·

Seismic data reveals surprising pause in Earth’s inner core rotation and a shift in direction

Study suggests Earth's inner-core started spinning other way f

According to a new study published in the journal Nature Geoscience, the inner core of the Earth may have stopped rotating faster than the rest of the planet around 2009  and then turned in an opposite direction.

  • The data hint that the inner core might even be in the process of shifting back towards subrotation. If so, something is probably happening to the magnetic and gravitational forces that drive the inner core’s rotation. Such changes might link the inner core to broader geophysical phenomena such as increases or decreases in the length of a day on Earth.

The research, conducted by seismologists at Peking University in Beijing, analyzed seismic data from the early 1990s and found that all paths that previously showed significant temporal changes have exhibited little change over the past decade. This globally consistent pattern suggests that inner-core rotation has recently paused.

The study also found that this recent pattern is associated with a gradual turning-back of the inner core as a part of an approximately seven-decade oscillation, with another turning point in the early 1970s.

This multidecadal periodicity coincides with changes in several other geophysical observations, especially the length of day and magnetic field. These observations provide evidence for dynamic interactions between the Earth’s layers, from the deepest interior to the surface, potentially due to gravitational coupling and the exchange of angular momentum from the core and mantle to the surface.

This discovery could help to shed light on the many mysteries of the deep Earth, including what part the inner core plays in maintaining the planet’s magnetic field and in affecting the speed of the whole planet’s rotation — and thus the length of a day. However, the study’s findings are just the latest installment in a long-running effort to explain the inner core’s unusual rotation, and may not be the final word on the matter.

In 1936, researchers discovered the inner core after studying how seismic waves from earthquakes travel through the planet. Changes in the speed of the waves revealed that the planet’s core, which is about 7 000 kilometers (4 349 miles) wide, consists of a solid center, made mostly of iron, inside a shell of liquid iron and other elements. As iron from the outer core crystallizes on the surface of the inner core, it changes the density of the outer liquid, driving churning motions that maintain Earth’s magnetic field. The liquid outer core essentially decouples the 2 400-kilometer-wide (1 491 miles) inner core from the rest of the planet, allowing it to spin at its own pace.

In 1996, the lead authors of the current study reported studying earthquakes that originated in the same region over three decades, and whose energy was detected by the same monitoring station thousands of kilometers away. Since the 1960s, the scientists said, the travel time of seismic waves emanating from those earthquakes had changed, indicating that the inner core rotates faster than the planet’s mantle, the layer just beyond the outer core.

Further studies refined estimates of the rate of that ‘super-rotation’, concluding that the inner core rotates faster than the mantle by about one-tenth of a degree per year.

However, not all researchers agree with these findings and more research is needed to fully understand the inner core’s rotation and its effects on the planet.

References:

1 Multidecadal variation of the Earth’s inner-core rotation – Yi Yang and Xiaodong Song – Nature Geoscience – January 23, 2023 – DOI: https://doi.org/10.1038/d41586-023-00167-1

2 Has Earth’s inner core stopped its strange spin? – Nature – January 23, 2023

Featured image credit: The Watchers

If you value what we do here, create your ad-free account and support our journalism.

Share:

Related articles



Your support makes a difference

Dear valued reader,

We hope that our website has been a valuable resource for you.

The reality is that it takes a lot of time, effort, and resources to maintain and grow this website. We rely on the support of readers like you to keep providing high-quality content.

If you have found our website to be helpful, please consider making a contribution to help us continue to bring you the information you need. Your support means the world to us and helps us to keep doing what we love.

Support us by choosing your support level – Silver, Gold or Platinum. Other support options include Patreon pledges and sending us a one-off payment using PayPal.

Thank you for your consideration. Your support is greatly appreciated.

Sincerely,
Teo Blašković

$5 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$50 /year

$10 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$100 /year

$25 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$200 /year

You can also support us on Patreon

support us on patreon

or by sending us a one-off payment using PayPal:


Commenting rules and guidelines

We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules:

  • Treat others with kindness and respect.
  • Stay on topic and contribute to the conversation in a meaningful way.
  • Do not use abusive or hateful language.
  • Do not spam or promote unrelated products or services.
  • Do not post any personal information or content that is illegal, obscene, or otherwise inappropriate.

We reserve the right to remove any comments that violate these rules. By commenting on our website, you agree to abide by these guidelines. Thank you for helping to create a positive and welcoming environment for all.

2 Comments

  1. My entire arguments about the current earth changes are centered on the changes that are taking place at the interior of the earth, and according to my understanding, these changes are caused by the increase of the external energy which powers the internal magnetic field of the earth, and without this external energy life on earth would be impossible, since the earth would stop spinning. However, as I stated many times over the years, when the energy build-up reaches the critical level, the shifting of the poles accelerates and the weather patterns that were stable for thousands of years change dramatically. Additionally, the spinning of the earth on its axis increases. Note also, that the complete reversal of the poles requires just around 40% decline in the strength of earth’s magnetic field. Now, the strength of earth’s magnetic field is approaching this value.

Leave a reply

Your email address will not be published. Required fields are marked *