The idea that the Earth consists of four layers has long been considered a core tenet of geology, taught to schoolchildren all over the world. Think of it like an onion: first there is the shell we live in and it contains water, soil and different layers of rocks. Next comes the mantle, the thickest layer, which makes up 67% of Earth’s mass. Then there is a liquid outer core, which is mostly made of iron and nickel. Finally, there is an inner core, which is believed to be solid and mainly composed of an alloy of iron and nickel.
Scientists were sure that these four distinguishable layers make up the interior of our planet. But that seems to be suddenly called into question thanks New study, Which provides evidence that the Earth’s inner core may in fact have two distinct layers.
The paper, written by scientists at the Australian National University, describes how researchers analyzed thousands of models from Earth’s inner core using Private search algorithm. Their goal was to study how long seismic waves take to travel across the planet based on decades of data collected by the International Seismological Center. By doing this, they can learn more about the inner core Anisotropy, A term referring to how differences in the composition of a particular substance change the properties of seismic waves.
In the process, scientists discovered that although there was not much difference when it came to the depth of the inner core, the slower seismic waves shifted at an angle of 54 degrees and the faster waves were traveling parallel to the Earth’s rotation axis.
“We have found evidence that may indicate a change in the structure of iron, suggesting the possibility of two separate cooling events in Earth’s history,” said lead author of the study, PhD researcher Joan Stevenson. statement.
Stephenson added, “The details of this major event are still a bit vague, but we have added another piece of the puzzle when it comes to our knowledge of the inner core of Earth.”
Stephenson explained in his book to Salon, “Our study confirms that there is a change of about 650 km in the inner core – adding one more piece to the puzzle. And most importantly, what makes this study unique, is the powerful treatment of uncertainty and the methods we use are used.” – We wanted to make sure that what we saw inside was definitely a change and not just a clutter of data. “
She added that although “it is very difficult to know its exact internal shape,” the scientists’ results indicate that “there may be a change from one form of iron to another in the depths of [inner core]. It is possible that this was due to some kind of dramatic event in the history of the earth that occurred with the cold of the earth. “
Stevenson and the ANU team aren’t the first scientists to suggest that there may be layers in Earth’s inner core. Stephenson herself admitted that “it was proposed two decades ago, but the data was very unclear,” noting that the team used “a very clever search algorithm to search thousands of internal core models.”
“It’s very exciting – and it might mean we have to rewrite the textbooks,” she added.
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