These new data can improve the understanding of the formation and evolution of the planet
The Earth has a core in its innermost part.but for some time now there has been evidence of the presence of another even smaller. A new study provides data suggesting that it would be an iron ball with a radius of about 650 kilometers.
The new data, which can improve the understanding of the formation and evolution of the planet, is collected in a study by scientists from the Australian National University published on Tuesday by Nature Communications.
The Earth is made up of different layers, like a matryoshka doll, and in the center, at a depth of 5,000 kilometers, there is a sphere almost entirely made of iron that forms its inner core with a radius of about 1,220 kilometers. The presence of another smaller nucleus, a new layer that is even more internal, is a hypothesis that has been the subject of debate and the new study provides more evidence. Probing Earth’s deepest interior is challenging and the Australian team used a technique based on measuring the rebounds of seismic waves created by earthquakes around the world as they travel through the interior of the planet.
Maurizio Mattesini, a researcher at the Institute of Geosciences (IGEO) of the Higher Council for Scientific Research (CSIC), highlights the importance of this research, in which he has not participated, and tells EFE that this new small nucleus within the inner nucleus, of the that very little was known, would be “the last piece of the matryoshka”.
Scientists Thanh-SonPham and Hvoje Tkalcic use a “quite innovative” technique to obtain new data about this small, even more internal nucleus, such as that its radius is 650 kilometers, and they have achieved “clearer evidence” of how this sphere behaves within the other, larger one that is the internal nucleus, he adds.
The study describes that the behavior of the small core when faced with the propagation of seismic waves is slightly different from what occurs in what we know as the inner core. In this new nucleus, the waves that go parallel to the axis of rotation of the Earth go faster, but if they move in a plane of 50 degrees they slow down.
This behavior -explains Mattesini- is not the same in the outermost part of the solid core. The high-speed axis is kept parallel to the terrestrial axis of rotation, but the low-speed axis occurs exactly in the equatorial plane, which is 90 degrees.
Thus, the so-called “seismic misotropy, which is a peculiar characteristic of the inner core, has been seen to change, depending on whether we look at the behavior of the new or the older one,” adds the scientist. Hence the hypothesis that there has been a different evolution of the material over the years, add. “The inner part is a more consolidated material, which has a different response to seismic waves compared to the outer part”, which “is still affected by the convection phenomenon, the material is moving and mixing”.
As for the chemical composition of the small nucleus, it is believed that it is similar to that of the larger one, basically iron, but it is not known if it is cubic or hexagonal, which is an important detail. “With this new article it seems that something more is known but the dispute is still open”.
Mattessi, also a professor of Earth Physics at the Complutense University of Madrid, points out that knowing exactly what is in the center of the Earth, its composition, structure and how it behaves, allows us to study how its evolution will be.