How to make tides on my world less destructive?

Question

I am currently developing an habitable moon oribiting a gas giant in a resonant orbit, however at the current time I am concerned about the effect of the gas giant on my world when it comes to tidal forces, which it seems that would be several thousands to several tens of thounsands stronger than what the moon.

Here is some general data:

Mass of the giant=3 times the mass of jupiter Diamter of the giant=1.04 times that of jupiter Moon mass=0.7 earths Moon diameter=0.898 earth diamters Moon rotation=36 hours

Moon scenarios:

1-The moon is at 713416 kms from the planet in a 3:2 spin orbit resonance, with an eccentricity of 0.01, which means about 11k times stronger tidal forces on average

2-The moon is at 1002864 kms from the planet in a 5:2 orbit resonance with an eccentricity of 0.025, which means about 4k times stronger tidal forces on average

For additional information about the moon:

The moon is covered 60-65% with water, with less deep oceans (compared with earth's) and relatively less contingous due to many faultlines raising chunky island chains. Think lots of seas and gulfs and widespread east-asian topology

First off, how bad would the actual tides be to the world in these two scenarios? And if they were actually apocalyptic, would there be a way to mitigate them that doesn't require changing the orbits? Is it possible to compensate for that by making the 'oceans' smaller and less contingous like with the islands?

Answer 1

It's conceivable to minimize the destructive effect of such intense tides by allowing the moon's solid crust to be very thin. The right composition of the moon's lithosphere, combined with abundant water, would likely mean a very fluid layer relatively shallow. A bit like the oceans believed to exist on Jupiter's and Saturn's moons, but made of fluid minerals rather than water. The flexing of a thin crust could absorb much of the tidal distortion. Tectonic plates on the planetward side would have to be quite small, and plates on the anti-planetward side would also have to be similarly small. Earthquakes and volcanism would be frequent, but with a sufficiently pliable sub-crustal layer, they need not be catastrophic.

Answer 2

I'm afraid I don't understand the math well enough to estimate the intensity of the tides. I'm simply going to assume they are apocalyptic. I'm also going to observe that fault lines producing island chains result in tide shifts being redirected through bottlenecks between the landmasses, which means tidal currents proportional to the intensity of the tide itself.

That last part means that the tides would absolutely be mitigated if the seas were less contiguous. The tidal forces would then be operating on the isolated bodies of water. This is like how tides are much weaker in lakes than in the ocean. The tides are there, of course, but reduced in magnitude.

But maybe the tides are just apocalyptic. Is that so bad? Aquatic organisms wouldn't be bothered, and land organisms would simply need to adapt. Many plants can survive being submerged for day at a time during floods, so a tide should be alright (neglecting issues of salt water, if your ocean is salty, then plants need to adapt to that too). You'd like even see some interesting adaptations like land animals that burrow during high tide to wait it out, and aquatic predators that specialize in digging out burrowed animals during high tide!

Civilization would be trickier. A modern/industrial civilization could engineer buildings to survive the high tides either by being low and air-tight to wait out the tides, or tall enough to be above them. At lower technologies, floating cities would be a necessity, a la Waterworld, except they could be tethered to the ground and simply float up when the tide waters rush in.

Answer 3

I'm afraid they will indeed be apocalyptic, and it's not just the oceans; there will be massive earthquakes and volcanic eruptions from the constant deforming of the solid body. Look at Io for an example of what it's likely to look like.

Is it possible to change the setting a bit, to make the moon tidally locked? That's the only thing that would realistically help, other than placing it much further away from the planet.