Secondary Collapse refers to which scenario?

• A. The collapse that occurs after the initial collapse of a structure; common causes include aftershocks, weather conditions, and movement of structural members.
• B. The collapse of a roof due to heavy snow.
• C. A sudden bowing of a doorway during a flood.
• D. A temporary loss of stability during excavation.

Answer: (A)

Secondary collapse is the risk of another portion of a structure giving way after the first collapse has already occurred. Once the initial failure happens, remaining elements such as walls, floors, or beams can be unstable and may fail if loads shift, debris settles, or external factors like weather, aftershocks, or movement of structural members apply new stresses. This is a critical concept in rescue work because it means conditions judged as “stable” can quickly become dangerous, trapping or injuring responders if they re-enter or extend operations without proper shoring, monitoring, and safe egress routes.

Explain why this best fits: it captures the ongoing danger after an initial collapse and the typical triggers that lead to further failure, which is what secondary collapse describes. The other scenarios describe different, primary failure situations: a roof collapse from heavy snow is a direct overload failure; a doorway bowing during a flood is a localized element failure due to pressure; a temporary loss of stability during excavation relates to trenching hazards rather than progression of collapse after an initial failure.