How do we explain the fall of WTC #7?

Question

How many explosions were heard before the fall of the other two TOWERS? How many seconds in difference?

Answer 1

Here is are a few crucial elements, the unusual structural design had damage to her south face, and it was accommodating a Con Edison substation, It had extreme weight bearing on the floors, plus it had burning diesel fuel leaking from large emergency generators, with all that, it just compromised the WTC 7’s structural being .......I heard that there will be a report, it's expected in early 2007

Answer 2

The explosions were from the impact of the planes. The other sounds you heard were of the WTC collapsing. It's very possible, with the geological formations at that part of the city plus the subways that the vibrations happened to hit #7 differently than other buildings nearby. Hence it fell and the others didn't.


There are a lot of explanations. For me, I rather doubt the building was intentionally brought down by anything other than Osama's "luck" in hitting the towers at the right speed and angle and the resulting collapse.

Answer 3

I would agree with the other answerers. There were only two explosions, which were the two full-sized planes that crashed into them at high speed leaving two pretty big holes in the towers. Have you ever heard of the Domino Effect? The giant holes left by airplanes weakened the structure of everything above them. So the top couple of floors fall on to the ones below it and the towers simply gave out to a little something called "The Laws of Physics" and "Newton's Laws of Motion".

Answer 4

Two, once when each plane hit.

Most likely cause of failure was the large gash in the building from the fall of the WTC. Even if only a few of the exterior columns were damaged it could cause damage to the structural integrity.

A prolonged fire condition was raging on at least 3 floors. The fire sprinkler systems could have been compromised due to significant loss of water pressure from the WTC. The fire pumps could have cavitated if the pressures on the supply started to fall below the 20's. A sprinkler system is designed to protect a small square footage. This building would have been designed at around 0.2gpm per sqft. over 2000 square feet. When you breach multiple sprinklers larger than that over multiple floors you are going to starve the system of it's intended demand. Sprinkler systems are designed to get occupants out, not put out the fire. Systems are designed only to control the fire until crews can get there to put the fire out. If you recall there weren't very many fire fighters available after the collapse.

Eventually the steel starts to sag from the heat and the whole thing pancakes.

Answer 5

Two. One plane for each tower. WTC7 was a sitting duck for the falling taller buildings, and was trashed by said falling buildings. A fire started inside, burned out several floors and the building collapsed. Several other buildings collapsed on that day, and others were dynamited later because of severe damage. All because of TWO AIRPLANES.