How does a normal fault operate?

In the context of a normal fault, the defining characteristic is that the hanging wall, which is the block of rock that sits above the fault plane, moves downward relative to the footwall, which sits below the fault plane. This movement typically occurs due to extensional stress within the Earth's crust, where tectonic plates are pulling apart from each other.

In a normal fault, the tension causes the hanging wall to slide downwards, effectively indicating that the correct answer highlights this downward movement. This type of faulting is common in regions where the Earth's crust is being stretched, such as at divergent plate boundaries or continental rift zones. The movement is a direct response to the forces acting on the crust that create an environment conducive to this type of displacement.

This understanding of the mechanics involved in normal faulting is crucial for analyzing geological formations and assessing associated seismic activity.