At the beginning of earthquakes, fault slip starts miles below the earth's surface and then extends outward and upward. Most earthquakes (small to moderate earthquakes, in particular) stop before the fault slip reaches the ground surface, but during large earthquakes the fault slip usually creates a break (or fault scarp) at the ground surface.
Fault Scarp: What to look for
Fault scarps appear as a step in the ground, and can be a few inches to several tens of feet high, but they are extremely difficult to recognize unless they are at least a few feet high.
With time, the scarp face becomes worn down by erosion and covered by vegetation, making the scarp much less obvious.