Explosions
Explosive Events in the Twin Towers
While the explosive nature of the events that destroyed the Twin Towers is evident in their gross features such as the mushrooming of the tops and the huge clouds of concrete dustproduced in the air, there are many specific observations that point to the detonations of explosions within the towers.
Eyewitness Reports
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Many eyewitnesses who were near the South Tower when it began its precipitous collapse reported sights and sounds of explosions. Several accounts are described in the evidence section.
Energetic Ejections of Dust and Objects
Explosive ejection of dust early in the collapse of the South Tower is clearly visible in the NBC video taken from far to the east, and in still framesfrom that video, portions of five of which are shown on the right. In addition to the large ejections of white dust from the left wall, the video shows a small high-speed ejection toward the back of the right wall, visible as a small white fleck in the first frame to the right.
Many of the photographs of the tower collapses show solid objects, such as sections of steel columns and aluminum cladding of the outer walls, being thrown ahead of the expanding dust cloud. This pattern is characteristic of explosive demolitions. According to Chapter 1 of FEMA's own reportpieces of the steel columns and plates of the perimeter walls were thrown over 500 feet from the towers. The distribution pattern they diagram suggests that, with both towers, perimeter wall pieces were thrown an average of about 150 to 200 feet outward. This is corroborated by the shape of thevertical holes in WTC 6.
South Tower Demolition Wave
A three-second movie shows about 2.5 seconds of the South Tower collapse starting at about three seconds into the plunge of the tower's top. The short movie shows the roughly spherical debris cloud nearly double in size, even accounting for the perspective. The leading edge of the wave is about to reach the 44th-floor sky lobby when the camera operator turns to run. The movie (mpeg) was found on plaguepuppy's cafe with the following description.
Though the view of the building is brief, looking at it in slow motion reveals some peculiar features. At the very start of the clip we can see how perfectly even the collapse is, advancing with what looks for all the world like rows of explosions progressing in a perfectly straight line around the building, and advancing down in an extremely uniform way. As the demolition wave advances there is only dust and smoke where the top of the building used to be, and a great quantity of dust mixed with small pieces of structural steel is ejected out horizontally at high speed. To account for this very rapid ejection of debris without the use of high explosives, especially in the early stages of the collapse, seems quite impossible.
If you look closely as the wave travels down it seems to spare the corners, perhaps letting them lag behind to help keep the implosion aligned. The demolition wave is clearly advancing ahead of the actual collapse of the structure, and speeds up as it travels down. The delays between demolition charges would have to be very precisely controlled to create this effect, suggesting to me that each floor was wired to a separate detonator, with control of the sequencing most likely done remotely. This would also allow the collapse to be triggered from the point of impact of the plane to make it look more realistic. Such sequencing could easily be done from a laptop connected wirelessly to the towers, as long as each floor could be detonated separately.
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Squibs
High-Velocity "Demolition Squibs" Are Visible in the Twin Towers' Collapses
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| A horizontal jet emerges from the northwest face of the North Tower. |
Squibs are "blasting caps (initiators) used in the explosive industry to set off high explosives." 1 In discussions of the collapses of the WTC skyscrapers, the term has been appropriated to describe the physical appearance of puffs or jets of dust emerging from buildings during a demolition, caused by the detonation of explosive charges. Several such "squibs" can be seen in videos and photographs capturing the collapses of the North and South Towers.
It has been suggested that the evident squibs could have been added to the photographs and videos after the fact, given that much of this evidence has found its way onto the web via undocumented routes. However, the squibs show up in many diverse videos and photographs, and we have not been able to find any showing the squibs to be absent. A conspiracy of incredible proportions would be required to forge such convincing evidence of squibs in such diverse sources.
Squibs in the North Tower
Some of the clearest visual evidence of squibs in the North Tower is found in a video bearing the KTLA 5 banner. It shows two very distinct squibs emerging from the North Tower's northwest side, which is in profile on the tower's right, at about two and five seconds into the collapse.
Photographs
The photograph on this page shows two puffs of dust emerging from the walls well below the expanding dust cloud. The position and timing of the one on the northwest (right) face suggest that it is an early stage of the second squib seen in the KTLA 5 video.
The puff in that photo on the northeast (left) side is also visible in the first photograph on this page, but the second squib on the northwest side has already been subsumed by the dust cloud.
The first photograph on this page shows a puff of dust to the right of the visible north corner of the North Tower. That appears to be the beginning of the first squib.
Most of the photographs of the North Tower collapse show it after the second squib has already been subsumed by the dust cloud. We can find no photographs of the North Tower that should show the squibs but do not.
