The choice of a 3D thermomechanical model is doing the load-bearing work here. Sarah Stamps's Silly Putty comparison is the physical point: hit it with a hammer and it cracks, pull it slowly and it stretches [11]. Rock behaves the same way, fracturing into faults and earthquakes near the surface and deforming gradually where it is hotter [12]. A model in which temperature sets how stiff each parcel of rock is can therefore ask whether flow at depth grips the base of the plate firmly enough to move it, which is what geophysicists mean by mantle traction [15].
The modelling was developed by Tahiry Rajaonarison, now a postdoctoral researcher at New Mexico Tech, who did his doctorate in Stamps's lab at Virginia Tech [5]. It has to satisfy two measurements of different kinds. One is the direction of surface motion from GPS. The other is the pattern in how seismic waves travel through the rock beneath the rift, the direction dependence seismologists call anisotropy, and the Virginia Tech account says the models trace the parallel motion and that matching wave pattern to the same source [2]. Reproducing two unlike observables with one flow field is a better test than reproducing either alone.
The observation that started this is worth pausing on. Stamps's GPS stations resolve surface motion at the millimetre scale using signals from more than 30 satellites orbiting roughly 25,000 kilometres up [10]. A millimetre is about one part in 25 billion of that range [17], and the along-rift component only emerged from more than twelve years of records [7].
The thing this doesn't tell you is whether the superplume is the only flow field that would work. A forward model that reproduces the data demonstrates sufficiency, not uniqueness, and the Virginia Tech summary reports the result and the observation without deformation rates or model misfit statistics [19]. The driving-force question also stays open on its own terms: the candidates remain lithospheric buoyancy, tied in East Africa to the unusually high topography of the African Superswell [14], mantle traction from below [15], or some combination of the two [13].
What the geodesy established is narrower and firmer. Shallow buoyancy forces account for much of the expected motion across the rift and not for the motion running along it [16]. That residual has been sitting unexplained in the largest continental rift system on Earth [9], and northward flow from a plume that starts deep under southwest Africa and shallows as it crosses the continent [4] is now the best-supported candidate for it [3].
