It seems like it would be hard to narrate a spell that can raise hills and sink swamps, but can't knock over a cottage or even ground a houseboat. Seven Days seems like it should really let you paint in broad strokes. In my mind, the way to limit it is to specify what can be done. Call From Beyond lets you summon a being who might be able to cast earthquake; to me, fretting about it being a Creation spell just seems like quibbling when it is already limited by the casting time and the need to be indirect.
I'm picturing it working like many terrain editors for games, where when you change the terrain shape, buildings, trees, loose rocks, and the like move with it.