Re: The moon only moves water around, and that’s a damned close planetary body.
It wasn't me who wrote that above. But, good point. Do you think the moon effects the crust enough to cause earthquakes?
I think that the moon’s gravity is ONE of the factors, not only of Earthquakes, but of Volcanoes.
As you said, the water movement also causes movement of the ground below it. Beaches rise and fall with the tides. The ground in your yard moves, albeit very slowly.