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The rotation of the Earth’s inner core may have stopped and may even be going into reverse, new research suggests.
The Earth is made up of a crust, a mantle, and an inner and outer core. solid The inner core is located about 3,200 miles below the Earth’s crust and is separated from the liquid outer core by a semi-solid mantle, which allows the inner core to rotate at a different speed than the Earth’s own rotation.
With a radius of about 2,200 miles, the Earth’s core is about the size of Mars. It consists mainly of iron and nickel, and contains about a third of the mass of the Earth.
In research published in the journal Nature Geoscience on Monday, Yi Yang, an associate research scientist at Peking University, and Xiaodong Song, a chair professor at Peking University, investigated seismic waves from earthquakes that passed through the Earth’s inner core along similar paths from the 1960s to the present day. how fast the inner core spins.
What they had found unexpected, they said. Since 2009, seismic records, which previously at a changed time; little difference. This, they said, suggested that the inner core of the rotation had been interrupted.
“We have shown surprising observations that the inner core has almost stopped rotating in recent decades and can experience a reversal,” they wrote in the study.
“When you look at the decade between 1980 and 1990, you see a clear change but when you look at 2010 to 2020, you don’t see much of a change,” added Song.
The spin of the inner core is driven by the magnetic field generated in the outer core and balanced by the gravitational effects of the mantle. Knowing how the inner core moves can shed light on how these layers interact with each other and other processes deep within the Earth.
But the speed of this rotation and whether it varies is debated, said Hrvoje Tkalcic, a geophysicist at the Australian National University, who was not involved in the study;
“The inner core doesn’t come to a full stop,” he said. The study’s findings, he said, “signal that the inner core is now more in sync with the rest of the planet than it was a decade ago, when it was moving a little faster.”
“Nothing cataclysmic happened,” he added.
Song and Yang argue that, based on their calculations, a small imbalance in the electromagnetic and gravitational forces can slow and even reverse the rotation of the inner core. They believe this is part of a seven-decade cycle, and the milestones before the one they detected in their data around 2009/2010 occurred in the early 1970s.
Tkalcic, who is the author of “Earth’s Inner Core: Revealed by Observational Seismology,” said the study’s analysis is sound. However, the study’s findings are “cautionary” for “the nature of the data and new methods” are needed to clarify this interesting question.
Song and Yang agree that more research is needed.
Tkalcic, who devotes an entire chapter of his book to internal rotation, suggested that the inner core cycle every 20 to 30 years, as opposed to 70 in the latest study. He explained why such variations occur and why it is so difficult to understand what is happening in the inner parts of the planet.
“Those of our studies are buried thousands of kilometers under our feet,” he said.
“We use geophysical methods to infer the internal properties of the Earth, and caution must be exercised until multi-disciplinary findings confirm our hypotheses and conceptual frameworks,” he explained.
“You can talk about seismologists as medical doctors who study the organs of patients’ bodies using imperfect or limited equipment. So, although we are making progress, our image of the interior of the Earth is still frightening, and we are still on the scene to find out.
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