North Tower Collapse Time: Quotes/Citation help needed

Sorry to post this as a blog entry but I need some help from the good people of this community...

I am currently in the process of making the first version of a short film regarding 9/11 physics (includes physics simulations :)), and I have two points where i'd like to quote official documents regarding the wtc tower collpase times. I already have a quote/citation for the south tower:

"...the south tower collapsed in ten seconds..." - 9/11 Commision Report, page 305

but I have been unable to locate a similar quote for the north tower. Can someone point me to an official document (NIST, FEMA, 9/11 Ommission) where they state the north tower collapse time? I have the pdf of the ommision report, and ncstar1 but I cant find a reference in those. (maybe i missed it)

any help would be greatly appreciated.

Once I have the first draft of this short presentation ready I will push it up to google and post a link on blogger. Thanks.

(ps- shills need not reply)


"Collapse Time"=="Demolition Time"

1. The speed of the wave of destruction that moved down the side of the buildings. It was at near free fall.
2. The demolition time as recorded by the seismic record.
3. The demolition time as timed and averaged by a random selection of people ;-)
4. The demolition time from initial motion of the spike on WTC1 to the falling of the still standing core columns.

See for high quality views of the demolitions.

Jumbo Jets Can Not Demolish Skyscrapers.


"6. How could the WTC towers collapse in only 11 seconds (WTC 1) and 9 seconds (WTC 2)—speeds that approximate that of a ball dropped from similar height in a vacuum (with no air resistance)?

NIST estimated the elapsed times for the first exterior panels to strike the ground after the collapse initiated in each of the towers to be approximately 11 seconds for WTC 1 and approximately 9 seconds for WTC 2. These elapsed times were based on: (1) precise timing of the initiation of collapse from video evidence, and (2) ground motion (seismic) signals recorded at Palisades, N.Y., that also were precisely time-calibrated for wave transmission times from lower Manhattan (see NCSTAR 1-5A)."

This is only for the first panels that hit the ground, not the whole thing.

That is important

"This is only for the first panels that hit the ground, not the whole thing."

Exactly. And those panels were from the plane impact zones, ie from the areas where the "collapse" started. Moreover, I'm not sure if NIST refers to panels that dropped to the ground beside the towers, or if the reference is to panels that reached the ground through the underlying structures.

In any case, it took several seconds more for the top of the upper falling portion(s) to reach the ground (or, to be more precise, the top of the accumulated rubble pile).


Thanks guys

Physics/Science/Mathematics do not lie, only people do.
9/11 was an INSIDE JOB

I'd say 15 seconds

I agree with Jim Hoffman who says that 15 seconds is a close approximation of both towers' collapse time.

It is clear that the South Tower did not collapse in 10 seconds. One should also remember that the "collapse" was over only after the upper part, too, was in itself destroyed.

Video Records Show 15-Second+ Durations

"Most of the more contemporary references to the ten-second collapse times appear to have originated with FEMA's Building Performance Study. Although the Report makes no claim about how long it took the Towers to "collapse", it includes the chart on the right describing the duration of seismic signals. That chart gives 10 and 8 seconds for the durations of the signals corresponding to the South and North Tower "collapses", respectively.

Apparently, the only official report that gives a duration for either of the "collapses" is the 9/11 Commission Report, which states that the South Tower collapsed in ten seconds in Chapter 9, Section 2 [...]

Video Records Show 15-Second+ Durations

Unlike seismic records, video recordings of the Towers' destruction allow the conclusive determination of lower bounds for the durations of each event, and those are much greater than ten seconds. Several live television broadcasts showed these events from their precipitous onsets to their explosive dust-shrouded conclusions. In each case, portions of the Tower below the exploding rubble clouds are visible up to at least the 12 second mark."