by Kevin Caruso
No one was expecting the Twin Towers to collapse; and the magnitude of the tragedy increased exponentially after the towers fell.
But why did they fall?
Basically, support structures in both towers were weakened after the planes crashed into them; then a fire ensued, which was fueled by jet fuel, and burned at incredibly high temperatures, causing the steel to melt.
The fireproofing was not designed to withstand such an impact and fire, and it could not prevent the metal from melting.
And once a floor collapsed, a domino effect occurred with the force of gravity taking over and essentially imploding the structure.
The following diagram gives additional information and visual aids:
