One has been identified mysterious donut structure hidden in the Earth’s core where the seismic waves travel more slowly than the rest of the nucleus: the discovery, which could explain some mysteries of the Earth’s magnetic fieldis published in the magazine Science Advances from researchers of theAustralian National University.
According to the results of the studythe donut-shaped structure It is found in the outermost part of the Earth’s core (the one formed by liquid iron and nickel), is parallel to the plane of theequator and is limited to low latitudes. «We do not know the exact thickness of the donutbut we have deduced that it reaches a few hundred kilometers below the boundary between the nucleus and coat“, says the geophysicist Hrvoje Tkalcic.
Instead of using traditional seismic wave analysis techniques to study signals generated by earthquakes within the first hour of the event, the researchers analyzed the waveforms many hours after the earthquakes were triggered. «Understanding the geometry “By analyzing the paths of the waves and how they pass through the volume of the outer core, we have reconstructed their travel times through the Earth, demonstrating that the newly discovered region has low seismic velocities,” he specifies. Tkalcic.
«The peculiar structure has remained hidden until now because previous studies have collected data with a lower volumetric coverage of the outer core, observing waves that were typically confined within an hour of the origin time of large earthquakes. We were able to obtain better volumetric coverage because we studied the reverberating waves for many hours after large earthquakes.”
There low propagation speed inside the liquid core «implies that in these regions we have a high concentration of light chemical elements which cause the seismic waves to slow down. These light elements, together with the differences in temperaturehelp mix the liquid in the outer core,” adds the geophysicist.
“The magnetic field is a fundamental ingredient that we need for life to exist on the surface of our planet. The dynamics of the Earth’s magnetic field are an area of great interest in the scientific community, so our results could promote further research on the magnetic field both on the Earth than on others planets».