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Rotation of earthA new study suggests that the inner core of the Earth may have paused and even reversed.
The Earth is made up of a crust, mantle, inner core and outer core.solid The inner core lies approximately 3,200 miles below the Earth’s crust and is separated from the semi-solid mantle by a liquid outer core. This allows the inner core to rotate at a speed different from the rotation of the Earth itself.
Earth’s core about 2,200 miles in radius It’s about the size of Mars. Composed mainly of iron and nickel, it contains about one-third of the mass of the Earth.
In a study published in the journal natural earth science On Monday, Yi Yang, an associate research scientist at Peking University, and Xiaodong Song, a senior professor at Peking University, have studied seismic waves from earthquakes that have passed through the Earth’s inner core along similar paths since the 1960s. , deduced how fast the inner core is rotating. .
What they found was unexpected, they said. Since 2009, seismic records, formerly change with the times, Little difference was seen. This suggests that the rotation of the inner core has paused, they said.
“The rotation of the inner core has nearly stopped over the last decade, a startling observation that suggests it may be undergoing retrograde,” they wrote in the study.
“If you look at the decade from 1980 to 1990, you see a clear change, but if you look at 2010 to 2020, you don’t see much change,” Song added.
The spins in the inner core are driven by the magnetic field generated in the outer core and balanced by gravitational effects in the mantle. Knowing how the inner core rotates can reveal how these layers interact and how other processes operate deep inside the Earth.
But the speed of this rotation, and whether it varies, is an ongoing debate, says Hrvoje Tkalcic, a geophysicist at the Australian National University. He was not involved in this research.
“The inner core never completely stops,” he said. The study’s findings “mean that the inner core is more in sync with the rest of the Earth than it was a decade ago when it was spinning a little faster,” he said.
“No cataclysms have happened,” he added.
Song and Yang, based on their calculations, argue that small imbalances in the electromagnetic and gravitational forces can slow and even reverse the rotation of the inner core. We believe that the tipping point prior to that detected in the data around 2009/2010 occurred in the early 1970s.
Tkalcic, author of “The Earth’s Inner Core: Revealed by Observational Seismology,” says the study’s “data analysis is on point.” However, the study’s findings “should be taken with caution” because “more data and innovative methods are needed to clarify this intriguing question.”
Song and Yang agreed that more research is needed.
Tkalcic, who devotes an entire chapter of his book to the rotation of the inner core, suggested that the inner core cycles every 20 to 30 years, rather than the 70 years suggested in the most recent study. He explained why such changes occur and why it is so difficult to understand what is happening in the deepest part of the Earth.
“Thousands of kilometers of what we study are buried under our feet,” he said.
“We use geophysical reasoning methods to infer the properties of the Earth’s interior, and caution is warranted until interdisciplinary findings confirm our hypotheses and conceptual framework.” he explained.
“Seismologists can be thought of like physicians who study the organs inside a patient’s body using imperfect or limited equipment. So despite advances, images of the Earth’s interior are It’s still a blur, still in the discovery phase.”
