Scientists have found the Earth’s crust beneath Kenya’s Turkana Rift is only 13 kilometers thick, far thinner than the 35 kilometers typical elsewhere in the region, indicating the African continent is further along in its split than previously understood.
The discovery, published in Nature Communications, shows the rifting process in eastern Africa has advanced beyond earlier estimates, with the crust weakened to a point where continued separation is more likely.
How researchers measured the crust’s thickness
The team led by Columbia University’s Lamont-Doherty Earth Observatory analyzed high-quality seismic data collected with industry partners and the Turkana Basin Institute. By tracking how sound waves moved through underground layers and combining the results with other imaging methods, they mapped sediment structures and calculated crust depth.
Along the rift’s center, the crust measures about 13 kilometers thick, while areas farther away exceed 35 kilometers. This sharp contrast reveals a geological process called “necking,” where the crust stretches and thins in the middle like pulled taffy.
Why the thinning crust accelerates the split
As the crust becomes thinner, it also becomes weaker, making it easier for rifting to continue, according to study lead author Christian Rowan. The weakened state promotes further stretching, increasing the likelihood of a complete break over geological time.
Co-author Anne Bécel said the findings suggest the region has reached a critical threshold in crustal breakdown, though the full separation will unfold over millions of years.
What the thin crust explains about human fossils
The intense volcanic activity and rapid crustal thinning in the Turkana Rift created conditions that helped preserve ancient human remains, offering a fresh explanation for the area’s rich fossil record. The same tectonic forces driving the continent’s split also shaped the landscape where early humans lived.
The East African Rift System, of which the Turkana Rift is a part, stretches from Ethiopia’s Afar Depression to Mozambique and separates the African plate from the Arabian and Somali plates. In Turkana, the African and Somali plates are moving apart at 4.7 millimeters per year.
How long will it take for Africa to split completely?
The source does not specify a timeline for the complete separation of the African continent, noting only that these changes unfold over immense timescales.
Is the Turkana Rift the only part of Africa rifting?
No, the Turkana Rift is part of the larger East African Rift System, which extends from the Afar Depression in northeastern Ethiopia to Mozambique and involves multiple tectonic boundaries.
