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I'm building a world that I would like to be quite realistic. One of the plot lines I've considered is plate tectonics that move at a rate of anywhere from 0.8 to 2.0 kilometers per year. This is in comparison to the Earth's rates of centimeters per year.

Would civilization be possible here? Obviously areas near fault zones would need constant maintenance to facilitate ground trade between them, and this would pose obvious dangers for any kind of mountainous peoples like dwarves or highlanders. But would it stop the rest of the world from developing life and civilization? What is the fastest tectonic drift that would be capable of supporting life, avoiding as much willingness to suspend rational thought as possible.

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No...no it would not. The energy created by that much tectonic motion would increase the ambient temperature of the planet significantly. Not only would civilization not develop but complex life (at least as we know it) would not exist.

The force created by a single 7.0 magnitude earthquake is somewhere around 199,000 tons of TNT 199,000 tons is 0.199 mega tons, which for reference lands you somewhere in-between Tunguska and modern nuclear weapons.

According to that article there are around 100 6.0 or greater earthquakes each and every year. If you were to increase the rate of movement to 2 km a year and linearly adjust that rate the number would go up to somewhere in the 10,000,000 range.

Its hard to say if that would work out in a linear fashion but either way that is a lot of energy and it wouldn't be the only sources either, volcanic eruptions would also be far more common, not to mention friction heat created by the plates moving.

Remember the Tunguska/Nuke note above...now imagine that is happening 10,000,000 times each year. Oh and it is worth mentioning that 10,000,000 nukes is 666 times the number of the global nuclear arsenal.

The extra tectonic activity would also poison the atmosphere (if it had ever become breathable at all that is.)

This question of mine(A world with far more mobile continents?) covers this topic, though without any particular rate in mind.

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  • $\begingroup$ Thinking about the levels of energy involved, I'm guessing that the plates are quickly going to settle down and move much slower. If that's not the case, the conditions required for that kind of tectonic movement to be sustained is probably extremely hostile to life as we know it. $\endgroup$ – Rob Watts Nov 12 '15 at 20:39
  • $\begingroup$ @RobWatts my thoughts exactly. $\endgroup$ – James Nov 12 '15 at 21:51
  • $\begingroup$ One could argue that such setting would require a much more agile mantle to begin with, taking energy levels involved orders of magnitude down. Consider for instance a water planet where large blocks of debris (say pumice) float and sufficient upwelling exists. Rapid tectonics? Yes. 10M nukes a year? Not so much... $\endgroup$ – Dallaylaen Nov 12 '15 at 21:55
  • $\begingroup$ @Dallaylaen but by definition that is not tectonics. $\endgroup$ – James Nov 13 '15 at 3:04
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Sure.

Let's say there is a location in the world that is 2,000 km from any fault lines; not a difficult situation to have. Further, assume a city can withstand a quake from fault lines that are at least 500 km away. There exists then a 1,000 km zone where cities can be built, and survive 500 to 1,250 years before they come within 500 km of the next fault zone. That's plenty of time for a city to grow and spread in an anti-driftward direction. Old cities are driftward, new cities are anti-driftward, with hundreds to over a thousand year for each to rise and fall.

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  • $\begingroup$ If the planets atmosphere was in equilibrium with the surface crusts output yes. There would be an area where there would be so many earthquakes that conventional buildings would not survive. In this swath of land nomadic tribes would be continually active. They would adjust to the constant earth quacks and not create permanent structures. If they are militaristic they would prey upon the older cities as they crumbled. If they were pacifistic they would take in refugees from these cities. Either way technology spread would be faster as people fled from their cities destruction. $\endgroup$ – PCSgtL Nov 12 '15 at 21:02
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Hmm. I'm no scientist, but I think it might be problematic.

Truly advanced civilizations develop in many different ways: they gain knowledge, yes, but they also build impressive buildings in which this knowledge will be stored for the ages.

You're looking at a situation in which earthquakes would likely be a daily occurrence. The landscape itself might shift under such pressure, making building a city a dicey game. Throw in some volcanic activity to boot.

If people are so preoccupied with simply surviving, will they be able to really develop new technologies, and advance? Sure, but far more slowly.

And then, of course, what happens when two plates collide - especially at that speed? (which would happen within a couple of centuries) Complete devastation.

Here's another question for you: say two very large tectonic plates collide. What now? Do they keep moving? Do they combine? Are continents forming and breaking apart every couple of centuries, with species migrating across landmasses and the weather changing drastically?

In all honesty, I think any civilization would face some pretty nasty obstacles.

They might stand a better chance if their civilization had a chance to evolve, and only then did an event set the instability of the tectonic plates in motion.

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