2024-01-01 10:30:27
But what is the core doing at the center of the Earth? Far from following the overall movement of other terrestrial envelopes, it seems in fact animated by its own dynamics. A new study reveals that in addition to rotating on itself with a different speed, it would also be animated by its own oscillation around its axis of rotation.
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The Earth rotates on its axis and with it, all of the geological envelopes that compose it. However, it seems that the rotation of these different layers is not completely synchronized. Previous studies have in fact shown that the inner core rotates at a different speed from that of the outer shells. A differential movement which participates in the generation of the earth’s magnetic field.
A core that does as it pleases!
A new study reveals that the inner core also oscillates. In other words, the solid-solid iron seed that occupies the center of the Earth behaves a bit like a spinning top regarding to stop. Researchers have just confirmed that the inner core oscillates around its axis of rotation periodically, following cycles lasting approximately 8.5 years. The results were published in review Nature Communications.
Additional constraints on the dynamics of the inner core and its structure
This 8.5 year signal had previously been detected during studies concerning the movement of the poles, the periodic movement of the Earth’s axis of rotation and variations in the length of the day. These data suggested that the inner core was driven by an oscillation of its own and different from that of the Earth’s mantle. The researchers thus highlighted a shift of less than 1° in the alignment of the axes of rotation between these two terrestrial envelopes. These results also make it possible to identify density heterogeneity within the inner core itself, providing significant constraints on the stratification of the seed. It thus appears that the northern hemispherenorthwest hemisphere of the inner core is denser than its other regions.
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