Chris Mohr at Skeptic magazine writes that “conspiracists are working hard to publicize their claims of scientific validity to the conjecture that the World Trade Center buildings were destroyed through controlled demolition.” He mentions a debate he had with Richard Gage, the founder of Architects & Engineers for 9/11 Truth, where more than 1,500 professional architects and engineers who question the official explanation for the collapse of the three World Trade Center buildings have signed a petition calling for a new—that is to say a real—investigation. “I thought initially that Gage might be on to something,” Mohr writes, “until I examined his science carefully” and debated him. In his article, he lists his responses to the controlled-demolition hypothesis. Sticking to the question of World Trade Center Building 7 (WTC 7), let’s examine Mohr’s arguments against the science behind the controlled-demolition hypothesis and in favor of the fire-induced collapse hypothesis. If you’re unfamiliar with WTC 7, you can watch it collapsing on 9/11 in the video below.
Mohr begins his case with the argument that “You cannot secretly prepare a controlled demolition of the two World Trade Center buildings … without anyone noticing anything unusual.” He does not mention it, but we may presume he thinks it would be just as impossible in the case of WTC 7, the third WTC building to collapse completely on 9/11. The main point to be made about this assertion is that it is not a scientific argument, but speculation. It for starters assumes that nobody noticed anything unusual in the days, weeks, and months before 9/11. But is that true? Since this possibility was never actually investigated, and thus building workers were never interviewed and asked whether they noticed any suspicious activity going on, we don’t really know. Also, while it may seem unlikely that this could be done, if the actual scientific evidence disproves the fire-induced collapse hypothesis and proves the alternative, then one has a priori knowledge that however unlikely, this must have occurred. So we must turn to the science, which Mohr does get to, eventually, as we shall see.
Mohr writes, “Though it is true that no tall steel frame buildings ever collapsed due to fire alone prior to 9/11, since then, other tall steel framed buildings have.” He is referring, of course, to WTC 7, which wasn’t hit by a plane. It did suffer significant debris impact damage from the collapse of the North Tower, but the National Institute of Standards and Technology (NIST), the government agency responsible for the investigation into the building’s collapse, acknowledged that the damage was neither an initiating nor determinative factor in the collapse. As the Federal Emergency Management Agency (FEMA) noted in its initial report, “Prior to September 11, 2001, there was little, if any, record of fire-induced collapse of large fire-protected steel buildings.” Following up on FEMA’s preliminary investigation, NIST noted in its final report that the collapse of WTC 7 “was the first known instance of the total collapse of a tall building primarily due to fires.” Richard Gage has observed that in every instance where a tall building (that is, a steel-framed skyscraper) has collapsed with characteristics like those of WTC 7, it was a known controlled demolition.
But Mohr says that it has since occurred that “other tall steel framed buildings have” “collapsed due to fire alone”. His example? “On May 13, 2008, a large part of the tall concrete-reinforced steel architecture tower at the Delft University of Technology in the Netherlands caught fire and thereafter had a very fast, nearly straight-down collapse mostly into its own footprint.” The first problem with Mohr’s example is that a reinforced concrete building is not a steel-framed building. Mohr is obviously unaware of the distinction between a building constructed with steel columns and beams (steel-framed) and a building constructed with concrete poured around reinforcing steel, or rebar (reinforced concrete). But let’s have a closer look, anyways, just for fun. Below is an image from the FEMA report showing what WTC 7 looked like after its collapse.
A 47-story, steel-framed building collapsed completely and mostly into its own footprint. Now here’s what the 13-story reinforced-concrete Faculty of Architecture building at Delft University looked like before it caught fire.
The first thing you just might possibly have noticed, if you were paying close attention, is that most of the building actually remained standing. The attentive viewer may have picked up on the fact that this doesn’t at all resemble the debris pile of WTC 7. So, to review Mohr’s record on this count, he falsely claims the Faculty of Architecture building was a steel-framed building before stating, oblivious to the distinction, that it was actually not. And then, by implication and by omission, he would have his readers believe the Faculty of Architecture building, like WTC 7, had collapsed completely and into its own footprint, when in it was just a partial collapse and most of the building remained standing. While Mohr asserted that “other tall steel framed buildings”, plural, have since collapsed from fire, presuming this is his best example—or non-example, rather—we may dismiss his false claim and move on. It remains true that this had never happened before 9/11, and it has never happened since.
