Frequently Asked Questions: Controlled Demolition

9-11 Research provides abundant evidence and analysis concerning the total destruction of the Twin Towers and Building 7. See this directory. We think that the evidence strongly supports the conclusion that all three buildings were destroyed by planned demolitions, and were not the result of plane crashes and fires. The following questions are frequently asked by people encountering the idea of the controlled demolition of the World Trade Center buildings. Other questions are addressed in other FAQs.

How could the Twin Towers, with so many tenants, and so many columns (240 perimeter columns, and 47 core columns) be wired for a controlled demolition without the operation being noticed?



This question assumes that the demolition of the Twin Towers would have to be set up like a conventional commercial one, with fuses and large numbers of cutting charges. First, note that the demolitions could have been controlled using wireless detonators, which have been commercially available for decades. Attack Scenario 404 describes how the charges could have been activated via radio signals in a precise fashion controlled by a computer.



Second, the demolitions may have been achieved without accessing the perimeter columns. The fact that the Twin Towers exploded into vast clouds of pulverized concrete, hurling steel assemblies up to 500 feet in all directions shows that they were destroyed with much more energy than a conventional demolition -- perhaps two orders of magnitude more. That gave the planners much more leeway in the placement of charges required to totally destroy the buildings. The core structures contained the building services such as elevators, and plumbing and cabling shafts. It would have been easy for people who controlled building security to surreptitiously install devices in hidden portions of the cores. Any such job would have been far simpler than the structural retrofit of the CitiCorp Tower in New York, carried out unbeknownst to the building's very tenants. 1



Third, explosive devices could have been disguised as or concealed within legitimate equipment, such as smoke alarms or ceiling tiles, and installed by workers oblivious to their surreptitious function. Numerous such possibilities are afforded by the properties of energetic materials.





This question assumes that the demolition of the Twin Towers would have to be set up like a conventional commercial one, with fuses and large numbers of cutting charges. First, note that the demolitions could have been controlled using wireless detonators, which have been commercially available for decades. Attack Scenario 404 describes how the charges could have been activated via radio signals in a precise fashion controlled by a computer. Second, the demolitions may have been achieved without accessing the perimeter columns. The fact that the Twin Towers exploded into vast clouds of pulverized concrete, hurling steel assemblies up to 500 feet in all directions shows that they were destroyed with much more energy than a conventional demolition -- perhaps two orders of magnitude more. That gave the planners much more leeway in the placement of charges required to totally destroy the buildings. The core structures contained the building services such as elevators, and plumbing and cabling shafts. It would have been easy for people who controlled building security to surreptitiously install devices in hidden portions of the cores. Any such job would have been far simpler than the structural retrofit of the CitiCorp Tower in New York, carried out unbeknownst to the building's very tenants. Third, explosive devices could have been disguised as or concealed within legitimate equipment, such as smoke alarms or ceiling tiles, and installed by workers oblivious to their surreptitious function. Numerous such possibilities are afforded by the properties of energetic materials. How could charges have been pre-positioned in the Towers in such a way that the plane crashes and fires wouldn't have set them off?



There are several possible answers to this. First, some charges may indeed have been set off by the crashes but masked by the huge fireballs created by the combustion of aerosolized jet fuel. Second, explosives can be engineered so that heat alone will not detonate them. The high explosive RDX, for example, requires the simultaneous delivery of high heat and pressure to induce detonation. 2 Third, the charges could have been arranged so as to avoid the regions that the attack planners expected to take direct hits from the aircraft, given that the planes may have been flown by GPS-equipped autopilots providing targeting accuracy to within a few meters. Fourth, it is relatively easy to design casings for explosives that would allow them to survive even the most violent assaults. The casings of jetliners' black boxes protect their contents from impact accelerations of 3,400 Gs and from temperatures of 2,000ºF for up to 30 minutes.



The first and second possibilities are probably what happened. Prior to 2001, the national laboratories and Pentagon contractors had developed advanced energetic nanocomposites which, in addition to providing much higher energy densities than conventional high explosives, were engineered to be very stable and require highly specific conditions for detonation.





There are several possible answers to this. First, some charges may indeed have been set off by the crashes but masked by the huge fireballs created by the combustion of aerosolized jet fuel. Second, explosives can be engineered so that heat alone will not detonate them. The high explosive RDX, for example, requires the simultaneous delivery of high heat and pressure to induce detonation. Third, the charges could have been arranged so as to avoid the regions that the attack planners expected to take direct hits from the aircraft, given that the planes may have been flown by GPS-equipped autopilots providing targeting accuracy to within a few meters. Fourth, it is relatively easy to design casings for explosives that would allow them to survive even the most violent assaults. The casings of jetliners' black boxes protect their contents from impact accelerations of 3,400 Gs and from temperatures of 2,000ºF for up to 30 minutes. The first and second possibilities are probably what happened. Prior to 2001, the national laboratories and Pentagon contractors had developed advanced energetic nanocomposites which, in addition to providing much higher energy densities than conventional high explosives, were engineered to be very stable and require highly specific conditions for detonation. Supposing that Building 7 was brought down by controlled demolition. Doesn't the fact that the Twin Towers came down in such a different fashion prove that they were not destroyed by controlled demolition?



