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The time difference between each of the figures was approximated from time given on the videotape.
~5:20:33 p.m. WTC 7 begins to collapse. Note the two mechanical penthouses at the roof on the east and west sides in Figure 5-20.
~5:21:03 p.m. Approximately 30 seconds later, Figure 5-21 shows the east mechanical penthouse disappearing into the building.
www.popularmechanics.com...
"There is no scientific basis for the conclusion that explosions brought down the towers," Lerner-Lam tells PM. "That representation of our work is categorically incorrect and not in context."
www.globalsecurity.org...
Geophysicists have already contributed critical data to terrorist investigations. It was geologists who determined there were no secondary explosions at the base of the World Trade Center towers — but only the impact of the airplanes and subsequent fires — that contributed to the towers' collapse on Sept. 11".
www.jnani.org...
This is easily shown to be fallacious. Firstly, as the one of Columbia authors confirmed in a later email, their seismic data “are far too weak in signal-to-noise ratio and far too speculative in terms of signal source to be used as a means of contradicting the impact times …” (Commission, p.462)
Originally posted by bsbray11
Do we have any live feeds of WTC7 with timestamps? Even if it doesn't show the Penthouse collapse directly?
3.3 Seismic Recordings.
Many CD theorists draw attention to seismic recordings as evidence of the CD theory. Griffin (for example), drawing on Hufschmid, cites seismic data from Columbia University to support the CD theory:
‘In each case, “the shocks increased during the first 5 seconds then dropped abruptly to a lower level for about 3 seconds, and then slowly tapered off.” This pattern, Hufschmid suggests, reflects the fact that the first explosives detonated were those near the tops of the towers, where the steel columns were the thinnest. The shocks get stronger as the detonation pattern, controlled by a computer programme worked its way down.’ (Griffin TNPH, p.19)
This is easily shown to be fallacious. Firstly, as the one of Columbia authors confirmed in a later email, their seismic data “are far too weak in signal-to-noise ratio and far too speculative in terms of signal source to be used as a means of contradicting the impact times …” (Commission, p.462) But the key mistake however, is the idea that any building is demolished by a progressive wave of explosions either working its way up or down a building.
but Wallace, Koper and Hollnack used its high-quality data in an analysis that found precisely when the explosion occurred, at 10:39:19.8 local time -- plus or minus two-tenths of a second, and the size of the bomb. The Nairobi bomb was deadly but fairly small, equivalent to 3 metric tonnes of TNT.
Page 462 : We also reviewed a report regarding seismic observations on September 11, 2001, whose authors conclude that the impact time of United 93 was "10:06:05±5 (EDT).)."Won-Young Kim and G. R. Baum,
"Seismic Observations during September 11, 2001,Terrorist Attack," spring 2002 (report to the Maryland Department of Natural Resources). But the seismic data on which they based this estimate are far too weak in signal-to-noise ratio and far too speculative in terms of signal source to be used as a means of contradicting the impact time established by the very accurate combination of FDR, CVR, ATC, radar, and impact site data sets.These data sets constrain United 93's impact time to within 1 second, are airplane- and crash-site specific, and are based on time codes automatically recorded in the ATC audiotapes for the FAA centers and correlated with each data set in a process internationally accepted within the aviation accident investigation community.
For me, the biggest question still is:
How and why did FEMA come to their conclusion that 20:33 was the initiation of WTC 7's collapse ?
I saw nothing happen in form of visual effects BEFORE the famous penthouse denting.
Returning to WTC 7, Popular Mechanics interviewed a NIST official and reported as follows:
-SNIP-
Videos of the fall of WTC 7 show cracks, or "kinks," in the building's facade just before the two penthouses disappeared into the structure, one after the other.
~5:20:33 p.m. WTC 7 begins to collapse. Note the two mechanical penthouses at the roof on the east and west sides in Figure 5-20.
~5:21:03 p.m. Approximately 30 seconds later, Figure 5-21 shows the east mechanical penthouse disappearing into the building.
Originally posted by LaBTop
and proofed them wrong in their most important interpretation of their own data :
The arrival time of the first main collapse surface waves.
And showed us all that there are even more massive waves arriving in front of those.
www.popularmechanics.com...
"There is no scientific basis for the conclusion that explosions brought down the towers," Lerner-Lam tells PM. "That representation of our work is categorically incorrect and not in context."
And there is strong evidence contradicting the idea that the seismic spikes indicated underground explosions including:
* There is no support in the large body of photographic and video collapse evidence for the idea of powerful explosions in the towers' basements at the onset of the collapses. Instead the evidence shows waves of destruction proceeding methodically downward from the crash zones to the ground.
