Before proceeding with this page let me explain a little something about explosives and how people perceive them.
I work in special effects. In films, great use is made of low velocity explosives such as untamped black powder and ANFO because they are low velocity explosives. With a great whoosh and roar they belch forth with fire and smoke in a manner that has caused folks to drop their popcorn in matinees ever since sound came in.
Movies have conditioned people to expect a certain look and sound to explosions, all based on very low velocity explosives. In a stunning ironic twist, moviegoers seem to perceive the slower explosions as more powerful.
Demolition experts will tell you that high brissive or high velocity explosives actually are more powerful, as they build up a powerful shock wave.
Here's what demolition experts use in steel framed buildings, the linear shaped charge ... It generates around 3,000,000 psi pressure ... at a speed in excess of 27,000 feet per second ... There are over 1000 different types of explosive ... With the use of delays we can control ... where the debris lands ... vibration ... noise level.
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The job of a shaped charge is to cut steel H-beams. "The way we do this is by cutting the beam at an angle which through a series of beams cut at the same angle will tend to make the building shift over and 'walk'"
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However, except for actually collapsing a structure, such explosives are unsuitable for film. The blast is over so quickly it can be missed while the film is moving between one frame and the next. There is very little visible smoke and flash, and the "crack" of a C-4 cutter charge is downright disappointing to hear.
Thus, the average person's awareness of what an explosion is supposed to look and sound like is based on the movies and low velocity explosives only. In not knowing what high velocity explosives sound like or feel like (as the shock wave moves through the earth), many people might not understand what they heard or felt on 9/11.
With the above in mind lets take a look at the collapse of World Trade Center 2...
"...and then all of a sudden it started like... it sounded like gunfire... you know, bang, bang, bang, and then all of a sudden three big explosions."
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"It [WTC 2] started exploding," said Ross Milanytch, 57, who works at nearby Chase Manhattan Bank. "It was about the 70th floor. And each second another floor exploded out for about eight floors, before the cloud obscured it all." [ASNE] "I saw small explosions on each floor." [Wing TV]
"It actually gave at a lower floor, not the floor where the plane hit, because we originally had thought there was like an internal detonation explosives because it went in succession, boom, boom, boom, boom, and then the tower came down." [Ed Cachia - Firefighter [Engine 53]]
One eyewitness whose office is near the World Trade Center told AFP that he was standing among a crowd of people on Church Street, about two-and-a-half blocks from the South tower, when he saw "a number of brief light sources being emitted from inside the building between floors 10 and 15." He saw about six of these brief flashes, accompanied by "a crackling sound" before the tower collapsed. Each tower had six central support columns. [American Free Press]
"We were there I don't know, maybe 10, 15 minutes and then I just remember there was just an explosion. It seemed like on television they blow up these buildings. It seemed like it was going all the way around like a belt, all these explosions." [Rich Banaciski - Firefighter (F.D.N.Y.)]
"When I looked in the direction of the Trade Center before it came down, before No. 2 came down, ..I saw low-level flashes. In my conversation with Lieutenant Evangelista, never mentioning this to him, he questioned me and asked me if I saw low-level flashes in front of the building, and I agreed with him because I thought -- at that time I didn't know what it was. I mean, it could have been as a result of the building collapsing, things exploding, but I saw a flash flash flash and then it looked like the building came down."
Q. "Was that on the lower level of the building or up where the fire was?"
A. "No, the lower level of the building. You know like when they demolish a building, how when they blow up a building, when it falls down? That's what I thought I saw. And I didn't broach the topic to him, but he asked me. He said I don't know if I'm crazy, but I just wanted to ask you because you were standing right next to me… He said did you see any flashes? I said, yes, well, I thought it was just me. He said no, I saw them, too." [Stephen Gregory - Assistant Commissioner (F.D.N.Y.)]
"Somewhere around the middle of the World Trade Center, there was this orange and red flash coming out. Initially it was just one flash. Then this flash just kept popping all the way around the building and that building had started to explode. The popping sound, and with each popping sound it was initially an orange and then a red flash came out of the building and then it would just go all around the building on both sides as far as I could see. These popping sounds and the explosions were getting bigger, going both up and down and then all around the building." [Karin Deshore - Captain (E.M.S.)]
"It was a frigging noise. At first I thought it was -- do you ever see professional demolition where they set the charges on certain floors and then you hear "Pop, pop, pop, pop, pop" That's exactly what -- because I thought it was that. When I heard that frigging noise, that's when I saw the building coming down." [Daniel Rivera - Paramedic (E.M.S.)]
As we are looking up at the building, what I saw was, it looked like the building was blowing out on all four sides. We actually heard the pops. Didn't realize it was the falling -- you know, you heard the pops of the building. You thought it was just blowing out. [Joseph Meola - Firefighter (F.D.N.Y.)]
The sight of the jumpers was horrible and the turning around and seeing that first tower come down was unbelievable. The sound it made. As I said I thought the terrorists planted explosives somewhere in the building. That's how loud it was, crackling explosive, a wall. That's about it. Any questions? [James Drury - Assistant Commissioner (F.D.N.Y.)]