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Inner core of Earth undergoing transformation, study finds

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February 12, 2025
3 min read

Inner core of Earth undergoing transformation, study finds

The surface of the inner core of the Earth could be changing, according to a new study from USC and published in Nature Geoscience. The scientists detected structural changes near the centre of the planet.

The changes have been a subject of debate for scientists. Most research has focused on assessing rotation but the principal investigator of the study, John Vidale, Dean’s Professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences, said that the researchers “didn’t set out to define the physical nature of the inner core. “What we ended up discovering is evidence that the near surface of Earth’s inner core undergoes structural change,” Vidale said.

This sheds light on the role that topographical activity can play on rotational changes in the deep in the centre of the planet. These could minutely alter the length of a day and relate to its ongoing slowing.

3,000 miles below the surface, the inner core is anchored by gravity within the molten liquid outer core. Until now, it was widely believed to be a solid sphere. The scientists initially set out to further chart its slowing.

“But as I was analyzing multiple decades’ worth of seismograms, one dataset of seismic waves curiously stood out from the rest,” Vidale said. “Later on, I’d realize I was staring at evidence the inner core is not solid.”

Using seismic waveform data, including 121 repeating earthquakes from 42 locations near the South Sandwich Islands in Antarctica between 1991 and 2024, they were able to catch a glimpse of what is taking place deep within the earth. As they looked at waveforms from receiver-array stations near Fairbanks in Alaska and Yellowknife in Canada, one data of seismic waves from the latter found uncharacteristic properties that had never been seen before by the team.

The physical activity in the inner core is believed to be driven by temporal changes in its shape, with recent research suggesting that the near-surface region undergoes viscous deformation, altering its form at the shallow boundary. The primary cause of this change is the interaction between the inner and outer core. While the outer core is known to be turbulent, this study reveals for the first time how its turbulence may disturb the inner core on a human timescale. This discovery could provide new insights into the dynamics of Earth’s core, aiding our understanding of its thermal and magnetic fields.

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