Mysterious Giant Blobs Under The Earth Are More Unstable Than We Realized

Two enormous blobs exist deep below the Earth’s mantle. One is located under Africa, whereas the other is practically exactly opposite, beneath the Pacific Ocean. However, these two masses are not symmetrical.

According to new study, the blob under Africa is far higher near the surface — and hence more volatile — than the blob beneath the Pacific. This discrepancy may eventually assist in explaining why Africa’s geology has been raised higher and why the landmass has been subjected to so many massive volcano outbursts over millennia.

The masses in the mantle are correctly referred to as “large low-shear-wave-velocity provinces,” abbreviated LLSVPs. This implies that seismic waves produced by earthquakes stall considerably as they pass through all these deep-mantle regions. This slowing implies that something regarding the mantle at this location is unusual, either in terms of concentration or heat — maybe both.

Researchers are unsure about the origins of the mantle blobs. There are two widely accepted theories. One would be that they are composed of crustal buildup that has separated from the Earth’s crust towards the mantle’s depths. Another possibility is that they are the remains of a magma ocean that occurred inside the lower mantle throughout the Earth’s early history. While this magma sea chilled and solidified, it may have left parts of the mantle that were thicker than the others.

Although the African blob may be a long way from the Earth’s surface — the mantle measures 1,800 miles (2,900 kilometers) depth overall — the volatility of this deep structure may have consequences for the surface of the planet. LLSVPs might be a reservoir of heated mantle material plumes that ascend higher. These plumes, in fact, have the potential to trigger supervolcano explosions, tectonic dislocation, and potentially continental disintegration. These processes take millions of years to complete and have been underway throughout Africa.

The researchers published their results in the journal Nature Geoscience.