A team of scientists led by Professor Fin Stuart from the University of Glasgow has unearthed fresh clues on the forces that shape East Africa. Their work examined gases from the Menengai geothermal field in central Kenya. The study appears in Geophysical Research Letters and lends weight to the idea that a vast mass of deep Earth material lies far beneath the rift region.

The scientists, including experts from the Scottish Universities Environmental Research Centre and the Kenya Geothermal Development Company, used high-precision mass spectrometry. Analysis of noble gas neon in the samples points to an origin deep in the mantle – at the boundary with the core. In striking fashion, the gas mix mirrors that found in volcanic rocks all along a stretch from the Red Sea up to Malawi. This match hints that a similar hot rock mass drives the volcanic activity along the long rift valleys that run through Ethiopia, Kenya, Uganda and Malawi.

Scientists have long puzzled about whether the rift valleys stem from near-surface work or if forces from the deep Earth take part in the process. Professor Stuart stated, “We have long been interested in how the deep Earth rises to surface, how much is transported, and just what role it plays on forming the large-scale topography of the Earth’s surface. 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 hundreds of metres higher than normal.” Biying Chen of the University of Edinburgh and SUERC explained, “These gases from our geothermal wells have provide valuable new insight into the Earth’s deep interior, helping us better understand not only the geological forces shaping East Africa but also the fundamental processes which drive the formation of our planet’s surface over millions of years.”

The findings serve as the first clear geochemical proof of a single deep mantle source feeding activity under southern Africa. This deep rock mass, labelled a ‘superplume’, may mirror similar features beneath parts of the Pacific near Hawaii. The work deepens our grasp of how mighty forces from below can shape large parts of our land and spark volcanoes.