Scientists are baffled after discovering Earth's inner core is DEFORMED

From a land of dinosaurs to a secret military base, science fiction has speculated wildly about what might be hiding at the centre of the Earth. Now, a study suggests that our planet's innermost depths could be even stranger than anyone had thought. Until now, it was widely believed that the inner core was a dense ball of iron floating at the centre of the molten outer core. However, scientists have been baffled to discover that the inner core is actually changing shape.

By looking at the shockwaves from earthquakes, researchers found evidence that the core is changing shape and shifting at the edges. 'The molten outer core is widely known to be turbulent, but its turbulence had not been observed to disrupt its neighbour the inner core on a human timescale,' said lead author Professor John Vidale, of the University of Southern California. 'What we're observing in this study for the first time is likely the outer core disturbing the inner core.'.

This revelation may shed light on the mystery of why the inner core's rotation appears to have been slowing down over recent years. Scientists previously believed the Earth's inner core was a solid ball of molten iron and nickel. But now, a new study suggests that it might not be a solid after all. The Earth is made up of four main structures: the outer crust, a semi-liquid mantle, a molten outer core, and the dense inner core.

While scientists obviously can't travel down to study these layers directly, they are able to learn about them by carefully recording earthquakes around the world. When the shockwaves from an earthquake pass through something dense, they are delayed or refracted, just like when a beam of light passes from air to water. By analysing hundreds of shockwaves, scientists can build up a model for the Earth's structure that would explain why the seismic data looks the way it does.

The most useful type of seismic activity for this purpose is tremors which occur at the exact same place at different times, called repeat earthquakes. Since the waves from repeat earthquakes all start in the exact same position, if they look different something must have changed in the planet's inner structure. Using this technique, researchers have discovered that the inner core's rotation is not constant.

In fact, the inner core's rotation completely changed direction in 2010 and has been slowly moving in the opposite direction since. Researchers analysed 168 pairs of repeat earthquakes in Antarctica which had been recorded by research stations in Canada and Alaska. By looking at how the earthquakes changed as they passed through the planet, the researchers built up a model of the planet's structure. The crust.

The crust is the rocky outer layer where all life exists. It is between 3 and 43 miles thick. The mantle. The mantle is the largest of the Earth's layers and consists of hot rocks. Measuring about 1,802 miles thick, it makes up 84 per cent of our planet's volume. The outer core. The outer core is about 1,367 miles thick and is comprised of a layer of liquid nickel and iron heated to 5,500°C (9,932°F).

The inner core. The inner core is a hot, dense ball of iron about the size of the moon where temperatures reach 5,200°C (9,392°F). It was actually this change in rotation which Professor Vidale had set out to study when he made his shocking discovery. The researchers gathered 168 pairs of repeating earthquakes from 42 locations around Antarctica's South Sandwich Islands between 1991 and 2024. These were paired with the waveforms which arrived at seismic receivers located in Fairbanks, Alaska and Yellowknife, Canada.

While the Alaskan data looked like the researchers expected, the seismic data from the Yellowknife station had some strange properties that had never been seen before. Professor Vidale says: 'As I was analysing multiple decades' worth of seismograms, one dataset of seismic waves curiously stood out from the rest. 'Later on, I'd realize I was staring at evidence the inner core is not solid.'. Using earlier models of the inner core's rotation, Professor Vidale realised that the seismic waves from repeat earthquakes looked different even when the core was supposed to have been in the same position.

Curiously, this was only the case for waves which grazed the edge of the inner core, while waves that passed straight through were unaffected. The researchers found that waves which skimmed the edge of the inner core (left) produced different results even when the core was in the same location, while waves which passed through (right) were unaffected. This suggests that the edge of the inner core may be changing shape.