Let's say that I'm going to bake a cake. I mix together some eggs, oil, flour, sugar, cocoa, milk and water. I pour the batter into a pan, pop it in the oven, and bake it at about 350 for about 25 minutes.
Did I bake a cake? Sure I did.
But, did I really? Wasn't it the chemical reaction caused by mixing various ingredients in the proper proportions and exposing them to heat that really baked the cake?
Yeah, that's what happened too.
Point being that plate tectonics certainly explain how earthquakes happen. Solar activities explain global warming too. Human beings have a biological make-up.
But, this doesn't mean that God isn't in control or is in effect causing these things.
Now, I happen to believe that sometimes an earthquake is just an earthquake. But, we do know that God can cause the plates to move, and sometimes it is His specific will that certain plates will move at certain times. We also know that whether the plates move simply because that's the nature of the world He created, or because He nudged a plate, it is all under His sovereign control. If He determines He doesn't want a particular plate to move, then it won't move.