Study confirms the rotation of Earth's inner core has slowed

[Jim__]

From phys.org

The inner core began to decrease its speed around 2010, moving slower than the Earth’s surface. Credit: University of Southern California
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University of Southern California scientists have proven that the Earth's inner core is backtracking—slowing down—in relation to the planet's surface, as shown in new research published in Nature.

Movement of the inner core has been debated by the scientific community for two decades, with some research indicating that the inner core rotates faster than the planet's surface. The new USC study provides unambiguous evidence that the inner core began to decrease its speed around 2010, moving slower than the Earth's surface.

"When I first saw the seismograms that hinted at this change, I was stumped," said John Vidale, Dean's Professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences. "But when we found two dozen more observations signaling the same pattern, the result was inescapable. The inner core had slowed down for the first time in many decades. Other scientists have recently argued for similar and different models, but our latest study provides the most convincing resolution."

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The inner core is a solid iron-nickel sphere surrounded by the liquid iron-nickel outer core. Roughly the size of the moon, the inner core sits more than 3,000 miles under our feet and presents a challenge to researchers: It can't be visited or viewed. Scientists must use the seismic waves of earthquakes to create renderings of the inner core's movement.

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