By Chris Skeldon 
One of the ships sent into space, Voyager 1, managed to reach interstellar space, beyond Pluto. The most powerful telescopes have been able to dive to close to the Big Bang. Not to mention the technology that has buried communications and development. But even so, still There is a lot to know and understand about the center of the Earth.
“Although the Earth's inner core is commonly believed to be a solid ball of iron, recent seismic observations indicate a slow flow of material, which has generated a great deal of interest and discussion” – Maurizio Mattesini, Professor of Physics at Complutense University of Madrid.
Despite significant advances in seismology, mineral physics, geodynamics, paleomagnetism and mathematical geophysics, The structure and evolution of the Earth's inner core remain mysterious. One of the most important questions is its thermal history and current thermal state. Several hypotheses have been proposed about the inner core undergoing convection: Simple high-viscosity transition mode or classic low-viscosity column-type convection. One investigation Recently published in the magazine nature He is trying to move forward on these issues.
in it, Modern seismic imaging has been used to probe the outer layer of the inner core regarding the isotropic pressure velocity and its comparison with recently developed attenuation maps. The pattern seen in the resulting tomograms is interpreted using recent data on iron viscosity as the appearance on the inner core surface of thermally driven flow. One A positive relationship was discovered between compression velocity, attenuation and temperature.
Breakthrough into the unknown
Although the convection of the outer core controls the heat flow across the inner core boundary, Internally driven internal convection It is a plausible model that explains a number of observations of the inner core, including the distinct variation in the outer inner core. a contrast It is the general property of matter according to which properties such as elasticity, temperature, conductivity, and speed of propagation of light vary depending on the direction in which they are examined.
Motivated by existing controversies about the behavior of the inner core (IC), and recent developments in Seismic tomography They were used to probe the outer 100 km layer of the integrated circuit looking for its compressed wave speed. The scheme uses strict treatment of uncertainty applied to data obtained with relatively small volumetric samples, especially in the Southern Hemisphere.
The study was led by Hrvoje Tkalić Australian National UniversityIn cooperation with the Complutense University of Madrid. As a result, Until now, the Earth's inner core was thought to be a solid ball of iron. But according to what the site said synchronizationYou Scientists have proposed a more stable central region, where convection has almost stopped, and an outer region where material flows.
Many theories and many doubts
By analyzing all available information, it was concluded that: The Earth's solid inner core could be in a state of convectionThe process by which heat produced in fluids is transferred due to temperature differences. This information was obtained through seismic images, experimental results at high pressure and temperature, and numerical simulations.
Maurizio Mattesini, Professor of Physics at Complutense University of Madrid“Although the inner core is generally thought to be a solid iron ball,” Sinek says, Recent seismic observations indicate a slow flow of material, which has generated a great deal of interest and discussion“These results allowed us to obtain a clearer picture of the Earth’s inner core.
According to researchers, it appears to consist of a The central part is more stagnant, as convection has almost been extinguishedHe is The outer part in which heat flows continue to drive material movement, at a speed ranging between 0.3 and 300 m/year. This new small core within the inner core, about which very little is still known, will be the final piece that will complete the innermost parts of our planet's sector.
News reference:
Tkalich, H. et al. Imaging the upper part of the Earth's inner core: a current flow model. Nature, 14, 2024.