Mohr next addresses the “billions of iron microspheres” found in the dust from the collapse of the buildings. He gets a bit ahead of himself here addressing the iron-rich microspheres before addressing the finding of unreacted thermitic material in the dust, which he arrives at later. But what the reader needs to understand here is that such microspheres are a natural byproduct of the thermitic reaction (which we’ll come to). Mohr simply dismisses the microspheres by asserting that if thermite and or nano-thermite was used to attack the steel structure to bring the building down, it “would leave tons of formerly melted iron blobs, not just microspheres.” What is his basis for this statement? He doesn’t say, but just leaves it at that. In fact, melted steel was recovered from WTC 7, which Mohr comes to next and we’ll get to momentarily.
But before we come to that, Mohr suggests two possible sources for the microspheres. When the buildings were built in the 1970s and “workers welded thousands of steel beams together, hot microspheres were splattered everywhere.” So maybe the workers didn’t sweep up at the end of the day. And either the building janitors did a very lousy job of cleaning up over many decades or all of these billions of microspheres were hidden away inside the walls, which, to be fair, is perfectly plausible. But Steven E. Jones, Jeffrey Farrer, Gregory S. Jenkins, Frank Legge, James Gourley, Kevin Ryan, Daniel Farnsworth, and Crockett Grabbe studied the “high-iron, relatively low oxygen spheres” found in the WTC dust and found that they “are unlike spheres gathered from cutting structural steel with an oxyacetylene torch.”
The second possibility Mohr suggests is that the fires in the buildings on 9/11 created the microspheres. He quotes a report from the R.J. Lee Group, Inc., which characterized the microspheres as being part of the “signature” of the WTC dust. Unlike Mohr, R.J. Lee did not suggest they were leftovers from the construction in the 1970s, but were created on 9/11, offering the following explanation, quoting Mohr’s citation: “Considering the high temperatures reached during the destruction of the WTC … Iron-rich spheres … would be expected to be present in the Dust.” Mohr actually cites the wrong R.J. Lee report, but R.J. Lee did suggest in another report that the fires in the buildings on 9/11 were the cause of the spheres. This is a significant error in that report, however, and apparently Mohr is as unaware as the report’s authors that the melting point of iron is about 1535 °C, similar to that of structural steel at about 1538 °C, while, according to NIST’s own estimation, the maximum temperature of any of the fires in any of the WTC buildings was about 1,000 °C, and of the steel samples is studied that had been exposed to the fires, NIST found “no evidence of exposure to temperatures above 600 °C for any significant time.” Doh!
“What about the sulfidized steel that melted and that FEMA found but which NIST ignored in their report?” Mohr next asks. He answers, “NIST didn’t ignore it.” Rather, “NIST determined that neither piece came from a supporting column in the collapse zone so it couldn’t have contributed to the collapse.” Mohr offers his readers a link to World Trade Center Disaster Study page of the NIST website, leaving his readers to search for this supposed information among the many thousands of pages from the many dozens of individual reports it produced that collectively make up this study. But it’s an obvious non-sequitur, whether coming from NIST or not, given the fact that beams, girders, and floor trusses in fact played a significant role in the collapses of the three buildings according to NIST’s own hypotheses for each. So all Mohr really offers is evidence of a cover up and scientific fraud (more of which we’ll also come to).
Mohr also fails to explain that of the two steel samples referred to, one came from one of the Twin Towers, but the other came from WTC 7. So what did NIST have to say about the steel sample recovered from WTC 7? Why, contrary to Mohr’s false assertion, NIST simply ignored it, claiming that “no steel was recovered from WTC 7” (NCSTAR 1-3, pp. iii, xliv, 115)! Doh!
Mohr adds that “Sulfidized steel melts at temperatures 1000° lower than regular steel so it could have ‘melted’ in a regular office fire.” Mohr would apparently have his readers believe that the steel used to build WTC 7 was “sulfidized steel” with a lower melting point than “regular steel”, by which he presumably means structural steel. But this was structural steel. What Mohr is really talking about is the finding of Barnett’s team at the Worcester Polytechnic Institute, included as Appendix C of the FEMA report, that there had been “a severe high temperature corrosion attack on the steel, including oxidation and sulfidation with subsequent intergranular melting”. At temperatures approaching 1,000 °C, “which is substantially lower than would be expected for melting this steel”, a “eutectic mixture of iron, oxygen, and sulfur” was formed that “liquefied the steel”. Office fires just don’t do that to structural steel.
