Did the World Trade Center Towers Collapse Because of Controlled Demolition?

The 9/11 Inside-Job Claim

The central claim of 9/11 inside-job conspiracy theorists is that the World Trade Center towers could not have collapsed, or at least could not have collapsed in the way they did, merely as a result of being struck by aircraft, and that consequently the towers must have been brought down by controlled demolition, using explosives which had been planted in the towers by conspirators.

The overall claim consists of a series of specific claims about the way the towers collapsed and other suspicious activity. A particularly authoritative discussion of these claims can be found in an article by Brent Blanchard, ‘A Critical Analysis of the Collapse of WTC Towers 1, 2, and 7 from an Explosives and Conventional Demolition Industry Viewpoint,’ 2006, a PDF originally posted at http://www.implosionworld.com and now available for download at the Internet Archive. The following account is largely a summary of Blanchard’s article.

Claim 1: The Towers’ Collapse Looked Exactly Like Explosive Demolitions

No, they didn’t. The towers collapsed in a very different way, exactly as if they had been struck by aircraft.

In a controlled demolition, explosives are placed on the lowest floors in order to allow gravity to do most of the work: destruction of the structural supports on the lowest floors causes these floors to collapse first, which then causes the upper floors to collapse. Photographic evidence shows that this did not happen in the case of World Trade Center towers one and two, which failed first at the high floors which were directly damaged by the aircraft. Only then did the floors above and below the impact zone begin to collapse.

If any explosives were involved in this type of collapse, they must have been placed on or close to the floors which were struck by the aircraft, either before the aircraft hit the towers or during the period between each collision and the subsequent collapse (WTC 1, the north tower, collapsed a little more than 1½ hours after it had been struck; WTC 2, the south tower, collapsed just under one hour after it had been struck). Neither of these scenarios is even remotely plausible, for several reasons:

Because weight was distributed around the perimeter of each tower, explosives would need to have been placed on a large number of beams on each of the affected floors.
Fires and widespread damage to the floors hit by the aircraft would have made it impossible for anyone to place explosives there after the collisions, even if anyone had dared to attempt such a clearly suicidal task.
Planting explosives beforehand requires a very improbable sequence of events to have happened:
1. The conspirators must have moved a large amount of material on each floor, in order to get access to the steel beams, without being noticed.
2. The conspirators must then have planted explosives on numerous beams, also without being noticed.
3. Both aircraft must have struck precisely the floors on which the explosives had been planted (alternatively, the holograms of the non-existent aircraft must have been precisely aligned with the appropriate floors).
The fewer floors on which explosives were planted, the more likely it was that the planes would miss their targets. The more floors on which explosives were planted, the more likely it was that the conspirators would be noticed.
In any case, even if all three of those unlikely events had occurred, any planted explosives would have been rendered ineffective by the force and heat generated by the collisions.

Claim 2: Each Tower Fell Straight Down, Into Its Own Footprint, Just Like a Controlled Demolition

No, they didn’t. Almost all of the falling debris ended up outside the footprint of each tower, with much of it damaging the surrounding buildings, including tower seven. The perimeter walls fell outward, as they must have done if they were prevented from falling inward when the interior areas were filled by the floor trusses that were pushed downward by the weight of the floors above.

Claim 3: Plumes and Other Evidence of Explosions Can Be Seen Shooting Outward Just Before Certain Floors Collapsed

Controlled demolition is not necessary to explain what was seen. Interior floor trusses failed slightly before exterior columns, leading to increased air pressure on the floor below which caused light-weight office items to be expelled through windows and doorways.

Claim 4: Witnesses Heard Explosions in the Towers

What the witnesses heard were loud, sharp noises. Explosive-like sounds are not always caused by explosives.

Explosives strong enough to break through steel columns would have caused vibrations in the ground that would have been recorded by seismographs. As it happens, a number of seismographs were in operation close enough to downtown Manhattan to have recorded ground vibrations at the time of the attacks. The vibration patterns they recorded were consistent with one strike on each tower, and were not consistent with a series of explosions.

