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    <title>Journal of Studies of Earth’s Deep Interior</title>
    <description>Journal of Studies of Earth’s Deep Interior: latest publications</description>
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      <title>Journal of Studies of Earth’s Deep Interior</title>
      <link>https://jsedi.episciences.org</link>
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    <pubDate>Tue, 02 Jun 2026 23:13:10 +0000</pubDate>
    <generator>Episciences</generator>
    <link>https://jsedi.episciences.org</link>
    <author>Journal of Studies of Earth’s Deep Interior</author>
    <dc:creator>Journal of Studies of Earth’s Deep Interior</dc:creator>
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      <title>Thermochemical models of outer core convection with heterogeneous core-mantle boundary heat flux</title>
      <description><![CDATA[Convection in Earth's outer core is driven by the release of heat and light elements at the inner core boundary. A key question is whether these buoyancy sources drive convection throughout the core, or whether a stable layer exists just below the core-mantle boundary (CMB). Recent simulations incorporating CMB heat flux heterogeneities propose locally stable ``regional inversion lenses'' (RILs) rather than a global layer, allowing stable and unstable regions to coexist. However, these simulations combine thermal and compositional anomalies, ignoring differences in diffusivities and boundary conditions. Here we simulate thermal, chemical, and thermochemical convection at Ekman number $E=10^{-5}$, with thermal and chemical flux Rayleigh numbers $\widetilde{Ra}_T=30-4000$ and $\widetilde{Ra}_ξ=30-100000$, and Prandtl numbers $Pr_T=1$ and $Pr_ξ=10$. Purely chemical simulations accumulate light elements below the CMB, forming locally stable regions near the poles or global layers, depending on $\widetilde{Ra}_ξ$. These chemically stratified regions persist in thermochemical simulations even when thermal forcing is destabilising. Introducing heterogeneous CMB heat flux produces thermally stratified RILs even with strongly destabilising compositional buoyancy. Our simulations reveal a diverse range of locations, properties, and morphologies of stable regions depending on $\widetilde{Ra}_T$ and $\widetilde{Ra}_ξ$, they can have a seismically detectable thickness and strength and might also have a signature in geomagnetic observations.]]></description>
      <pubDate>Fri, 15 May 2026 18:51:53 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.17084</link>
      <guid>https://doi.org/10.46298/jsedi.17084</guid>
      <author>Naskar, Souvik</author>
      <author>Mound, Jonathan E.</author>
      <author>Davies, Christopher J.</author>
      <author>Clarke, Andrew T.</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <category><![CDATA[Earth and Planetary Astrophysics]]></category>
      <category><![CDATA[Geophysics]]></category>
      <dc:creator>Naskar, Souvik</dc:creator>
      <dc:creator>Mound, Jonathan E.</dc:creator>
      <dc:creator>Davies, Christopher J.</dc:creator>
      <dc:creator>Clarke, Andrew T.</dc:creator>
      <slash:comments>0</slash:comments>
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    <item>
      <title>Principal component analysis of the 2010 reversal of core-surface flow beneath the Pacific Ocean</title>
      <description><![CDATA[This paper is published after peer review in the Journal of Studies of Earth's Deep Interior (jSEDI).In this paper, we investigate the behaviour of the fluid flow in the Earth's outre core throughout the 21st century. The flow of the liquid iron cocktail in the Earth's outer core generates the geomagnetic field and its rate of change, the secular variation. Assuming that magnetic diffusion is negligible on timescales shorter than 100 years, we can invert SV observations from ground observatories and geomagnetic satellites for models of the fluid flow at the top of the core. We investigate core-surface flow, modelled from observations of SV from 1997 to 2025. Historically, the core-surface flow has been predominantly westward, as required to maintain a westward-drifting magnetic field, which is associated with a planetary gyre of westward flow, offset from the Earth’s rotation axis. This gyre does not affect the flow in the equatorial Pacific, and we find that the flow here changes in 2010 from weakly westward to strongly eastward. Our model suggest that the Pacific eastwards flow has been weakening since 2020. The rise of the strong eastward flow in the Pacific is contemporary with a change in behaviour in the inner core, as observed from geodesy and seismology, and we hypothesise that these changes in the deep interior triggered the inferred changes in flow beneath the Pacific. ]]></description>
      <pubDate>Wed, 06 May 2026 15:48:43 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.17268</link>
      <guid>https://doi.org/10.46298/jsedi.17268</guid>
      <author>Madsen, Frederik Dahl</author>
      <author>Howard, Isobel</author>
      <author>Brown, William</author>
