How can unstable rock be considered stable?

Unstable rock can be considered stable when it is secured against movement by protective systems. This involves using various engineering techniques or equipment to reinforce the rock, preventing potential landslides or falls. Protective systems can include shoring, rock bolts, netting, or other stabilization methods that ensure the rock remains in place and does not pose a hazard to workers or the surrounding environment.

In contrast, leaving unstable rock exposed to air could lead to weathering and further destabilization. Excavating quickly may create additional hazards, as it can disrupt the integrity of rock formations. Similarly, removing only small pieces of rock does not inherently stabilize the remaining structures and may not adequately address the issues of instability. Thus, securing the rock against movement is the most effective means of considering unstable rock to be stable.