CoChat
Sign Up
Cited by 25High-pressure geophysics and materialsSeismic Waves and Analysisearthquake and tectonic studies

Inner core backtracking by seismic waveform change reversals

Open access
Wang, Wei, Vidale, John E., Pang, Guanning, Koper, Keith D., Wang, Ruoyan·2024·Nature
DOI 10.1038/s41586-024-07536-4PMC PMC11236701
Open this paper in CoChat — free account

Abstract

The solid inner core, suspended within the liquid outer core and anchored by gravity, has been inferred to rotate relative to the surface of Earth or change over years to decades based on changes in seismograms from repeating earthquakes and explosions 1,2. It has a rich inner structure 3–6 and influences the pattern of outer core convection and therefore Earth’s magnetic field. Here we compile 143 distinct pairs of repeating earthquakes, many within 16 multiplets, built from 121 earthquakes between 1991 and 2023 in the South Sandwich Islands. We analyse their inner-core-penetrating PKIKP waves recorded on the medium-aperture arrays in northern North America. We document that many multiplets exhibit waveforms that change and then revert at later times to match earlier events. The matching waveforms reveal times at which the inner core re-occupies the same position, relative to the mantle, as it did at some time in the past. The pattern of matches, together with previous studies, demonstrates that the inner core gradually super-rotated from 2003 to 2008, and then from 2008 to 2023 sub-rotated two to three times more slowly back through the same path. These matches enable precise and unambiguous tracking of inner core progression and regression. The resolved different rates of forward and backward motion suggest that new models will be necessary for the dynamics between the inner core, outer core and mantle.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1038/s41586-024-07536-4

Cites

1 of 1 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The exact time of the inner-core rotation reversal is not well constrained by the data, but the best-fit time of 2010 is generally consistent with the turning point of around 2009 from Yang and Song (2023) and Wang et al. (2024).

    “The exact time of reversal is not well constrained in our data, but the time of 2010 from the best-fit spline is generally consistent with the turning point of around 2009 from Yang and Song (2023) and Wang et al. (2024) (Figures 4a and 4b)”

    From Pattern of Inner‐Core Differential Rotation From Long‐Term Earthquake Sequences and USArray Network (2026) · cites this paper as Wang et al. (2024)

  • The paper's robust results support the transition model of inner-core differential rotation proposed recently.

    “By averaging more available data than possible from doublet pairs, we provide robust results supporting the transition model of the IC differential rotation proposed recently (Wang et al., 2024;Yang & Song, 2023)”

    From Pattern of Inner‐Core Differential Rotation From Long‐Term Earthquake Sequences and USArray Network (2026) · cites this paper as Wang et al., 2024