      <author>Whaler, Kathryn</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <category><![CDATA[Geomagnetism]]></category>
      <category><![CDATA[Core dynamics]]></category>
      <dc:creator>Madsen, Frederik Dahl</dc:creator>
      <dc:creator>Howard, Isobel</dc:creator>
      <dc:creator>Brown, William</dc:creator>
      <dc:creator>Whaler, Kathryn</dc:creator>
      <slash:comments>0</slash:comments>
    </item>
    <item>
      <title>Geodynamo simulations spanning millennia in the physical conditions of Earth's core</title>
      <description><![CDATA[A geodynamo simulation is presented where the Earth's core density, rotation rate, convective power and electrical conductivity are matched, while viscous losses are maintained minor in the force balance and power budget. Improving over earlier preliminary calculations, the simulation is integrated over near 1700 years in physical time, and realistically renders the time scale range between interannual hydromagnetic waves and secular convective motions. The solution has been obtained by gradually approaching these conditions along a path in model parameter space. A quasi-geostrophic, magneto-Archimedes-Coriolis (QG-MAC) force balance is confirmed, with the characteristic length scale of the system remaining near the planetary scale. Without the need for extrapolation, the morphology, variations and dynamics of the velocity, convective density anomaly and magnetic fields are in excellent quantitative agreement with geomagnetic and geodetic observations supplied over the past centuries by navigation, observatories and satellites. In particular, the simulation reveals the contribution of interdecadal magneto-Coriolis waves to geomagnetic variations in the vicinity of  60-yr periods. This direct validation of the convective geodynamo paradigm additionally offers a quantitative and first principle-based physical link between the observable signals and deep Earth geodynamic parameters. The model confirms that a convective power (or Ohmic dissipation) level near 3 TW is needed to account for the observed geomagnetic variations, and that the top of the core should be convectively neutral or unstable. Explaining the core-originated interannual to decadal variations of the length of day through electromagnetic core-mantle coupling requires a lower mantle conductance on the order of 10^9 S. It may also become possible to constrain the outer core electrical conductivity from the observed patterns of interannual magneto-Coriolis waves. Finally, the simulation can be considered a reliable source of prior information for solving geomagnetic inverse and prediction problems.]]></description>
      <pubDate>Tue, 05 May 2026 00:00:00 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.17790</link>
      <guid>https://doi.org/10.46298/jsedi.17790</guid>
      <author>Aubert, Julien</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <category><![CDATA[Earth's core]]></category>
      <category><![CDATA[geodynamo]]></category>
      <category><![CDATA[geomagnetism]]></category>
      <category><![CDATA[simulation]]></category>
      <category><![CDATA[[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]]]></category>
      <dc:creator>Aubert, Julien</dc:creator>
      <slash:comments>0</slash:comments>
    </item>
    <item>
      <title>Joint Bayesian inference of Earth's magnetic field and core surface flow on millennial timescales</title>
      <description><![CDATA[Understanding Earth's core dynamics over millennial timescales requires models that jointly describe the evolution of the geomagnetic field and core surface flow, while accommodating the sparse, irregular, and uncertain nature of archaeomagnetic and palaeomagnetic data. We present a new Bayesian core field and core flow modelling framework that utilises archaeo/palaeomagnetic data directly, combining a reduced stochastic representation of core surface dynamics derived from numerical geodynamo statistics with a probabilistic treatment of observational and chronological uncertainties. A key innovation is an efficient discrete marginalisation of age uncertainties, which avoids the convergence difficulties associated with co-estimating ages in high-dimensional Hamiltonian Monte Carlo inversions. The framework aims to reconstruct the coupled evolution of the geomagnetic field and core surface flow over the past 9000 years while preserving dynamical correlations implied by the prior geodynamo time series. Tests using synthetic data generated from an Earth-like geodynamo demonstrate that the method reliably recovers large-scale geomagnetic field variations and key aspects of core dynamics, including long-term westward drift and the evolution of planetary-scale eccentric gyres. These results show that, when combined with physically informed priors, archaeo/palaeomagnetic data can constrain millennial-scale core flow, paving the way for reconstructions based on real data.]]></description>
      <pubDate>Tue, 31 Mar 2026 00:00:00 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.17320</link>
      <guid>https://doi.org/10.46298/jsedi.17320</guid>