What was this eutectic mixture that melted the steel, and where did the sulfur come from? Mohr doesn’t trouble himself to actually offer any kind of explanation. Barnett’s team noted, “No clear explanation for the source of the sulfur has been identified.” The New York Times called these findings “Perhaps the deepest mystery uncovered in the investigation”. So did the sulfur come from the gypsum wallboard that is used to provide fire resistance to the building? That question answers itself. Sulfur in gypsum is in the form of calcium sulfate (CaSO4·2H2O) and not iron sulfide (FeS), so one would have to explain how the gypsum could have reacted with other materials at high temperatures in order to free the sulfur to produce iron sulfide. To date, there remains no explanation for this “deepest mystery” that is consistent with the fire-induced collapse hypothesis.
Stephen E. Jones and others have observed, however, that sulfur can be added to thermite to produce thermate, with the addition of sulfur effectively lowering the melting point of the steel. Jonathan H. Cole, P.E., performed a series of experiments with thermate and was able to reproduce similar results as observed with the WTC 7 sample.
Mohr next comes to the unreacted thermitic material found in the dust, where he addresses the findings of a team of scientists led by Dr. Niels Harrit of the Department of Chemistry at the University of Copenhagen, Denmark, which were published in the peer-reviewed Open Chemical Physics Journal. (Mohr forgot to provide a link for his readers to go and read the paper for themselves, so here you go). Mohr doesn’t actually address most of the findings of Harrit, et al. He never tried to reproduce their experiments to verify or falsify their findings. Instead, he simply suggests that they should have also done additional experiments that they didn’t do. We could get into these other tests Mohr thinks should have been done, but it isn’t necessary; it suffices to observe that Mohr also didn’t perform these additional experiments he thinks would be required to be absolutely certain that the substance found in the dust is nanothermite. Instead, he simply seems to presume that if these additional tests were conducted, they would falsify their findings. But that is not science. (It should also be pointed out that Harrit, et al, stated explicitly that further studies should be conducted to better understand the nature of these materials, but found that those tests they did perform were sufficient to conclude with reasonable certainty that the material was nano-thermite.)
Mohr’s best effort to challenge their actual findings is to say that “They compared the sudden energy spike of their burning chips with the spikes of known nanothermites, and found that their chips ignited at around 150° C. [sic] lower than the known nanothermites, and the energy release was off between their chips and the nanothermites by a factor of at least two. Yet they called this a match for nanothermite!” Turning to their paper, Harrit, et al, found that “the red/gray chips from different WTC samples all ignited in the range of 415-435 °C” when thermal analysis was conducted by heating the chips using a differential scanning calorimeter. They stated that “Ordinary thermite ignites at a much higher temperature (about 900 °C or above) … than super-thermite [a.k.a. nano-thermite].” Mohr doesn’t say where he gets his information for the temperature at which nanothermite ignites, but turning to the source provided by Harrit, et al, for the statement just quoted, we find that “The ignition point of the traditional thermite material is ~325 °C higher than that for the nanocomposite.” Thus, we may deduce that nano-thermite ignites at about 575 °C. This is presumably where Mohr gets his “around 150 °C” difference between the ignition point of the chips found in the dust and “known nanothermites”.
One problem here is that Harrit, et al, were dealing with an apparently theretofore unknown nano-thermite with a different composition from the “known” source. But the main point to take away from this, as the source cited states, is “that the nanostructured energetics … are much easier to ignite and burn much more rapidly than the conventional thermite composites.” Thus, ultimately, Mohr’s observation only serves to reinforce the finding of Harrit, et al, that the thermitic material found was not conventional thermite, but some kind of nano-thermite.
Mohr also doesn’t provide a source for his assertion about the energy yield of nano-thermite, but as to his assertion that the material found in the dust was off “by a factor of at least two”, turning to the Harrit, et al, paper, they state that the energy release for each sample varied, with the yields “estimated to be approximately 1.5, 3, 6, and 7.5 kJ/g, respectively.” They explain this by noting, “Variations in peak height as well as yield estimates are not surprising, since the mass used to determine the scale of the signal … included the gray layer”, which “was found to consist mostly of iron oxide so that it probably does not contribute to the exotherm, and yet this layer varies greatly in mass from chip to chip.”
They also noted that these reactions produce iron-rich microspheres like those that are part of the “signature” of the WTC dust.
