Ridge Push, Or Bridge Over Troubled Magma.

Usually Ridge Push as a boundary force, is considered to be produced by the gravity effect. Hot mantle up-wells under the ridge, and this gives a topography-induced horizontal pressure gradient.

The problem with the approach is that I can't imagine the speed of the mantle upwelling to dynamically maintain heavy rock above the floor level at hundreds meters (if not kilometers). And, as Earth rotates, it is just impossible for mantle to up-well to sea floor perpendicularly to it. Besides, it's hard to imagine the nature of topography of the upwelling line.

But, why for two these phenomena not to reverse cause and consequence? Let "Magma Transportation On The Temperature Gradient" mechanism consume magma by lifting it up hundred meters. Fresh incoming magma would create hotter region under the ridge. The resulting bridge of solidified magma over the hot magma would push off the boundaries.

(Well, the post should, probably be titled "Troubled By Earthquakes Ridge Over Hot Upwelling Magma" :-)
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reposted from http://sukhotinsky.blogspot.com/
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