Scientists have finally confirmed the theory that Earth has a solid core after uncertainty persisted on the subject for more than 80 years.
For a long time it has been believed that Earth has a solid iron core, but no evidence has ever been found and it has been announced as the "holy grail" of global seismology.
Finally, the problem was solved by a new technique that was used for the first time to measure the thickness of the Antarctic ice sheet.
The researchers created a "fingerprint" of our planet from the echoes of earthquakes and discovered that the innermost region of the planet is really solid, but not as difficult as scientists believed.
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Scientists have finally confirmed the theory that Earth has a solid core after uncertainty persisted on the subject for more than 80 years. Tracked the origins of a specific seismic wave as a test of the solid core of the Earth
Associate Professor Hrvoje Tkalčić and PhD Scholar Than-Son Phạm of the National University of Australia (ANU) studied cutting waves, or "J waves", in the inner core of the Earth.
J waves are produced by earthquakes and only travel through solid objects.
The internal cutting waves can not be observed directly, since they have so little energy, so the researchers looked for a creative way to detect them.
To do this, they observed the similarities between the signals received in different places after the big earthquakes.
A version of this method, known as the correlation wave field method, has been used to calculate the thickness of the ice shelf in Antarctica.
The same team turned its method to the thorny problem of understanding the most intimate secrets of the Earth.
The inner core is where the magnetic field (left) of the earth is generated and maintained. The geomagnetic field represents a shield around our planet that protects us from the cosmic radiation without which life on the surface of the Earth would be impossible.
"We are discarding the first three hours of the seismogram and what we are seeing is between three and 10 hours after a major earthquake occurs," said Dr. Tkalčic.
& # 39; We want to get rid of the big signs & # 39;
These "echoes" of earthquakes were compared with many others from different readings of the same earthquakes and this produced an "Earth fingerprint".
The theory that the Earth has a solid core was first proposed in 1936, when the Danish seismologist Inge Lehmann reanalyzed the data of the magnitude 7.3 earthquake of 1929 that struck the southern island of New Zealand.
HOW IS THE INSIDE OF THE EARTH?
The Earth is made up of several different layers, each with unique properties.
At the deepest level is the inner core that is believed to be solid. This produces the magnetic field of the Earth and protects us from cosmic radiation.
The next layer is the Earth's liquid core, which is a fluid layer approximately 2,200 km (1,400 miles) thick and composed mainly of iron and nickel.
The mantle is the largest region of the underground Earth and represents about 84 percent of the volume of the planet.
It sits between the cortex and the outer core and is divided into two sections: upper and lower.
The asthenosphere is a part of the upper mantle that lies below the lithosphere and is thought to be involved in the movement of plate tectonics.
The lithosphere is the region of the planet that is known as the crust and some patting of the upper mantle. It presents everything that we consider the terrain.
It is composed predominantly of silica and is divided into tectonic plates.
The boundary between the Lithosphere and the Asthenosphere (LAB) is defined by a difference in response to stress.
Plaques and the lithosphere often remain rigid, but the weaker, viscous asthenosphere can move and is known to move.
This movement causes the plates to move towards, below and below others, and the LAB is the root cause behind the tsunamis and earthquakes, as well as the formation of the mountain range.
The Earth is made up of several different layers, each with unique properties. These are: lithosphere, asthenosphere, mantle and core (in the photo)
The green dots are receptors on the surface of the Earth and the red dots are large earthquakes. Researchers at the National University of Australia (ANU) found that this was a fingerprint of the Earth.
The researchers claim that this study demonstrates the existence of J waves (or transparent waves) in the inner core (in the image) and that this is proof that the inner core is solid
The detectors in Europe picked up the waves and the experts realized that this would be impossible if the core were liquid, as was thought in the 19th and early 20th centuries.
This theory was widely accepted and taught to schoolchildren today, but it has never been proven conclusively.
These researchers claim that this "closes a search of 80 years to find them and confirms a solid but smooth inner core," the scientists say.
"We found that the inner core is really solid, but we also find that it is softer than previously thought," explains Associate Professor Tkalčić.
"It turns out that, if our results are correct, the inner core shares some similar elastic properties with gold and platinum.
"The inner core is like a time capsule, if we understand it, we will understand how the planet was formed and how it evolves."
The research has been published in the journal Science.