In September 2005 a fissure several metres wide opened within days in Ethiopia's Afar depression. No earthquake in the usual sense, no destroyed villages, but a crack that made visible what has been happening here for millions of years: the continent is coming apart.
East Africa sits on a seam. Along the East African Rift the Somali plate is pulling away from the larger Nubian plate. It is the same movement that pushed South America and Africa apart long ago. The difference is that here you can watch it begin.
Seven millimetres a year
The speed is unspectacular, and that is exactly what makes it remarkable. In the Afar region the rift opens by roughly 6.9 millimetres a year. Further south, in Kenya and Tanzania, it is only two to five. Fingernails grow faster. Measuring that movement takes no tape measure but a GPS station that knows its own position to a fraction of a millimetre over years.
What makes those millimetres special is their direction. Three rift arms meet in the Afar depression: the East African Rift, the Red Sea and the Gulf of Aden. Geologists call such a place a triple junction. Two of the three seams are already filled with sea water. The third is not.
Two of the three seams are already sea. The third is still desert.
— TerraTally · Planet desk
That is why the Afar depression matters so much to researchers. It is one of the few places on land where the birth of an ocean floor stays within reach. Elsewhere the process lies under kilometres of water and can only be approached with ships and submersibles. Here it lies in the sun, in one of the hottest regions on Earth, and the instruments simply stand on the ground.
At a glance
6.9 mm
Rift opening per year in Afar
3
Rift arms meeting in one place
20 to 30
Million years to a new sea
Reports about the rift lean towards drama. Saying that Africa is splitting makes it sound like a date one could wait for. It is not. Estimates suggest that at today's rates a sea the size of the present Red Sea could form in some 20 to 30 million years. Even that is not a certainty but a projection that assumes the plates keep their pace.
The fissure of 2005 was therefore not a starting gun but an episode. The movement does not spread evenly across the years. It builds up and then releases within days, and in those days the ground catches up on what would otherwise have taken decades.
For the people who live there the rift is not a question about the future anyway. It is the present: a volcanically active zone, an earthquake region, a landscape of salt lakes and lava fields. Salt has been cut and traded in that landscape for centuries. What brings researchers from abroad has been a living for the region for generations.
The map we know is a snapshot. It was never stable. It simply changes more slowly than a human life lasts.