Sunday, 10 December 2006

The disintegrating North tower spire

The Strange Collapse of the Spire

From Plaguepuppy

An odd remnant of the core of the north tower remained standing for about 15 seconds after the main collapse, then seemed to abruptly disintegrate into a narrow column of dust where huge steel box columns had been...

The jagged triangular spire of steel columns seen above is a portion of the service core that remained standing after the main body of the dust cloud from the north tower collapse had reached the ground. It can be seen in several still pictures and at least one video, and appears to be about 2/3 the height of the building, say 60-70 floors, narrowing down to just a single column at the top. This grouping of columns is only a portion of the core, most likely one corner and the area around it, perhaps as much as a third of the core's area at the bottom. For some reason this group of columns has not fallen with the rest, though many of the cross-braces that tied them together are gone.

Given that the rest of the core disappears so completely it is hard to understand how the collapse could slice so cleanly around the spire without pulling it down as well. The core was extremely robust, designed to be able to support the entire weight of the buildings several times over and was the principal gravitational support of the building. Far from being mere "service cores," they comprised 47 rectangular steel box columns tied together by thousands of steel cross braces. The largest of these box columns were 18"x36", the smallest about 16"x16", all with steel walls 4" thick at the base and tapering in stages to 1" at the top the top, and were anchored directly to the bedrock.

The outer walls' primary function was to brace against wind loads, and they were not counted upon for weight bearing, though they did of course carry some weight in the resting state. By placing the support against wind loading right at the surface where the loads occur the whole structure could be lighter with the same amount of lateral stability. But under static conditions the core carried most of the load.

This construction picture gives a sense of how massive the core really was. Notice the four construction cranes standing on the corners of the partially built core. These sat on built-up columns created at each corner and were formed by tying together the four columns closest to each corner. Diagonal braces were also added on the vertical sides to make them more rigid. These corner columns were very substantial structures that were gradually added to as the building grew, and were designed to support the massive cranes and the weight of the materials they lifted into place.

Video Clips of the Disintegration

Click picture for AVI clip of WTC-1 collapse (needs Divx codec)

MPEG version with sound

In this view the spire can be seen in the wake of the debris cloud just as it reaches the ground. (And incidentally at that moment the scene to the left of the dust cloud gets much brighter, a brightness visible in many images. Its possible source is beyond the scope of this discussion.) This remnant of the core remains standing for a little less than 20 seconds, swaying a bit from side to side but showing remarkably little inclination to topple over. It then abruptly begins to drop straight down on itself in an apparent free fall, but after falling for about a quarter of its height it suddenly turns to dust. It is heavy dust that continues to drop straight down in place with very little dispersion or wind drift, suggesting that the particles were dense, more or less what one would expect to see if the steel of the columns had turned all at once into a coarse powder.

Animated GIF close-up

This is a close-up taken from the above CNN footage, showing only the appearance and collapse of the spire.

Pictures of the Disintegration

Beyond the mysterious shattering and disappearance of the upper ~30% of the core, there is a much more serious anomaly. The "spire" stood for about 20 seconds after the debris cloud fell away from around it, swaying slightly without tipping over despite its height and lack of support. It then began to drop straight down in place, but after dropping only a little way it abruptly turned into dust in place, very much as the towers themselves did.

Still upright, top column leaning a bit

Before and after views of the core remnant just as it turns to dust. In the first picture WTC-7 is directly in front of the spire, and the camera is above ground level. The second picture is shot from street level, and we have moved to the right relative to WTC-7.

Four Views of the WTC-1 Collapse: note how dust cloud drifts to left, away from WTC-7, leaving spire behind

We can use the left-hand edge of WTC-7 as a reference to mark the position of the spire relative to the original tower. The framing of the picture changes and the view pulls back to a wider angle as we go through the sequence, making WTC-7 get smaller and move a little to the right. Despite this shift we can see that the top of the spire as seen in the last picture just matches the midline of the intact tower in the first frame, indicating that it was part of the core.

But if the spire represents a part of the core, there is something else shown here that is very unusual. Why does main dust cloud from the collapse move off to the left, leaving the spire off by itself? In fact the spire has a smaller dust cloud of its own that can be seen in the second and third frames, a remnant left behind as the axis of the collapse shifts, but most of the material in the cloud is now off to the left, still in a more or less cylindrical distribution. The midline of the collapse actually shifted during the collapse; this very dense pyroclastic slurry of pulverized concrete, gypsum and building contents somehow shifted its center of mass away from its original location, centered on the core. And what is that odd vertical cloud of smoke at the center? A gravitational collapse should create a net downward movement of the dust cloud, without such a vertical jet of smoke. In fact close-up pictures of the WTC-2 collapse show the debris cloud being pulled back in toward the center of the collapse, indicating a negative pressure.

Some Thoughts in the Face of the Impossible

What could possibly be going on here? I really wish this were an artifact, that the resolution of the images wasn't good enough to quite make out what is going on. But the remarkable consistency between what we see in the video clip and in the still images, particularly the single shot taken the instant after it had turned to dust, creates the unavoidable impression that in some mysterious way the steel columns shatter into dust. Could stresses generated during the collapse have weakened the steel? Perhaps the shockwaves of those "dust ejections" (whatever name you may apply, they look a lot like explosions) that we saw during the collapses has changed the microcrystalline grain structure of the remaining steel in such a way that it became extremely brittle. Something very unusual has happened to these particular steel beams, something that caused them to not merely topple or crumple in segments but to disintegrate in place. It is difficult to imagine any mechanism during a gravity driven collapse that could so alter the structure of steel that it might disintegrate under its own weight - no amount of shaking can create that kind of metal fatigue.

The selectivity of the initial collapse that left behind this portion of the core while removing the rest is also difficult to explain. Consider how cleanly the cross-braces have been sliced off along that single column at the top, short pieces of the vertical plates welded to each of the core columns sheared off without so much as generating enough force to pull down this single unsupported column. Something very energetic has removed the rest of the building from around this slender structure with remarkable delicacy, shattering and utterly removing all but this small bundle of surviving columns. And at the same time something has caused the center of mass of the thousands of tons of debris from the building to shift several hundred feet from the original location during the ten seconds or so of its collapse, leaving the spire well outside the debris cloud that has spawned it. This cannot be wind drift, for the debris cloud was much too dense and fast-moving to drift like smoke.

Could electrostatic forces generated by movement of particles account for some of this? Could the pyroclastic slurry of the collapse function like a thunderhead or Van de Graff generator, perhaps accounting for the visible glow as well as the displacement of the dust cloud? Could electrostatic repulsion somehow push the dust cloud off to the side? The final bimodal dust cloud seems very inconsistent with the extreme symmetry of the early stages of the collapse, so some asymmetric force must be at work. And could the force involved also have created the bright glow visible in so many images of the collapses? The following picture (from Eric Huffschmid's "Painful Questions") shows the glow on the upper left, with debris flying out in all directions, but in an oddly asymmetric pattern:

Something inescapably strange is going on in these pictures, something no official explanation of the collapses has come close to accounting for. Beyond this I make no claims, and have no insider knowledge. Based on the photographic evidence there can be no question that explosives, and possibly other weapons systems based on "black technologies" were used in the WTC demolitions. Otherwise one can only suppose that the laws of physics underwent a profound but temporary change on September 11, 2001, as indeed the political and moral climate of our country underwent a dark and fateful change. And it is precisely this change that was clearly the intent behind the vast high-tech magic show that was 9/11. In politics as in physics, things do not happen for no reason.

Part 2: A Clearer View of the Spire's Demise

A Clearer View of the Spire's Demise

PAX-NBC Video of the North Tower Collapse

Click above for MPEG version of clip, here for AVI.

The image above shows what I have referred to as the spire, a remnant of the core of the North Tower that remained standing for about fifteen seconds after the collapse. This clip was part of a PAX/NBC compilation of views of the North Tower collapse, and is shot from east and a bit north of the tower, with the Woolworth Building in the foreground. The emergence and subsequent collapse of this peculiar remnant of the core is discussed in more detail in my first article about this object:: The Strange Collapse of the "Spire".

Near the beginning of the PAX/NBC compilation above, there are about ten seconds of footage from the same camera taken just as the collapse began. The image below is from the beginning of that footage.

(click to view video)

After the upper portion of the tower has disappeared into the dust cloud the footage is intercut with a telephoto view from the north, and we do not return to this camera angle until the spire is about to collapse. Here is an interesting WMV clip of the formation of the spire from another vantage point to help bridge the gap. And another interesting Quicktime video showing the north tower collapse from the northeast, with the spire becoming visible at the very end.

The picture below is the first frame following the missing footage of the emergence of the spire, and catches it at the end of its fifteen seconds of stability. Notice that the stubs of broken-off cross braces can still be seen along the single column at the top of the structure.

Here is a close-up of the top of the spire just after it became visible that shows these in better relief, cropped from a still photo found at Here Is New York:

Immediately after this the spire begins to fall straight down along its own axis, at least initially without any change in appearance. But at about the point when its top is even with the tapering roof of the Woolworth Building a distinct change takes place.

All at once the outline of the previously solid looking steel columns begins to become less well defined. Very soon after this it is clear that the steel columns have turned into a fine powder, though remaining in a narrow vertical column somewhat wider than the original outline. The heavier portion of the dust settles straight down fairly quickly, leaving only an insubstantial wisp of lighter dust that drifts off to the left. It has been suggested that this was simply dust that had been somehow clinging to the columns, but it would be difficult to explain how any amount of dust could cling to the vertical sides of the columns after being scoured by the turbulent cloud from which it emerged. And in any case it is clear from this footage that the sharp outline of the original columns is completely lost well before they reach the bottom of the screen.

Because this video was taken with a tripod-mounted camera located close to the collapse the image is sharper than the other known footage of the event (seen here). There can be no doubt that the cluster of steel box columns comprising the spire, after surviving the violence of the collapse itself, did in fact disintegrate almost at the moment that it began to fall. I cannot begin to speculate on the kind of technology needed to make this happen, but can say with some certainty that even conventional explosives would not create such a disintegration, and nothing that could happen in a gravitational collapse would resemble this.

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