Abstract
The difference between the travel times of com-pressional waves that turn in the Earth's liquid outer core (PKP-BC) and those that run in the solid inner core (PKIKP-DF) is primarily sensitive to structure near the inner-core boundary. Such differential travel times measured from short-period waveforms are consistent with small-amplitude deviations from radial symmetry except when ray paths are nearly parallel to the Earth's spin axis. These near-axial paths consistently produce large travel-time anomalies, providing compelling evidence for large-amplitude, axisymmetric aniso-tropy in the outermost portions of the inner core.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Masters, G. & Gilbert, F. Geophys Res. Lett. 8, 569–571 (1981).
Ritzwoller, M., Masters, G. & Gilbert, F. J. geophys. Res. 91, 10203–10228 (1986).
Ritzwoller, M., Masters, G. & Gilbert, F. J. geophys. Res. 93, 6369–6396 (1988).
Woodhouse, J. H., Giardini, D. & Li, X.-D. Geophys. Res. Lett. 13, 1549–1552 (1986).
Giardini, D., Li, X.-D. & Woodhouse, J. H. Nature 325, 405–411 (1987).
Giardini, D., Li, X.-D. & Woodhouse, J. H. J. geophys. Res. 93, 13716–13742 (1988).
Li, C.-D., Giardini, D. & Woodhouse, J. H. J. geophys. Res. 96, 551–577 (1991).
Widmer, R. thesis, Univ. of California, San Diego (1991).
Poupinet, G., Pillet, R. & Souriau, A. Nature 305, 204–206 (1983).
Morelli, A., Dziewonski, A. M. & Woodhouse, J. H. Geophys. Res. Lett. 13, 1545–1548 (1986).
Shearer, P. M., Toy, K. M. & Orcutt, J. A. Nature 333, 228–232 (1988).
Shearer, P. M. & Toy, K. M. J. geophys. Res. 96, 2233–2247 (1991).
Dziewonski, A. M. & Anderson, D. L. Phys. Earth planet. Inter. 25, 297–356 (1981).
Dziewonski, A. M. & Gilbert, F. Geophys. J. R. astr. Soc. 44, 7–17 (1976).
Kennett, B. L. N. & Engdahl, E. R. Geophys. J. Int. 105, 429–465 (1991).
Boyd, T. M. & Creager, K. C. J. geophys. Res. 96, 2267–2291 (1991).
Cormier, V. F. & Choy, G. L. Geophys. Res. Lett. 13, 1553–1556 (1986).
Brown, J. M. & McQueen, R. G. J. geophys. Res. 91, 7485–7494 (1986).
Jeanloz, R. & Wenk, H. R. Geophys. Res. Lett. 15, 72–75 (1988).
Chandrasekhar, S., Hydrodynamic and Hydromagnetic Stability (Clarendon, Oxford, 1961).
Wenk, H. R., Takeshita, T., Jeanloz, R. & Johnson, G. C. Geophys. Res. Lett. 15, 76–79 (1988).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Creager, K. Anisotropy of the inner core from differential travel times of the phases PKP and PKIKP. Nature 356, 309–314 (1992). https://doi.org/10.1038/356309a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/356309a0
- Springer Nature Limited
This article is cited by
-
Up-to-fivefold reverberating waves through the Earth’s center and distinctly anisotropic innermost inner core
Nature Communications (2023)
-
Superionic effect and anisotropic texture in Earth’s inner core driven by geomagnetic field
Nature Communications (2023)
-
The Geodesic Ray Transform on Spherically Symmetric Reversible Finsler Manifolds
The Journal of Geometric Analysis (2023)
-
Superionic iron alloys and their seismic velocities in Earth’s inner core
Nature (2022)
-
Dynamic history of the inner core constrained by seismic anisotropy
Nature Geoscience (2021)