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Why Fact-check? Why preserve a visual record?

The Website Written as a Book
Introduction to Book
1: Science and Subjective Viewpoints
2: Toward Accurate Collapse Histories
....2.1: Progressive Floor Collapses in the Twin Towers
....2.2: General Global Characteristics of Collapses
....2.3: Mathematical Basis of ROOSD Propagation
....2.4: WTC1 Accurate Collapse History
....2.5: WTC2 Accurate Collapse History
....2.6: WTC7 Accurate Collapse History
3: WTC Collapse Misrepresentations
....3.1: Purpose of the NIST Reports
....3.2: NIST WTC1 Misrepresentations
....3.3: NIST WTC7 Misrepresentations
....3.4: NIST WTC2 Misrepresentations
....3.5: Reviewing the Purpose of NIST and FEMA Reports
....3.6: Bazant Misrepresentation of Collapse Progressions
....3.7: Block Misrepresentations of Collapse Progressions
....3.8: AE911T Misrepresentations of the Collapses
4: Scientific Institutions Can Be Unaware of Contradiction
5: Reassessing the Question of Demolition
....5.1: The Case of WTC1
....5.2: The Case of WTC2
....5.3: The Case of WTC7
6: WTC Collapse Records Studied as Meme Replication
....6.1: Meme Replication in Technical Literature
....6.2: Meme Replication in Mass Media
....6.3: Meme Replication in Popular Culture
....6.4: John Q Public and the WTC Collapse Records

WTC Twin Towers Collapse Dynamics

Official, Legal Attempts to Explain Collapses

Academic Attempts to Explain Collapses Reviewed

On the Limits of Science and Technology

WTC Video Record

WTC Photographic Record
WTC1 Attack to Collapse
WTC2 Attack to Collapse
Fire Progression, WTC1 North Face
Fire Progression, WTC1 South Face
Fire Progression, WTC1 East Face
Fire Progression, WTC1 West Face
Fire Progression, WTC2 North Face
Fire Progression, WTC2 South Face
Fire Progression, WTC2 East Face
Fire Progression, WTC2 West Face
Debris: WTC1 Around Footprint
Debris: WTC2 Around Footprint
Debris: From WTC1 Westward
Debris: From WTC1 Northward
Debris: From WTC2 Eastward
Debris: From WTC2 Southward
Debris: Plaza Area, Northeast Complex
Debris: Hilton Hotel, Southwest Complex
Debris: General, Unidentified Locations
9/11 Debris: An Investigation of Ground Zero
Airplane Debris around WTC Complex
Damage to Surrounding Buildings
Perimeter Column Photo Record
Perimeter Columns: Types of Damage
Core Box Columns: Types of Damage 1
Core Box Columns: Types of Damage 2
Complete Photo Archive

WTC Structural Information

Log In


Remember Me

Online Misrepresentations of the WTC Collapses

Forum, Blog Representations of the WTC Collapses

The Book Tested Through Experiments

Miscellaneous Notes, Resources

New Ideas in Education

20 Years of Misrepresenting Twin Towers Collapses

Accurate Collapse History of WTC7

Accurate Collapse History of WTC7



The collective visual record of the WTC7 collapse is examined directly and independently of all other sources, groups or individuals. The movement of the structure during the initial column failure sequence is mapped and traced back to the earliest point of detectable movement from multiple angles. Features of the initial failure sequence can be understood as a rapid succession of 7 identifiable events occurring in the following order:

1) Movement Detected from 2 Minutes before Collapse
2) Increase of rocking 6 seconds before visible collapse
3) Ejections and overpressurizations
4) Collapse of the East Penthouse
5) Collective core failure
6) Perimeter response
7) Acceleration downward

Collapse Progression and Rubble Distribution

1) Movement Detected from 2 Minutes before Collapse

The earliest detectable movement leading into the visible collapse process was never recognized in the NIST report shown in section 3.3). There is nothing within the NIST computer simulations that can explain this type of movement.

The trace process of the northwest corner using sub-pixel tracing (syntheyes) demonstrated:

This camera angle is called the "camera #3 viewpoint" within the NIST report.

The corner started to rock back and forth at about 90 seconds before the visible collapse began. The movement is detectable by overlaying frames of the video.

