Research from Australian National University confirmed the existence of a core inside Earth’s inner core.
The Earth’s solid inner core remains one of the most enigmatic parts of our planet, despite numerous studies in the fields of seismology, geodynamics, mineral physics and materials science.
Making up only 1% of Earth’s total volume with a temperature of over 5,000 degrees Celsius, understanding the structure, current dynamics and evolution of the inner core is vital to understanding Earth’s thermal history.
In particular, this provides insights to the geodynamo, without which life would not exist as we know it today.
“Investigating the structure of the inner core can help us understand more about the Earth’s history and evolution,” said study’s lead author Dr. Joanne Stephenson, a researcher in the Research School of Earth Sciences at the Australian National University.
For the study, Dr. Stephenson and her colleagues from the Australian National University, Professor Hrvoje Tkalčić and Professor Malcolm Sambridge, used data from the International Seismological Centre (a database of seismic arrivals gathered from seismological institutions globally) in conjunction with the so-called ‘neighbourhood algorithm.’
“We got around this by using a very clever search algorithm to trawl through thousands of the models of the inner core,” Dr. Stephenson said.
“While this new layer is difficult to observe, its distinct properties may point to an unknown, dramatic event in the Earth’s history,” she added.
“We found evidence that may indicate a change in the structure of iron, which suggests perhaps two separate cooling events in Earth’s history.”
“The details of this big event are still a bit of a mystery, but we’ve added another piece of the puzzle when it comes to our knowledge of the Earth’s inner core.”
It was believed that Earth only had 4 layers: Crust, mantle, outer core, and inner core. With this discovery, text-books must be corrected.
Scientists detect inner layers by measuring speeds of seismic waves caused by earthquakes. For more information about these waves, read the post about internal discontinuities.