CNN Indonesia
Sunday, 28 Jan 2024 07:54 IWST
Illustration. Scientists in China discovered the Earth’s core wobbles every 8.5 years. (iStockphoto/Cimmerian)
Jakarta, CNN Indonesia —
Scientists at China found every 8.5 years Earth’s inner core swaying around its axis of rotation. This shift is most likely caused by a small misalignment between the inner core and the Earth’s mantle—the layer beneath the Earth’s crust.
At a depth of about 2,896 kilometers below the Earth’s surface, the Earth’s core is divided into a liquid outer boundary and a mostly solid inner layer.
This region plays a role in determining a number of Earth’s geophysical dynamics, from the length of the day to the Earth’s magnetic field, which helps protect humans from the harmful rays emitted by the Sun.
The new study was published Dec. 8 in the journal Nature Communications suggests a tilt in the Earth’s inner core could eventually cause changes in the shape and motion of the liquid core, leading to potential shifts in the Earth’s magnetic field.
To understand how this core works, in 2019, geophysics researchers led by Hao Ding of Wuhan University analyzed the movement of the Earth’s rotation axis relative to the Earth’s crust, known as polar rotation.
They detected slight deviations in polar motion that occur approximately every 8.5 years, indicating a potential “inner core wobble,” similar to the wobble when a top spins.
Meanwhile in their latest research, Ding and his fellow researchers further confirmed this cycle by measuring small shifts in day length around the world and comparing them to variations in polar motion they previously identified.
The length of the day itself is controlled by the periodic movement of the Earth’s rotation axis.
As a result, their data shows this wobble is most likely caused by the 0.17 degree tilt between the Earth’s core and mantle, which contradicts traditional Earth rotation theories that assume the rotation axis of the Earth’s core and the rotation axis of the Earth’s mantle coincide.
This tilt may indicate that the northwestern hemisphere of the inner core may be slightly denser than the other layers. In addition, there are indications of differences in density between the Earth’s inner and outer core.
John Vidale, a professor of Earth sciences at the University of Southern California, said the new study “helps see the compositional differences between the metals in the solid inner core and the liquid outer core and estimates the direction and speed of the inner core’s wobble.
“There isn’t any [dalam studi ini] that could save humanity, but this research adds a basic building block to understanding our planet,” he said, quoted from Live Science.
Furthermore, the research team ruled out atmospheric, oceanic and hydrological influences that might cause deviations in polar motion other than core wobble. However, it is difficult to ensure that these sources do not play a role.
According to Vidale, many experts were needed to compile the type of analysis carried out in this research.
These findings are thought to help researchers understand the dynamics between the Earth’s inner core and processes that impact humans, from earthquakes to changes in the magnetic field.
Indonesia Surrounded by 13 Megathrust (Photo: CNNIndonesia/Asfahan Yahsyi)
(lom/dmi)
2024-01-28 00:54:39
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