The distance that the rocks on opposite sides have moved is called a slip. Faults can have a single fracture in the rock or numerous closely spaced fractures that are referred to as a fault zone. Faults can move repeatedly becuase once a fault forms, it's easier to move that fault than to create a new one when tectonic stress is still applied to that region. Groundwater moves through faults, joints, and fractures and mineral ore deposits often concentrate within faults. Faults are divided into types based on the relative movement along the cracked rock.
Most faults tend to dip into the Earth at an angle, and therefore have an upper and lower side.
The upper side or roof of the fault is referred to as the hanging wall while the lower side is called the footwall. If the angle of the dip isn't 90 degrees, then the land which appears to be hanging over a lower portion before movement is called the hanging wall. Normal faults are when the hanging wall has moved down relative to the footwall. Normal faults form when tectonic forces stretch the Earth's crust, pulling it apart. A graben is a wedge-shaped block of rock that drops between a pair of normal faults.