The tragic physics of the deadly explosion in Beirut
wired.com
wired.com
What isn’t quite so obvious is that roughly half the energy was also wasted upwards, and that a startlingly worse case would have been if the explosives had been slightly interred, coupling the blast more closely to the ground and enhancing amplitude of the p-waves and providing plenty of really substantial debris raining down after basically ‘earth-quaking’ the buildings.
Roughly combining the two 50% ‘wastages’ leaves you with about only one quarter of the energy was actually really channeled into destruction, which I’m going to be charitable and call a third. In ‘ideal’ conditions you might’ve had three times as much devastation, and that’s a pretty shocking thing to consider, given the actual carnage.
NOTE: I had appended these considerations in a more inchoate form to the tail-end of another comment, but I figured I’d make them an item of their own and tidy them up a bit. Apologies for the duplication.
However it seems very irresponsible to keep 85% of the country's grain in a single spot. It's scary how so many single points of failure exist.
EDIT: As for the grain silos being “single points of failure”, that depends on the scope of the system you’re considering. Nationally, yeah... but internationally, there’s plenty and it’s being shipped in. So there’s actually more redundancy than the narrow-scope analysis would suggest. The 85% figure is just a figment of where one draws the borders, and national borders probably don’t have much valence in the given context (fortunately). Now, if we were speaking about 85% of the world’s ability to ship grain... now that would be a catastrophe of unimaginable proportions.
No, half of the remaining energy. You can't discard two halves and expect to have something left.
Half stayed on-shore; of that half, half went into the sky. That’s half of a half which is a quarter, which I’m rounding up to a third because later I take the reciprocal so the higher proportion is a more conservative estimate.
2) you might be right I didn't pursue video evidences of shredded fingers and stayed with the dude saying
Then there are also illegal fireworks like 'Bex nitraat' (Bex is the brand name, and nitraat doesn't require translation) from Poland. Those will maul the entire hand, and are a guaranteed loss of fingers.
There is other illegal stuff like a 'Vlinderbom' (Butterfly bomb, known as a Spanish cracker in other countries). These have the explosive power of a small hand grenade and the aftermath of using one incorrectly doesn't need elaboration.
Also dry ice in bottles was fun and spud cannon got me interested in physics. Good times.
An old friend used to work in a chemical factory in, must have been Minnesota in the 60s or 70s.
She would talk about how they had a row of sheds with three walls for mixing certain dangerous chemicals. Each shed had an open or really thin wall facing the river.
If one went up, well, that person was probably gone, but at least it wouldn't start a chain reaction. It would explode in exactly one direction -- away from the plant, away from all the other dangerous chemical sheds.
An American contractor spotted and reported the potential danger at least four years ago, but U.S. officials denied they were aware of the findings until last week, after the blast."
This particular tit-bit at the end of the article is a gem. Times like these tend to also bring the best in some of us.
https://en.m.wikipedia.org/wiki/Vince_Coleman_(train_dispatc...
The death toll could have been worse had it not been for the self-sacrifice of an Intercolonial Railway dispatcher, Patrick Vincent (Vince) Coleman, operating at the railyard about 750 feet (230 m) from Pier 6, where the explosion occurred. He and his co-worker, William Lovett, learned of the dangerous cargo aboard the burning Mont-Blanc from a sailor and began to flee. Coleman remembered that an incoming passenger train from Saint John, New Brunswick, was due to arrive at the railyard within minutes. He returned to his post alone and continued to send out urgent telegraph messages to stop the train. Several variations of the message have been reported, among them this from the Maritime Museum of the Atlantic: "Hold up the train. Ammunition ship afire in harbor making for Pier 6 and will explode. Guess this will be my last message. Good-bye boys." Coleman's message was responsible for bringing all incoming trains around Halifax to a halt. It was heard by other stations all along the Intercolonial Railway, helping railway officials to respond immediately.
