. They further suggest pore pressure modeling as a practical alternative to direct in-situ pore pressure observation which can then be used for stress build-up monitoring.
- I. W. Yeo
- , M. R. M. Brown
- & K. K. Lee
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Article
| Open AccessSeismic ground vibrations give advanced early-warning of subglacial floods
Subglacial lakes and jökulhlaups (glacier outburst floods) are common in volcanic and glaciated environments, and can pose potential threats to communities living downstream. Here, the authors find that seismic tremor signals during subglacial floods can be used to locate and track the speed and size of the flood before it arrives at the river system, and improves previous methods of early glacial flood warning by a factor of 5.
- Eva P. S. Eibl
- , Christopher J. Bean
- & Kristin S. Vogfjörd
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Article
| Open AccessIntradecadal variations in length of day and their correspondence with geomagnetic jerks
Earth rotation variation reflects the physics, dynamics and the magnetic field changes of Earth’s interior. The authors find a significant ~8.6 year periodic increasing oscillation in length of day and its good link to geomagnetic jerks related to Earth’s core oscillations, which may be used to predict the future jerk timings.
- Pengshuo Duan
- & Chengli Huang
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Article
| Open AccessSlip bursts during coalescence of slow slip events in Cascadia
Slow slip events are commonly observed on natural faults all around the world and are suggested to precede large magnitude and/or high frequency earthquakes. The authors here identify merging phases of slow slip events using continuous GPS measurements and define areas and periods at risk of large earthquake occurrence.
- Quentin Bletery
- & Jean-Mathieu Nocquet
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Article
| Open AccessSeismic evidence for subduction-induced mantle flows underneath Middle America
The motions of subducted slabs are expected to drive mantle flow around slab edges, however, evidence of deep mantle flow has so far remained elusive. Here, the authors present a Full Waveform Inversion 3-D anisotropy model which allows them to infer deep subduction-induced mantle flows underneath the Mid-Americas and the Caribbean.
- Hejun Zhu
- , Robert J. Stern
- & Jidong Yang