Controlled demolitions can be engineered in many different ways. Normally, the purpose of a controlled demolition is to remove a structure while avoiding damage to adjacent structures, and to do so economically. Typically, a tall building is demolished by placing thousands of cutter charges adjacent to columns throughout the building, then detonating them in a precise order, starting with interior structures, and progressing outward and upward. Destroying the interior columns allows unsupported weight to pull the exterior inward, and destroying the building from the ground up allows the weight of the building to be harnessed to do much of the destruction. The result is an implosion, producing a vertical collapse and a consolidated rubble pile.



The objective of controlled demolition applied to the Twin Towers was the decidedly different one of producing collapses that could be explained as having been caused by the aircraft crashes and fire damage. Hence, the destruction was started around the crash zones and then moved downward.





Controlled demolitions can be engineered in many different ways. Normally, the purpose of a controlled demolition is to remove a structure while avoiding damage to adjacent structures, and to do so economically. Typically, a tall building is demolished by placing thousands of cutter charges adjacent to columns throughout the building, then detonating them in a precise order, starting with interior structures, and progressing outward and upward. Destroying the interior columns allows unsupported weight to pull the exterior inward, and destroying the building from the ground up allows the weight of the building to be harnessed to do much of the destruction. The result is an implosion, producing a vertical collapse and a consolidated rubble pile. The objective of controlled demolition applied to the Twin Towers was the decidedly different one of producing collapses that could be explained as having been caused by the aircraft crashes and fire damage. Hence, the destruction was started around the crash zones and then moved downward. Even if the Twin Towers were destroyed by explosives, is it correct to call them controlled demolitions when they don't look anything like cases previously seen? And what was controlled about the Towers being exploded?



The "collapses" were, in some respects, very chaotic events which don't look very controlled. However, they must have been carefully engineered. In addition to having to determine the quantities and placement of explosives necessary to achieve the total destruction of the Towers, the planners had to plan the timing of their detonations with some precision. It is clear from photographs and videos of the Towers' destruction that the zones of destruction moved downward at about the same rates as the exploding rubble clouds descended, so that these zones remained concealed by the clouds. If these zones of destruction moved either too quickly or too slowly, they would have become visible below or above the rubble clouds, blatantly contradicting the official account of gravity-driven collapses.





The "collapses" were, in some respects, very chaotic events which don't look very controlled. However, they must have been carefully engineered. In addition to having to determine the quantities and placement of explosives necessary to achieve the total destruction of the Towers, the planners had to plan the timing of their detonations with some precision. It is clear from photographs and videos of the Towers' destruction that the zones of destruction moved downward at about the same rates as the exploding rubble clouds descended, so that these zones remained concealed by the clouds. If these zones of destruction moved either too quickly or too slowly, they would have become visible below or above the rubble clouds, blatantly contradicting the official account of gravity-driven collapses. Does the controlled demolition of the Twin Towers by insiders necessarily mean that the attack was an inside job? Is is possible that the Towers were prepared for demolition years in advance as part of a contingency plan to bring the towers down symmetrically should a terrorist attack threaten to topple them?



This theory is not even remotely plausible. First, such a plan would be highly illegal and require a level of secrecy on par with the engineering of the attack itself. Any leak of the plan to reporters, law enforcement, insurance companies, or tenants would empty the Trade Center and trigger an avalanche of lawsuits. Who would work in a skyscraper laced with bombs?



Second, there would be no rationale for such a plan, since no skyscraper had ever collapsed. The 1993 garage bombing did not even come close to threatening Towers' structural integrity. Third, whoever made the decision to trigger the demolitions did so knowing there were hundreds of firefighters, and perhaps thousands of civilians, still alive within the Towers. Since adjacent buildings had been evacuated, that decision was an act of mass homicide with no conceivable justification in lives or property saved. Fourth, any plan to destroy the Towers as a safety precaution would presumably have looked something like a conventional demolition, with charges starting at ground level -- not at specific points near the tops that happened to correspond to the plane crashes.





More on this topic can be found in the FAQ: Controlled Demolition With Aluminothermics, which is part of the essay Explosives Found in World Trade Center Dust -- an exposition describing the discovery of active thermitic materials in small chips in the dust.

References