Seismic activity on 9/11

[Mrrm1235]

Just wondering if anyone has made the following argument regarding the thermite claim often proposed by truthers. Suppose that thermite was used to weaken either building prior to its collapse. If this were the case then the ability of the falling upper section to exert a force on the stationary lower section would be greatly diminished. It then follows that one would not expect much seismic activity as the towers collapsed (due to the lack of a force acting on the ground through the bottom section).
BTW : I'm still trying to derive a relationship between the seismic readings and the force exerted on the ground by the tower itself...any ideas?

[Sam.I.Am]

Nothing could act as a "Shock absorber" to attenuate the seismic waves in that situation. At best, and this would have to be in an absolute perfect situation (which we certainly didn't see on that day), you might see a slight decrease in a signal at the very instant of failure but realistically a seismograph would never detect the difference and even if it could you would have nothing to compare it to in order to detect the difference.

[Java Man]

It then follows that one would not expect much seismic activity as the towers collapsed (due to the lack of a force acting on the ground through the bottom section).

I believe it would work the other way around. There would be more perceived seismic activity. As less energy is consumed in deforming the structure there is more energy to create bigger seismic waves.

[triforcharity]

Not to mention IIRC, the seismic signatures were very small during the initial collapse, but as the loose debris started to impact the ground, is when the spikes began to be much more intense.

Here is some useful information on what you would see in a typical explosion, and also for a controlled demolition.
http://web.mst.edu/~rogersda/umrcourses/ge342/Forensic%20Seismology-revised.pdf

Now, compare that to the 9/11 Seismic data
http://www.mgs.md.gov/esic/publications/download/911pentagon.pdf

Here is a paper by Ryan Mackey about seismic data from 9/11
http://www.jod911.com/drg_nist_review_1_0.pdf

About page 48 ff.

Gravy's reasearch
http://sites.google.com/site/wtc7lies/seismicreports%2Ccontrolleddemo%2C1993%2Cskysc

Pat's (??) site on the Seismic data
http://www.911myths.com/html/seismic_proof_.html

NIST's info on the seismic data
http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm


Hope this helps!!

[Mrrm1235]

I beg to differ. I'm talking about seismic activity produced as the upper section collides with the lower section. If the lower section had been weakened already then it could not have exerted a large force on the upper section and, hence, the upper section could not exert a large force on the lower. So why was the ground shaking?

[Mrrm1235]

Could you not compare the reading to the reading from when the planes hit the towers?

[triforcharity]

What's your point? What are you getting at? I am slightly confused.....

[Thunder]

this thread makes no sense.

[Mrrm1235]

Thanks for the info!

[Mrrm1235]

What I'm getting at is this. If the lower section had been weakened prior to the collapse then it would not be able to exert a very large force on the upper section. Thus, the upper section would not be able to exert a very large force back and one would not expect seismic activity. This was under the assumption that the seismic activity was due to the increased force acting on the lower section as it was crushed by the upper section which, it turns out, is incorrect. My goal was to use the seismic data to determine the force exerted on the lower section by the upper section during the collapse but since it turns out that the seismic data was a result of falling debris it's not going to work out.

[leftysergeant]

My goal was to use the seismic data to determine the force exerted on the lower section by the upper section during the collapse but since it turns out that the seismic data was a result of falling debris it's not going to work out.

There are increases in seismic activity in all three structures prior to the debris hitting the ground.

That in the towers is consistant with progressive collapse and shows no sign of explosive spikes prior to the first impact of the debris on the gorund.

There is a good twenty seconds or so of seismic activity in WTC 7 prior to its total collapse, again, none of it suggesting explosives. If you look at the data from the dam-busting bombing on the Ruhr, you will note an almost straight vertical spike with reverbrations followed by a near-total drop-off.

Does that help?

[Oystein]

I believe it would work the other way around. There would be more perceived seismic activity. As less energy is consumed in deforming the structure there is more energy to create bigger seismic waves.

The seimic spikes would be sharper - shorter in time, higher amplitude.

However, the question is: shorter / higher compared to what? in any case we would have to compare actual seismic data with predictions from theory, if we want to assess the numerical size of individual features. As far as I see, the only measures that can be taken from the data and be compared with some theory are the duration and the total energy. Other than that, you can look at the wave profile - how the signal builds up over time, how there are few spikes of relatively low pronunciation, and engage in qualitative debate of these details. Quantitative discussion of these would be difficult.

[T.A.M.]

Oih, here we go again.

The "Seismic" issue has been dealt with, to death, on this forum. Do a search on "the google" with the key words "Seismic" and "JREF".

TAM:)

[Thunder]

Mrrm- do you believe that 9-11 was an inside job?

[Mrrm1235]

No, no, no... I do not believe 9/11 was an inside job.
I am trying to develop another argument to refute the "truthers" claim that thermite was used to weaken the building before the collapse. My goal is to derive a relationship between the force acting on the lower section during the collapse and seismic activity...that's it. The plan was to use this relationship to determine the force exerted by the building on the ground and then use that to determine the force exerted on the lower section by the upper section...in an attempt to prove that thermite was not used.

[T.A.M.]

I applaud your effort, but that will not likely prove that thermite was NOT used. You have to understand, truthers are NEVER convinced by anything that refutes their argument. They call it faked...simple as that.

But once, again I applaud your ambition. My first post still stands. Seismic Topic has been done here before, and JREF + SEISMIC in a google search might help

TAM:)