Scientists have discovered a torus-shaped region in the Earth’s liquid outer core that could explain the mysteries of the magnetic field surrounding the planet.
A team from the Australian National University (ANU) has discovered a torus-shaped region within the Earth’s liquid core, thousands of kilometres below the surface. The findings, published in the journal Science Advances, provide new insights into the dynamics of the Earth’s magnetic field. Futurism The structure within the Earth’s liquid core has only been found at low latitudes and parallel to the equator. It has never been seen before, according to ANU seismologists.
The Earth has two cores (a solid inner core and a liquid outer core). Surrounding the core is the mantle. The newly discovered torus lies at the top of the outer core, where the liquid core meets the mantle. ANU geophysicist Professor Hrvoje Tkalčić said seismic waves travel more slowly in this region than in the rest of the outer core. The researchers don’t know exactly how thick the torus is, but they speculate it extends several hundred kilometres below the boundary between the core and the mantle.
Instead of using the usual seismic wave observation technique and the signal generated by an earthquake in the first hour after the shaking, the ANU team analysed the similarities between waveforms many hours after the earthquake started, leading to the unique discovery.
“By understanding the shape of the waves’ paths and how they propagate across the volume of the outer core, we were able to reconstruct their travel times through the Earth, demonstrating that the newly discovered region has low seismic velocities,” Tkalčić explains. “This strange structure was previously hidden because previous studies collected data at a smaller scale in the outer core by observing waves limited to within an hour of a large earthquake.”
Dr Xiaolong Ma, co-author of the study, said the findings shed some light on the dynamics of the Earth’s magnetic field. The outer core is made up mainly of liquid iron and nickel, and the violent movements of the electrically conductive liquid create the magnetic field that surrounds the Earth, helping to sustain and protect all life from the effects of solar wind and harmful radiation. By better understanding the composition of the outer core, including its chemical elements, scientists can predict when the magnetic field will weaken or stop.