Encyclopedia of Solid Earth Geophysics

Living Edition
| Editors: Harsh K. Gupta

Earth’s Structure, Core

  • Lianxing WenEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-030-10475-7_150-1

Definition

Structure ofEarth’s core is referred to as the properties of velocity, density, attenuation, anisotropy, composition, and surface feature of Earth’s core and how these properties change with depth, geographic location, and time.

Attenuation is a measure of material’s ability to absorb energy as seismic waves pass through it.

Anisotropy is a material property that is directionally dependent.

Mushy zone is a layer of mixing solid inner core and liquid outer core materials.

Overall Structure

The Earth’s core occupies the center portion of Earth with a radius of 3480 km. It consists of a liquid outer core and a solid inner core. Earth’s core is composed of Fe/Ni and some minor light elements, such as S, C, O, and Si. Those light elements are preferentially enriched in the outer core after the continuing solidification of outer core material to the inner core. Seismic compressional velocity and density exhibit jumps at the inner core boundary at a radius of about 1221 km. The...
This is a preview of subscription content, log in to check access.

Bibliography

  1. Alboussière T, Deguen R, Melzani M (2010) Melting-induced stratification above the Earth’s inner core due to convective translation. Nature 466:744–747.  https://doi.org/10.1038/nature09257CrossRefGoogle Scholar
  2. Aubert J, Amit H, Hulot G et al (2008) Thermochemical flows couple the Earth’s inner core growth to mantle heterogeneity. Nature 454:758–761.  https://doi.org/10.1038/nature07109CrossRefGoogle Scholar
  3. Dai Z, Wang W, Wen L (2012) Irregular topography at the Earth’s inner core boundary. Proc Natl Acad Sci U S A 109:7654–7658.  https://doi.org/10.1073/pnas.1116342109CrossRefGoogle Scholar
  4. Ishii M, Dziewonski AM (2002) The innermost inner core of the Earth: evidence for a change in anisotropic behavior at the radius of about 300 km. Proc Natl Acad Sci 99:14026–14030CrossRefGoogle Scholar
  5. Morelli A, Dziewonski AM, Woodhouse JH (1986) Anisotropy of the inner core inferred from PKIKP travel times. Geophys Res Lett 13:1545–1548CrossRefGoogle Scholar
  6. Niu F, Wen L (2001) Hemispherical variations in seismic velocity at the top of the Earth’s inner-core. Nature 410:1081–1084CrossRefGoogle Scholar
  7. Tanaka S, Hamaguchi H (1997) Degree one heterogeneity and hemispherical variation of anisotropy in the inner core from PKP(BC) – PKP(DF) times. J Geophys Res Solid Earth 102:2925–2938CrossRefGoogle Scholar
  8. Tian D, Wen L (2017) Seismological evidence for a localized mushy zone at the Earth’s inner core boundary. Nat Commun 8:165.  https://doi.org/10.1038/s41467-017-00229-9CrossRefGoogle Scholar
  9. Wen L (2006) Localized temporal change of the Earth’s inner core boundary. Science 314:967–970.  https://doi.org/10.1126/science.1131692CrossRefGoogle Scholar
  10. Yao J, Tian D, Sun L, Wen L (2019) 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 124:6720.  https://doi.org/10.1029/2019JB017532CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  1. 1.Department of GeosciencesState University of New York at Stony BrookStony BrookUSA