Earthquake study from China: rotation of the inner core of the earth has probably stopped

The Earth's inner core has apparently stopped spinning, a study shows.

Researchers suspect that it will soon change its direction of rotation.

Beijing – The earth has a complicated structure, somewhat resembling an onion: it is made up of several layers, for example there is the inner core, which is solid and surrounded by the liquid outer core.

The inner core of the earth rotates and vibrates - sometimes rotating in one direction, sometimes in the other.

Researchers know this because they track the movement of seismic waves in the individual layers of the earth during earthquakes in order to learn more about the interior of the earth.

But now a study published in the journal

shows that the movement of the Earth's inner core relative to the mantle has apparently stopped.

A research team from the University of Beijing examined so-called seismic doublets for the study - these are pairs of earthquakes that had almost the same strength at the same place at different times.

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Inside the earth there is a solid inner core surrounded by a liquid core.

(archive image)

© IMAGO/Cover Images

Surprising find: Earth's inner core has apparently stopped moving

Researchers Yi Yang and Xiaodon Song found that the seismic waves differed significantly between 1995 and 2008 - they concluded that this happened because the Earth's core was rotating.

The pairs of earthquakes between 2009 and 2020, on the other hand, were very similar - the Chinese researchers concluded that the earth's core must have stopped rotating relative to the rest of the earth around 2009.

While this realization may sound scary, it is not a cause for concern.

Using data from the 1960s and 1970s, the researchers found that the Earth's core appears to vibrate over a 70-year period, changing direction about every 30 years.

The research team's theory: Until the early 1970s, the Earth's inner core rotated westward, then paused and reversed direction.

Since then, it has been rotating to the east and slightly faster than Earth.

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The inner structure of the earth is complex.

There is the inner solid core and therefore the liquid core.

This is surrounded by the earth's mantle.

© imago

Earthquakes show: Earth's core has stopped rotating

This phenomenon has apparently been happening again since 2009: the Earth's core has stopped rotating relative to the Earth's mantle and will soon be rotating in the opposite direction again.

"If the oscillation model is correct, we expect that the inner core will rotate more slowly than the surface by the mid-2040s," researcher Song explains in an email to the portal 

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Another exciting discovery made by the Chinese researchers also relates to the rotation of the Earth's core: if it moves in a westerly direction, the days on Earth apparently become 0.01 milliseconds shorter - if the inner core of the Earth rotates to the east, they become one The researchers write in their study that the day is 0.12 milliseconds longer.

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Transparency Note: The study, originally published on January 23, 2023, was updated by the authors on January 31, 2023 to include a note that the Earth's inner core

has stopped rotating

This article has been slightly revised accordingly.

List of rubrics: © IMAGO/Cover-Images