After reading a report on the attack against the UN that killed Sergio Vieira de Mello it seemed apparent that maybe the intention all along was to make the building crumble and crush the UN representative underneath if the blast didnt get him.
I am no engineer… so this seemed at best speculation. Then thinking back to the attacks carried out in the past there seemed to be hints to prod my curiousity. Some questions arose too:
The 2 embassies in Africa suffered similar “demolishing” effects. Or did Al Qaeda just put something massive to blow up like the Oklahoma incident ? Were the bombs especially designed to flatten the buildings ?
The USS Cole was targeted in a specifically critical area of the ship ? Was the dinghy boat trying to get a critical area or is the midship area ideal to try and sink it ?
WTC ended up crashing… even thou they were pretty big and solid. The Bali bombings got a high number of casualties.
I know explosives demand a certain amount of traning and study… and that might mean easily coordination with engineers. My intention is not to discuss WHO did WHAT… but if attacks are being carried out with greater than expected Expertise and Knowledge ? This might also mean inside information or acess to blue prints ? Or just plain luck hitting the right spot in buildings ?
There is not a huge amount of technical expertise needed to demolish things effectively, if one is not worried about collateral damage to the surroundings.
I have an MS and BS-ME. If anyone had asked me a year before 9/11 how to bring down the WTC towers, and I was an irresponsible person, I would have listed a plane crash among the ways it could be done. If anyone had asked me how to blow up a large building like in OK City without using “professional” explosives, if was irresponsible enough to suggest things, one of my suggestions would have been ANFO. I’m not sure that the Cole was necessarily hit in its most vital area, although it was effective. I would not have personally thought of motorboats used in that manner, as I would have thought that there would have been higher security involved. But given no security, I’m sure I would have thought up small boats.
Mechanical and structural Engineers like myself know a lot of things about how buildings and structures go together, and how they fall down or come apart. Add to this the large number of people who receive detailed demolition training in the military Engineering corps, and those who train with professional commercial demotition teams, and there are a lot of people that have a good level of knowledge on how to bring things down.
I hope this thread won’t turn into a liberal arts vs. engineers thread like I’ve seen before on other boards, where English and Film majors talk about how Engineers need to be “monitored” by the government so we all don’t run around destroying things.
Anthracite… so from the skimp info given on most of these attacks… especially the African Embassies and the UN building… does it appear that they have pretty good technical planning behind these attacks or just an awful lot of explosives ?
External building structure hits tend to rely on just huge amounts of explosives. Buildings sometimes do have a “strong” side to them - one side with especially few windows, one which contains elevator and service shafts, or for some reason or another has been reinforced (the building I’m in now is divided into two zones - one can reputedly take 220-mph winds, the other only 130-mph). And there are some obvious things too - corners are stronger and the blast doesn’t hit as “solidly” (using a non-technical term) as there isn’t enough frontal area to absorb the blast.
Distance is key. When dealing with external explosives, the inverse square law comes into play very quickly, which essentially means you want to get as close as possible to the building, since in a non-directional explosion, the force on the target will greatly diminish as you move away from it. The recent Marriott bombing is an example of that - it was so close that the building and its occupants ended up absorbing most of the blast from a large 3D angle of effect.
Not knowing anything really about the specifics, I could not comment much on the technology or planning of the current atrocities, including the Indian ones. You may want to examine in detail the Oklahoma City atrocity, as it was incredibly uncomplicated but horrifyingly successful.
What’s the main defense of a building against a structure hit? Simple - keep the cars and trucks at a distance with tank-trap type barriers. A long distance away, perhaps as much as 300 feet. While this is not practical in most all urban areas, the amount of explosives a few people can carry up to a building quickly is not likely to result in mass destruction. Of course, now we have the situation of airplanes as missiles, so really there isn’t much to do to defend against those.
The MO in all the above seems the same to me; drive up with a load of explosives and ‘boom’ – only exception was 9/11 and after OBL/a-Q tried the ‘boom’ method in 1993. Frankly, it’s difficult to imagine there’s much time to locate ‘Position A’, you just point yourself in the general direction and get as close as you can before you’re stopped.
Thing about 9/11 was that it did demonstrate ‘terrorism’ had crept into the post-Grad, family-man, whole-lot-to-lose middle classes (and away from it’s usual base of the teen hot-head with an AK47 growing up in uneducated poverty), but the primary expertise there was in the flying. Beyond 9/11, I’m not aware we’ve seen any new sophistication. More money oiling the works and organisation, maybe, which can make things look of a higher quality.
I believe I’ve read expressions of surprise by OBL that the Towers actually came down, and he’s from a major construction family fwiw.
If you were to fill a semi trailer with fertilizer based explosives, would it be possible to shape the explosion somehow to direct more of it at the building, Anthracite? I know that shaped charges are used in the military, and that the explosive container of a nuclear bomb is a kind of shaped charge, but can you do such a thing with something as low-tech as a truck full of fertilizer?
By all means, shy away from the details so you’re not telling anyone how to do it. I’m just curious if it’s possible.
They didnt expect to drop the towers from what Osama said … but they certainly tried to get as much damage as possible. The flying expertise was gained in US soil… so not sure that “counts”. I was thinking more of the planning phase itself.
The truck bomb was used in Lebanon 1982 and in other ocassions... so its an old tactic. I was just curious to see if its being used with a modicum of more sophistication since buildings are collapsing with frequency in these attacks. The terrorists themselves are coming from a wider background for sure...and various nationalites working together... always a bad sign.
I plead ignorance as to whether something of that magnitude can be shaped in a manner similar to ordinance. I’m strongly suspecting it would be very difficult with that level of power and that flimsy a container to direct a charge, but I would have to defer to a munitions expert. There is also the issue of proper detonation - IIRC from my talks with an ex-professor who worked for the Army (who had very interesting stories to tell about why certain things are like they are on the M16, but that’s another story), proper shaping of a large blast relies a lot of exact timing, both in the trigger mechanism and the explosive media itself. Something like ANFO, which can be a relatively inconsistent material, is very difficult to detonate with proper timing or sequence. He was talking about fractions of milliseconds in timing, of course. He said that other “more reliable” explosives are limited by timing and “programming”, so to speak, but that was not something he ever got into.
By far, the worst thing that can be done is to have the vehicle enter the building before exploding.
I think that in the case of 9/11 the terrorists Technial/Enginerring skills were not that good. Because it does not take a genius to know that if you crash a huge plane full of jet fuel, into a tall building, it might collapse.
I also think that their Technical/Engineering knowledge was limited as if they had of crashed the planes lower down the WTC then the damage would have been a lot worse and the buildings may have even collapsed faster killing a lot more people, obviously from our point of view we are very very lucky they did not do that, but from a terrorists point of view it seems strange they did not do that.