In the 1978 movie Superman, why does Superman spin the earth only far enough to save Lois?

I watched the classic Superman movie the other day on TV, and was wondering why Superman only spun the earth back just enough to save Lois from the earthquake in the car. Why didn't he spin it back further to save the earth from being hit with the second missile and prevent the earthquake from happening in the first place?|||It's a movie. Common sense is sacrificed for entertainment value and suspense.