Two Giant Blobs Are Moving Near Earth’s Core… What Is Happening 1,800 Miles Below Us?

Beneath our homes, highways, and oceans lies a part of Earth we will never see. About 1,800 miles down, at the boundary between the molten outer core and the solid mantle, scientists have identified two enormous structures. Each one is as wide as a continent. And new research suggests they may be slowly shifting over time.

These deep formations are known in scientific studies as large low shear velocity provinces, or LLSVPs. They sit at the very base of the mantle, where temperatures and pressures are extreme. For years, researchers believed they were mostly stable. Now, seismic data and computer models are painting a more dynamic picture.

How Did Scientists Discover These Hidden Giants?


No drill can reach that depth. Instead, scientists rely on earthquakes.

When an earthquake strikes, it sends seismic waves through the planet. These waves travel at different speeds depending on what they pass through. By collecting data from earthquakes around the world, researchers build three-dimensional maps of Earth’s interior using a method called seismic tomography.

In the late twentieth century, these maps revealed something unusual. Two vast regions near the core-mantle boundary showed slower-than-normal shear wave speeds. One lies beneath Africa. The other rests beneath the Pacific Ocean.

Multiple peer-reviewed seismic studies confirmed the finding. The regions stretch thousands of kilometers across and rise as much as 1,000 kilometers upward from the core mantle boundary. The slower waves suggest the material inside these provinces differs in temperature, composition, or both.

They are not small pockets. They are massive and persistent features in Earth’s deep interior.

What Are These Blobs Made Of and Where Did They Come From?

This is one of the biggest questions in modern geophysics.

One leading explanation is that the blobs are made of dense, chemically distinct rock. Over billions of years, oceanic plates sink into the mantle through subduction. Some researchers propose that this recycled material accumulates at the bottom of the mantle, gradually forming large provinces with different chemical properties.

Another theory looks back to Earth’s earliest days. A 2023 study published in Nature used giant impact simulations and mantle convection models to examine the aftermath of the collision between early Earth and a Mars-sized body often called Theia. That impact is believed to have formed the Moon.

According to the study, fragments of Theia’s mantle could have mixed into Earth’s interior and eventually settled near the core-mantle boundary. These dense remnants may have survived for billions of years, forming the continent-sized blobs observed today.

Neither theory has been fully proven. Both are supported by modeling, geochemical reasoning, and seismic evidence. Scientists continue to test these ideas with improved imaging and simulations.

Are the Blobs Really Moving and How Do We Know?

For a long time, LLSVPs were treated as relatively fixed features. But recent three-dimensional mantle convection models suggest they may respond to slow-flowing currents deep within Earth.

New research examining seismic anisotropy shows that the edges of these provinces may deform under the influence of subducting slabs and rising mantle plumes. Subducting slabs are cold pieces of oceanic crust that sink into the mantle. Mantle plumes are hot upwellings that rise toward the surface.

Studies of the Pacific LLSVP reveal sharp boundaries in some areas and more gradual transitions in others. This pattern suggests long-term interaction with mantle flow. The movement is extremely slow, unfolding over millions of years. But in geological terms, that still counts as motion.

Why Do These Deep Structures Matter to Us

It may feel distant, but what happens deep inside Earth affects the surface.

Mantle plumes that feed volcanic hotspots, including places like Hawaii and Iceland, are thought to originate near the edges of these deep provinces. Their presence may influence where volcanic activity occurs.

Long-term changes in these structures could also shape plate tectonics and the cycle of supercontinents. Even heat flow from the core, which affects Earth’s magnetic field and cooling history, may be linked to how these blobs behave.

By mapping and modeling these deep regions, scientists connect Earth’s hidden interior to the landscapes and oceans we know.



What Does This Reveal About Our Planet

The idea that continent-sized structures sit near the core and may slowly shift challenges the simple image of Earth as a neat stack of layers. Instead, the planet appears dynamic and complex, shaped by forces operating far below our feet.

Every earthquake recorded and every simulation run on powerful computers brings researchers closer to understanding this hidden world.

Far beneath daily life, two giant provinces continue to influence Earth’s long story. Quietly, slowly, and steadily, they remind us that our planet is still very much alive inside.