Seismologists have confirmed the existence of Earth’s innermost core, proving a hypothesis first proposed twenty years ago.
Seismologists from The Australian National University (ANU) have confirmed that the Earth’s interior is comprised of five layers, not four – proving a previously-unconfirmed hypothesis first proposed by scientists twenty years ago.
The traditional model of the Earth’s composition depicts four layers: the crust, the mantle, the liquid outer core, and the solid inner core.
The study, published in Nature Communications, has confirmed the existence of another distinct layer within the inner core, dubbed the “innermost inner core.”
An increase in seismic monitoring stations around the globe has made it possible to record an unprecedented amount of data, enabling scientists to confirm the long-held hypothesis.
Seismic waves from earthquakes travel directly through the Earth’s centre, to the “antipode” at the opposite point of the Earth, and then return to the origin of the quake.
Measurement and analysis of the variation in travel times of these seismic waves allows scientists to make inferences about the makeup of these internal structures.
Like the surrounding inner core, the innermost inner core is made up of a solid, iron-nickel alloy.
However, variation in the speed of seismic waves as they enter the innermost inner core prove it to possess a distinctly different structure to the surrounding layer.
This distinction could be caused by different arrangements of iron atoms, or by differing alignments of growing crystal structures.
Research author Professor Hrvoje Tkalcic said the research was a clear indication that an update to the four-layer model was needed.
“This research, I would say, puts the final nail in the coffin of the old images we have of the Earth’s structure with only four layers. They’ll need to redo the textbooks,” Tkalcic said.
There is still much to learn about the Earth’s interior.
Tkalcic also explained that study of the Earth’s centre can provide valuable clues about the evolutionary history of life on Earth.
“By understanding the interior of the Earth, we can understand how the planet formed, and it can help us shed light on massive events in the planet’s history. The core is a time capsule that has that information,” said Tkalcic.
You can read the full study in Nature Communications.