Videos
Other broadcasts besides KTLA 5's showed one or both of the squibs on the tower's northwest wall. This video, taken from close to the North Tower's base, shows the first squib very distinctly as a conical jet of gases that are lighter in color than the expanding dust cloud above.
This video (in wmv format) clearly shows the second squib emerging from the North Tower's northwest side.
This video broadcast by CNN provides one of the most complete records of the North Tower's collapse. It hides the squibs behind the banner, but even so you can distinctly see the second squib through the bluish semi-transparent part of the banner.
Another video shows the two squibs as clearly as the KTLA 5 video, and from a similar vantage point. It is not available on this site, but is found on the video 911: The Greatest Lie Ever Sold.
Squibs in the South Tower
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| Broad dust ejections emerge from mechanical equipment floors of the South Tower. |
Squibs are also apparent in the South Tower's collapse, though they don't appear to be as energetic as the two North Tower squibs examined above. In this photograph a red arrow highlights a row of puffs of dust emerging from the southeast face of the South Tower about 10 floors below the bottom of the zone of total destruction.
The same squibs are clearly visible in the first two collapse sequences of this ABC News video montage of the South Tower collapse.
Gravity-Collapse Explanations
Defenders of the gravity collapse theory consistently invoke the explanation that the ejections of dust are caused by pancaking floors squeezing out air and dust. The Popular Mechanics article attacking 9/11 Truth contains the following passage.
Like all office buildings, the WTC towers contained a huge volume of air. As they pancaked, all that air--along with the concrete and other debris pulverized by the force of the collapse--was ejected with enormous energy. "When you have a significant portion of a floor collapsing, it's going to shoot air and concrete dust out the window," NIST lead investigator Shyam Sunder tells PM. Those clouds of dust may create the impression of a controlled demolition, Sunder adds, "but it is the floor pancaking that leads to that perception."
NIST's final Report on the Twin Towers mentions the piston theory to attempt to explain away the ejections:
The falling mass of the building compressed the air ahead of it, much like the action of a piston, forcing material, such as smoke and debris, out the windows as seen in several videos.
There are several problems with this explanation, which we designate the piston theory.
- The squibs contain thick dust of a light color, apparently from crushed concrete and gypsum. But these materials would not have been crushed until the pancaking floors above impacted the floor emitting the squib. Thus the dust would not be produced until the air was already squeezed out, so there was no source of the dust for the squib.
- The squibs emerge from the facade 10 to 20 floors below the exploding rubble cloud inside of which the tower is disintegrating. The thick clouds appear to contain the pulverized concrete of the floor slabs, which was the only concrete component of the tower. But the piston theory requires that the floors have already pancaked down to the level of the squib, making them unavailable for the production of the concrete dust more than 10 floors above.
- The piston theory requires a rather orderly pancaking of the floor diaphragms within the intact sleeve of the perimeter wall. Such a process should have left a stack of floor diaphragms at the tower's base at the end of the collapse. But there was no such stack. In fact, it is difficult to find recognizable pieces of floor slabs of any size in Ground Zero photographs.
- The North Tower exhibits three distinct sets of squibs at different elevations of the building. Each set is visible as two distinct squibs on the same floor, one emerging from about the horizontal center of each of the tower's two visible faces. This pattern is is far too focused and symmetric to be explained by the piston theory, which would produce similar pressures across each floor and over successive floors.
- The pancaking of floors within the perimeter wall would have created underpressures in the region above the top pancaking floor. But we seen no evidence of dust being sucked back into the tower.
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Shattering of Structure
The Twin Towers' Frames Disintegrated Before Falling
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| This photograph shows the top of the South Tower disintegrating as it has only just begun to fall. Note the curves in the edges of the walls above the zone of collapse. |
There is clear visual evidence that the structural frames of many stories above the impact zones in both towers were shattered before the tops had fallen significant distances. The evidence is particularly strong in the case of the South Tower.
A movie taken from the east gives one of the most complete records of the South Tower collapse. The motion of the top revealed by the movie has some very strange features. At first the motion consists of a tipping of the approximately 30 stories above the impact zone as a unit, about a fulcrum in or around the impact zone. The tipping motion accelerates for about 2.5 seconds. Then, at about the time the first large ejections of dust start at the impact zone, the motion of the top changes: It begins to fall precipitously, and its rotation (imparted by the tipping) rapidly decelerates and virtually ceases after a second.
The rapid downward acceleration indicates that the fulcrum has been destroyed. This is difficult to reconcile with a gravity-driven collapse. Since the top had already tipped about 15 degrees, the downward force on the building's structure below the fulcrum was already decreasing. One would expect the tipping to continue, eventually resulting in the top falling like a tree.
