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rotation of PlaceNew research shows that the inner core is on hiatus and may even be reversing.
The Earth consists of the crust, the mantle, and the inner and outer cores. Solid the inner core lies about 3,200 miles below the Earth’s crust and is separated from the semisolid mantle by a liquid outer core that allows the inner core to rotate at a different rate than Earth’s rotation.
Earth’s core with a radius of about 2,200 miles roughly the size of Mars. It is composed mainly of iron and nickel and contains about one third of the mass of the Earth.
In a study published in the journal Natural Geology on Monday, Peking University researcher Yi Yang and Peking University professor Xiaodong Song studied seismic waves from earthquakes that have traveled similar paths through the Earth’s inner core since the 1960s to determine how fast the inner core is rotating. .
What they found was unexpected, they said. Seismic records since 2009, earlier changed over time showed little difference. They said this indicated that the inner core had stopped rotating.
“We make the surprising observation that the inner core has almost stopped spinning over the past decade, and that there may be a reversal.”
“When you look at the decade between the 1980s and 1990s, you see a clear change, but when you look at the 2010s to 2020s, you don’t see much change,” Song added.
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 is changing is debated, said Hrvoje Tkalcic, a geophysicist at the Australian National University who was not involved in the study.
“The inner core doesn’t stop,” I said. The study’s finding, he said, “suggests that the inner core is now more aligned with the rest of the planet than it was a decade ago when it was spinning a little faster.”
“Nothing cataclysmic,” I added.
According to their calculations, Song and Yang claim that a small imbalance in the electromagnetic and gravitational forces can slow down or even reverse the rotation of the inner core. They believe that this is part of a seven-decade cycle, and that the turning point before the period they found in their data in 2009/2010 occurred in the early 1970s.
Tkalcic, author of “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” as “more data and innovative methods are needed to shed light on this intriguing issue.”
Song and Yang agree that more research is needed.
Devoting an entire chapter of his book to the rotation of the inner core, Tkalcic suggested that the cycle of the inner core is every 20 to 30 years, rather than the 70 years suggested in a recent study. I explained why such changes occur and why it was so difficult to understand what was happening in the deepest parts of the planet.
“Our research facilities are buried thousands of kilometers beneath our feet,” he said.
“We use geophysical inference techniques to infer the properties of the Earth’s interior, and caution should be exercised until multidisciplinary findings confirm our hypotheses and conceptual frameworks,” he said.
“You can think of seismologists as doctors who study the internal organs of patients’ bodies using imperfect or limited equipment. So, despite the progress, our picture of the inner Earth is still fuzzy and we are still in the discovery phase.”
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