TY  - JOUR
AU  - Deuss Arwen
PY  - 2014//
TI  - Heterogeneity and Anisotropy of Earth's Inner Core
T2  - 0084-6597
JO  - Annual Review of Earth and Planetary Sciences
SP  - 103
EP  - 126
VL  - 42
IS  - 1
PB  - Annual Reviews
KW  - body waves
KW  - dynamics
KW  - free oscillations
KW  - iron
KW  - mineralogy
KW  - seismology
KW  - solidification
KW  -
N2  - Seismic observations provide strong evidence that Earth's inner core is anisotropic, with larger velocity in the polar than in the equatorial direction. The top 60–80 km of the inner core is isotropic; evidence for an innermost inner core is less compelling. The anisotropy is most likely due to alignment of hcp (hexagonal close-packed) iron crystals, aligned either during solidification or by deformation afterward. The existence of hemispherical variations used to be controversial, but there is now strong evidence from both seismic body wave and normal mode observations, showing stronger anisotropy, less attenuation, and a lower isotropic velocity in the western hemisphere. Two mechanisms have been proposed to explain the hemispherical pattern: either (a) inner core translation, wherein one hemisphere is melting and the other is solidifying, or (b) thermochemical convection in the outer core, leading to different solidification conditions at the inner core boundary. Neither is (yet) able to explain all se...
SN  - 0084-6597
UR  - http://dx.doi.org/10.1146/annurev-earth-060313-054658
N1  - exported from refbase (http://publi.ipev.fr/polar_references/show.php?record=5915), last updated on Sat, 06 Jul 2024 10:00:16 +0200
ID  - DeussArwen2014
ER  -