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What could cause the continents to drift much faster than is today. I mean, much faster. Let's say it should take about 1-2 million years from this enter image description here

to this enter image description here

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    $\begingroup$ Roughly speaking that looks like about 25 times faster plate movement. Meaning about 25 times more earthquakes (!) and more violent ones at that (625 time the kinetic energy involved). Even light plates would not offset the increase in velocity (linear vs. quadratic effects). $\endgroup$ – StephenG Mar 17 '18 at 22:42
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    $\begingroup$ @StephenG why a quadratic function? $\endgroup$ – RonJohn Mar 18 '18 at 0:38
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There are a few issues that regulate the speed of CD:

  1. Upwelling: of magma at the rift zones.
  2. Inertia: the plates undergoing CD are big and heavy.
  3. Firmness: of the asthenosphere (upper mantle). That's what the continents float on, and it's movement causes a plate to move. Controlled by heat in the lower mantle and outer core.
  4. Friction: of rock at the subduction zones.

Thus, to speed things up...

  1. Hotter core to make more magma rise at the rift zones.
  2. Lighter continents?
  3. The hotter core will also soften the asthenosphere, making it move faster.
  4. Slipperier rocks (like talc) at the subduction zones.

enter image description here

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  • $\begingroup$ A model answer. You specified the conditions necessary to make faster CD work, and then how to achieve that. It was also a joy to read. Plus one. $\endgroup$ – a4android Mar 18 '18 at 8:28
  • $\begingroup$ I believe the current model for CD is ~90% due to slab pull, with ridge push providing 5-10%. Most of your solutions will have a negligible effect in this sense, and none will provide a factor of 25 increase in speed. $\endgroup$ – Dubukay Mar 18 '18 at 17:16
  • $\begingroup$ @Dubukay interesting. Would items 4-5 make it easier for slab pull to occur faster? I ask that, because a colder asthenosphere and sticky rocks would counteract gravity's tug. $\endgroup$ – RonJohn Mar 18 '18 at 17:30
  • $\begingroup$ @RonJohn I’m actually not sure about the correlation between asthenosphere temp and plate speed. I asked Willk about that too, because his answer assumes the same. On geologic scales, I think the friction of plate on plate is pretty negligible- otherwise we’d see a large difference in subduction speeds between the various permutations of continents and oceanic plate collisions. $\endgroup$ – Dubukay Mar 18 '18 at 17:39
  • $\begingroup$ Water in the asthenosphere is thought to be necessary for subduction, so you might consider adding "more water in planetary formation". $\endgroup$ – rek Mar 18 '18 at 21:43
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1:New moon.

The tidal flexing caused by a massive orbital satellite ultimately produces frictional heating. This topic is covered here:

https://astronomy.stackexchange.com/questions/757/how-much-of-an-effect-does-the-moon-have-on-earths-liquid-mantle

Jupiter's moon Io is an example: this moon is largely heated by tidal forces. So too your earth with faster continental drift - a new satellite might impart tidal forces such that the mantle heats up and drift speeds up./


2: Interior heats up more - either because of production of more rapidly decaying daughter radionuclides or the addition of fresh radionuclides.

Another way to heat the interior and move plates faster would be to have the nuclides heating the earth produce more heat. This could happen via an increase in decay products to isotopes which more rapidly decay and so over the short term produce more heat. Heating of the earths interior is caused by radioactive decay.

In some circumstances, decay of certain isotopes produce daughter isotopes which decay faster and so more heat is produced. I asked about this here.

https://physics.stackexchange.com/questions/351327/is-decay-heat-proportional-to-half-life

Here is a diagram from @Farcher's answer. The third instance, non equilibrium shows a place in the course of decay where the heat transiently increases.

diagram of radioactive decay / heat plots

You could also just add more fuel to the fire. For example, suppose a collision event entailing a meterorite comprised largely of uranium, or americium or the like. The dense meteorite would make its way towards the center of the earth and once there contribute to heating of the core.

If you are not wanting to speed up plate tectonics but just have it be faster from the get go, have your planet with more radioactive nuclides in the core from the start.

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  • $\begingroup$ You’re assuming that a warmer mantle will have faster plate motion- do you have a good source for that? $\endgroup$ – Dubukay Mar 18 '18 at 17:20
  • $\begingroup$ @Dubukay - Mantle heat drives plate tectonics. newscenter.lbl.gov/2011/07/17/kamland-geoneutrinos Generally if heat is making something happen more heat makes it happen faster / less heat = slower. Easy to check that principle in the lab; tricky with tectonic plates. $\endgroup$ – Willk Mar 19 '18 at 19:46

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