Thanks to seismic technologies and radar interferometry, an international team of researchers has been able to analyse in detail an episode of East African rift expansion, in the Lake Natron region, in northern Tanzania. Amongst these researchers, who in particular demonstrated that the expansion was accompanied by deep magma intrusion (what geologists call ‘dykes’), was University of Liège doctoral student, who is financed by Federal Scientific Policy (Action-2 of the Royal Museum for Central Africa (Terveuren): Christelle Wauthier.

With a quite geological slowness, and at a rate of hardly a few millimetres a year, but in a completely inexorable fashion, Africa is being cut in two along a North-South line of over a 9,000 kilometres which runs from the Red Sea to Mozambique, to the east of the continent: the rift. This discontinuous ‘line’ is the witness to the phenomenon of expansion between two continental tectonic plates (in this particular case the Somalian plate and the Nubian plate), which are moving apart along the length of a network of very old geological fractures, the rift’s ‘inheritance’. This phenomenon will one day (terribly far off on a human scale) lead to the creation of an oceanic opening, which is what the Red Sea is. This expansion activity also leads to associated seismic activity, the play of faults and fractures, and, eventually, to ascents of ‘magma’, fused rock originating from the magmatic or igneous mantle. These magma ascents can be of two types. They are called ‘extrusive’ when the magma climbs as far as the surface. This is volcanism. They are called ‘intrusive’ when they do not discharge outwards into the open air, but instead infiltrate deep into faults and fractures, creating what geologists call a ‘dyke’.