According to researchers at the Chinese Academy of Sciences in a study published in the Journal of Geophysical Research: Solid Earth, a deep-learning system has sifted through more than two million earthquake recordings from 1990 to 2024 to uncover nearly 175,000 faint seismic signals near the boundary between Earth’s mantle and core. This comprehensive global map reveals that strange features at the bottom of the mantle are far more extensive than previously thought, providing researchers with clear priority targets for future exploration of Earth’s deep interior.
Machine Learning Uncovers Hidden Seismic Signals
Analyzing decades of seismic data requires immense computational power and careful sorting. According to the study, researchers trained a deep-learning algorithm to examine millions of seismic waveforms from almost 5,000 earthquakes collected over three and a half decades. The system initially sorted recordings by quality and scanned for faint seismic waves known as PKP precursors. These specific waves travel through Earth’s outer liquid core and arrive at surface detectors just ahead of much stronger seismic waves, helping scientists map unusual structures deep inside the planet.
Traditionally, geologists had to inspect these records manually, which was slow work prone to disagreements over whether a signal was genuine. In this recent study, researchers manually checked and corrected the AI model’s mistakes during the training process. Ultimately, the system identified 174,929 high-quality PKP precursor signals—surpassing all previous studies combined by a factor of ten.
Mapping Continuous Belts and Ancient Remnants
Earlier maps of the bottom of the mantle typically showed isolated, random structures. With the expanded dataset from the Chinese Academy of Sciences team, researchers can now see that several of these patches actually connect into much larger, continuous belts.
According to research from 2023, the deep mantle contains a variety of materials, including continental crust, sediments, oceanic crust, and primitive mantle materials. Under the enormous pressures and temperatures at the core-mantle boundary, this material can chemically differentiate or partially melt. The authors conclude that these small-scale structures may be thermochemical piles shaped by subducted slab remnants, localized partial melting, mineral transitions, and interactions with giant blobs known as large low-shear-velocity provinces.
Probing Deep-Earth Mysteries and Volcanic Hotspots
Understanding these structures helps scientists track how the mantle moves and how hot magma feeds volcanoes or deep-ocean ridges. These dynamics influence whether volcanic eruptions occur and how severe they become. Furthermore, the findings may shed light on how tectonic plates formed and what causes imbalances in Earth’s magnetic field.
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The new map highlights six specific regions—including areas beneath high-latitude Eurasia, Central Asia, and the South Atlantic—that were poorly sampled in past studies. The research team recommends prioritizing these zones for future, higher-resolution investigations using multiple types of seismic waves.
Frequently Asked Questions
What are PKP precursors? PKP precursors are faint seismic waves that arrive at detectors shortly before stronger seismic waves, getting deflected or scattered by variations in material near the core-mantle boundary.
Why are scientists using machine learning for seismology? Manual inspection of millions of earthquake recordings spanning decades is exceptionally slow. Deep-learning algorithms can screen vast datasets efficiently, though human researchers still verify and correct the model’s outputs.
What lies at the core-mantle boundary? According to recent geological studies, the core-mantle boundary hosts complex structures like large low-shear-velocity provinces, ultra-low-velocity zones, and thermochemical piles made of subducted slab remnants and mantle materials.
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