A Hidden Blob Beneath Africa Is Fueling Volcanoes—and It Could Split the Continent in Two

Here’s what you’ll learn in this story:

The East African Rift System (EARS) is one of the most impressive geologic features on the planet—not to mention one of the most volcanically active and geothermally rich.
Understanding what drives EARS is of immense importance, but scientists have debated if the rift is powered by one giant superplume or a few smaller plumes located along its 4,000-mile length.
Scientists recently analyzed neon isotope ratios from a new geothermal field in Kenya, anddiscovered that ratios of the isotope are similar to other readings from other parts of the rift system, which provides strong geochemical evidence for the superplume theory.

In East Africa, geothermal energy is big business, and that’s all thanks to the East African Rift System (EARS). One of the largest rift systems on Earth—stretching 4,000 miles from Ethiopia in the north to Malawi in the south—EARS is filled with rift valleys and active volcanic regions that form some of the world’s most famous volcanoes, including Mount Kilimanjaro. This volcanic activity also means that eastern Africa is a geothermal hotspot. For example, a large majority of Kenya’s electricity (90% of which comes from renewable sources) is of geothermal origin.

Geothermal being so lucrative in the region has some positive side effects for scientists studying the ever-fascinating EARS. Because companies do so much experimental drilling for locating and running geothermal fields, scientists can use that data to gain a better understanding of what’s driving these geologic processes in the first place. Although the running theory is that hot, buoyant deep-mantle upwelling drives the rifting process, it’s been very difficult to figure out if this comes from one deep-sourced plume or multiple plumes along the EARS’ 4,000-mile expanse.

Now, in a new study, scientists at the University of Glasgow—armed with data gathered at the Menengai geothermal field in Kenya—analyzed of the noble gas neon and determined that it originates in the deep mantle (likely between the outer core and the mantle). Using high precision mass spectrometry, the team also determined a common “fingerprint” of gases across a far distance, which supports the idea that EARS is powered by one singular “superplume” rather than multiple, shallower processes. The results were published in the journal Geophysical Research Letters.

“We have long been interested in how the deep Earth rises to the surface, how much is transported, and just what role it plays in forming the large-scale topography of the Earth’s surface,” Fin Stuart, the senior author of the study, said in a press statement. “Our research suggests that a giant hot blob of rock from the core-mantle boundary is present beneath East Africa, it is driving the plates apart and propping up the Africa continent so it’s hundreds of meters higher than normal.”

To investigate whether EARS is in fact powered by a superplume, Stuart and his team first needed to analyze neon isotopes, as noble gasses can reveal deep Earth behavior. However, these gases are also easily contaminated, both by the atmosphere and by other noble gases formed in the lithosphere. Luckily, by analyzing noble gases from the Kenyan geothermal field, scientists found that contamination was minimal. Additionally, they discovered that those same neon isotopic features had also been observed in other parts of the rift system—including in basalts from the Afar plume in Ethiopia, and in the Western Rift Valley between Uganda and the Democratic Republic of the Congo. This study “provid[es] the first geochemical evidence for a common deep mantle beneath the entirety of the East African Rift System,” the authors wrote.

This data also aligns with a 2023 study from Virginia Tech that investigated why EARS displayed deformations parallel to the rift rather than perpendicular (which is more typical). Their analysis supported the idea that a deep-rooted superplume must be driving a northward-moving magma flow in order for these strange deformations to take shape.

While EARS appears somewhat static—at least, to our lifespan-limited perspectives—the rift could eventually tear Africa in two, so what we’re now witnessing could one day result in the birth of an entirely new ocean. However, not all rifts turn into oceans, so we won’t know for sure until geologic history takes its course.

You Might Also Like