What is a major cause for secondary collapses when handling debris?

Vibrations are indeed a major cause for secondary collapses when handling debris. During rescue operations, particularly in collapsed structures, moving debris can create vibrations that may destabilize already precarious loads. The process of extracting victims or clearing pathways often involves heavy machinery or physical force, which can induce additional movement in the surrounding materials.

Understanding that vibrations can lead to further collapse highlights the importance of careful planning and execution during rescue missions. Teams must consider the stability of the remaining structure and the potential for vibrations to trigger a secondary failure.

The other options, while potentially hazardous in specific scenarios, do not directly contribute to the immediate risk of secondary collapses in the same manner as vibrations. For example, while fire may pose a risk in terms of thermal structural failure, it is the immediate mechanical vibrations from the rescue efforts that most directly impact the structural integrity of debris and surrounding materials in a collapsed area.