Mohr suggests that attempts to replicate the findings of Harrit, et al, have been “dismal”. He says Mark Basile made the same “error” of not performing the additional experiments Mohr thinks would be required to prove beyond any doubt the material is nano-thermite, and that he didn’t measure the energy released. And yet Basile was nevertheless able to replicate their principle findings that from which it could be reasonably determined that the chips were unreacted thermitic material. Mohr writes that a “chemist named Frédéric Henry-Couannier got another dust sample from the original experimenters and wrote, ‘Eventually the presence of nanothermite could not be confirmed.’” Yet Henry-Couannier also noted the “chemical composition of layers” of the red/gray chips found in the dust was “roughly confirmed” by his own study and was “Compatible with the nanothermite hypothesis”. He was not able to ignite any of his chips, however. He concluded that there were two possibilities, that either the chips “are from nanothermite that were deactivated in all my samples” or that Harrit, et al, were deceived or disinformation agents whose work is intended “to protect the secrecy of the genuine destruction technology at the origine of red chips and up to thousand tons of molten iron in the dust” (sic). Whoa. What was that? He continues: “The numerous metallic microsphers at the surface of some of these chips point toward an obvious link with a high power density process hence certainly related to the destruction technology employed to bring down the towers.” Whoa. Note that Mohr doesn’t disclose that Henry-Couannier is a conspiracy theorist who seems to think that some kind of directed energy beam weapon, some “new highly powerful weapons” developed by the U.S. Department of Defense, was used to destroy the WTC buildings. Moreover, while Henry-Couanier on one hand says he could not get the chips to ignite, and that there was “no evidence of molten iron production” when he heated them, also suggests that the “red-red chips” he studied didn’t ignite because they “are just fragments originating from red-grey chips that already reacted at the WTC and for this reason cannot react anymore”, and then seemingly contradicts himself by stating that the chips “can even burst [sic] when heated and expel iron rich particles, even microspheres which often seem to appear at their surface.” Whew! Little wonder Mohr doesn’t want to go there.
Mohr lastly states that the R.J. Lee Group “didn’t find thermitic material”. But what he really means to say is that R.J. Lee never tested any of the material it found in the dust to determine whether any of it was thermitic or not. NIST, incidentally, also has admitted that it never looked for evidence of thermitic materials, offering as explanation the logic that since it was “unlikely” any such evidence existed, there was no point in looking for it. (No, really. No kidding. You couldn’t make this stuff up.)
So now we come to some more really fun stuff. Mohr next address the fires in WTC 7, saying that “conspiracists like to show an NYPD photograph of small fires on the north face of Building 7.” His point is not exactly clear, but presumably he means to say that “conspiracy theorists” argue that the fires in WTC 7 were not that significant. Let us stipulate there were very serious fires in WTC 7. Mohr writes, “NIST reported that many fires burned themselves out in 20-40 minutes and then moved on. The fires left behind not only burned out areas, but structurally weakened areas as the beams and columns expanded, sagged, and contracted again.” Okay, so what’s his point? Well, essentially, that fire did the trick of bringing down WTC 7 in the manner in which it came down. The problem with this argument is that it is false.
We’ll come to free-fall shortly, but the fundamental point Mohr fails to address is that NIST’s fire-induced collapse hypothesis requires—bear with me here—that there be fires burning in the northeast corner of the twelfth floor in order to cause the thermal expansion of 13th floor beams, which pushed a girder off of its seat at critical Column 79, causing a series of cascading floor failures that caused Column 79 to buckle and fail due to the lack of lateral support, which led to a progressive series of column failures that resulted in a “global collapse” where the entire structure fell “as a single unit”. Got that? There are numerous problems with this hypothesis, but when it comes to the fires in WTC 7, there’s one problem in particular that stands out, which is that according to NIST’s own analysis of the available photographic and video evidence, the fire on the 12th floor had already burned through the northwest area and had moved on to the western end of the building by the time of its collapse at 5:20 p.m (NCSTAR 1-9 Vol. 1, Chapter 5). So how did NIST deal with this little problem? Simple! They ignored their own evidence and falsified the data they input into their computer model by inserting raging fires in the northeast area of the 12th floor at the time of collapse. Mohr makes no effort to address this fatal flaw in the fire-induced collapse hypothesis or the evidence off scientific fraud on the part of NIST.
