In verinage, the weight of the building above the break provides all of the energy which destroys the structure below it. In this alone, the destruction of the towers exactly resembles verinage. But in normal verinage, the bearing walls, rather than the floors, are impacted and crushed. In the towers, they were merely disconnected from the lateral supports and shoved aside.
One point should be addressed here befre someone who does not know what they are talking about brings it up. The companies doing verinage have set a limit on how tall a structure the will demolish in this way. Twoofers assume that this is because there is some arresting factor that might come into play or that friction will exhaust some of the energy.
Quite the contrary. As the process continues, more energy is availlable because falling rubble gains momentum.
The problem is one of controlling the spread of debris. The rubble will want to come down faster than the lower structure will get out of the way, and will thus find a path of lesser resistance out to the sides. Their current maximum height is the height beyond which an unacceptable amount of material will fall outside the designated safe zone. As you can see from video of the towers, the radius of the debris plume increases rapidly until it reaches the ground, for exactly the reasons I have described.