[1] https://en.wikipedia.org/wiki/Halifax_Explosion [2] https://en.m.wikipedia.org/wiki/Vince_Coleman_(train_dispatc...
The glass damage must be horrible. Your entire home covered in tiny pieces of glass.
I hate when glass breaks at home because no matter how much you clean, it gets everywhere and months later you discover small shards in some distant place.
Once I tripped on my way home after grocery shopping, almost at the destination. It wasn't even a big fall, but some glass bottles broke. They were next to plastic bags filled with oats. In the "recovery operations" I conducted afterwards, I threw away the remainders of the bottles and cleaned the oats bags under flowing water, to get rid of the glass bottle's contains on the bags. As I did this, I noticed the oats themselves getting wet, below the transparent plastic. I wondered, how can this happen, it's supposed to be water-proof. Then I found a tiny, almost invisible cut where a glass shard has entered the plastic bag. It was a big shard and I don't know what had happened had someone not noticed it and ate it.
Horrified, I threw away the entire bag of oats, the risk of more, possibly smaller shards remaining was too big. Other bags which passed the "water test" I kept and I ended up eating their contents.
I hope the people of Beirut are doing similar checks for their stored food, for their own safety. I read that many folks already have glass shards in their bodies due to the explosion but that's past damage that can only be managed. The future damage is preventable.
Watch this video at .25x to really see how glass reacts in the pressure wave. You can see the look on the bride's face as the initial vibrations/sound reaches her. Then, you can actually see the window pane bow like a wind sail.
https://www.cbc.ca/radio/asithappens/as-it-happens-friday-ed...
But I could equally imagine it’s some lesser explosion before the main blast.
Supersonic airplanes move past the speed of sound(280-340m/s in air) and generate wavefront at its interfaces with air but the resulting disjoint tsunami wave expands at the speed of sound and heard as single ‘bang’ when it reaches ears or microphones
So there’s no way one could hear the bang through air before visual bang hits
However the speed of sound is about 10x faster on solid mediums such as ground or seawater so could be those
You can hear several sonic booms in this video, although they're from low-flying planes: https://www.youtube.com/watch?v=jmhU7SEo4gg. The higher the plane, the more distinct and "bassy" the "booms". Here's another example, a bit higher, a bit more distinct: https://www.youtube.com/watch?v=M_KbZON5sW0
Shockwaves propagate faster than sound by definition.
The speed of sound depends on the medium, as a few replies have mentioned.
And in the same vein, what happens to peoples’ eyeglasses?
Does anyone know?
Eyeglasses are actually almost always made of dense plastic material these days for better refractive indexes so they shatter differently, also I wonder if physics people consider it to be practically suspended in thin air at the scales of these explosions
I can't imagine a situation where my glasses might shatter before my face would.
Windows break because they're thin and extend over large area, which make them flex a lot.
[0] https://en.wikipedia.org/wiki/Enschede_fireworks_disaster
If we'd expect that, then we'd have bigger problems in the first place.
That said, even regular windows were launched into people's houses (along with their frames) so I guess it wouldn't necessarily help here.
Laminating the glass would probably help for your regular/occasional explosion, but not for this, as you'd just have a giant pane smack you hard i guess.
I guess that process is also expensive?
> The energetic breaking of tempered glass still creates a lot of splinters though.
Interesting. I guess my only real experience with tempered glass was dropping a shower door while installing it. It absolutely shattered into a million pieces right away, but they weren't what I'd describe as splinters. More like little cubes without particularly sharp.
Unless there were also splinters everywhere, and I just didn't notice in the mess of my bathroom.
I broke a shower door too, while cleaning it. There were definitely splinters mixed in with all those cubes (and some in the hair on my arms). I'd imagine the physics is similar to when you snap a piece of uncooked spaghetti while holding it close to its ends - sometimes you end up with a small energetic middle piece that flies away.
But really this isn't especially similar.