(LT/: however there is strong evidence in the 3 seismic records of preceeding explosion signals!)
* Underground explosions would have produced strong P waves, but the seismic stations registered only strong S waves.
P waves oscillate horizontally -- parallel to the direction of travel; whereas S waves oscillate vertically -- perpendicular to the direction of travel.
Short Note on the "evidence", from myself, LaBTop :
It is exactly the "methodically downward" collapses "from the crash zones to the ground" of all 3 towers, which intuitively triggered most viewers antipathy against the official explanation of a natural gravitational collapse for those 3 buildings.
One would in the case of a natural collapse of a steel high-rise, expect a combination of chaotic sub-collapses, each of them held or slowed down for milliseconds to seconds by buckling and breaking of huge parts of the exterior steel plates plus cladding, combined with unseen brakage of core collumns, at a much lower point than the actual observed collapse front. You can see that kind of natural, fully gravitational collapse, in the YouTube video of the burning collapse of the top part of the Madrid tower in the night. Steel parts keep tumbling, hanging and tumbling again onto eachother on their way down, you do not see a methodical collapse front.
Especially the 3 strongly reinforced mechanical floors in both North and South towers should have caused a sure visible slowing down of a real gravitational collapse, and would have been great tower body movement blockers and changers, causing various parts of the collapsing towers to change direction, tilting or turning around the vertical center axis of collapse.
Exactly that methodical collapse is a strong indication of unnatural interference by humans.
A Timeline for the North Tower.
It would be useful if collapse events evident in videos could be associated with seismic signal features.
Since some news broadcasts have real-time clocks on their banners , it may be possible to match visual events with features of the seismic signals.
Consider the North Tower, whose entire collapse was recorded by the abovementioned CNN live feed, which has a clock on its banner. That clock does not have a second counter, but its minute counter flips to 10:29 37 seconds after collapse starts, which places the collapse start, according to the CNN clock, at 10:28:23.
Various pages on columbia.edu put the origin time of the signal at the source at 10:28:31, plus or minus 1 second. This is based on an estimate of 2KM/s travel speed for the S waves, which, given the PAL station's distance of 34 KM from the WTC, gives a travel time of 17 seconds.
That the larger spikes of the seismic signatures of the tower collapses were produced by falling rubble does not preclude that the towers were destroyed with explosives. In a typical demolition, numerous small explosives are used to shatter the columns supporting the building. Unless the explosives are detonated simultaneously, they are unlikely to produce detectable seismic signatures. If explosives were responsible for the towers' destruction, they were numerous and were detonated in a synchronized but progressive manner, contributing little to the recorded seismic disturbance.
Originally posted by LaBTop
That the larger spikes of the seismic signatures of the tower collapses were produced by falling rubble does not preclude that the towers were destroyed with explosives. In a typical demolition, numerous small explosives are used to shatter the columns supporting the building. Unless the explosives are detonated simultaneously, they are unlikely to produce detectable seismic signatures. If explosives were responsible for the towers' destruction, they were numerous and were detonated in a synchronized but progressive manner, contributing little to the recorded seismic disturbance.
In my opinion, he tells you, LeftBehind, that all your links to seismic scientists declaring not seeing any explosives signs in the LDEO graphs, are worthless, since ""they are unlikely to produce detectable seismic signatures"" and ""contributing little to the recorded seismic disturbance"".
He's telling you and me to do not bother with a quest for explosion marks, since there never will be any......
geopubs.wr.usgs.gov...
The Seattle Kingdome was a domed sports stadium located in downtown Seattle near the Seattle fault. The Seattle Kingdome was imploded (demolished) at 8:32 AM local time (16:32 UTC) on March 26 (JD 086), 2000. The seismic energy produced by implosion of the Kingdome was equivalent to a local earthquake magnitude of 2.3. Strong impacts produced by the implosion of the Kingdome generated seismic arrivals to frequencies as low as 0.1 Hz.
And regarding your remark :
""They looked at the data and saw that no explosives were used, then attempted to match it up with the known collapses.""
Originally posted by LaBTop
ofcourse you are right, I was too hastely trying to depict to the reader how the effects of planes and explosives would work out on such huge buildings. And speed of the hitting object must also be included, if over a certain speed, the object will go through the whole building like it was butter, and then far less impact energy would have been transfered to the building. Imagine a black belt karateka slicing with his hand through a plank.
That's why you see less seismic energy in the half miss plane impact. Also less core collumns were hit in that case.