Mohr next discusses the fact that BBC reporter Jane Standley announced that WTC 7 had collapsed before it had yet done so and while it was visible still standing right behind her. CNN and Reuters also reported the collapse before it had actually occurred. Mohr addresses this by chalking it up to reporter error and saying, “It is not hard to imagine how such mistakes could be made, especially when there is no time to sift through and analyze fast-moving information.” Fair enough. No doubt, particularly imaginative readers may well be able to come up with a plausible explanation for how a 47-story skyscraper could mistakenly be reported by numerous news agencies to have collapsed before it actually had collapsed.
Mohr next quotes firefighters who said they thought that WTC 7 would collapse due to the debris impact damage it sustained and from the fires. Yet, again, NIST itself acknowledged that the impact damage was neither an initiating nor determinative factor in the collapse, and its own photographic and video evidence showing that the fire had already burned out in the northeast area of the 12th floor is fatal to its fire-induced collapse hypothesis.
Finally, Mohr comes to the free-fall collapse of WTC 7. He saved the best for last, and we can have some real fun with this one. He notes that NIST acknowledged that WTC 7 “collapsed ‘at gravitational acceleration’ for eight stories over 2.25 seconds.” So how does Mohr deal with free-fall? He offers a convoluted explanation that in part relies on NIST, but which also departs from their findings. This requires a bit of background information and explanation, but briefly: Where he relies upon NIST is their finding that over the first 18 stories, the “global collapse”—that is, the collapse of the entire building “as a single unit”, which occurs after an initial collapse within the core as indicated by the east penthouse falling below the visible roofline—occurred in three stages. However, NIST’s “Stage 1”, the first 1.75 seconds of global collapse, never really happened. What NIST was measuring to create the illusion of a “Stage 1” of collapse was observed movement towards the center of the roofline on the north face of the building, from a video shot from street level and looking upward at the building. After the penthouse begins to descend, movement of the roofline is visible. However, this movement is not indicative of the onset of global collapse, but rather due to the fact that as the core collapsed under the east penthouse, the northern façade was pulled inward. The observed movement of the roofline was not indicative of downward, but of lateral displacement of the roofline. In truth, global collapse began with a sudden onset of free-fall, NIST’s “Stage 2” of collapse. During Stage 3, WTC 7 was at near free-fall as it encountered resistance from the structure below.
Translated into meaningful terms, Mohr effectively argues that as the core columns collapsed, it pulled the perimeter columns inward, so that they “snapped like a stick”, and as each perimeter column “snapped” the load it was carrying shifted to other columns. This all occurred “over about two seconds”, he says, alluding to NIST’s false claim of a 1.75 second “Stage 1” of collapse. Mohr departs from NIST when he comes to the 2.25 seconds of free-fall. He acknowledges that free-fall occurred, but says, “Free-fall collapse speed [sic] does not mean no resistance, it means no net resistance.” What he means is that in addition to the downward force of gravity and the upward force of resistance offered by the load-bearing steel columns, there was also the “variable leveraged downward forces due to connections to other parts of the building.” Got that? So what he is saying is the connections between the perimeter columns and the interior of the building provided a downward force additional to the force of gravity. Got that? So gravity plus the downward force provided by the connections between the perimeter columns and the interior. Thus, according to this argument, if the core of the building was collapsing at the acceleration of gravity, the beams connecting the core to perimeter columns would provide a downward force additional to the force of gravity, so that the perimeter columns would collapse at a rate of acceleration even greater than free-fall. That is to say that the beams were doing work as they collapsed. Of course, Mohr argues that since there was no controlled demolition, the perimeter columns did offer resistance to the collapse, but that the beams connecting the core to the perimeter columns “functioned as levers” providing a force additional to the force of gravity upon the columns, so that the net resistance was zero. If that doesn’t make any sense to you, don’t worry, that’s not an indication that Mohr’s knowledge of physics is vastly superior to yours, but that you just recognize how ridiculous this argument is. Mohr is essentially saying that the building threw itself downward with forces additional to the force of gravity.
So how did the beams do this work? What force was applied to them to cause them to act as “levers”? Where did this energy come from? And a lever requires a fulcrum, so what was the fulcrum in this case? And remember that a lever works by providing force at one end so that it applies force on the other end in the opposite direction. How does a “lever” that is accelerating downward at one end apply a force at the other end so that it accelerates downward at an even greater rate?
Setting aside the asinine nonsense, what does free-fall acceleration actually mean for WTC 7? Turning to Newton’s laws of motion and the law of conservation of energy, what it means is that all of the building’s potential energy was converted to kinetic energy, which means that there was no energy available to do the work of buckling columns (that is, overcoming the resistance of the columns) as required by the fire-induced collapse hypothesis. That is to say that free-fall absolutely disproves the official explanation for the collapse of WTC 7. For free-fall to occur, all of the buildings load-bearing columns had have offered zero resistance to the force of gravity, which means they had to have been cut, and there are no two ways about it.