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

Research works printed but not linked: 31

  1. [1]Zhang J Inner core differential motion confirmed by earthquake waveform doublets Science 2005 309 1357 1360 10.1126/science.1113193 16123296 · DOI · Paper page
  2. [2]Vidale JE Dodge D Earle PS Slow differential rotation of the Earth’s inner core indicated by temporal changes in scattering Nature 2000 405 445 448 10.1038/35013039 10839537 · DOI · Paper page
  3. [3]Deuss A Heterogeneity and anisotropy of Earth’s inner core Annu. Rev. Earth Planet. Sci. 2014 42 103 126 10.1146/annurev-earth-060313-054658 · DOI · Paper page
  4. [4]Shearer, P. M. in Treatise on Geophysics 2nd edn, Vol. 1 (ed. Schubert, G.) 759–787 (Elsevier, 2015).
  5. [5]Souriau, A. & Calvet, M. in Deep Earth Seismology 2nd edn, Vol. 1 (ed. Romanowicz, B. A.) 725–7573 (Elsevier, 2015).
  6. [6]Brett H Hawkins R Waszek L Lythgoe K Deuss A 3D transdimensional seismic tomography of the inner core Earth Planet. Sci. Lett. 2022 593 117688 10.1016/j.epsl.2022.117688 · DOI
  7. [8]Yang Y Song X Origin of temporal changes of inner-core seismic waves Earth Planet. Sci. Lett. 2020 541 116267 10.1016/j.epsl.2020.116267 · DOI
  8. [9]Yang Y Song X Temporal changes of the inner core from globally distributed repeating earthquakes J. Geophys. Res. Solid Earth 2020 125 e2019JB018652 10.1029/2019JB018652 · DOI
  9. [10]Yang Y Song X Inner core rotation captured by earthquake doublets and twin stations Geophys. Res. Lett. 2022 49 e2022GL098393 10.1029/2022GL098393 · DOI · Paper page
  10. [12]Vidale JE Earle PS Evidence for inner‐core rotation from possible changes with time in PKP coda Geophys. Res. Lett. 2005 32 L01309 10.1029/2004GL021240 · DOI
  11. [13]Vidale JE Very slow rotation of Earth’s inner core from 1971 to 1974 Geophys. Res. Lett. 2019 46 9483 9488 10.1029/2019GL083774 · DOI · Paper page
  12. [14]Wang W Vidale JE Earth’s inner core rotation, 1971 to 1974, illuminated by inner-core scattered waves Earth Planet. Sci. Lett. 2022 577 117214 10.1016/j.epsl.2021.117214 · DOI
  13. [15]Tsuboi S Butler R Inner core differential rotation inferred from antipodal seismic observations Phys. Earth Planet. Int. 2020 301 106451 10.1016/j.pepi.2020.106451 · DOI
  14. [16]Tkalčić H Young M Bodin T Ngo S Sambridge M The shuffling rotation of the Earth’s inner core revealed by earthquake doublets Nat. Geosci. 2013 6 497 502 10.1038/ngeo1813 · DOI · Paper page
  15. [17]Pang G Koper KD Excitation of Earth’s inner core rotational oscillation during 2001–2003 captured by earthquake doublets Earth Planet. Sci. Lett. 2022 584 117504 10.1016/j.epsl.2022.117504 · DOI · Paper page
  16. [18]Buffett BA Gravitational oscillations in the length of day Geophys. Res. Lett. 1996 23 2279 2282 10.1029/96GL02083 · DOI
  17. [19]Ding H Chao BF A 6-year westward rotary motion in the Earth: Detection and possible MICG coupling mechanism Earth Planet. Sci. Lett. 2018 495 50 55 10.1016/j.epsl.2018.05.009 · DOI
  18. [20]Gillet N Jault D Canet E Fournier A Fast torsional waves and strong magnetic field within the Earth’s core Nature 2010 465 74 77 10.1038/nature09010 20445627 · DOI
  19. [21]Gillet N Jault D Finlay CC Planetary gyre, time‐dependent eddies, torsional waves, and equatorial jets at the Earth’s core surface J. Geophys. Res. Solid Earth 2015 120 3991 4013 10.1002/2014JB011786 · DOI
  20. [22]Rosat S Gillet N Intradecadal variations in length of day: coherence with models of the Earth’s core dynamics Phys. Earth Planet. Inter. 2023 341 107053 10.1016/j.pepi.2023.107053 · DOI
  21. [23]Wang W Vidale JE Seismological observation of Earth’s oscillating inner core Sci. Adv. 2022 8 eabm9916 10.1126/sciadv.abm9916 35687683 PMC9187225 · DOI
  22. [24]Yao J Sun L Wen L Two decades of temporal change of Earth’s inner core boundary J. Geophys. Res. Solid Earth 2015 120 6263 6283 10.1002/2015JB012339 · DOI
  23. [25]Yao J Tian D Sun L Wen L Temporal change of seismic Earth’s inner core phases: inner core differential rotation or temporal change of inner core surface? J. Geophys. Res. Solid Earth 2019 124 6720 6736 10.1029/2019JB017532 · DOI
  24. [26]Mäkinen AM Deuss A Global seismic body-wave observations of temporal variations in the Earth’s inner core, and implications for its differential rotation Geophys. J. Int. 2011 187 355 370 10.1111/j.1365-246X.2011.05146.x · DOI
  25. [27]Yang Y Song X Multidecadal variation of the Earth’s inner-core rotation Nat. Geosci. 2023 16 182 187 10.1038/s41561-022-01112-z · DOI · Paper page
  26. [28]Tkalčić, H. The Earth’s Inner Core: Revealed by Observational Seismology (Cambridge Univ. Press, 2017).
  27. [29]Shih SA Chao BF Inner core and its libration under gravitational equilibrium: Implications to lower-mantle density anomaly J. Geophys. Res. Solid Earth 2021 126 e2020JB020541 10.1029/2020JB020541 · DOI
  28. [30]Niu F Wen L Hemispherical variations in seismic velocity at the top of the Earth’s inner core Nature 2001 410 1081 1084 10.1038/35074073 11323668 · DOI
  29. [31]Kennett B Engdahl ER Buland RP Constraints on seismic velocities in the Earth from traveltimes Geophys. J. Int. 1995 122 108 124 10.1111/j.1365-246X.1995.tb03540.x · DOI
  30. [32]Yao J Tian D Sun L Wen L Comment on “Origin of temporal changes of inner-core seismic waves” by Yang and Song (2020) Earth Planet. Sci. Lett. 2021 553 116640 10.1016/j.epsl.2020.116640 · DOI
  31. [33]Yang Y Song X Reply to Yao et al.’s comment on “Origin of temporal changes of inner-core seismic waves” Earth Planet. Sci. Lett. 2021 553 116639 10.1016/j.epsl.2020.116639 · DOI

Cited by

Sorted by citations

Authors
Wang, W., Vidale, J. E., Pang, G., Koper, K. D., & Wang, R.
Affiliations
  • University of Southern California (US)
  • Cornell University (US)
  • University of Utah (US)
Corresponding author
Vidale, John E.
ORCID
Venue
Nature
Publisher
Springer Science and Business Media LLC
Published
2024-06-12
Volume
631
Issue
8020
Pages
340-343
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
DOI
10.1038/s41586-024-07536-4
PMC
PMC11236701
OpenAlex
W4399567364
Cited by
25
References
1
Citations by year
2026: 7 · 2025: 12 · 2024: 6
FWCI
6.46
Type
journal article
Language
en
Open access
Licence
Locations
  • Nature (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
National Science Foundation (2041892)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Geophysics › High-pressure geophysics and materials
  • Physical Sciences › Earth and Planetary Sciences › Geophysics › Seismic Waves and Analysis
  • Physical Sciences › Earth and Planetary Sciences › Geophysics › earthquake and tectonic studies
Keywords
Earth's inner core, inner core rotation, repeating earthquakes
MeSH terms
North America, Rotation, Time Factors, Earthquakes, Magnetic Fields

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review