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Madrid, October 19 (EUROPA PRESS) .- Researchers at the Australian National University (ANU) believe they have obtained direct evidence of the solidity of the inner core of the Earth.
They developed a way to detect cutting waves or "J waves" in the inner core, a type of wave that can only move in solid objects. The research was published in Science.
"We found that the inner core is really strong, but we also find that it is more flexible than expected," said Associate Professor Hrvoje Tkalcic.
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 evolved. "
The shear waves of the inner nucleus are so small and so weak that they can not be directly observed.In fact, their detection is considered the" holy grail "of global seismology since the scientists had initially predicted that the inner nucleus was solid 80 years ago
The so-called correlation field method used by these scientists Analyzes the similarities between the signals of two receivers after a large earthquake, instead of direct wave arrivals. A same technique was used by the same team to measure the thickness of the ice in Antarctica.
"We give up the first three hours of the seismogram and we observe about three to ten hours after a major earthquake. . We want to get rid of the big signals, "Tkalcic said.
" Using a global network of stations, we take each pair of receivers and each major earthquake, which is a lot of combinations and we measure the similarity between the two. seismograms. This is what is called cross-correlation, or measure of similarity. From these similarities, we build a global correlogram – a kind of fingerprint of the Earth. "
The study shows that these results can be used to demonstrate the existence of J waves and infer the speed of the cutting wave in central nucleus
although this specific information on shear waves is important, Tkalcic says that the results of this research on the inner core are even more exciting.
"For example, we still do not know what the exact temperature of the inner core, age of the internal nucleus or rapidity with which it solidifies, but with these new advances in world seismology, we arrive little by little.
"The understanding of the inner core of the Earth has direct consequences for the generation and maintenance of the geomagnetic field, and without this field, there would be no life on the surface of the Earth." [19659013] window .___ gcfg = {lang: -in-US & # 39;
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