Mohr ends by asking a bunch of “If … then ….” questions. Most seem directed at the Twin Towers, but addressing those with some relevance also to the collapse of WTC 7:
If 4500 degree nanothermites were used to pulverize almost every inch of every concrete floor, then how could there have been millions of sheets of paper with an ignition temperature of only 451° raining down on the sidewalks?
This is a strawman argument. To my knowledge, nobody has suggested that nano-thermite was used “to pulverize almost every inch of every concrete floor”. To bring the building down, the steel load-bearing columns would have to be cut and gravity would do the rest. No nano-thermite or explosives would be used on the floors at all. Any use of nano-thermite would be targeted at the connections or the columns themselves.
If 4500 degree nanothermites were used extensively even at the top to cause a supposed upward explosion, then why were first responders able to walk over the wreckage less than an hour after the Tower collapses?
This refers to the Twin Towers and not WTC 7, but it should be noted that the debris was so hot in some places that the soles of workers’ boots melted and steel toes would heat up to unbearable temperatures. Doh!
If there were 2800 degree rivers of molten steel in the debris, then why do NASA thermal images show maximum temperatures in the rubble of only 1400°?
NASA’s thermal images only recorded surface temperatures, implying significantly higher temperatures under the debris. Mohr doesn’t mention it, but there are also numerous credible eyewitness reports as well as photographic evidence of molten steel in the debris piles. And, as Mohr already acknowledged, samples of steel that had been melted were in fact recovered from the debris.
If the debris pile had 2800 degree temperatures, then why were firefighters able to pour millions of gallons of water all over it and not trigger the deadly thermal explosions that are caused when water comes in contact with molten steel or iron?
In fact, firefighters did have to take care in their efforts because there was indeed a danger “that applying water to cool the steel could cause a steam explosion that would propel nearby objects with deadly force”, as the U.S. Department of Labor’s Occupational Safety & Health Administration noted in a report on the dangers of the Ground Zero worksite. Doh! The real question is: How, if firefighters poured millions of gallons of water, as well as the chemical fire suppressant Pyrocool, in addition to several rainfalls, did fires continue to burn within the debris piles for months?
If the lateral ejection of beams were caused by explosive nanothermites, then there would have been deafening 140 db sounds that can’t be muffled by more than a few db or you lose the explosive force of the shock wave itself.
This is again with reference to the Twin Towers, but still relevant, if nano-thermite was used in WTC 7. Mohr offers no source for his claim that nano-thermite would create “deafening 140 db sounds” when ignited. But the clue here is his reference to “the explosive force of the shock wave itself”. With conventional explosives used in controlled demolitions, like RDX, it is the pressure of the explosion that cuts through steel columns. With thermitic materials, however, it isn’t a high-pressure “shock wave”, but the exothermic reaction that melts through the steel. One patented device designed to employ thermitic materials for applications including demolition notes that a “primary disadvantage” of conventional demolition charges “is that they generate excessive noise and debris upon detonation”, while “Thermite-based cutting devises which employ a cutting flame produce relatively little over pressure.” While regular thermite is an incendiary, as the Department of Defense points out, nano-thermite has the potential for uses in “high-power, high-energy composite explosives”. But nano-thermite is “explosive” because of the great amount of energy it releases, not via high pressure “shock waves”, but via the even more energetic and more rapid exothermic reaction compared to regular thermite.
If there had been large explosions prior to the collapse, then they would have been a part of the seismic record, and they were not.
This is a non-sequitur. Mohr repeats the same fallacy, apparently assuming thermitic materials would “explode” in the sense that they would create a high-pressure “shock wave”. If conventional explosives were also used in conjunction with thermite, fewer would be required. And the fact is that there were explosions taking place that were documented on video. Many eyewitnesses reported explosions, explosions were captured on the audio of a number of videos, news reporters talked about explosions taking place well after the collapse of the Twin Towers, and there was speculation by some reporters live on air that these were cars exploding after having caught fire as a result of the collapses. It may be that there was some other such source of the explosions, but one can hardly deny that they took place. Two distinct explosions can be heard in the audio track of one video of WTC 7 immediately prior to the observable collapse of the east penthouse.