The nucleus of the Earth whose J waves are solid and sweeter than previously thought: study

According to one study, the inner core of the Earth is solid and softer than previously thought, which could help us better understand how the planet was formed.

Researchers at the Australian National University (ANU) have developed a way to detect shear waves, or "J waves" in the inner core – a type of wave that can only cross solid objects.

"We found that the inner core is indeed solid, but we also found that it was more flexible than previously thought," said Hrvoje Tkalcic, associate professor at ANU. .

"It turns out that if our results are correct, the inner core shares similar elastic properties with gold and platinum.The inner core looks like a time capsule.If we understand it, we will understand how the planet is formed, and how it evolves, "said Tkalcic.

According to the study published in the journal Science, internal shear waves are so small and weak that they can not be observed directly.

Their detection is considered the "holy grail" of global seismology since scientists predicted for the first time that the central nucleus was solid in the 30s and 40s, the researchers said.

Their so – called wave field correlation field method examines the similarities between the signals of two receivers after a major earthquake, rather than the direct wave arrivals.

The same team used a similar technique to measure the thickness of ice in Antarctica.

"We are throwing the first three hours of the seismogram and we are anticipating a major earthquake between three and ten o'clock.We want to get rid of the big signals," said Tkalcic.

The study shows that these results can then be used to demonstrate the existence of J waves and infer the speed of the shear wave in the inner core.

Although this specific information on shear waves is important, Tkalcic said the results of this research on the inner core are even more exciting.

"For example, we do not yet know what the exact temperature of the inner nucleus is, how old it is, or how fast it solidifies, but with these new advances in global seismology, we are slowly getting there," Tkalcic said. .

"The understanding of the Earth's inner core has direct consequences on the generation and maintenance of the geomagnetic field, without this field there would be no life on the surface of the Earth," Tkalcic said.

(With agency contributions.)