structure itself or an aftershock. so the survivability profile really starts to shrink after about 48 hours. and the risks to rescuers increase with every passing hour, really, and with every aftershock. >> how concerned are you, chuck, that this building, this school, might suffer additional collapse? >> you know, not knowing the construction of the structure initially, it's really kind of difficult to say. but once any structures, bones if you will, have been compromised, than anything really is possible. the structural integrity is gone and it's really just being held up by its broken pieces. so the potential for secondary collapse is very real. >> how does the weather factor into this? because my understanding is that it rained there last night. how could that impact the rescue