Eddie Gonzales Jr. – MessageToEagle.com – A USC study suggests the Earth’s inner core surface is changing, detecting structural changes near the planet’s center.
Image credit: USC
Scientists have long debated changes in the inner core, but mainly focusing on rotation.
Already earlier, USC researchers reported in their study that the rotation of Earth’s inner core was proven backtracking—slowing down—in relation to the planet’s surface.
John Vidale, a professor at USC, noted they didn’t aim to define the inner core’s physical nature.
“What we ended up discovering is evidence that the near surface of Earth’s inner core undergoes structural change,” Vidale said. The finding sheds light on the role topographical activity plays in rotational changes in the inner core — including changes that have minutely altered the length of a day — and may also relate to the inner core’s ongoing slowing.
Redefining the inner core
Located 3,000 miles below the Earth’s surface, the inner core is anchored by gravity within the molten liquid outer core. Until now the inner core was widely thought of as a solid sphere.
The original aim of the USC scientists was to further chart the slowing of the inner core.
“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.”
The study utilized the seismic waveform data of 121 repeating earthquakes from 42 locations near Antarctica’s South Sandwich Islands that occurred between 1991 and 2024.
As the researchers analyzed the waveforms from receiver-array stations located near Fairbanks, Alaska, and Yellowknife, Canada, one dataset of seismic waves from the latter station included uncharacteristic properties the team had never seen before.
“At first the dataset confounded me,” Vidale said. It wasn’t until his research team improved the resolution technique did it become clear the seismic waveforms represented additional physical activity of the inner core.
Deformed inner core
The physical activity is best explained as temporal changes in the shape of the inner core. The new study indicates that the near surface of the inner core may undergo viscous deformation, changing its shape and shifting at the inner core’s shallow boundary.
The most likely cause of the structural change is interaction between the inner and outer core. “The molten outer core is widely known to be turbulent, but its turbulence had not been observed to disrupt its neighbor the inner core on a human timescale,” Vidale said. “What we’re observing in this study for the first time is likely the outer core disturbing the inner core.”
Vidale said the discovery opens a door to reveal previously hidden dynamics deep within Earth’s core, and may lead to better understanding of Earth’s thermal and magnetic field.
Written by Eddie Gonzales Jr. – MessageToEagle.com Staff Writer