Far beneath East Africa, thousands of miles below the surface, lies a vast structure that no one has ever directly seen, and Arizona State University researchers now suggest it is taller, lighter, and perhaps still climbing toward the world above. It is one of two colossal blobs resting on the boundary with the core, the other sitting beneath the Pacific, and the pair may hold clues to how the planet's deep interior has shaped the land we stand on. The findings, which compare seismic evidence with hundreds of simulations, suggest that these hidden masses are not twins but have followed differe
Giant Mantle Blob Beneath Africa Is Rising, Study Finds, Possibly Fueling East African Volcanism
It may still need a few million years to reach the surface.
Mark
So what's actually new here? We've known about these blobs for a while.
Mimi
The comparison. Yuan and Li found the African pile is much taller than the Pacific one, roughly 620 miles higher, and less dense.
Mark
Why does density matter?
Mimi
A lighter pile is less stable, and Yuan says that gives it the ability to keep moving up.
Luke
Careful, though. "Keep rising" is a model-based inference. Nobody has measured it moving.
Mark
Right, the speed hasn't been calculated?
Mimi
Correct. Yuan said so directly, and she isn't sure whether it ever reached the surface before.
Luke
And the volcanism link is framed as "may explain." Li's wording is hedged, and the 2020 study tied it to southeastern Africa, not the whole region.
Mark
What about the earthquake and supervolcano talk?
Mimi
That's Yuan's possibility, millions of years out, and only if the blob is still rising.
Luke
So it's a hypothesis about deep time, not a forecast anyone should plan around.
Il Polso
- A hidden mass under Africa stands roughly 620 miles taller than its Pacific twin, a contrast that surprised the researchers who measured it.
- Its lower density makes it less stable, so it may still be drifting upward through the mantle rather than sitting quietly at rest.
- Researchers are testing seismic readings against hundreds of convection simulations to learn what these piles are made of and how they behave.
- The unanswered questions are how fast the African blob is rising and whether it has already broken through to the surface in the past.
Far beneath East Africa, thousands of miles below the surface, lies a vast structure that no one has ever directly seen, and Arizona State University researchers now suggest it is taller, lighter, and perhaps still climbing toward the world above. It is one of two colossal blobs resting on the boundary with the core, the other sitting beneath the Pacific, and the pair may hold clues to how the planet's deep interior has shaped the land we stand on. The findings, which compare seismic evidence with hundreds of simulations, suggest that these hidden masses are not twins but have followed different histories. Whether the African giant will one day reach the surface, and what it might bring, remains a question the deep Earth has not yet answered.
Far below East Africa, thousands of miles down, sits a structure no one has ever seen directly. Researchers at Arizona State University report that it is taller and lighter than its counterpart on the far side of the planet, and that it may still be moving upward.
The structure is one of two enormous blob-like masses resting above the outer core, one beneath the Pacific and one beneath Africa. Seismologists know them as Low-Shear-Velocity Provinces, dense piles possibly built from recycled oceanic crust or iron-rich material, and they are known to shape processes in both the mantle and the core.
Qian Yuan and Mingming Li combined seismic analysis with hundreds of mantle convection simulations. Their models showed the African pile is far less dense, and therefore less stable, than the Pacific one. The African blob rises to roughly 990 to 1,100 miles, while the Pacific structure reaches only 430 to 500 miles. The contrast suggests the two have different compositions and histories.
The blobs have been linked to volcanism before. A 2020 study tied the African one to activity in southeastern Africa between 155 and 95 million years ago, and Li suggests it may have been rising in recent geological time, which could help explain eastern Africa's elevated terrain and intense volcanism.
Yuan is careful about what remains unknown. The team has not calculated how fast the structure moves, nor whether it has ever reached the surface. If it keeps rising, it could need a few million years to get there, possibly bringing more supervolcanoes and earthquakes. The open questions are the ones to watch: how fast the African blob is moving, and whether it has ever broken through before.
Far below East Africa, thousands of miles down, sits a structure no one has ever seen directly. Researchers at Arizona State University now report that it is taller and lighter than its counterpart on the far side of the planet, and that it may still be moving upward.
The structure is one of two enormous blob-like masses in the lowermost mantle, resting above the outer core. One lies beneath the Pacific Ocean, the other beneath Africa. Scientists first detected them through seismic observations, and they are known as Low-Shear-Velocity Provinces, or LLSVPs. They are thought to be dense thermochemical piles, made of recycled oceanic crust or iron-rich material, and they are known to influence processes in both the mantle and the core.
The new work, published in Nature Geoscience, comes from Qian Yuan and Mingming Li. They combined seismic analysis with hundreds of mantle convection simulations to test what these piles are and how they sit within the mantle. The simulations showed that the two differ in density. The African pile appears far less dense than the Pacific one, and therefore less stable.
The difference in height is large. The African blob rises to a maximum of about 990 to 1,100 miles, while the Pacific structure stands between 430 and 500 miles. That puts the African one roughly 620 miles higher. The researchers said these contrasts point to different compositions, dynamics and evolution histories for the two anomalies. Yuan told Newsweek the team suspected the African structure was taller but was surprised by how much taller it proved to be.
LLSVPs have been tied to volcanism before. At their edges they appear able to generate plumes that reach the surface, deflecting mantle flow upward. A 2020 study linked the African blob to volcanic activity in southeastern Africa between 155 and 95 million years ago. Li said the African LLSVP may have been rising in recent geological time, which could help explain the elevated surface topography and intense volcanism in eastern Africa.
Yuan was careful about what remains unknown. Because the African pile is relatively lighter, she said, it can keep moving upward. But the team has not calculated how fast it is rising, and it is not certain whether the structure has already reached the surface at some point in the past. If it keeps rising, she said, it could still need a few million years to get there. In that case, she said, Africa might see more supervolcanoes and earthquakes millions of years from now.
Beyond volcanism, the blobs have been linked to topographic changes, magnetic fields and the motion of tectonic plates. Yuan said the combination of seismic results and geodynamic modeling offers new insight into the largest structures in Earth's deep interior and how they interact with the surrounding mantle. She added that the work has far-reaching implications for understanding the present-day state and evolution of the deep mantle, and the nature of mantle convection.
The open questions are the ones to watch: how fast the African blob is moving, and whether it has ever broken through before.
Citazioni salienti
The Africa LLSVP may have been rising in recent geological time, which may explain the elevated topography and intense volcanism in eastern Africa.— Mingming Li, Arizona State University
The rising speed has not been calculated, and it is unclear if the blob already reached the surface in the past.— Qian Yuan, to Newsweek (paraphrased)
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