A new USC study led by Professor John Vidali showed that the Earth’s inner core may be more dynamic than we think.
Located more than 5,000 kilometers beneath our feet, the inner core has - for decades - been thought of as a solid sphere that rotates in lock with the planet’s surface.
USC scientists' research has already confirmed that the iron core appears to spin back and forth, sometimes speeding up or slowing down. But Vidali’s newest discoveries suggest that the Earth’s core is also changing shape.
“What we found is it seems like the surface of the inner core is changing over time,” Vidali said. “It seems to be rising and falling maybe a kilometer or so in the span of a few years, which we didn’t expect. When we look at the seismic waves that go through it, we can see the way waves are changing.”
That simple discovery suggests the inner core is not solid at all.
As for how the discovery came about, Vidali said it was – in fact – a complete accident.
“We were looking for something else. We were looking for structures near the surface and saw waves from the inner core that were changing where they shouldn’t have been changing,” Vidali said. “That was back 25 years ago.”
About five years ago, Vidali revisited old data to collect new information and began a new wave of investigation.
“Just last year, we finally proved exactly how it was moving,” he said.
Vidali said that it’s too soon to know all the implications of the discovery. But using this data, researchers are continuing to investigate how the Earth’s core affects factors like the length of a day, the tide, and the Earth’s magnetic field.