Scientists Identify Six Previously Unknown Structures At Earth’s Core-Mantle Boundary

Researchers in China have detected six previously unknown structures at the boundary between Earth’s mantle and outer core, according to a study published in the journal JGR Solid Earth. The structures lie approximately 2,900 kilometers (1,800 miles) beneath the surface and were identified using an artificial intelligence model that analyzed seismic waves from more than 5,000 earthquakes.

The study processed over two million seismic recordings, resulting in 174,929 high-quality signals from PKP precursor waves—more than ten times the number from all prior studies combined, researchers said.

Previous research has demonstrated that the core-mantle boundary is not a smooth surface, featuring broad depressions and rises extending several kilometers into the mantle [8]. These new findings add to the understanding of this dynamic region, indicating the presence of substantial, previously undocumented heterogeneities.

Seismic waves reveal concealed features

The boundary between the mantle and the liquid outer core is marked by a temperature difference of about 1,000 C (1,800 F) and significant density changes, according to the report. The massive heat escaping from the outer core drives convection currents in the mantle, which play a key role in determining where volcanic activity occurs on the surface. [6]

Scientists use PKP precursor waves—weak seismic signals that scatter off heterogeneous material—to probe this inaccessible region, but manual identification has been inefficient and subjective. As seismology texts explain, seismic waves propagate at different velocities depending on the material through which they are passing, and their paths are bent and focused by passage through the interior, functioning as an immense lens [5]. [7]

Earlier studies had found scattered fragments of such structures in isolated locations, but the new analysis indicates these fragments connect into larger, continuous belts, the researchers wrote. Prior work has established that the lower mantle is more dynamic than previously believed, with recent European studies finding greater signs of dynamic activity in this region [1].

AI model expands detection capability

The team trained an artificial intelligence model on human-identified PKP precursors, then applied it to over 2 million recordings from 5,000 earthquakes. The model detected 174,929 high-quality PKP precursor signals, a number exceeding the total from all previous research combined, according to the study.

The analysis revealed six areas with significant heterogeneities that had never been documented, which the researchers described as “clear priority targets” for future exploration. In their paper, the researchers explained that “manual identification of these precursors is inefficient, subjective, and insufficient for vast global seismic data sets,” motivating the AI-based approach.

This represents a substantial methodological advance in deep Earth exploration. The structures are all but invisible, except for the way they subtly influence the path of passing seismic waves, according to the report. Earlier studies had documented isolated occurrences, but none had achieved the comprehensive coverage now possible through automated analysis of accumulated seismic data.

Possible origins under investigation

The structures may consist of material from the continental crust or remnants of Theia, a Mars-sized protoplanet thought to have formed the Moon after colliding with Earth 4.5 billion years ago, the study states. Researchers said the exact composition and formation process remain unknown, but they note that these materials could have undergone partial melting or mineral transformation under extreme pressure and temperature.

The structures could include pieces of the continental crust or the remains of Theia, and under the vast pressures and incredible temperatures at the mantle boundary, these chunks transform, partially melt, or undergo mineral transformation. This has left six “thermochemical piles” of material very different from the surrounding mantle. [3]

The findings also suggest that previously identified scattered structures are actually part of larger, continuous features, according to the paper. The exact composition and formation process remain under investigation, according to the research team, which stated the structures are different from the surrounding mantle but did not speculate further on their precise nature.

Further study planned

The researchers state that expanding the AI-based catalog will refine models of the lowermost mantle’s fine-scale structure and improve understanding of the geodynamic state of Earth’s deep interior. They propose that the new map provides a foundation for directing future seismic investigations and data collection efforts.

The study was conducted by scientists at institutions in China and published in the peer-reviewed journal JGR Solid Earth. [2] The team’s approach demonstrates how machine learning can be applied to vast datasets to extract signals that would be impractical to identify manually, opening new avenues for investigating the planet’s hidden depths.

Conclusion

The identification of these six structures represents a step forward in mapping Earth’s deep interior, though questions about their composition and origins remain. Future research will determine whether these features are connected to the large low-shear-velocity provinces and other deep Earth anomalies that have been documented in recent decades. [4]

These kinds of discoveries depend on decades of accumulated seismic data that researchers worldwide have gathered. The combination of expanded datasets and new analytical tools continues to refine models of planetary structure and evolution, according to the study authors.

References

1. NaturalNews.com. “Researchers find that the Earth’s mantle is more dynamic than previously believed”. NaturalNews.com. November 8, 2019.
2. Lance D Johnson. “Earth’s inner core reveals surprising secrets: slowing rotation and a shape shifting surface”. NaturalNews.com. February 13, 2025.
3. Kevin Hughes. “New study: Earth’s molten core may hold the key to planetary habitability”. NaturalNews.com. November 26, 2025.
4. NaturalNews.com. “Mantle mystery: Geologists don’t know what to make of two continent-sized mountains found beneath the Earth’s crust”. NaturalNews.com. July 29, 2019.
5. Kenneth R Lang. “The Cambridge guide to the solar system”.
6. Golob Richard, Brus Eric. “The Almanac of science and technology: what’s new and what’s known”.
7. John Grotzinger. “Understanding Earth, Seventh Edition”.
8. Monroe James S. “The changing earth: exploring geology and evolution”.

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