The discovery of the regional variations in the lower mantle where it meets the core, which are up to three times greater than expected, will help scientists explain the structure of Earth and how it formed.
"Where the mantle meets the core is a more dramatic boundary than the surface of Earth," said the lead researcher, Associate Professor Hrvoje Tkalčić, from The Australian National University (ANU).
"The contrast between the solid mantle and the liquid core is greater than the contrast between the ground and the air. The core is like a planet within a planet." said Associate Professor Tkalčić, a geophysicist in the ANU Research School of Earth Sciences.