Definition
Differential rotation of the inner core refers to the difference between the rotation of the Earth’s solid inner core and the daily rotation of the Earth’s crust and the mantle.
Background
Driven by gravity, the Earth differentiated into iron core and rocky mantle at the early stage of its formation. The central core is liquid because of high temperature; but at the center of the Earth, an inner core is formed and gradually grows as the Earth cools, and the liquid iron freezes under tremendous pressure (3 million times the atmospheric pressure). The size of the inner core is slightly smaller than that of the moon. Separated from the solid mantle by the fluid outer core, the inner core is thus free to rotate independently under an external torque.
The early idea of inner core rotation came from studies of the geodynamo, which generated the Earth’s magnetic field. Gubbins (1981) first suggested that electromagnetic forces between the electrically conducting inner core and the...
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Song, X. (2011). Differential Rotation of the Earth’s Inner Core. In: Gupta, H.K. (eds) Encyclopedia of Solid Earth Geophysics. Encyclopedia of Earth Sciences Series. Springer, Dordrecht. https://doi.org/10.1007/978-90-481-8702-7_43
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