There are plenty of videos of actual nuclear explosions.. e.g. https://www.youtube.com/watch?v=mP3bcPvgIG8
Feynman disagrees: https://www.realclearscience.com/blog/2016/04/what_its_like_...
I don't think his statement "bright light can never hurt your eyes" is correct, and I think "I got behind a truck windshield, because the ultraviolet can't go through glass, so that would be safe" is pretty questionable: glass filters ultraviolet, but I don't think it blocks it completely.
But fact is: Feynman looked at an atomic explosion and he wasn't blinded.
There’s been some strange tendency of late to conflate the weapons effects of nuclear or thermonuclear explosions with those of “really big amounts of conventional high explosive”. While that may even hold true at a sufficiently great radius, the proximate effects due to the near-instantaneous radiated energy is something that has no comparable analogue in the conventional world.
These effects are not really militarily useful, which is why even in the realm of small tactical nuclear weapons there has been a tendency towards minimising or not emphasising them, but...
The power of a nuclear weapon, intended properly as energy released per unit time, is in a league of it’s own.
Aside: for all the horror, at least this happened at the quayside and half the explosive force radiated away almost harmlessly over the sea. That basically halved the actual destruction at the outset. If it had been in the middle of the city, there would have been twice the damage.
EDIT: A startlingly worse case would have been if the explosives had been slightly interred, coupling the blast more closely to the ground and enhancing amplitude of the p-waves and providing plenty of really substantial debris raining down after basically ‘earth-quaking’ the buildings.
NOTE: Took the last paragraphs and placed them into their own comment, with logical conclusion. Apologies for the duplication.
Haven't people been using kilotons and megatons of TNT equivalent as a measure of nuclear bomb energy since the 1950s?
Atomic/nuclear survivors account often starts with a blinding flash then move to a mushroom cloud and scorched world, also consider that the wreck of the building directly under Hiroshima nuke still stands to this day
AFAIK that building survived not because nuclear blasts produce weak shockwaves, but rather because it was a very strong earthquake resistant building in the first place, and because it handled being loaded from above well (concrete and brick generally handle compression well.) If it had been a bit further to the side, I think it might not have remained standing.
Also note that you can hit "." on a paused video on youtube to go frame-by-frame.
Some observations:
* The camera vibrates long before the pressure wave reaches it. I assume this is due to energy traveling through the ground (i.e. an earthquake).
* On the third building from the bottom left there is some light reflected from another building's windows. Once the camera stops moving, these seem to still be moving.
* As the camera falls, two frames show a Nikon camera strap and a separate camera. It appears as if the photographer is taking stills. I haven't been able to find that these photographs were published, perhaps none were taken of the blast.
Had to check it out, earthquake p-waves travel really fast!
"Typical values for P-wave velocity in earthquakes are in the range 5 to 8 km/s."
1 - Earthquake
2 - Sound (sounded like rolling thunder or a jet breaking the sound barrier)
3 - Pressure wave (felt as a sudden, short-lived, strong wind at that distance)
I guess it makes it a proper shock wave, rather than just sound.
That's an amazing view. Terrifying. CGI people will be basing Hollywood explosions on this for years to come.
https://en.wikipedia.org/wiki/Halifax_Explosion
To this date Halifax has a medical specialty: eye damage. People were looking at the fire on board the boat and ended up with plate glass shards in their eyes.
I'm curious, is there something specific about "high explosives" vs "low explosives", beyond just the magnitude of energy released, that explains why some generate shock waves and others pressure waves?
Does that make any sense?
Or is diesel injected in to the cylinder in a way that more or less produces a controlled combustion?
"octane" is the ability of a fuel to "resist combustion" from compression. Diesel fuel is not rated in "octane" but the opposite: the ability for it to combust from compression. For some reason in the "old days", it was commonly thought by some that by adding some diesel to gasoline that it would help "lubricate" the motor (as diesel does have an oily feel). However mixing diesel with gasoline only lowers its octane rating.
