GPS stations across East Africa kept measuring ground sliding parallel to the rift, a motion no stretching model predicted. The explanation, confirmed by 3D thermomechanical modeling, is a continent-sized fountain of hot mantle flowing north beneath Africa.
Documented
The motion that broke the model
Continental rifts are supposed to deform perpendicular to the rift, the direction of the pull. D. Sarah Stamps' twelve-plus years of GPS data from thirty-plus satellites showed parts of East Africa also deforming parallel to the rift. Tahiry Rajaonarison's 3D thermomechanical models reproduced the anomaly only with northward mantle flow from the African Superplume, and the same flow explains the seismic anisotropy, the way earthquake waves travel faster in one direction through the rock below.
Assessment: Documented: geodesy plus modeling, published in the Journal of Geophysical Research. The rift has a second engine, and it runs along the tear, not across it.
Stories
The plume wars
What drives the rift has been a live fight for decades: shallow lithospheric buoyancy, the weight of the high African Superswell plateau, versus deep mantle traction, the drag of flowing rock under the plate. The new work does not pick a winner; it assigns perpendicular motion to buoyancy and the anomalous parallel motion to the plume. Both engines, different gears.
Assessment: Stories: the field spent years choosing between two causes and landed on both. The debate was a partition problem, not a verdict.
Interesting claims
Stamps' Silly Putty planet
The reason the same lithosphere cracks and flows at once, per Stamps: hit Silly Putty with a hammer and it breaks, pull it slowly and it stretches. Earth works on both clocks simultaneously, which is why a continent can be torn in two weeks at one spot and stretched imperceptibly everywhere else.
Assessment: Interesting: the physics of planetary breakup is sitting in a toy-store egg, and the analogy is load-bearing.
Sources and further reading
Rajaonarison, Stamps et al., Journal of Geophysical Research (2023): northward superplume flow explains the rift-parallel deformation and seismic anisotropy
Virginia Tech News, Jun 2023 and ScienceDaily, Sep 2026: twelve years of millimeter-scale GPS from 30-plus satellites
The team's 2021 modeling study assigning rift-perpendicular motion to lithospheric buoyancy
D. Sarah Stamps: the Silly Putty framing of time-scale-dependent lithosphere behavior
Worth asking
If a plume that size has been running under the continent the whole time, how much of Africa's map is plumbing?