Science Olympiad Dynamic Planet Practice Test

Which type of fault allows rocks on either side to move past each other with little or no downward motion?

1. Reverse fault

2. Normal fault

3. Strike-slip fault

4. Thrust fault

The correct answer is: Strike-slip fault

The correct answer is a strike-slip fault because this type of fault is characterized by horizontal movement, where the rocks on either side of the fault slide past one another with minimal vertical movement. This lateral movement occurs due to shearing forces, which are stresses that cause deformation along the fault line without significant up or down displacement of the crust in the vertical direction. Strike-slip faults are commonly associated with transform plate boundaries, where different tectonic plates grind against each other. An example of a strike-slip fault is the San Andreas Fault in California, where two blocks of the Earth's crust are sliding horizontally relative to one another. In contrast, reverse faults and thrust faults involve primarily vertical motion, where one block of rock is pushed up over another. Normal faults involve the downward motion of the hanging wall block relative to the footwall block, which is caused by extensional forces. Therefore, while reverse and normal faults involve significant vertical displacement, a strike-slip fault specifically features horizontal movement, making it the correct choice for this question.