A team of researchers from theAustralian National University (ANU) discovered the existence of a vast “donut” shaped area in the Earth’s fluid outer core. Studying the speed of the seismic waves In this layer, scientists have identified a slow downwhich testifies to the presence of a region with characteristics different from the rest of the nucleus. The discovery is important because it revealed that the outer nucleus is not uniform and because the presence of this area could influence the functioning of the Earth’s magnetic field.
Discovery of the ring structure in the outer core
The nucleus It is the innermost layer of the Earth, divided into external (fluid) and internal (solid), both consisting of iron And nickelThe researchers focused on the outer core, analyzing the trend in this layer of seismic waves generated by high-magnitude earthquakes. Seismic waves propagate within the Earth at different speeds depending on the materials they encounter. Scientists have detected a slow down in the upper part of the outer core which attests to the presence of an area with a different composition and density compared to the rest of the layer. In particular, the low speed of wave propagation suggests that the area is made up of light chemical elements such as silicon, oxygen and hydrogen. The shape of the structure was reconstructed by studying the geometry of the seismic wave paths. It would be a shape toroidring-shaped, reminiscent of a donut. Its thickness has not yet been determined exactly, although it is believed that it could extend for hundreds of kilometers parallel to the plane of the Earth’s equator.
The structure had not been identified until now because previous studies had analyzed seismic waves that propagated within an hour of the earthquake, taking into account smaller core volumes. In this case, however, they were analyzed larger volumes studying seismic waves that also propagate many hours after the earthquake.
The consequences on the Earth’s magnetic field
To explain the existence of the Earth’s magnetic field, geophysicists refer to a dynamoa machine that transforms the kinetic energy of a conductor in motion in direct electric current, which generates a magnetic field. In turn, the magnetic field helps to create an electric current in the moving conductor. The magnetic field is therefore self-sustaining. In the case of our planet, which can be considered a natural dynamo, the conductor is represented by convective motions affecting the fluid materials of the outer core. The Earth’s magnetic field is essential because it acts as a shield against the particles of the solar windwithout which life on Earth would not be possible.
The presence of the ring structure in the outer core could influence the distribution of convective motions inside and here the presence of light elements would encourage the fluid mixing. Consequently, this area may have a impact on the Earth’s magnetic field. Having a deeper knowledge of the Earth’s core also helps to make comparisons with the characteristics of the other planets in the Solar System and to better understand their evolution.
For further information, here is a video on the reversals of the Earth’s magnetic field:
