ANU scientists have discovered a torus-shaped region in Earth’s liquid outer core that could help explain mysteries about the planet’s magnetic field, highlighting the need for continued interdisciplinary research in this area.
Scientists from the Australian National University (ANU) have discovered a ring-shaped region in the Earth’s liquid core, thousands of kilometres below our feet. This discovery provides a new understanding of the dynamics of our planet’s magnetic field. The structure of the Earth’s liquid core is only found at low latitudes and is parallel to the equator. According to ANU seismologists, it had not been detected until now.
The Earth has two core layers: the inner core, a solid layer, and the outer core, a liquid layer. The Earth’s core is surrounded by a mantle. The newly discovered donut-shaped region is located at the top of the Earth’s outer core, where the liquid core meets the mantle.
Co-author of the study, Dr Xiaolong Ma, said the discovery reveals some mysteries about Earth’s magnetic field dynamics.
“There are still unsolved mysteries of the Earth’s outer core, which require interdisciplinary studies such as seismology, mineral physics, geomagnetism and geodynamics,” Dr. Ma said.
Instead of using traditional methods such as observing seismic waves and signals generated by earthquakes within the first hour, ANU scientists analysed similarities between waveforms hours after the earthquake began, leading to a unique discovery.
“By understanding the geometry of the wave’s trajectory and how it crosses the volume of the outer core, we reconstructed the time of its passage through the Earth and showed that the recently discovered region has low seismic velocities,” said Professor Tkalcic.
“The peculiar structure has remained hidden until now because previous studies collected data with smaller volumetric coverage of the outer core by observing waves limited to an hour after the onset of strong earthquakes. “We were able to get much better volumetric coverage because we were studying the reflected waves for hours after the big earthquakes.”
Values for understanding the Earth’s magnetic field
Co-author of the study, Dr Xiaolong Ma, said the discovery reveals some mysteries about Earth’s magnetic field dynamics.
“There are still mysteries to be solved about the Earth’s outer core, requiring multidisciplinary efforts such as seismology, mineral physics, geomagnetism and geodynamics,” Dr. Ma said.
The outer core consists mostly of liquid iron and nickel, and the energetic movement of the conductive liquid creates Earth’s magnetic field, which shields the Earth around it and helps support all life by protecting it from damaging solar winds and harmful radiation.
Scientists believe that understanding more about the composition of Earth’s outer core, including the light chemical elements, is key to understanding the magnetic field and potentially predicting when it could end or weaken.
“Our findings are interesting because such low velocities in the liquid core mean that these regions have high concentrations of light chemical elements that can cause seismic waves to slow down. These light elements, together with the temperature difference, help to mix the liquid in the outer core,” said Professor Tkalchich.
“The magnetic field is a fundamental component that we need to sustain life on the surface of our planet. “The dynamics of the Earth’s magnetic field are of great interest to the scientific community, so our results could contribute to larger studies of magnetic fields both on Earth and on other planets.”
Source: Port Altele
