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The idea that the Earth has four layers has long been considered a basic principle of geology, taught to schoolchildren all over the world. Think of it like an onion: first there is the crust, where we live and contains water, soil, and various layers of rock. Next is the mantle, the thickest layer, which makes up 67% of the land mass. Then there is a liquid outer core, which is mainly made up of iron and nickel. Finally, there is an inner core, which is believed to be strong and mostly made of an iron-nickel alloy.
Scientists were certain that these four discernible layers made up the bowels of our planet. But this suddenly seems to be called into question thanks to a new study, which proves that the inner core of the Earth may in fact have two distinct layers.
The article, written by scientists at the Australian National University, describes how researchers analyzed thousands of models of the Earth’s inner core using a special research algorithm. Their goal was to study the time it takes for seismic waves to travel across the planet based on decades of data compiled by the International Seismological Center. By doing this, they could learn more about the inner core. anisotropy, a term that refers to how differences in the composition of a given substance alter the properties of seismic waves.
During the process, the researchers found that while there was not much variation in the depth of the inner core, the slower seismic waves changed at an angle of 54 degrees and the waves were faster. were parallel to the axis of rotation of the Earth.
“We found evidence that could point to a change in the structure of iron, possibly suggesting two distinct cooling events in Earth’s history,” said lead author of the study, the researcher. PhD Joanne Stephenson, in a press release.
Stephenson added: “The details of this great event are still a bit of a mystery, but we have added another piece to the puzzle regarding our knowledge of the Earth’s inner core.”
Writing to Salon, Stephenson explained that “our study confirms that there is a change at about 650 km in the inner core – adding another piece to the puzzle. What makes this study unique is the vigorous processing of the ‘uncertainty and the methods we used – we wanted to make sure that what we were seeing inside was really a change and not just noise in the data. “
She added that while it is “incredibly difficult to know exactly what it looks like on the inside,” the scientists’ results suggest that “maybe there is a change from one form of iron to another. deep in the [inner core]. Potentially due to a dramatic event in Earth’s history that occurred when Earth cooled down.
Stephenson and the ANU team aren’t the first researchers to suggest that there may be layers in the Earth’s inner core. Stephenson herself admitted that it was “proposed a few decades ago, but the data was very unclear”, noting that the team had used “a very smart search algorithm to browse through thousands of kernel models. internal”.
She added: “It’s very exciting – and it could mean that we have to rewrite the textbooks.”
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