Another thing I didn't realize that humans didn't know: the gravitational pull of moon and sun influence earthquakes quite a bit. You have a giant ball of mostly-molten rock with a comparatively thin crust, a slightly smaller ball of probably-solid rock and a humongous sphere of flaming gas yanking on it. How would you NOT connect these with the crust sometimes wobbling? I can't remember how many SF stories I've read about tidal earthquakes, and especially, the uses of tidal energy on a planet for making it hot when a star isn't close enough and/or for powering earth-engines. And let's not forget reams of folklore about high-tide earthquakes. 0_o