Related Experiment Video
Updated: May 2, 2026

Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
Tidal dissipation and the strength of the Earth's internal magnetic field
1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA. bbuffett@berkeley.edu
Abstract:
Magnetic fields at the Earth's surface represent only a fraction of the field inside the core. The strength and structure of the internal field are poorly known, yet the details are important for our understanding of the geodynamo. Here I obtain an indirect estimate for the field strength from measurements of tidal dissipation. Tidally driven flow in the Earth's liquid core develops internal shear layers, which distort the internal magnetic field and generate electric currents. Ohmic losses damp the tidal motions and produce detectable signatures in the Earth's nutations. Previously reported evidence of anomalous dissipation in nutations can be explained with a core-averaged field of 2.5 mT, eliminating the need for high fluid viscosity or a stronger magnetic field at the inner-core boundary. Estimates for the internal field constrain the power required for the geodynamo.
More Related Videos
Related Concept Videos
Tidal Forces
Magnetic Fields
A magnetic field is defined by the force that a charged particle experiences...
Divergence and Curl of Magnetic Field
Magnetostatic Boundary Conditions
Magnetic Damping
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
Magnetic Declination

