The idea that the earth has four layers has long been considered a basic principle of geology, taught to schoolchildren around the world. Think of it like an onion: First there is the crust, this is where we live and contains water, soil and various rock layers. Next comes the mantle, the thickest layer, which makes up 67% of the earth’s mass. Then there is a liquid outer core that mostly consists of iron and nickel. Finally, there is an inner core that is believed to be solid and consists mainly of an iron-nickel alloy.
Scientists were certain that these four observable layers exist inside our planet. But it suddenly seems to be in doubt thanks to new study, which provides evidence that the inner core of the earth can actually have two different layers.
The paper, written by scientists at the Australian National University, describes how researchers analyzed thousands of models of the earth’s inner core using a special search algorithm. Their goal was to study how long it took seismic waves to travel across the planet based on decades of data compiled by the International Seismological Center. By doing so, they were able to learn more about the nuclei anisotropy, a term that refers to how the differences in the composition of a given substance change the properties of seismic waves.
In the process, the scholars discovered that although there is not much variation in the depth of the inner core, slower seismic waves have changed at an angle of 54 degrees and faster waves have run parallel to the Earth’s axis of rotation.
“We have found evidence that may indicate a change in the structure of iron, indicating two separate cooling events in Earth’s history,” the study’s lead author, PhD researcher Joanne Stephenson, said in a statement.
Stephenson added: “The details of this great event are still a bit of a mystery, but we’ve added another piece of the puzzle regarding our knowledge of the Earth’s inner core.”
Stephenson writes to Salon, explaining that “our study confirms that there is a change in about 650 km in the inner core – which adds another piece to the puzzle. What is important to make this study unique is the powerful treatment. of uncertainty and the methods we use – we wanted to make sure that what we saw inside was definitely a change and not just noise in the data. ‘
She added that although it is ‘incredibly difficult to know exactly what it looks like inside’, the scientists ‘results suggest that’ perhaps a change from one form of iron to another deep inside [inner core]. Possibly due to a dramatic event in the Earth’s history that occurred while the Earth was cooling down. ‘
Stephenson and the ANU team are not the first scholars to suggest that there may be layers in the Earth’s core. Stephenson himself admitted that it was proposed a few decades ago, but the data was very unclear, pointing out that the team “used a very clever search algorithm to pull through thousands of models of the inner core.”
She added: “It’s very exciting – and it could mean we have to write the textbooks.”
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