ASBOG Practice Exam

From an observational standpoint, how does a normal or reverse fault appear to move?

1. Side to side

2. Up or down

3. Down only

4. Diagonal

The correct answer is: Up or down

A normal or reverse fault primarily involves vertical movement of the Earth's crust. In a normal fault, the block of crust that lies above the fault plane, known as the hanging wall, moves downward relative to the block of crust below the fault plane, referred to as the footwall. This downward movement is a characteristic of extensional tectonic settings, where the crust is being pulled apart. Conversely, in a reverse fault, the hanging wall moves upwards relative to the footwall. This upward movement typically occurs in compressional tectonic environments, where the Earth's crust is being pushed together, resulting in the hanging wall being thrust over the footwall. Thus, both types of faults are illustrative of vertical displacement, which manifests as either upward motion in reverse faults or downward motion in normal faults. This vertical movement is what distinguishes them from other fault types, such as strike-slip faults, where the motion is primarily horizontal. The other options, such as side to side, down only, and diagonal, do not accurately capture the primary characteristic of movement associated with normal and reverse faults. Side to side suggests horizontal movement, which is not the case, while "down only" fails to recognize that reverse faults involve upwards movement. Diagonal does not accurately describe the distinct