Here's a breakdown:

* Tensional stress: This occurs when forces pull rocks apart, stretching them.

* Normal fault: In a normal fault, the hanging wall (the block of rock above the fault) moves downward relative to the footwall (the block of rock below the fault). This downward motion is driven by the tensional stress pulling the rocks apart.

Visualizing the motion:

Imagine pulling on a rope tied to a heavy object. The rope represents the Earth's crust, and the object represents a block of rock. As you pull, the rope stretches, and the object moves downward. This is similar to what happens in a normal fault.

Key points:

* Normal faults are commonly found in areas where the Earth's crust is being stretched and thinned, such as divergent plate boundaries or rift zones.

* The hanging wall block moves down, which is the opposite of a reverse fault where the hanging wall moves up.

Let me know if you have any other questions!