Disappearing Angular Momentum
The deceleration of the top's rotation is even more discrediting to the idea of a gravity-driven collapse, which cannot explain the documented changes in angular momentum. Conservation of angular momentum is the tendency of a rotating solid object to continue rotating at the same rate in the absence of torque. Initially the block consisting of the top 30 stories of the tower acted as a solid object, and rotated about a fulcrum near the impact zone. Although the fulcrum was the axis of rotation, the block had two types of momentum: the angular momentum of the block around its center of gravity, and the linear momentum of its center of gravity tilting away from the tower's vertical axis. When the portion of the building below the collapse zone disintegrated, the block would preserve its angular momentum by continuing to rotate at the same rate (but the acceleration of the rotation would cease due to the removal of the torque that was being applied by intact columns at the fulcrum). But in reality, the rotation of the block rapidly decelerated as the downward plunge began. Once the fall started, any resistance it encountered from parts of the building would have imparted torque on the block in the same direction as the original fulcrum, and would have accelerated its rotation.
Given the apparent absence of any torque to counter the rotation of the block, the slowing of its rotation can only be explained by the breakup of most of the block, which would have destroyed its moment of inertia.
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Concrete Pulverization
Twin Towers' Concrete Turned to Dust in Mid-Air
A striking feature of the Twin Towers' destruction was the pulverization of most of the concrete into gravel and dust before it hit the ground. This is evident from the explosive mushrooming of the towers into vast clouds of concrete as they fell, and from the fact that virtually no large pieces of concrete were found at Ground Zero, only twisted pieces of steel. 1 Estimates put the size of the particles, which also included gypsum and hydrocarbons, in the ten- to 100-micron range. 2
Some idea of the volume of the dust clouds can be obtained by examining photographs taken shortly after each tower collapsed.
The researcher calling himself plaguepuppy articulated the thoroughness of the destruction and its incompatibility with the official explanation.
In trying to come to terms with what actually happened during the collapse of the World Trade Towers, the biggest and most obvious problem that I see is the source of the enormous amount of very fine dust that was generated during the collapses. Even early on, when the tops of the buildings have barely started to move, we see this characteristic fine dust (mixed with larger chunks of debris) being shot out very energetically from the building. During the first few seconds of a gravitational fall nothing is moving very fast, and yet from the outset what appears to be powdered concrete can be seem blowing out to the sides, growing to an immense dust cloud as the collapse progresses.
The floors themselves are quite robust. Each one is 39" thick; the top 4" is a poured concrete slab, with interlocking vertical steel trusses (or spandrel members) underneath. This steel would absorb a lot of kinetic energy by crumpling as one floor fell onto another, at most pulverizing a small amount of concrete where the narrow edges of the trusses strike the floor below. And yet we see a very fine dust being blown very energetically out to the sides as if the entire mass of concrete (about 400,000 cubic yards for the whole building) were being converted to dust. Remember too that the tower fell at almost the speed of a gravitational free-fall, meaning that little energy was expended doing anything other than accelerating the floor slabs.
Considering the amount of concrete in a single floor (~1 acre x 4") and the chemical bond energy to be overcome in order to reduce it to a fine powder, it appears that a very large energy input would be needed. The only source for this, excluding for now external inputs or explosives, is the gravitational potential energy of the building. Any extraction of this energy for the disaggregation of the concrete would decrease the amount available for conversion to kinetic energy, slowing the speed of the falls. Yet we know that the buildings actually fell in about 9 seconds*, only slightly less than an unimpeded free-fall from the same height. This means that very little of the gravitational energy can have gone toward pulverizing the concrete.
Even beyond the question of the energy needed, what possible mechanism exists for pulverizing these vast sheets of concrete? Remember that dust begins to appear in quantity in the very earliest stages of the collapses, when nothing is moving fast relative to anything else in the structure. How then is reinforced concrete turned into dust and ejected laterally from the building at high speed?
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| Evidence indicates that the hundreds of thousands of tons of concrete in the Twin Towers was converted almost entirely to dust. |
Both reports of workers at Ground Zero and photographs of the area attest to the thoroughness of the pulverization of the concrete and other non-metallic solids in the towers. 3 An examination of our extensive archives of images of Ground Zero and its immediate surroundingsreveals no recognizable objects such as slabs of concrete, glass, doors, or office furniture. The identifiable constituents of the rubble can be classified into just five categories:
- pieces of steel from the towers' skeletons
- pieces of aluminum cladding from the towers' exteriors
- unrecognizable pieces of metal
- pieces of paper
- dust
Pyroclastic Flows
Many observers have likened the Towers' destruction to volcanoes, noting that the Towers seemed to be transformed into columns of thick dust in the air. An article about seismic observations of events in New York City on 9/11/01, relates the observations of scientists Won-Young Kim, Lynn R. Sykes, J.H. Armitage:
The authors also noted that, as seen in television images, the fall of the towers was similar to a pyroclastic flow down a volcano, where hot dust and chunks of material descend at high temperatures. The collapse of the WTC generated such a flow, though without the high temperatures. 4
* 15 seconds is a much more accurate estimate of total collapse time than 9 seconds. (See this time analysis of the North Tower collapse.) Yet the 9-second figure is widely repeated in the literature of both detractors and supporters of the official story.
