During 1967 and 1968 a linear swarm of earthquakes was recorded between Tierra del Fuego and Cameroon. The swarm was an extension of the Cameroon Line of volcanic activity and its timing corresponded to the rapid southwestern extension of the South Atlantic Magnetic Anomaly. Clearly something was happening in the Mantle.
A new physical mechanism is proposed whereby heat is transported upward in molten blobs of magma, which rise through the solid Mantle as solid melts above and congeals below them due to convection within the blob. The mechanism is “liquid-in-solid convection”. Sufficiently large blobs carry their own magnetic field due to magneto-hydrodynamic dynamo effects. These rising MHD dynamos account for rapid changes in the surface geomagnetic field and are also manifested as “plumes”, “diapers” and “LVZs”. Convecting blobs are initiated by Rayleigh-Bernard convection within the molten core.
Chapters 14 and 15 of The Fluid Catastrophe by John Reid