Buried thousands of kilometers beneath your feet lie two continent-sized anomalies—massive, slow-seismic zones scientists now believe could be the ancient remains of a planet that slammed into Earth billions of years ago. According to new 2025 research, these structures—called Large Low-Velocity Provinces (LLVPs)—may be iron-rich chunks of Theia, the long-lost planet that created the Moon.
Earth’s Core May Be Hiding a Dead Planet
Beneath Africa and the Pacific Ocean, seismic data has revealed two giant regions with mysterious properties. They’re denser than the surrounding mantle, absorb seismic waves differently, and span areas larger than entire continents. These LLVPs have puzzled geophysicists for decades—but a new theory may finally decode their origin.
In a groundbreaking 2025 study published in Nature, scientists propose that these “blobs” are relics from the ancient planet Theia—the very body that collided with Earth during the Moon’s formation event 4.5 billion years ago.
Theia: Planetary Ghost Turned Geological Fossil
The giant-impact hypothesis has long suggested the Moon formed from debris after a Mars-sized planet hit Earth. But what happened to the rest of Theia?
Caltech-led researchers simulated the collision at high resolution. Their findings? A significant portion of Theia’s iron-rich mantle didn’t just vanish—it became embedded in Earth’s deeper layers. Over time, this material sank to the lower mantle, forming what we now detect as the LLVPs.
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Density: 2–3.5% heavier than surrounding mantle
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Size: Nearly twice the Moon’s volume
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Location: Below Africa and the central Pacific
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Composition: Likely enriched in iron and other heavy elements
Planetary Remnants Still Shaping Earth Today
These buried fragments aren’t just geological leftovers. Researchers believe they may:
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Act as anchors influencing mantle convection
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Drive superplume activity—powering volcanoes like Hawaii and Iceland
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Play a role in Earth’s plate tectonics and magnetic field
If Theia’s remnants did survive, Earth has literally been carrying another planet inside it—affecting its evolution from the inside out.
What This Means for Exoplanets and Cosmic Evolution
The implications go well beyond Earth. If planetary mergers like the Earth-Theia impact can leave lasting internal fingerprints, similar hidden structures may exist in other terrestrial planets. Mars, Venus, and exoplanets in dynamic young systems might all hide their own planetary ghosts beneath the surface.
Earth’s Hidden Heart May Not Be Earth at All
What was once considered random seismic noise now appears to be a time capsule from a cataclysmic collision. These ancient structures are rewriting our understanding of planetary formation, internal dynamics, and Earth’s violent beginnings.
The Moon may have risen from that fiery crash—but Theia never left. It sank, stayed silent, and reshaped our world from within.
FAQ:
Q: What are LLVPs?
A: Large Low-Velocity Provinces—massive dense mantle zones beneath Africa and the Pacific that slow seismic waves.
Q: What is the Theia hypothesis?
A: The idea that a Mars-sized planet collided with Earth, forming the Moon and leaving remnants inside Earth.
Q: Why are scientists linking Theia to LLVPs now?
A: 2025 research shows LLVP density and composition match simulations of Theia’s mantle material.
Q: What role do LLVPs play in Earth’s geology?
A: They may anchor mantle convection, influence tectonics, and drive superplume volcanism.