      <author>Nilsson, Andreas</author>
      <author>Suttie, Neil</author>
      <author>Troyano, Marie</author>
      <author>Gillet, Nicolas</author>
      <author>Aubert, Julien</author>
      <author>Irbäck, Anders</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <category><![CDATA[Geophysics]]></category>
      <dc:creator>Nilsson, Andreas</dc:creator>
      <dc:creator>Suttie, Neil</dc:creator>
      <dc:creator>Troyano, Marie</dc:creator>
      <dc:creator>Gillet, Nicolas</dc:creator>
      <dc:creator>Aubert, Julien</dc:creator>
      <dc:creator>Irbäck, Anders</dc:creator>
      <slash:comments>0</slash:comments>
    </item>
    <item>
      <title>Constraints on the lower mantle electrical conductivity from length-of-day changes</title>
      <description><![CDATA[We investigate how the radial profile σ(r) of the lower mantle electrical conductivity affects the downward continuation of the time-varying magnetic field to the core surface and the resulting inverted core motions. We compare core flow predictions to the length-of-day (LOD) with geodetic records, in order to assess how plausible the considered conductivity profiles are. The core flow inverse problem, mixing the information carried by single spherical harmonic magnetic coefficients, makes it non trivial to infer the delay expected for LOD predictions. Our results indicate that the timescale characteristic of the mantle filter in the low-frequency limit yields an integral measure of σ(r) allowing us to select admissible conductivity models. Models of σ(r) inferred from magnetospheric and tidal sources over the satellite era involve mantle filter lags less than a couple of months and provide the best fit to LOD variations. Other conductivity profiles constructed based on mineralogical properties and iron partitioning inferred for deep mantle rocks (i.e., σ increasing from a few S/m at 1200 km depth up to some tens of S/m ~ 300 km above the core surface, with a more conducting D'' layer) are acceptable.  A highly conducting layer of thickness O(10 km) or thinner cannot be excluded.]]></description>
      <pubDate>Fri, 07 Nov 2025 00:00:00 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.16005</link>
      <guid>https://doi.org/10.46298/jsedi.16005</guid>
      <author>Gillet, Nicolas</author>
      <author>Martinec, Zdenek</author>
      <author>Lepage, Thea</author>
      <author>Jault, Dominique</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <category><![CDATA[[SDU]Sciences of the Universe [physics]]]></category>
      <dc:creator>Gillet, Nicolas</dc:creator>
      <dc:creator>Martinec, Zdenek</dc:creator>
      <dc:creator>Lepage, Thea</dc:creator>
      <dc:creator>Jault, Dominique</dc:creator>
      <slash:comments>0</slash:comments>
    </item>
    <item>
      <title>Influence of background magnetic fields on the excitation of Magneto-Coriolis modes inside the Earth's core</title>
      <description><![CDATA[Magneto-Coriolis (QG-MC) waves are considered an important part of the rapid dynamics of the Earth's outer core.The detailed characteristics of these waves are however still under scrutiny.In this study we explore the sensitivity of the QG-MC waves to the background magnetic field over which they propagate and the frequency of a periodic perturbation that we impose.We retrieve QG-MC modes by analysing the velocity fields, where they are most easily observed.Concentrations of QG-MC waves in the magnetic field at the core surface in our model are reminiscent of recently observed geomagnetic jerks.The QG-MC waves are weakly sensitive to the details of the background magnetic field during their travel in the bulk and their frequency at the core surface remains close to that of the initial perturbation.This is a potential asset for the prediction of their evolution.Moreover, the waves in the system exhibit a complex relation with the initial perturbation: when the frequency of the initial pulsation is greater than a threshold -- depending on the Alfvén speed of the medium -- inward QG-Alfvén waves are recovered at the core mantle boundary instead of QG-MC waves, and we find that the waves evolve from QG-MC to QG-Alfvén waves depending on the input frequency.Thus, gradually increasing the input frequency in the system, we retrieve the dispersion relation for QG-MC waves with an evolution from a k_s^4 slope to a k_s^1 slope, where k_s is the cylindrical radial wavenumber, as waves transition from QG-MC to QG-Alfvén waves.We actually recover all the components of the dispersion relation from QG-MC waves at low pulsation \omega to QG-Alfvén and inertial waves at high pulsation \omega.Applying our results to the Earth's core, we expect to be able to recover QG-MC waves with confidence in the Earth core with periods between 57y and 2.8y.]]></description>
      <pubDate>Thu, 23 Oct 2025 22:27:58 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.15652</link>
      <guid>https://doi.org/10.46298/jsedi.15652</guid>
      <author>Barrois, Olivier</author>
      <author>Aubert, Julien</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <dc:creator>Barrois, Olivier</dc:creator>
