Jakarta –
The dense, swirling ball at the center of Earth’s inner core appears to have stopped recently, and is now possibly spinning in the opposite direction from decades earlier.
This suspicion was revealed by a recent study conducted by two scientists from Peking University in China. The two reported mysterious movements in the Earth’s core by studying seismic wave data from earthquakes exploding through the Earth’s inner core.
By looking at the changes in these waves, they can find out what is happening in the inner layers of the Earth, much deeper than any drill and instrument can reach.
As quoted from IFL Sciencetheir data details changes in seismic waves over decades, starting with records over Alaska from the early 1960s to records collected in 2021.
The data showed that core sections that had previously shown clear signs of variation suddenly showed very little change around 2009, which they said indicated that the rotation of the inner core had stalled.
They also pick up on notable changes in the tides that started around the early 1970s suggesting these breaks were part of an oscillation that occurs every seven decades or so, when the inner core gradually returns in the opposite direction.
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Earth’s Core. Photo: IFL Science
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How the Earth’s core works
The inner workings of the Earth are very mysterious. Its structure can be divided into four main layers: the crust, the mostly solid mantle, followed by the liquid outer core, and finally the solid inner core which is composed of iron and nickel. .
Because the inner core is separated from the rest of the solid Earth by a liquid outer core, it can perform a different rotation than the Earth’s surface. The inner core’s spin is governed by the magnetic field generated in the molten metal outer core, as well as the effects of mantle gravity.
However, the theory about the movement of this inner core is not agreed upon. Many researchers previously thought that the planet’s deepest geological layers rotate alongside the rest of the planet at a slightly faster rate than the surface, but it’s now believed that this isn’t so easy.
Last year, research suggested that the Earth’s core oscillates, swaying gently and rotating from one direction to the other in a cycle. Interestingly, they found some unusual data from the early 1970s, such as this new study published in the scientific journal Nature Geoscience.
The results show that the inner core moved slowly in a different direction between 1969 and 1971, a sub-rotation of at least a tenth of a degree per year, compared to the direction it had moved between 1971 and 1974.
“From our findings, we can see that the Earth’s surface is shifting compared to its inner core, as people have been suggesting for the past 20 years,” said John E. Vidale, study co-author and Professor of Earth Sciences and Dean of USC Dornsife College of Letters, Arts. and Science, in a statement in 2022.
“However, our recent observations show that the inner core rotated slightly slower from 1969-1971, then moved in the other direction from 1971-1974,” they wrote.
Impact on Earth
The strange movements of the Earth’s core may seem very far from us. But his behavior actually affects the lives of Earth’s inhabitants on its surface.
The Earth’s core, especially its outer core, influences the planet’s magnetic field. Since the North Magnetic Pole was first scientifically documented in the early 19th century, it has traveled 2,250 kilometers across the upper reaches of the Northern Hemisphere from Canada to Siberia.
Between 1990 and 2005, the rate of this movement increased from less than 15 kilometers per year to around 50-60 kilometers per year. This flux is likely the effect of two magnetic “lumps” of molten material in the planet’s interior, causing massive shifts in its magnetic field.
Flux is the flow of physical properties in space. This understanding forms the basis of the field concept in physics and mathematics, with two major applications: in displacement phenomena and in surface integrals.
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