The inner core of the Earth is solid, sweeter than thought; said study

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. (Representation photo: Reuters)

The central core of the Earth is solid and more tender than expected, according to a study that could improve our understanding of the formation of the planet.

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 softer than we had previously thought," said Hrvoje Tkalcic, an associate professor at the University of California. ANU.

"If our results are accurate, it turns out that the inner core shares 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, "said Tkalcic.

According to the study published in the journal Science, 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 core 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 throw the first three hours of the seismogram and we observe it between three and ten hours after a major earthquake. 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 is the exact temperature of the inner core, what is the age of the inner core, or how fast it solidifies, but with these new advances in global seismology, we are getting there slowly, "says Tkalcic.

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