Researchers from the Abdus Salam International Centre for Theoretical Physics (ICTP) have determined that silicon is responsible for slowing seismic waves in Earth’s inner core, a region where these waves are known to travel unusually slowly. Scientists Zhi Li and Sandro Scandolo reached this conclusion in a groundbreaking study published in *Nature Communications*, which is the first to consider the role of light elements, such as silicon, in the core’s composition.
The study demonstrates that silicon profoundly influences the atomic arrangement of the iron alloy under the core’s extreme pressure and temperature conditions. According to their findings, silicon stabilizes the alloy into a cubic structure rather than a hexagonal one, which explains the slow propagation of seismic waves.
Located over 5,000 kilometers beneath the surface, where temperatures exceed 6,000 degrees Celsius and pressure is over three million times atmospheric pressure, Earth’s inner core cannot be explored directly. The team applied artificial intelligence methods to study its microscopic structure, a necessity for unlocking its secrets. Previous studies, which focused primarily on pure iron, showed it crystallizes into a hexagonal structure under such conditions.
This computationally intensive research, which required training AI algorithms and running large-scale simulations, was made possible by early access to the ‘Leonardo’ supercomputer, one of the world’s fastest machines at the time. The project was funded by the Italian National Centre for HPC, Big Data, and Quantum Computing, established under the National Recovery and Resilience Plan (Pnrr).
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