Diesel engines avoid pre-ignition knocking by compressing only air. There is no compression of air/fuel mix. The fuel is injected into the hot, compressed air at the top of the compression stroke (at something like 3000+ PSI, IIRC).
The fuel does not have to be particularly volatile because of the high compression and the injector's atomization.
In theory, diesel engines can run on "anything". Diesel engines have been run on crude oil taken directly from the ground (of good purity), and on vegetable oil.
30,000 to 40,000 PSI
https://www.buyautoparts.com/blog/4-common-diesel-fuel-injec...
It mostly because the high pressure pump use the Diesel for lubrication so if you use something else the pump destroy itself sending tiny metal shards down the pipe and into the injectors.
That's why accidentally running a diesel car on gas turn expensive fast. The contrary is much cheaper as just have to flush the fuel lines and you're good to go.
The fuel is what burns turning into combustion byproducts. Larger volume -> high pressure -> physics magic I don't feel like explaining -> shock wave. Burning pure AN is a waste, you're basically burning super lean. Add fuel and you get closer to stoic. More efficient reaction -> more output volume per input volume -> more bang.
It's like the difference between making a bunch of gas fuel (like propane or something) go up as a woosh vs a bang but with solid inputs instead of gasses.
Nothing to do with a transition to high explosive, although it will destroy an engine just the same.
As a child, a friend and I were electrolyzing water, in an enclosed space. And so the hydrogen flashed. But the concentration was so low that the air just turned faint blue. There was no damage, to us or the building.
0) https://www.stuff.co.nz/national/114372936/how-did-anyone-su...
And my understanding of the "condensation wave" is that it's formation and dissipation is highly dependent on local conditions like humidity, temperate, etc.
She claims that measuring the speed of that "condensation" wave proves it's not a shockwave, the actual shockwave can move faster than the "condensation wave" (because it's formation and dissipation is highly variable).
High explosives cause air to be blown apart such that you're no longer just talking about a pressure wave, but talking about air flying with momentum faster than the speed of sound in a shockwave (at least until the shockwave loses energy and becomes a pressure wave).
I would expect the condensation wave (if one exists, which as you said is more likely during conditions of high relative humidity) to travel in sync with either a pressure wave or a shockwave though.
"High explosives produce shock waves; low explosives, like ammonium nitrate, produce pressure waves, which have a bit of slope to their shape, a period of time over which the pressure increases more gradually."
But a shock wave is an area of high pressure, so it's a "pressure wave" too.
And at least according to this Los Alamos article [1], "low explosives" versus "high explosives" is basically the difference between deflagration (rapid burning, e.g. black powder) versus detonation (chemical conversion happens faster than the speed of sound through the material, e.g. TNT).
By that definition, ammonium nitrate, is a high explosive. That's why they use it as the main blasting agent in mining operations.
[1]https://www.lanl.gov/museum/news/newsletter/2017/2017-04/hig...
pressure waves travel below speed of sound, shock waves travel faster than the speed of sound.
But her comment that ammonium nitrate is a "low explosive" doesn't line up with what I've read.
If you've ever done model rocketry you're restricted to low explosives for both motors and ejection charges, at least in the US.
"Explosive materials may be categorized by the speed at which they expand. Materials that detonate (the front of the chemical reaction moves faster through the material than the speed of sound) are said to be "high explosives" and materials that deflagrate are said to be "low explosives"."
Note that the relevant speed of sound here is the speed of sound in the material, not the speed of sound in air at STP. Once the reaction rate goes supersonic, the pressure rise becomes very sharp, like a shock wave in front of a supersonic jet. The very sharp pressure rise means that there's very little force pushing/scattering the explosive before there's enough pressure to crush the explosive sufficiently to cause it to react, so momentum is sufficient to contain the explosive long enough to get most of it to react, without the need for any container to hold it in place.
