They reveal that the inner core of the Earth is solid

Sydney (Australia) .- The central nucleus of the Earth is solid although softer than expected, according to a study published in Australia ] which hope to help understand how our planet was formed .

The expert in seismography Hrvoje Tkalcic and doctoral candidate Than-Son Pham, National University Australian (ANU), could detect in the core central the so-called waves J or Osborn waves which only cross solid objects. [19659003] "It turns out, if our results are correct, that the inner core of the Earth shares similar elastic properties with gold and platinum," Tklacic said in a statement. ; ANU.

The core of the Earth resembles a time capsule. . If we understand it well, we will understand how the planet was formed and how it evolves, he added.

The J waves of the Earth's inner core are so small and so weak that they can not be observed directly, so the power to detect them has always been there. a challenge for seismologists since scientists claimed for the first time that it was solid.

In an attempt to detect them, scientists have applied the so-called wave-field correlation method which observes the similarities between the signals that reach two different receivers after a powerful earthquake instead of observing incoming waves. directly.

This is a technique that the same team used to measure the thickness of the ice cover. Antarctica

"We got rid of the first three hours of the seismograph and we focused on what happened between three and ten hours after an earthquake, Vitar the most important signals," said the scientist.

Scientists, who were working with a global network of stations, compared the seismographs of each pair of observatories of each major earthquake to detect their similarities.

"From these similarities, we build an overall correlogram, that is, a kind of footprint of the Earth," said the expert.

The research, published in the journal Science Magazine, can be used to demonstrate the existence of J. waves and to derive shear wave velocity, also called shear waves or S waves, in the inner core of the Earth, which still has many mysteries.

"For example, we still do not know what is the exact temperature in the nucleus inside the Earth, its age or rapidity of solidification, but with these new advances in global seismology, we can achieve "said the seismologist.

Tklacic also pointed out that the understanding of the Earth's core has direct consequences on the generation and maintenance of geomagnetic fields, because without them, there would be no life on the surface of the planet, the statement added.

In 2015, scientists from the University of Illinois (United States) and Nanjing (China) developed studies suggesting that the inner core of the Earth contains crystals of white. different alignment, formed under different conditions, and that the planet could have undergone a dramatic change during this period.

The Sphere ] The center of the Earth which extends over more than 5,000 kilometers, began to solidify about a billion years ago and continues to grow about 0.5 millimeter a year.