Forces behind Continental Drift. A concept of mid oceanic ridge self-spreading.

The key point of this article is that a mid oceanic ridge is self-spreading.

The oceanic crust is rather thin around a mid oceanic ridge. Moon/Sun induced deformations cause ruptures in the crust within the ridges. The ruptures are filled with magma, magma cools down and gets solidified. On the next half of Moon-cycle the crust would deform the opposite way, causing more ruptures on the opposite side of the crust.

The thickness of the mid oceanic ridge is self-regulated. The greater force is required to spread the crust, the slower it would move, the thicker the ridge will be. East Pacific Rise spreads the crust that will be sub-ducted in Pacific Ring of Fire, a relatively little force is required, thus the crust in the ridge is rather thin and the speed of the spreading is rather high. Mid-Atlantic Ridge has to spread not only ocean crust, but also the entire America, thus it is much thicker and much slower.

Crust sub-ducting in Pacific Ring of Fire takes a relatively little force from the mid oceanic ridges - the work is "done" by Moon/Sun. The sub-ducting crust and its environment are elastic, but not ideally elastic. When Moon deforms them, the crust would move slightly by the push force of mid oceanic ridge. But when Moon would restore the surface's shape, the crust won't return totally back, thus, the slight force from the ridge would sub-duct the crust in a small step.
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reposted to http://divergent-boundaries.blogspot.com/
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