Scientists Uncover Mysterious ‘Doughnut’ Structure in Earth’s Core

Researchers from the Australian National University (ANU) have made a surprising discovery deep within our planet. They’ve found a doughnut-shaped region thousands of kilometers beneath our feet, nestled within Earth’s liquid outer core. This finding could reshape our understanding of Earth’s magnetic field and its importance to life on our planet.

A Hidden Layer Revealed

The newly discovered region sits at the top of Earth’s outer core, where liquid metal meets the solid mantle above. It forms a band parallel to the equator, confined to low latitudes. While its exact thickness remains unknown, researchers estimate it extends a few hundred kilometers beneath the core-mantle boundary.

Professor Hrvoje Tkalčić, a geophysicist at ANU and co-author of the study, explains: “The region sits parallel to the equatorial plane, is confined to the low latitudes and has a doughnut shape. We don’t know the exact thickness of the doughnut, but we inferred that it reaches a few hundred kilometres beneath the core-mantle boundary.”

What makes this region unique is that seismic waves travel more slowly through it compared to the rest of the outer core. This slower speed suggests a higher concentration of light chemical elements in the area, which could play a crucial role in stirring the liquid outer core.

Why It Matters

Understanding Earth’s core is vital for several reasons:

1. Earth’s magnetic field: The outer core, primarily composed of liquid iron and nickel, generates our planet’s magnetic field through its vigorous movement.
2. Protection from solar radiation: This magnetic field shields Earth from harmful solar winds and radiation, making it essential for life as we know it.
3. Climate and geological processes: The core’s dynamics influence various Earth processes, including plate tectonics and long-term climate patterns.

Dr. Xiaolong Ma, a co-author of the study, emphasizes the significance of this discovery: “There are still mysteries about the Earth’s outer core that are yet to be solved, which requires multidisciplinary efforts from seismology, mineral physics, geomagnetism and geodynamics.”

A New Approach to Seismic Analysis

Traditional seismic wave observations typically focus on signals generated within the first hour after an earthquake. However, the ANU team took a different approach. They analyzed similarities between waveforms many hours after earthquake origin times, allowing them to achieve much better volumetric coverage of the outer core.

Professor Tkalčić describes their method: “By understanding the geometry of the paths of the waves and how they traverse the outer core’s volume, we reconstructed their travel times through the Earth, demonstrating that the newly discovered region has low seismic speeds.”

This innovative technique enabled the researchers to uncover a structure that had remained hidden from previous studies. It highlights the importance of continually refining and expanding our scientific methods to make new discoveries about our planet.

The implications of this discovery extend beyond Earth science. As Professor Tkalčić notes, “The magnetic field is a fundamental ingredient that we need for life to be sustained on the surface of our planet.” By improving our understanding of Earth’s core dynamics, we gain valuable insights into the long-term stability of our magnetic field and, by extension, the habitability of our planet.

As research continues, this newfound structure in Earth’s core may provide crucial clues about the evolution of our planet’s magnetic field and its potential future changes. It serves as a reminder that even after centuries of scientific inquiry, our planet still holds mysteries waiting to be uncovered.

Test Your Knowledge

1. Where is the newly discovered doughnut-shaped region located? a) In Earth’s inner core b) At the top of Earth’s outer core c) In Earth’s mantle
2. What characteristic of this region distinguishes it from the rest of the outer core? a) It has faster seismic waves b) It has slower seismic waves c) It has no seismic activity
3. Why is understanding Earth’s outer core important? a) It generates Earth’s magnetic field b) It controls the planet’s rotation c) It regulates surface temperature

Answer Key:

1. b) At the top of Earth’s outer core
2. b) It has slower seismic waves
3. a) It generates Earth’s magnetic field