      <dc:creator>Aubert, Julien</dc:creator>
      <slash:comments>0</slash:comments>
    </item>
    <item>
      <title>Evidence of a ULVZ near Vanuatu from Sdiff postcursors</title>
      <description><![CDATA[Thin anomalous structures known as ultra-low velocity zones (ULVZs) have been found on the core-mantle boundary (CMB) and have extreme velocity reductions. These features are detected due to their effect on seismic waves that travel through them, typically producing precursors or postcursors. In this study we use postcursors to shear core-diffracted waves (Sdiff+) that sample the CMB near Vanuatu to detect and characterise the properties of a ULVZ. We identified a total of 19 earthquakes originating from the South Pacific Rise region detected by stations across East Asia — particularly Japan — showing Sdiff+ signals. Of these events, six with the highest quality Sdiff+ signals are included in a Bayesian inversion of travel times using the 2D Wavefront Tracker we previously developed. A subset of events was selected for further analysis by modelling using 3D full waveform synthetics for a range of parameters. The comparison of the real data with the synthetic waveforms suggests that a ULVZ is located to the southeast of Vanuatu at 172.2±0.9 °E and 22.9±1.1 °S and its broad-scale structure can be approximated as a cylinder with a height of 20±5 km, radius 240±50 km, and shear wave velocity reduction of 30±5%. These parameters are comparable to other ULVZs previously detected and modelled with Sdiff and Sdiff+. There are appreciable uncertainties in the location along the NW-SE direction due to the distribution of earthquakes and seismic arrays, as well as trade-offs between the height, size and velocity reduction of the ULVZ. Other studies using SPdKS, ScP and PcP have reported detections of ULVZs in the proximate region, some of which are consistent with the well-fitting parameter space of the ULVZ in this study. The Vanuatu ULVZ lies within the southwest edge of the Pacific large low velocity province. There is potentially a mantle plume rooted by this ULVZ that has diverted towards the hotspots on the eastern Australian plate around the Tonga slab, although most tomographic models do not show a continuous plume here. ]]></description>
      <pubDate>Thu, 16 Oct 2025 14:07:38 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.15883</link>
      <guid>https://doi.org/10.46298/jsedi.15883</guid>
      <author>Martin, Carl</author>
      <author>Harmsma, Lobke</author>
      <author>Atkins, James</author>
      <author>Deuss, Arwen</author>
      <author>Cottaar, Sanne</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <category><![CDATA[ultra-low velocity zone]]></category>
      <category><![CDATA[deep Earth seismology]]></category>
      <dc:creator>Martin, Carl</dc:creator>
      <dc:creator>Harmsma, Lobke</dc:creator>
      <dc:creator>Atkins, James</dc:creator>
      <dc:creator>Deuss, Arwen</dc:creator>
      <dc:creator>Cottaar, Sanne</dc:creator>
      <slash:comments>0</slash:comments>
    </item>
    <item>
      <title>The mantle-inner core gravitational mode of oscillation in a strong magnetic field regime</title>
      <description><![CDATA[The mantle-inner core gravitational (MICG) mode is the free mode axial oscillation between the mantle and inner core sustained by the gravitational torque between their degree 2 order 2 density structures.  As part of this mode, the tangent cylinder (TC) is entrained to move jointly with the inner core, and the oscillations of the TC launch Alfvén waves propagating in the region outside the TC.  Here, we investigate how the MICG is altered by the strength of the internal magnetic field in the core which controls the travelling speed of Alfvén waves.  We show that the MICG mode remains a distinct normal mode of oscillation of the core-mantle system only when Alfvén waves are attenuated before they traverse the width of the fluid core.  For an internal magnetic field strength of a few mT, as we expect in Earth's core, Alfvén waves can readily traverse the width of the core, and the MICG mode is absorbed into the spectrum of torsional oscillation (TO) modes.  The MICG period retains a dynamical influence, acting as a point of resonance for TO modes, and marking the transition from a TO mode that is weakly impacted by gravitational coupling to one in which the motion of the TC (including the inner core) is strongly restricted. Our results imply that the observed 6-year periodic signal in the length of day cannot be interpreted as the signature of the MICG mode and must instead be caused by TO modes, or more generally, by the propagation of Alfvén waves.  ]]></description>
      <pubDate>Fri, 26 Sep 2025 00:00:00 +0000</pubDate>
      <link>https://doi.org/10.46298/jsedi.15735</link>
      <guid>https://doi.org/10.46298/jsedi.15735</guid>
      <author>Dumberry, Mathieu</author>
      <category><![CDATA[Journal of Studies of Earth’s Deep Interior]]></category>
      <dc:creator>Dumberry, Mathieu</dc:creator>
      <slash:comments>0</slash:comments>
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