Skip to main content

Thank you for visiting nature.com. 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.

Measurements of electric anisotropy due to solidification texturing and the implications for the Earth's inner core

An Erratum to this article was published on 25 September 1997

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Photograph of the exterior surface of a slice of a directionally solidified, 97% Sn–3% Pb (by weight) alloy.
Figure 2: Left, diagram of the Earth's inner core in a plane containing the rotation axis, showing the direction of heat flow.
Figure 3: Compressional wave travel-time residuals inferred seismologically (asterisks)6 and predicted by.

References

  1. Morelli, A. D., Dziewonski, A. M. & Woodhouse, J. H. Anisotropy of the inner core inferred from PKIKP travel times. Geophys. Res. Lett. 13, 1545–1548 (1986).

    Google Scholar 

  2. Woodhouse, J. H., Giardini, D. & Li, X. D. Evidence for inner core anisotropy from free oscillations. Geophys. Res. Lett. 13, 1549–1552 (1986).

    Google Scholar 

  3. Creager, K. C. Anisotropy of the inner core from differential travel times of the phases PKP and PKIKP. Nature 356, 309–314 (1992).

    Article  ADS  Google Scholar 

  4. Tromp, J. Support for anisotropy of the Earth's inner core from free oscillations. Nature 366, 678–681 (1993).

    Article  ADS  Google Scholar 

  5. Shearer, P. Constraints on inner core anisotropy from PKP(DF) travel times. J. Geophys. Res. 99, 19647–19659 (1994).

    Google Scholar 

  6. Su, W. & Dziewonski, A. M. Inner core anisotropy in three dimensions. J. Geophys. Res. 100, 9831–9852 (1995).

    Google Scholar 

  7. 7. Song, X. Anisotropy in central part of inner core. J. Geophys. Res. 101, 16089–16097 (1996).

    Google Scholar 

  8. Porter, D. A. & Easterling, K. E. Phase Transformations in Metals and Alloys(Chapman &Hall, London, (1992)).

    Book  Google Scholar 

  9. Chalmers, B., Principles of Solidification(Wiley, New York, (1964)).

    Google Scholar 

  10. Glatzmaier, G. A. & Roberts, P. H. Dynamo theory then and now. Int. J. Eng. Sci.(in the press).

  11. Cormier, V. F. Inner core structure inferred from body waveforms. Eos 75, 67 (1994).

    Google Scholar 

  12. Souriau, A. & Romanowicz, B. Anisotropy in inner core attenuation: a new type of data to constrain the nature of the solid core. Geophys. Res. Lett. 23, 1–4 (1996).

    Google Scholar 

  13. Wenk, H. R., Takeshita, T., Jeanloz, R. & Johnson, G. C. Development of texture and elastic anisotropy during deformation of hcp metals. Geophys. Res. Lett. 15, 76–79 (1988).

    Google Scholar 

  14. Karato, S. I. Inner core anisotropy due to the magnetic field-induced preferred orientation of iron. Science 262, 1708–1711 (1993).

    Google Scholar 

  15. Stixrude, L. & Cohen, R. E. High-pressure elasticity of iron and anisotropy of Earth's inner core. Science 267, 1972–1975 (1995).

    Google Scholar 

  16. Stacey, F. Physics of the Earth(Brookfield, Brisbane, (1992)).

    Google Scholar 

  17. Yoshida, S., Sumita, I. & Kumazawa, M. Growth model of the inner core coupled with the outer core dynamics and the resulting elastic anisotropy. J. Geophys. Res. 101, 28085–28103 (1996).

    Google Scholar 

  18. Rutter, J. W. in Liquid Metals and Solidification(ed. Maddin, R.) 243–262 (American Society of Metals, Cleveland, (1958)).

    Google Scholar 

  19. Haasen, P. Physical Metallurgy(Cambridge Univ. Press, (1978)).

    Google Scholar 

  20. Barrett, C. & Massalski, T. B. Structure of Metals(Pergamon, New York, (1980)).

    Google Scholar 

  21. Sherman, D. M. Stability of possible Fe–FeS and Fe–FeO alloy phases at high pressure and the composition of the Earth's core. Earth Planet. Sci. Lett. 132, 87–98 (1995).

    Google Scholar 

  22. Fearn, D. R., Loper, D. E. & Roberts, P. H. Structure of the Earth's inner core. Nature 292, 232–233 (1981).

    Article  ADS  Google Scholar 

  23. Esbensen, K. H. & Buchwald, V. F. Planet(oid) core crystallization and fractionation-evidence from the Apaghlik mass of the Cape York iron meteorite shower. Phys. Earth. Planet. Inter. 29, 218–232 (1982).

    Google Scholar 

  24. Bergman, M. I., Fearn, D. R., Bloxham, J. & Shannon, M. Convection and channel formation in solidifying Pb–Sn alloys. Metallurgical Transactions A 28, 859–866 (1997).

    Google Scholar 

  25. Bergman, M. I. & Fearn, D. R. Chimneys on the Earth's inner–outer boundary? Geophys. Res. Lett. 21, 477–480 (1994).

    Google Scholar 

  26. Worster, M. G. Natural convection in a mushy layer. J. Fluid Mech. 224, 335–359 (1991).

    Google Scholar 

  27. Loper, D. E. Structure of the inner core boundary. Geophys. Astrophys. Fluid Dyn. 25, 139–155 (1983).

    Google Scholar 

  28. Doornbos, D. J. The anelasticity of the inner core. Geophys. J. R. Astron. Soc. 38, 397–415 (1974).

    Google Scholar 

  29. Saxena, S. K.et al. Synchrotron X-ray study of iron at high pressure and temperature. Science 269, 1703–1704 (1995).

    Google Scholar 

  30. Simmons, G. & Wang, H. Single Crystal Elastic Constants and Calculated Aggregate Properties(MIT Press, Cambridge, MA, (1971)).

    Google Scholar 

  31. McSkimin, H. J. Ultrasonic measurement techniques applicable to small solid specimens. J. Acoust. Soc. Am. 22, 413–418 (1950).

    Google Scholar 

  32. Roth, W. Scattering of ultrasonic radiation in polycrystalline metals. J. Appl. Phys. 19, 901–910 (1948).

    Google Scholar 

  33. Mason, W. P. & McSkimin, H. J. Energy losses of sound waves in metals due to scattering and diffusion. J. Appl. Phys. 19, 940–946 (1948).

    Google Scholar 

Download references

Acknowledgements

I thank K. Bishop (Matec Instruments) and B. Li for assistance with the ultrasonic measurements; J. Bloxham, W. Dunbar, D. Fearn, C. Francis, W. Kuang, H. Ma, R. O'Connell, M. Shannon, F. Spaepen, J. Tromp, and especially S. Zatman for suggestions; G. Glatzmaier and S. Yoshida for providing preprints; and J. Bloxham, supported by the David and Lucile Packard Foundation and the NSF, and Harvard University, for providing facilities. This work was supported by a Cottrell College Science Award of the Research Corporation.

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Bergman, M. Measurements of electric anisotropy due to solidification texturing and the implications for the Earth's inner core. Nature 389, 60–63 (1997). https://doi.org/10.1038/37962

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/37962

Comments

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.

Search

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