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

A groundbreaking study has revealed a striking new feature deep within the Earth's core, about 2,890 kilometers beneath the surface. Researchers have discovered a doughnut-shaped formation within the outer core where seismic waves travel roughly 2% slower than in other parts of the core.

Published Findings

The research, detailed in Science Advances, identifies a ring-like zone parallel to the equator within the molten outer core. This unique structure was detected through seismic waves generated by earthquakes, which allow scientists to probe the core's internal structure.

Seismic Wave Analysis

Professor Hrvoje Tkalcic, a geophysicist at Australian National university and a co-author of the study, explained that while direct access to the core is not yet feasible with current technology, scientists can infer its properties by studying seismic waves. By comparing seismic data from different latitudes, they found that waves slowed down upon reaching the doughnut-shaped zone, suggesting it affects wave propagation.

Significance of the Discovery

The discovery of this outer core structure is vital because it is integral to generating and maintaining Earth's magnetic field, which shields the planet from harmful solar radiation. The movement of molten iron and nickel within the core creates a dynamo effect that sustains the magnetic field.

The doughnut-shaped region likely contains lighter elements such as oxygen, hydrogen, silicon, sulfur, or carbon, which are essential for the molten metal currents driving the magnetic field.

Core Characteristics

With a radius of approximately 3,480 kilometers, the outer core is slightly larger than Mars. It is primarily made up of iron and nickel, with some lighter elements mixed in.

Professor Tkalcic noted that while the exact thickness of the doughnut-shaped structure is still undetermined, it is estimated to extend several hundred kilometers below the core-mantle boundary. This new insight enhances our understanding of the Earth’s core dynamics and its magnetic field.