“Donut” Discovered in the Earth’s Core

This remarkable discovery, achieved through the analysis of seismic waves generated by earthquakes, provides new insights into the dynamics of our planet’s interior and its potential role in sustaining life.

Professor Hrvoje Tkalčić and Dr Xiaolong Ma spearheaded the study employing sophisticated methods to track the seismic wave patterns that penetrate the various layers of the Earth. These waves, produced by tectonic activity, are typically examined in the immediate aftermath of an earthquake. However, the researchers innovatively extended their observations to include the faint echoes of seismic waves hours after an initial tremor, revealing significant differences in travel speeds of waves near the poles compared to those near the equator.

Their detailed analysis highlighted a region several hundred kilometres thick, situated just above the outer core and near the mantle boundary, where seismic waves decelerated by approximately two per cent. This was best attributed to the presence of a torus-shaped (donut-like) zone encircling the equator.

Significance of the Donut-Shaped Structure

The Earth’s inner structure is complex and classified into four layers: the crust, mantle, liquid outer core, and solid inner core. Within these strata, the outer core—comprised of molten nickel and iron—plays a pivotal role in generating the planet’s magnetic field. This geodynamo mechanism, driven by convection currents and the Earth’s rotational forces, forges powerful magnetic vortices essential for deflecting harmful solar radiation.

The newly discovered donut-shaped region is posited to be rich in lighter elements such as silicon, sulphur, oxygen, hydrogen, or carbon. These elements, along with temperature variances, are thought to drive convective currents within the outer core, thereby contributing to the generation of the magnetic field. Without these swirling motions, the magnetic shield protecting Earth would not exist, exposing its surface to lethal solar wind and radiation.

Implications for Earth’s Habitability and Beyond

The magnetic field’s crucial role in safeguarding life on Earth cannot be overstated. It protects the planet from charged particles emitted by the sun which could otherwise obliterate the DNA of living organisms. So the discovery of this deep-seated donut-shaped region provides vital clues towards understanding the intricate processes maintaining the magnetic field and, by extension, life on Earth.

Professor Tkalčić emphasises the potential broader ramifications of their findings. The presence of such a structure could inform astrobiological studies and guide the search for habitable planets. Identifying similar geological and magnetic field conditions on other planets could be retrospectively linked to the existence of life.

Future Research Directions

This landmark discovery invites further investigation to understand the detailed mechanics of how this newly identified region influences the geodynamo. It also  sparks the prospect of parallel studies of other terrestrial planets and moons, enhancing our understanding of their magnetic properties and potential habitability.