January 30, 2023

Earth’s inner core may have stopped turning and could go into reverse, study suggests

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Circulation of EarthNew research suggests that its interior may have stalled and may even reverse.

Earth is made up of the crust, mantle, and inner and outer cores. solid The inner core lies about 3,200 miles below the Earth’s crust and is separated from the semi-solid mantle by the liquid outer core, which allows the inner core to rotate at a different rate than the rotation of the Earth itself.

With a radius of about 2,200 miles, the center of the Earth About the size of Mars. It consists mostly of iron and nickel, and makes up about one-third of the Earth’s mass.

In research published in the journal Nature Geoscience On Monday, Peking University Associate Research Scientist Yi Yang and Peking University Chair Professor Zhaodong Song studied seismic waves from earthquakes that have traveled through Earth’s interior along similar paths since the 1960s. To measure how fast the inner core is spinning. .

What he found was unexpected, he said. Since 2009, earthquake records, which previously changed over time, showed little difference. This suggested, he said, that the rotation of the inner core had stopped.

“We show surprising observations that indicate that the inner core has almost stopped its rotation in recent decades and may be experiencing a reversal,” they wrote in the study.

“When you look at the decade between the 1980s and 1990s you see a clear change but when you look at 2010 to 2020 you don’t see much change”.

The rotation 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 rotates can shed light on how these layers interact and other processes deep within the Earth.

However, the speed of this rotation, and whether it varies, is debated, said Australian National University geophysicist Hrvoje Tkalcic, who was not involved in the research.

“The inner core doesn’t come to a full stop,” he said. The results of the study mean the inner core is now more in line with the rest of the planet than it was a decade ago when it was spinning a little faster, he said.

“Nothing catastrophic is happening,” 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 that the turning point before the one detected in their data around 2009/2010 occurred in the early 1970s.

Tkalcic, author of “The Earth’s Inner Core: Revealed by Observational Seismology,” said the study’s “data analysis is sound.” However, the study’s findings “should be taken with caution” because “more data and advanced methods are needed to shed light on this intriguing issue.”

Song and Yang agreed that more research is needed.

Tkalcic, who devoted an entire chapter of his book to inner core rotation, suggested that the inner core rotates every 20 to 30 years, rather than the 70 suggested in the latest study. He explained why such variations occur and why it was so difficult to understand what happens in the innermost part of the planet.

He said that the objects of our study are buried thousands of kilometers under our feet.

“We use geophysical inference methods to infer Earth’s internal properties, and caution should be exercised until multidisciplinary results confirm our hypotheses and conceptual framework.”

“You can think of medical doctors like seismologists who study the internal organs of patients’ bodies using imperfect or limited equipment. So, despite progress, our picture of the interior Earth is still blurry, And we’re still in the discovery phase.”

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