Earth’s inner core has been losing momentum since 2010

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Earth is made up of different layers. (code image) © Ian Cuming/Imago

Seismic waves help researchers probe the Earth’s interior. Now a new study shows what’s happening in Earth’s inner core.

LOS ANGELES – Earth’s inner core has slowed relative to Earth’s surface since 2010. This is the conclusion of a study conducted by a research team at the University of Southern California (USC). You should know that the Earth has different layers: the inner core consists of solid iron and nickel and is the same volume. monday. It is surrounded by the Earth’s outer core, which contains a liquid nickel-iron melt.

Because the Earth’s inner core only begins at a depth of more than 5,000 kilometers, it is impossible for researchers to study it directly. Therefore, indirect methods are used, usually seismic waves from earthquakes are studied to learn more about the Earth’s interior. In the current study, a research team led by John Vidal (USC), among others, performed their analysis using repeated earthquakes. There was work In a special issue Nature Published.

Earth’s core can only be probed by seismic waves

The team analyzed 121 consecutive earthquakes recorded in the South Sandwich Islands between 1991 and 2023. The study also includes data from Soviet nuclear tests from 1971 to 1974 and repeated French and American nuclear tests.

The result of the research surprised even the team: since about 2010, the inner core of the Earth has slowed down compared to the surface of the Earth. “When I saw the seismic maps that marked this change, I was amazed,” Vidal recalled in one. Notice from his university. “But when we found two dozen observations that showed the same pattern, the conclusion was inescapable. The inner core has decreased for the first time in decades.”

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Earth’s inner core oscillates and changes its direction of motion

After decades of studying Earth’s interior, research suggests that the inner core oscillates — sometimes it turns in one direction, then the other. Last year, a study was published that showed that the movement of the Earth’s inner core has completely stopped relative to the Earth’s surface.

Earth is made up of different layers.  From outside to inside: Earth's crust, (upper and lower) mantle, outer core and inner core.  (thumbnail)
Earth is made up of different layers. From outside to inside: Earth’s crust, (upper and lower) mantle, outer core and inner core. (thumbnail) © IMAGO/ Simsek

According to Vidal, the speed of the Earth’s inner core is affected by, among other things, the motion of the outer core of liquid iron. According to the researcher, denser regions of the Earth’s rocky mantle above also play a role. It is not yet clear what effect the slow movement of Earth’s inner core has on the planet’s surface. However, the USC researcher can imagine that breaking the core could shorten the length of a day by fractions of a second. “On the order of thousandths of a second, it’s very difficult to observe, almost lost in the noise of the oceans and atmosphere,” Videl said.

In the future, the research team would like to more closely analyze the movement of the Earth’s inner core to find out why it changes. “The dance of the inner core may be more vibrant than we yet know,” Videl explains. (tab)

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