Definitions for "Normal Fault"
Keywords:  footwall, fault, downward, dip, hanging
A fault, with an angle usually between 45-90 degrees, at which the hanging wall (upper block) has moved downward relative to the footwall (lower block).
A fault in which the hanging-wall block moves down the slope of the fault.
A normal fault can result from vertical motion of two adjacent blocks under horizontal tension. (It also occurs in rocks under compression if stress is unequal in different directions. In this case, the minimum and maximum compressive stresses must be applied horizontally and vertically respectively.) In a normal fault, the upper of the two adjacent blocks of rock slips relatively downward. (See reverse (thrust) fault and Figure 1.)