Chalo, it seems I missed an obvious video of the south tower collapse:
[youtube]qhyu-fZ2nRA[/youtube]
The point of collapse is shown a number of times in the first two minutes. You can see the top part of the building leaning where one edge has collapsed. Of course it can only lean so far before the extra load of the shifted mass causes further local failure. Then inertia takes over and the whole lot comes down like a well designed demolition implosion, which exploits such inherent weaknesses in the structure of a building.
eTrike, The video appears to be taken from a longer one I believe I saw earlier, but without the banging sounds. I'd need to trawl back through youtube and find the original to compare. If the sounds are real then they're probably of the floors pancaking (I believe the rapid emission of puffs of smoke/dust, seemingly floor-by-floor as the building collapses indicate the same).
[youtube]qhyu-fZ2nRA[/youtube]
The point of collapse is shown a number of times in the first two minutes. You can see the top part of the building leaning where one edge has collapsed. Of course it can only lean so far before the extra load of the shifted mass causes further local failure. Then inertia takes over and the whole lot comes down like a well designed demolition implosion, which exploits such inherent weaknesses in the structure of a building.
eTrike, The video appears to be taken from a longer one I believe I saw earlier, but without the banging sounds. I'd need to trawl back through youtube and find the original to compare. If the sounds are real then they're probably of the floors pancaking (I believe the rapid emission of puffs of smoke/dust, seemingly floor-by-floor as the building collapses indicate the same).