It may be impossible to drill deep into the Earth, but by studying how tremors from earthquakes travel through the Earth, scientists have gained new insight into our planet’s core.
Reported in the journal Nature Geoscience, researchers from China and the US say that the Earth’s inner core, may itself have an inner region made up of a distinct structure of iron crystals, that was previously undiscovered.
The scientists from University of Illinois in the US and colleagues at Nanjing University in China studied how tremors from earthquakes changed and reflected as they travelled through different layers of the Earth.
The seismic wave data suggests that the Earth’s inner core, a solid region with a radius of around 1,220 km, is made up of two parts.
In the “outer inner core”, iron crystals are aligned from north to south, while in the “inner inner core” they are lined up in an east-to-west direction.
Professor Xiaodong Song commented:
“The fact that we have two regions that are distinctly different may tell us something about how the inner core has been evolving. For example, over the history of the earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the key to how the planet has evolved. We are right in the center – literally, the center of the Earth”