Claim 5: Witnesses, Films and Photographs Show that Molten Steel Was Present

The essence of the claim is that fires caused by burning jet fuel could not have reached a temperature high enough to melt steel, but a non-detonating compound such as thermite could have done so. Witnesses, including firefighters and demolition crews, claimed to have seen molten steel; a film shows a yellow liquid flowing from one of the towers before it collapsed; and photographs show a red-hot metal which is claimed to be steel.

Much of this evidence is dealt with in this article: https://web.archive.org/web/20191202052413/http://911myths.com/html/wtc_molten_steel.html. Objections include:

Witnesses who claimed to have seen molten metal could not have been certain that the metal was steel.
Some of the witnesses who were reported to have mentioned ‘molten steel’ referred only to molten metal and did not identify the metal as steel. In other cases, they did not claim to have seen anything themselves but were repeating something they had been told.
Some of the witnesses who used the word ‘molten’ were describing metal that was red-hot. Molten metal, by definition, is liquid. Steel that is red-hot has not yet reached its liquid state, and is still solid.
Photographs that are claimed to show molten steel do not in fact show molten steel. For example, some photographs depict a mechanical digger extracting a metal object; if the object were molten steel, the object would have been so hot that the equipment would not have functioned.
The yellow liquid which a film shows to be flowing from one of the towers was claimed to be molten steel because yellow is the colour of steel at the temperature at which steel melts. But this yellow liquid was not necessarily molten steel. Other metals, such as aluminium which turns white as it melts, will turn yellow as the temperature increases beyond the metal’s melting point. The aircrafts’ fuselages contained a substantial amount of aluminium.
A scientific paper, which claimed to show traces of thermitic material in debris from the World Trade Center towers, has been criticised on several grounds; for example:
- The samples have not been independently verified.
- The chain of possession of the samples, which might rule out contamination, has not been demonstrated.
- The paper was published in a pay-to-publish journal and was not adequately peer-reviewed.
- Similar samples have been shown to be paint rather than anything suspicious.

Claim 6: Steel Columns Were Removed Quickly from the Site and Sent Overseas to Prevent Examination

No, they weren’t. The steel columns were processed in much the same way as in any demolition project. The only notable difference is that the steel from the World Trade Center was subjected to closer than usual examination.

Because of their size, the steel columns were treated separately from the other debris. This is what happened to them:

They were piled up near the work site.
They were transferred a few blocks north to a site next to the Hudson River.
They were moved onto barges, which carried the steel to a site in Staten Island.
At this site, the steel was examined and catalogued by forensic investigators and other officials.
After several months of investigation, the steel was shipped to China.

Claim 7: WTC 7 Was Demolished with Explosives, after its Owner Said “Pull It”

The term “pull it” has a specific meaning in the demolition industry: attaching one end of long cables to part of a structure and the other end to heavy machinery, which would pull the structure to one side. No explosives are involved. There is no evidence that such a method was used on this building. The tower was in any case too large for such a method to be used.

Larry Silverstein, the owner of WTC 7, used the words “pull it” in a television interview. It is clear from the context that he was referring to pulling firefighters from the building because the fire was out of control and the building was close to collapsing. The relevant part of the interview is in this 25-second-long clip: https://www.youtube.com/watch?v=Wq-0JIR38V0. Silverstein states:

I remember getting a call from the, er, fire department commander, telling me that they were not sure they were going to be able to contain the fire, and I said, “We’ve had such terrible loss of life, maybe the smartest thing to do is pull it.” And they made that decision to pull and we watched the building collapse.

Even if Silverstein had instructed the firefighters to demolish his building, his opinion would not have meant anything. The building was under the control of the emergency services. And, of course, even if Silverstein (along with the fire department commander) had been part of a conspiracy to blow up the building, he would hardly have admitted it in a television interview.

There is no reason to suppose that WTC 7 must have been demolished by explosives. It had suffered significant damage on the side facing the collapsed WTC 1; a fire had broken out on its lower floors; and no evidence of explosions was detected via seismographs.

Claim 8: No Other Steel-Framed Buildings Have Collapsed Due to Fire

On the contrary. many steel-framed structures have collapsed due to fire. In any case, fire was not the sole cause of the collapse of the World Trade Center towers.