WTC destruction comparison matrix

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Overview

This page is for comparison of the following, with regard to the destruction of steel-framed high-rise buildings:

common attributes of different causes of destruction (earthquakes, fires, explosions, controlled demolition)
attributes found in the destruction of WTC1, WTC2, and WTC7 on 9/11

The Matrix

Table

The left side of the table ("CAUSE") shows attributes found in common causes of building collapse. The right side of the table shows actual attributes observed in the collapses of WTC1, WTC2, and WTC7.

CAUSE →	demolition	earthquake	explosion	fire	WTC1	WTC2	WTC7
Center first	Y	N	?	N	Y	?	Y
Clean cuts	Y	N	?	N	Y?	Y?	?
Collapse zone	Y	N	?	?	Y	Y	Y
-- at bottom	Y	?	?	?	N	N	Y
Comparable size	N	Y	?	Y	N	N	N
Deformations	N	Y	?	Y	N	?	N
Ejection	N	N	Y	N	Y	Y	N
Flashes	Y	N	?	N	Y	Y	?
Free-fall	Y	N	?	N	Y	Y	Y
Pulverization	Y	N	Y	N	Y	Y	?
Recognizable	N	Y	?	Y	N	N	N
Squibs	Y	N	?	N	Y	Y	Y?
Symmetry	Y	N	?	N	Y	Y	Y
Toppling	N	Y	?	?	N	y/n	N

The most rigorous way to pursue this analysis would be to have a complete list of all known steel-frame building collapses which have been described in any detail (or for which there are images or videos), and come up with a correlation between each cause-of-collapse and each collapse attribute. It would then be possible to calculate, with a reasonably small margin of error, the likelihood of each possible cause-of-collapse being responsible for each of the three collapsed WTC buildings.

I don't know where to find such data at this time, but one can certainly begin compiling a list of steel-frame building collapses along with any details known.

Attributes

Center first: the middle of the building begins collapsing slightly before the outside edges
Clean cuts: where shaped charges were used to sever steel beams, the cuts are clean and typically at a sharp angle (to control the direction of collapse)
Collapse zone: the area of the building where most of the collapsing and disintegration takes place. In controlled demolitions, the collapse zone is at the base of the building; above this point, the building is largely intact as it falls. In other types of collapse, there may be multiple points of collapse, and disintegration after the initial failure does not progress smoothly or continuously; there typically is no "zone" where collapsing occurs as a continuous process.
Comparable size: the rubble of the collapse is of a size/volume comparable to the original structure
Deformations: notable deformations in the building's structure are visible before the onset of collapse
Ejection: solid materials are ejected forcefully from the building during collapse, typically in a horizontal direction, landing some distance away from the main body of the post-collapse structure
Flashes: faint flashes of light are seen shortly before and during collapse
Free-fall: building collapses quickly; technically not "free-fall" speed, but within an order of magnitude
Pulverization: large volumes of dust are produced
Recognizable: after collapse, the building is still recognizably the same structure, albeit severely distorted by the collapse. Basic structural frame is still holding together.
Squibs: small puffs of dust or smoke seen shortly before onset of collapse or during collapse
- actually a slight misnomer; the term "squib" technically refers to the devices which cause these puffs – but within the context of this discussion, we'll use it to refer to the puffs themselves
Symmetry: the building collapses nearly symmetrically, rather than from one side first
Toppling: the building collapses on its side, with significant horizontal displacement and deviation from the vertical

Also need one or more attributes having to do with the characteristics of fire: evidence of extreme heat, color of smoke, degree to which building is engulfed in flame. Note that fire has never caused collapse of a high-rise.

Molten iron

Causes

demolition (short for controlled demolotion): rapid onset, symmetrical, collapses from bottom, collapses inward into its own footprint, collapses quickly, squibs above point of explosion, clouds of dust and smoke, center first, collapsed building unrecognizable / no integrity, small chunks, molten iron often found (from thermite)
earthquake: asymmetrical, toppling, recognizable integrity
explosion: thick, dense, billowing, enormous clouds of dust and smoke, flashes of light, explosive sounds
fire: (has never caused a high-rise to collapse, so only examples are from smaller buildings)

Buildings

Some notes on observed characteristics of the collapses of the WTC buildings

Center first:
- WTC1: the antenna mast started coming down shortly before the outside of the building.
- WTC7: the "penthouse" at the top center of the main roof started coming down shortly before the rest of the roof; the roofline visibly sags in the middle at the beginning of collapse.
Clean cuts: there is at least one photograph showing a girder in the wreckage of WTC1 or 2 cleanly cut at a steep angle, described by architect Richard Gage as exactly the sort of thing one would see had thermite been used. (Need to collect some pictures of known cases of thermite usage.)
Deformation: The closest thing to a deformation in any of the WTC buildings prior to collapse was the tilting of the top floors of WTC2 about 1 second before collapse began. The structural damage from the airplane impact might conceivably have been the cause of this tilting, if it turns out that the tilting was in the direction of the aircraft's entry point (to be investigated), as this would (intuitively) be the point of greatest damage.
Toppling: The top floors of WTC2 began toppling shortly before demolition, but this does not appear to be related to the main body of the demolition: toppling of part of a building would not appear to have ever caused the remainder of the building to collapse in a straight-down direction, therefore something else must have caused the remainder of the collapse.

Links

Sources

2007-04-20 Proof of Controlled Demolition 911. part 1 by Richard Gage