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There are a number of indications of the potential for a secondary collapse at an Urban Search and Rescue incident.
Causes of Secondary Collapse:
* Aftershocks
* Cutting or moving load bearing structures
* Vibration from heavy machinery
* Too many people on the rubble pile
* Uncoordinated rescue efforts
* Uncontrolled water flow from main supply lines
* Snow
The three most common signs that you can pick up on are:
| Movement in the Structure |
- Movement in any floor, ceiling and roof
- Movement of ornamental shop fronts
- Movement of unsupported or non-load bearing walls
- Movement of structural beams
- Columns and walls out of plumb
- Ceiling sagging
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Visual Alertness |
- Fire consuming location where sprinkler tank is housed
- Uneven surface, heavy signs on section/whole of the roof
- Cracks appearing in the exterior walls
- Sagging or bulging walls/chandelier shaking or swaying
- Large fire which has been unsuppressed for more than 20 minutes involving two or more floors
- Walls showing smoke or water infiltrating through
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| Hearing Alertness |
- Creaking and groaning types of noises
- Interior explosions, rumbling noises, hissing sounds, electrical arcing
- Strong winds
- Safety warning signals
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