Question

Many fault lines are obvious at the surface. How can the epicenter of an earthquake be located miles away from the fault line?

The epicenter is the place of greatest damage, and it can be miles from the site of the earthquake.
The earthquake happened at a place where there is no fault, so the epicenter is not near a fault line.
The fault line does not extend straight down from the surface, so the focus is not directly beneath the point where the fault reaches the surface.
Some large earthquakes have more than one epicenter, and these epicenters can be far from the fault line.