Video Transcript
Which of the following statements best describes the difference between a normal
fault and a reverse fault? (A) A normal fault has a footwall that moves downward relative to the hanging wall,
while a reverse fault has a footwall that moves upward. (B) A normal fault has a hanging wall that moves downward relative to the footwall,
while a reverse fault has a hanging wall that moves upward. (C) A normal fault has a hanging wall that moves upward relative to the footwall,
while a reverse fault has a hanging wall that moves downward. (D) Normal faults display horizontal displacement, while reverse faults show no
displacement. (E) Reverse faults display vertical displacement, while normal faults show no
displacement.
To answer this question, we need to understand a few key terms. Firstly, a fault is a fracture in a rock mass along which there has been an
observable amount of displacement. As all faults have an observable amount of displacement, we can eliminate answer
choices (D) and (E). Let’s go ahead and remove these answer choices.
The surface along which movement takes place at a fault is known as the fault
plane. The rock mass that lies above the fault plane is called the hanging wall. And the rock mass that lies below the fault plane is called the footwall. When a rock body experiences tensional forces and a fault forms, the hanging wall
moves downward relative to the footwall along the fault plane. This type of fault is known as a normal fault.
When a rock body experiences compressional forces and a fault forms, the hanging wall
moves upward relative to the footwall. This is known as a reverse fault.
We can now identify the statement that best describes the difference between a normal
fault and a reverse fault. The correct statement is “a normal fault has a hanging wall that moves downward
relative to the footwall, while a reverse fault has a hanging wall that moves
upward.”
