A new study suggests that the Earth’s inner core’s swirling solid ball may have just stopped and may even be rotating in the opposite direction from prior decades.
By analyzing data on seismic waves from earthquakes that have ripped through the Earth’s inner core, a pair of researchers from Peking University in China have been examining the movements of the planet’s enigmatic interior.
They can gain some insight into what is happening in the Earth’s innermost layers—far deeper than any drills and sensors can penetrate—by observing changes in these waves. Their data, starting with Alaskan records from the early 1960s up to recordings acquired in 2021, demonstrates the change in seismic waves over a number of decades.
They claim that the inner core rotation stalled since the data showed that regions of the core that had previously displayed extremely apparent signals of variation suddenly exhibited very little change about 2009.
Additionally, they noticed significant wave variations beginning in the early 1970s, which suggests that this stop was a component of an oscillation that happens roughly every seven decades and involves the inner core gradually rotating in the opposite way.
The workings of Earth’s interior are a mystery. Its structure may be roughly divided into four main layers: an outer crust, a mainly solid mantle, an outer core formed of liquid metal, and an inner core composed of iron and nickel.
The inner core can rotate at a different rate than the surface of the Earth because it is divided from the rest of the solid Earth by the liquid outer core. The magnetic field produced by the liquid metal outer core and the gravitational influences of the mantle both influence how fast the inner core spins.
There is disagreement among the hypotheses on how this inner core moves. It was once widely assumed by researchers that the planet’s deepest geological layer rotates together with the rest of it at a somewhat quicker rate than the surface, but this is now seen to be less certain.
Research from the previous year suggested that the Earth’s inner core oscillates, softly swaying and swirling in a cycle from one direction to the other. It’s interesting to note that, similar to this latest study, they discovered some odd data from the early 1970s.
The findings revealed that, in comparison to the direction it was moving in between 1971 and 1974, the inner core was sub-rotating at least a tenth of a degree in a different direction between 1969 and 1971.
In a statement released in 2022, John E. Vidale, study co-author and Dean’s Professor of Earth Sciences at USC Dornsife College of Letters, Arts, and Sciences, claimed that “from our data, we can show the Earth’s surface movements compared to its inner core, as others have asserted for 20 years.” But according to our most recent measurements, the inner core rotated a little slower between 1969 and 1971 before turning around between 1971 and 1974.
Although the odd motions of the Earth’s core may appear to be far away from us, their effects on life above the surface are real.
The planet’s magnetic field is affected by the core of Earth, more specifically its outer core. The North Magnetic Pole has moved roughly 2,250 kilometers (1,400 miles) across the upper reaches of the Northern Hemisphere from Canada toward Siberia since it was first seen scientifically in the early 19th century.
The speed of this movement increased from less than 15 kilometers (9.3 miles) per year in 1990 to around 50 to 60 kilometers (31 to 37 miles) per year in 2005. This flux is most likely the result of two magnetic “blobs” of molten material in the planet’s interior, which have shifted the planet’s magnetic field by a massive amount.