Planet Within a Planet: Rotation of the Inner Core of Earth
- 13 December 1996
- journal article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 274 (5294) , 1883-1887
- https://doi.org/10.1126/science.274.5294.1883
Abstract
The time dependence of the orientation of Earth's inner core relative to the mantle was determined using a recently discovered 10-degree tilt in the axis of symmetry of the inner core's seismic-velocity anisotropy. Two methods of analyzing travel-time variations for rays traversing the inner core, on the basis of 29 years of data from the International Seismological Centre (1964–1992), reveal that the inner core appears to rotate about 3 degrees per year faster than the mantle. An anomalous variation in inner-core orientation from 1969 to 1973 coincides in time with a sudden change (“jerk”) in the geomagnetic field.Keywords
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