The blue line indicates the moment when visible collapse first begins.

high resolution here

high resolution here

2) Increase of rocking 6 seconds before visible collapse

About 6 seconds before the collapse first becomes visible the northwest corner starts to rock more intensely. This movement was detected by the NIST and they consider it to be the earliest detectable motion. The first visible movement was the collapse of the east penthouse and is indicated in the graph. Once the east penthouse begins to fall, the rocking becomes much more intense until the whole core starts to fall collectively about 4 seconds later.

Building Rocks Horizontally Before Collapse

The NIST measurements are posted over independent confirmation. During this rocking motion from 6 seconds before the earliest visible collapse, both sets of measurements match well.

Jet Flames from 13th Floor Just Before Collapse
E Penthouse Collapse and Suction


4) Collapse of the East Penthouse

E Penthouse Free-falls Through Building

The facade behavior is examined using color enhancement during the east penthouse collapse:

5) Collective core failure

The first phase of core collapse is the east penthouse shown at 0:06 in this video:

The second phase seems to involve the rest of the collective core, which follows about 4 seconds later.

6) The perimeter response

Perimeter deformation as a response to the failure of the core is clearly observable:

Mapping the deformations from various angles allows for rough global model of perimeter flexure. The model describes the witnessed flexure of the perimeter as being the result of the core dropping in three sections as shown:

Perimeter Deforming During Early Motion

Rough global model of early deformation

Drop curves for perimeter near the center, northwest corner and northeast corner compared

Coupled reaction between core and perimeter

Drop rates and velocities of core and perimeter compared

It appears that the core was slowed down by the perimeter. The core appears to have strained the floors, took down the perimeter and catapulted the outer shell downwards until the floors were once again less strained. After this it appears the whole interconnected unit fell together.

7) Downward isplacement, velocity, and acceleration of northwest corner of WTC7

Point tracked (marked) compared to static object (also marked)

Downward displacement:


The acceleration profile given by the NIST is in green. A much more accurate acceleration profile is given in red. Free fall acceleration is marked by a blue line:

high resolution here

Multiple methods of extracting downward acceleration from displacement data yield the same trends:

The following gif shows the effect of varying the polynomial degree which fits the displacement graph on the resulting acceleration profile. Is starts with a zero degree fit and increases the polynomial degree in steps of 2:

Increasing the degree of the polynomial doesn't have much effect on the resulting acceleration trend.

So how is it possible for the perimeter to drop faster than free fall?

Core and perimeter were still connected through the floor system. Once the core dropped near gravitational acceleration the core-floor-perimeter could have acted like a spring system. First, the core pulled the perimeter inwards. Secondly, the perimeter failed at a very low elevation and was then pulled downwards by the "floor-springs". The falling core was slowed down at the same time until the entire system fell as one unit.

Of course the center of mass of the entire system cannot exceed gravitational acceleration, but a point on the extremity of the perimeter can.


Due to the early fall of the east penthouse, one can assume that the core and perimeter on the east side of the building were not coupled together during the building collapse. The perimeter flexure, as it responded to collective core failure, also shows that the east side of the perimeter was decoupled from the core while the center area and west side of the perimeter was tightly coupled to the collective core.

There is further evidence of this during the collapse progression process. The section of the perimeter located farthest east fell slower than the rest of the perimeter and actually folded in on top of and over the rest of the building as shown in this short slow motion video:

The resulting rubble distribution of the collapse of this 47 story building was quite compact:

There are more images of the resulting rubble at this link:

Building Folds Into Compact Rubble Pile

WTC 7: Observed Features of the Collapse Process

----------BEFORE COLLAPSE-----------
Jennings Testimony of Explosions
Damage to the South Side, Internal and External
Premature Reports of WTC7 Collapse
Movement Detected from 2 Minutes before Collapse
Jet Flames from 13th Floor Just Before Collapse
E Penthouse Free-falls Through Building
Early Movement Summary
Perimeter Deforming During Early Motion
NE Corner Folds In and Over Building
WTC7 Acceleration Compared with Tall Building Demo
Fire Much Less Intense Than Other High-Rises

Continue to part 3: WTC Collapses Misrepresented

Created on 07/02/2012 09:08 PM by admin
Updated on 05/31/2015 10:07 AM by admin
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