One possible explanation for the immense uplift of Africa causing the superswell is dynamic topography.
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Dynamic topography is the reason why the geoid is high over regions of low-density mantle.
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Dynamic topography and mantle density variations can explain 90 % of the long-wavelength geoid after the hydrostatic ellipsoid is subtracted out.
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The mid-ocean ridges are high due to dynamic topography because the upwelling hot material underneath them pushes them up above the surrounding seafloor.
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By predicting the region s topographic response to the low-density anomaly using dynamic topography calculations, an almost perfect model of the elevated topography of the superswell is achieved.
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Since both the density and the dynamic topography provide approximately the same magnitude of change in the geoid, the resultant geoid is a relatively small value ( being the difference between large but similar numbers ).
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Areas that are rifting apart, such as mid-ocean ridges and the East African Rift, have mountains due to thermal buoyancy related to the hot mantle underneath them; this thermal buoyancy is known as dynamic topography.
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Features of deeper delamination of the lower lithosphere have also been hypothesised to play important roles in the long term ( > million year ), large scale ( thousands of km ) evolution of the Earth's topography ( see dynamic topography ).
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However, normal seismic activity beneath the swell, as well as lack of detected heat flow, caused scientists to suggest dynamic topography as the cause, in which the motion of the hot and buoyant mantle plume supports the high surface topography around the islands.
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The low heat across the Hawaiian Swell indicates that it is not supported by a buoyant crust or upper lithosphere, but is rather propped up by the upwelling hot ( and therefore less-dense ) mantle plume that causes the surface to rise through a mechanism known as " dynamic topography ".
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