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Following heavy rains in Kenya, a giant crack appeared in the ground in the Suswa region late last month that caused part of a highway to collapse near the capital city of Nairobi, as the BBC reported. News of the massive crevice has shed light on the fact that Africa might be splitting in two but has also left the scientific community somewhat divided: Some believe the crack is rooted in tectonic activity, and others believe it’s nothing more than erosion.
Geologists do agree that Africa — the world’s second-largest continent, with an area of 11.73 million square miles — could very slowly split into two masses of land due to a geological rifting on the eastern side of the continent that started 25 million years ago. Currently, the spreading rate is a few millimeters per year, so the geological phenomenon will play out slowly over roughly 50 million years, according to National Geographic. When an actual divide happens, an island would be created in the Indian ocean consisting of parts of what are currently Ethiopia, Somalia, Kenya, and Tanzania.
But whether the recently exposed crack — which measured 50 feet deep and 65 feet wide in some areas, according to the Kenyan newspaper Daily Nation — is evidence of that split is disputed by some.
The fissure appears in the East African Rift, a part of East Africa's Great Rift Valley, which runs south from Jordan to Mozambique. National Geographic explains that a rift valley is a lowland region where tectonic plates spread apart, and this rift valley is one of the largest in the world. The two tectonic plates that are moving from one another in the East African Rift are the Nubian Plate (a larger plate that contains most of Africa) and the Somalian Plate. Collectively, the two plates are also rifting away from the Arabian Plate, which already separates Africa from the Middle East.
Lucia Perez Diaz, a postdoctoral researcher on tectonics at Royal Holloway, University of London, wrote in The Conversation that “questions remain as to why it has formed in the location that it did and whether its appearance is at all connected to the ongoing East African Rift.”
The location of the crack, coupled with supposed seismic activity in the area, have some geologists wondering if it’s an early sign of the split to come.
“The valley has a history of tectonic and volcanic activities,” geologist David Adede told the Daily Nation. “Whereas the rift has remained tectonically inactive in the recent past, there could be movements deep within the Earth’s crust that have resulted in zones of weakness extending all the way to the surface.”
Kevin Furlong, professor in geosciences at Penn State, agrees that that explanation is possible but expressed skepticism about connecting the Kenyan crack straight to tectonic activity. He told Teen Vogue, “It is possible to link the crack to the plate motions, but it is probably not correct to call this crack a direct example of the plate boundary itself.”
Geologist Ian Hamling believes weather — specifically, the recent downpour in the area — is more likely responsible than tectonic activity.
“While the scale of the crack is impressive given the coincidence of heavy rain and flooding which hit the area, and [the lack of] obvious damage [aside] from the crack itself, I think it is much more likely to be a weather-related phenomenon rather than something tectonic or volcanic,” Hamling said. “We are fortunate now to have a huge suite of satellite data at hand which can also help us try understand what happened. If this were related to fault movement or magmatic activity then there would have been a lot of ground deformation, which we would be able to detect using some of this satellite data. However, images acquired over the region do not show any of the expected ground displacements we would expect to see if this had occurred.”
Stephen Hicks, a seismology researcher at the University of Southampton, England, believes erosion of soil is the reason behind this particular fissure. Writing for The Guardian, he made the case that there’s no direct link connecting the crack's formation with tectonic plate movement. “Given the evidence available at present, the best and simplest explanation is that this crack was in fact formed by erosion of soil beneath the surface due to recent heavy rains in Kenya,” he wrote.
Historically, such rifts are nothing new. Furlong says it’s a “current example of a process that has gone on for much of Earth’s history.” For instance: Africa and South America split about 140 million years ago. Or take Gondwanaland — an ancient supercontinent consisting of modern-day South America, Africa, Arabia, Madagascar, India, Australia, and Antarctica — that begin the first stage of its breakup into many of the present-day continents 180 million years ago.
“It is always tempting to try to link short-term events such as this crack forming or even many earthquakes to being part of a plate boundary," said Furlong. "It is probably more correct to think of these all as manifestations of the active processes, which over time will lead to the final separation of Africa into two separate plates.”
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