References
2. World Trade Center Dust Analysis Offers Good News For New Yorkers, sciencedaily.com, 12/24/02 [cached]
3. Sifting Through the Dust at Ground Zero, EnviroNews.com, [cached]
4. Damage to Buildings Near World Trade Center Towers Caused by Falling Debris and Air Pressure Wave, Not Ground Shaking, Seismologists Report, columbia.edu, 11/16/01 [cached]
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Vast Volumes of Dust
Dust From Collapses Expanded to Many Times The Towers' Volumes
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| This photograph shows the dust from the North Tower disintegration about 30 seconds after the start of its disintegration. |
Both Towers exploded into vast dust clouds, which photographs show to be several times the volumes of the intact buildings by the time the destruction reached the ground. The dust clouds continued to expand rapidly thereafter, growing to easily five times the buildings' original volume by 30 seconds after the initiation of each collapse.
The dust clouds rapidly invaded the surrounding city, filling the cavernous spaces between nearby skyscrapers in seconds. Eyewitness reports were consistent that it was impossible to outrun the dust clouds. Photographs can be used to calculate the speed at which the dust cloud from the North Tower grew. There is a photograph of the North Tower dust showing the spire and showing dust 700 feet in front of the nearest part of the building's footprint. That distance is calculated using buildings as reference points. Since it is known from real-time movies that the spire fell about 30 seconds after the initiation of the collapse, and that it took about 10 seconds for the bottom of the dust cloud to reach the ground, the average speed of advance on the ground in that direction was approximately 35 feet per second.
Another feature of the dust clouds was that they upwelled in immense columns, climbing to over the height of Building 7 (over 600 feet) in the seconds immediately after each collapse.
Such behavior clearly indicates the input of huge quantities of heat far in excess of what the friction of a gravity-driven collapse could produce.
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Shredding of SteelTwin Towers' Steel Frames Ripped to Small Pieces
A feature of the collapses that is less obvious than the symmetrically mushrooming tops or the vast clouds of concrete dust is their effect on the towers' steel frames. The only large remnants of the towers standing after the collapses were base sections of the perimeter walls extending upward several stories. Some of these sections were about 200 feet wide by 80 feet tall. Virtually all of the remaining steel was broken up into small pieces:
****************************************************************** SymmetryThe Demolition-Like Symmetry of the Twin Towers' Falls
Getting buildings to fall vertically (i.e.: symmetrically about their vertical axes) is what the art and science of controlled demolition are all about. By causing a building to fall vertically into its footprint, demolitions experts avoid damage to surrounding buildings. This is achieved through the careful placement and timing of explosives so as to cause the simultaneous and symmetric failures of all the main structural supports. Given the strength and resilience of steel, the failure to break even one of the major columns in a steel-framed building could cause it to tip to one side as it collapsed. It is inconceivable that any random event or combination of events, such as aircraft collisions, fires, or fuel tank explosions, could cause the simultaneous failure of all the support columns in a building -- especially a tall steel-framed building -- needed to cause it to collapse vertically. Both of the Twin Tower collapses exhibited remarkable symmetry. The North Tower's collapse commenced suddenly. The top of the tower seemed to effortlessly telescope down into the intact portion of the building. The collapse remained symmetrical from start to finish. The South Tower's collapsebehavior was more complex. Its top first tipped for about two seconds, then started to descend. Despite the initial asymmetry of the collapse, it became more and more symmetric after the top started to fall. Once the top disappeared into the enormous dust cloud, there was no further evidence that the top had started to topple, except for a leaning anvil-shaped cloud of darker dust. The centered collapses meant the falling mass followed the path of maximum resistance. That's the opposite of how we expect a structure to behave when it falls apart in any kind of natural process. Even if the towers were made out of clay, we wouldn't expect them to collapse in such a dead-centered fashion. It's all the more incredible that a steel structure would shred itself by falling into itself instead of falling over.
There are many examples of steel-framed buildings undergoing unintentional collapses as a result of severe earthquakes. In contrast to the destruction of the Twin Towers, no such collapses have been vertical or total -- let alone explosive. Rather, steel-framed buildings destroyed by earthquakes have toppled. *************************************************** |
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