Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Slow differential rotation of the Earth's inner core indicated by temporal changes in scattering


The finding that the Earth's inner core might be rotating faster than the mantle1 has important implications for our understanding of core processes, including the generation of the Earth's magnetic field2,3. But the reported signal is subtle—a change of about 0.01 s per year in the separation of two seismic waves with differing paths through the core. Subsequent studies of such data have generally supported the conclusion that differential rotation exists4,5,6, but the difficulty of accurately locating historic earthquakes7 and possible biases induced by strong lateral variations in structure near the core–mantle boundary8 have raised doubt regarding the proposed inner-core motion9. Also, a study of free oscillations10 constrained the motion to be relatively small compared to previous estimates and it has been proposed that the interaction of inner-core boundary topography and mantle heterogeneity might lock the inner core to the mantle11. The recent detection of seismic waves scattered in the inner core12 suggests a simple test of inner-core motion. Here we compare scattered waves recorded in Montana, USA, from two closely located nuclear tests at Novaya Zemlya, USSR, in 1971 and 1974. The data show small but coherent changes in scattering which point toward an inner-core differential rotation rate of 0.15° per year—consistent with constraints imposed by the free-oscillation data10.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Slant stack of the wavefield incident on LASA from the two nuclear tests.
Figure 2: Cartoon of inner-core scattering path.
Figure 3: Amplitude and time difference as a function of radial and transverse slowness.


  1. 1

    Song, X. D. & Richards, P. G. Seismological evidence for differential rotation of the Earth's inner core. Nature 382, 221–224 (1996).

    ADS  CAS  Article  Google Scholar 

  2. 2

    Glatzmaier, G. A. & Roberts, P. H. A three-dimensional self-consistent computer simulation of a geomagnetic field reversal. Nature 377, 203–209 ( 1995).

    ADS  CAS  Article  Google Scholar 

  3. 3

    Kuang, W. L. & Bloxham, J. An earthlike numerical dynamo model. Nature 389, 371–374 (1997).

    ADS  CAS  Article  Google Scholar 

  4. 4

    Song, X. Joint inversion for inner core rotation, inner core anisotropy, and mantle heterogeneity. J. Geophys. Res. 105, 7931– 7944 (2000).

    ADS  Article  Google Scholar 

  5. 5

    Creager, K. C. Inner core rotation rate from small-scale heterogeneity and time-varying travel times. Science 278, 1284– 1288 (1997).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Song, X. & Li, A. Support for differential inner core superrotation from earthquakes in Alaska recorded at South Pole station. J. Geophys. Res. 105, 623–630 ( 2000).

    ADS  Article  Google Scholar 

  7. 7

    Poupinet, G., Souriau, A. & Coutant, O. The existence of an inner core super-rotation questioned by teleseismic doublets. Phys. Earth Planet. Inter. 118, 77–88 (2000).

    ADS  Article  Google Scholar 

  8. 8

    Breger, L. & Romanowicz, B. Three-dimensional structure at the base of the mantle beneath the central Pacific. Science 282, 718–720 (1998).

    ADS  CAS  Article  PubMed  Google Scholar 

  9. 9

    Souriau, A., Roudil, P. & Moynot, B. Inner core differential rotation: Facts and artefacts. Geophys. Res. Lett. 24, 2103– 2106 (1997).

    ADS  Article  Google Scholar 

  10. 10

    Laske, G. & Masters, T. G. Rotation of the inner core from a new analysis of free oscillations. Nature 402, 3397–3400 (1999).

    Article  Google Scholar 

  11. 11

    Buffett, B. A. Geodynamic estimates of the viscosity of the Earth's inner core. Nature 388, 571–573 ( 1997).

    ADS  CAS  Article  Google Scholar 

  12. 12

    Vidale, J. E. & Earle, P. S. Fine-scale heterogeneity in the Earth's inner core. Nature 404, 273– 275 (2000).

    ADS  CAS  Article  PubMed  Google Scholar 

  13. 13

    Green, P. E., Frosch, R. A. & Romney, C. F. Principles of an experimental large aperture seismic array (LASA). Proc. IEEE 53, 1821– 1833 (1965).

    Article  Google Scholar 

  14. 14

    Capon, J. Analysis of Rayleigh-wave multipath at LASA. Bull. Seismol. Soc. Am. 60, 1701–1731 ( 1970).

    Google Scholar 

  15. 15

    Marshall, P. D., Porter, D., Young, J. B. & Peachall, P. A. Atomic Weapons Establishment Report O 2/94 (Her Majesty's Stationery Office, London, 1994).

  16. 16

    Engdahl, E. R. & Felix, C. P. Nature of travel-time anomalies at Lasa. J. Geophys. Res. 76, 2706–2715 (1971).

    ADS  Article  Google Scholar 

  17. 17

    Haddon, R. A. W., Husebye, E. S. & King, D. W. Origin of precursors to P′P′. Phys. Earth Planet. Inter. 14, 41– 70 (1977).

    ADS  Article  Google Scholar 

  18. 18

    Earle, P. S. & Shearer, P. M. Observations of high-frequency scattered energy associated with the core phase PKKP. Geophys. Res. Lett. 25, 405–408 ( 1998).

    ADS  Article  Google Scholar 

  19. 19

    Bhattacharyya, J., Shearer, P. M. & Masters, T. G. Inner core attenuation from short period PKP(BC) versus PKP(DF) waveforms. Geophys. J. Int. 114, 1–11 (1993).

    ADS  Article  Google Scholar 

  20. 20

    Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. Phys. Earth Planet. Inter. 25 , 297–356 (1981).

    ADS  Article  Google Scholar 

Download references


We thank the Albuquerque Seismological Laboratory and B. Woodward and H. Bolton for access to LASA data. Discussions with K. Creager, P. Richards, T. Wallace, A. Souriau and P. Davis were helpful.

Author information



Corresponding author

Correspondence to John E. Vidale.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Vidale, J., Dodge, D. & Earle, P. Slow differential rotation of the Earth's inner core indicated by temporal changes in scattering. Nature 405, 445–448 (2000).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing