Scientists find a hidden layer inside Earth’s inner core at 5000°C that may reshape what we know about the planet’s magnetic field

It looks like we might have to rewrite the textbooks. What we have always known about the Earth’s deep interior has changed, and researchers have provided us with new information. Scientists recently uncovered hidden structures deep inside Earth, buried nearly 1,800 miles below the surface. This revelation alters our understanding of Earth’s evolution and behaviour by providing previously unheard-of insights into its inner workings.

Joanne Stephenson, a geophysicist at the Australian National University, clarified that the four primary layers of the Earth are the crust, the mantle, the outer core, and the inner core. Much of what we know about the Earth’s subsurface is based on what seismic waves and volcanoes have whispered and disclosed, and scientists and geologists have confirmed this for years until this recent discovery.

Exposing the secret layers of the Earth’s deep interior

Deep within the Earth, at the boundary between the mantle and the core, rest two enormous and unusual features: large low-shear-velocity provinces and ultra-low-velocity zones. According to a recent study in Nature Geoscience, led by Rutgers geodynamicist Yoshinori Miyazaki, these structures have puzzled researchers for decades.

Large low-shear-velocity provinces are enormous masses of extremely hot, dense rock — one positioned beneath Africa and the other under the Pacific Ocean. Ultra-low-velocity zones resemble thin, partly molten layers that cling to the core in puddle-like patches. Both strongly slow seismic waves, suggesting they contain materials or conditions unlike the surrounding mantle.

“These are not random oddities,” said Miyazaki. “They are fingerprints of Earth’s earliest history. If we can understand why they exist, we can understand how our planet formed and why it became habitable.”

Leaking core materials and a long-lost magma layer

The research team suggested that the missing factor explaining these structures is the core itself. Their model indicates that over billions of years, elements such as silicon and magnesium gradually escaped from the core into the mantle.

This mixing would have disrupted the formation of strong chemical layers and may also account for the unusual composition of the large low-shear-velocity provinces and ultra-low-velocity zones, which the scientists interpret as the cooled remains of a “basal magma ocean” altered by core-derived material.

“What we proposed was that it might be coming from material leaking out from the core,” Miyazaki said. “If you add the core component, it could explain what we see right now.”

What are the implications and meaning for Earth’s past, present, and future?

The implications associated with these hidden structures are far-reaching. Interactions between the mantle and core may have influenced how Earth released heat, how volcanic activity developed, and even how the atmosphere changed over time.

This perspective may help clarify why Earth ended up with oceans and life, while Venus became extremely hot and Mars turned cold and barren. “Earth has water, life and a relatively stable atmosphere,” Miyazaki said. “Venus’ atmosphere is 100 times thicker than Earth’s and is mostly carbon dioxide, and Mars has a very thin atmosphere. We don’t fully understand why that is.”

The study also suggests that these deep features may help fuel volcanic hotspots such as Hawaii and Iceland, creating a direct link between Earth’s interior and the surface. New questions are also raised by the discovery — what specifically led to the formation of these structures, and what connections do they have with the rest of the planet’s evolution?

“Even with very few clues, we’re starting to build a story that makes sense,” Miyazaki said. “This study gives us a little more certainty about how Earth evolved, and why it’s so special.”