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] This revelation may shed light on the mystery of why the inner core's rotation appears to have been slowing down over recent years.
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.
By looking at how the earthquakes changed as they passed through the planet, the researchers built up a model of the planet's structure] By looking at the shockwaves from earthquakes, researchers found evidence that the core is changing shape and shifting at the edges.
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.
