The shape of Earth's 'core' may have changed over the past 20 years...

Author: Duan Yuechu

In the vast universe, the Earth is our home, and every mystery of it has attracted human curiosity. The Earth's inner core, a mysterious area hidden deep inside the Earth, has always been the focus of scientists' research. Recently, a breakthrough research result on the Earth's inner core has attracted widespread attention, revealing to us the unknown secrets of the Earth's inner core.

The research results were published in the journal Nature Geoscience in 2025. We have long known that the Earth's solid inner core plays a key role in maintaining the Earth's magnetic field, and that inner core growth is the main driver of convection within the liquid outer core. Previous studies have suggested that the Earth's inner core has rotated or changed shape over time, but the two are not synchronous. This new study clearly points out that the shape of the Earth's inner core is very likely to have changed in the past 20 years.

How did scientists discover this amazing phenomenon? They carefully analyzed the seismic waves generated by 168 sets of repeated earthquakes around 2010. Some of these seismic waves were generated after the inner core returned to the same position, which means that any differences in each set of seismic waves could not be caused by the rotation speed. Through careful observation and analysis, scientists found that although the seismic waves generated by each set of earthquakes that passed through the inner core had the same properties, the seismic waves that only grazed the inner core had completely different properties. Based on this, scientists believe that the change in the shape of the inner core over time is the best explanation for this phenomenon.

This research result is of extraordinary significance, and its value and role cannot be underestimated. From the perspective of the Earth's magnetic field, the Earth's magnetic field is like the Earth's "umbrella", which can resist the invasion of cosmic rays such as the solar wind and protect life on Earth from harm. The Earth's inner core plays a vital role in maintaining the Earth's magnetic field, and changes in the shape of the inner core are likely to have a profound impact on the stability of the Earth's magnetic field. If changes in the shape of the inner core cause changes in the Earth's magnetic field, then creatures on Earth may face a series of problems. For example, the migration of birds may be disturbed because they usually rely on the Earth's magnetic field to determine the direction; some marine organisms that rely on magnetic fields for navigation may also lose their way.

In terms of the internal dynamics of the Earth, changes in the shape of the inner core reflect the movement and interaction of materials inside the Earth. The interior of the Earth is a dynamic world. The convection of the liquid outer core and the exchange of materials between the inner and outer cores are all closely related to the evolution of the Earth. Understanding the changes in the shape of the inner core will help us understand the dynamic mechanism of the Earth's interior more deeply, and thus better predict the future evolution trend of the Earth. For example, by studying the relationship between changes in the shape of the inner core and earthquakes and volcanic activities, we can improve our ability to predict natural disasters and provide stronger guarantees for human survival and development.

As for what drives the changes in the shape of the inner core, scientists have put forward several interesting hypotheses. One view is that there may be "volcanoes" and "landslides" similar to the surface at the boundary between the inner and outer cores. At this junction, matter may constantly melt and freeze into new structures, just as volcanic eruptions and landslides on the surface of the earth change the terrain. This dynamic change of matter may cause changes in the shape of the inner core. Another hypothesis is that the iron in the inner core may surge to the surface of the inner core, thereby changing the mass distribution and shape of the inner core. Another view is that the traction of the density anomaly at the bottom of the lower mantle and the drag generated by the convection of the outer core, these powerful forces may also have an impact on the shape of the inner core. However, scientists also admit that these are only hypotheses at present, and further research is still needed to provide a more precise explanation.

The research result of the change of the shape of the Earth's inner core has opened a new window for us, allowing us to glimpse the mysteries deep inside the Earth. It not only enriches our understanding of the Earth, but also points out a new direction for future Earth science research. I believe that with the unremitting efforts of scientists, we will eventually uncover more secrets of the Earth's inner core and better understand the blue planet we live on.

References:

Vidale, JE, Wang, W., Wang, R. et al. Annual-scale variability in both the rotation rate and near surface of Earth's inner core. Nat. Geosci. (2025).