11 September 2025
In the past, scientists thought that Africa sat upon a single tectonic plate. But since the 1970s, evidence has been mounting that the African plate is rupturing into two new plates – dubbed the Nubian and Somali plates – along the East African Rift.
Geologists and geophysicists are still debating what might be causing this to happen. The current leading theory is that plumes of heat within Earth’s mantle are making the lithosphere (the crust and solid upper mantle) beneath Kenya and Ethiopia dome and stretch.
The thinning lithosphere has generated huge volcanic eruptions called flood basalts – which send lava gushing from emerging fissures like flood waters – and fractured the brittle continental crust into a series of faults. From above, these faults, which together make up the greater Rift Valley, look like deep crevices and elongated basins separated by regions of higher land.
How fast is Africa splitting?
GPS measurements show that across the East African Rift, the Nubian and Somali plates are diverging at an average rate of 7mm (0.2in) per year, slowly pulling the continent apart. Today, the rift remains above sea level, but as it widens, the land within the valley will sink.
Eventually, oceanic waters could flood in, separating the entire Horn of Africa from the mainland. The jury’s still out on whether this will happen, but if it did it would take tens of millions of years. The Red Sea and the Gulf of Aden are examples of similar rifts at more advanced stages of evolution.
As for the crack that alarmed the world in 2018 – the consensus among geologists today is that it was a pre-existing crevice that had lain undetected because it was packed with volcanic ash from eruptions in the distant past. It was suddenly exposed during heavy rains when the deep layers of waterlogged ash collapsed. Panic over – for now, at least.
source:sciencefocus