Without detonation, burning ammonium nitrate would have had a hard time building up pressure higher than the bursting pressure of the windows on the warehouse. Sure, the bursting pressure of the widows of the warehouse is high enough to break nearby windows and do damage, but orders of magnitude less damage than seen in this case. In the case of a deflagration, the generated overpressure is usually limited by the strength of the container (in this case, the warehouse). In a detonation, the reaction rate is such that the solid/liquid becomes a very hot gas essentially in-place (most secondary high explosives have very few solid reaction products).
There's basically a hierarchy of tendency to transition from normal burning (deflagration) to detonation (supersonic flame front): primary high explosives, secondary high explosives, insensitive high explosives, low explosives. Low explosives are difficult or impossible to get to detonate. Primary high explosives are typically the most dangerous, because they easily detonate once they start burning. (Also, the sort of instability for easy deflagration-to-detonation transition also correlates with instability when struck/dropped/crushed. The most common commercial primary explosives are lead azid and mercury fulminate, which obviously also throw around toxic heavy metal compounds.)
Insensitive high explosives are used in things like weapons that are designed to travel through brick walls or steel armor and explode on the other side. In such a case, (in the pre-electronic age), you'd have something like a momentum-based striker that strikes a percussion cap when the weapon makes impact, igniting a low explosive delay element (timing train) made out of something like solid pressed black powder, which would burn for a predictable period of time before igniting a small amount of primary explosive (e.g. lead azide). The primary explosive would start out deflagrating, but it easily undergoes deflagration-to-detonation transition, and detonates. The detonation shock wave from the primary high explosive sets of a small amount of secondary high explosive (say, PETN), which gives enough kick to set of the main charge of insensitive high explosive (such as ammonium picrate).
The compression of nuclear weapon fission primaries is usually done via insensitive high explosives that are also resistant to radiation degradation. Even though accidental detonation in a crash/drop would unlikely to cause a nuclear explosion, spreading toxic radioactive plutonium everywhere is still Very Bad (TM). I'm not a chemist, but I would guess that chemical stability against radiation degradation also correlates with pressure/temperature stability of insensitive high explosives.
During the Vietnam war, supposedly soldiers would sometimes burn C4 plastic explosives to heat food. C4 is basically RDX mixed with just enough polymer to make it into a pliable putty. RDX is very unlikely to undergo DTD transition, so this was relatively safe-ish, and RDX is chemically similar to hexamine solid fuel tablets used in some camping stoves. Dynamite is also a secondary high explosive, but nitroglycerine-containing dynamites are significantly less safe to burn than RDX.
That was my thought as well. I was skeptical of the article saying it wasn't a detonation of ammonium nitrate and that a shockwave wasn't generated.
I'm not sure about AN, but ANFO is a tertiary explosive. But primary/secondary/tertiary is a matter of sensitivity, not detonation velocity.
now both speeds will be slower than the speed of light in vaccum (as that is the highest speed that can be attained)
as the light "slows" down from faster speed to its normal speed radiation is emitted
The cloud wave is clearly expanding but it is behind the pressure wave that blows out windows on both the front and back (relative to the wave) of the highrise buildings.
Spectacular and horrifying physics.
It's a great article, and I know that I'm being pedantic, but chemical explosions need not involve oxygen. For example, consider acetylene and silver acetylide, with a carbon-carbon triple bond. Or lead azide, with a nitrogen-nitrogen triple bond.
They do need an oxidiser though. Which may or may not involve oxygen. You’re right of course, but redox itself has some poorly chosen jargon.
The jargon being that an oxidiser is an substance that can accept electrons, and doesn't have to by oxygen.
There’s also an enormous continuum of timescales, all the way from the detonation of high explosives, to deflagration of low explosives, combustion of fuels, to... sedate rusting, which is just oxidation of iron or steel. YMMV.
When lead azide detonates, you get elemental lead and diatomic nitrogen. So yes, the Pb++ oxidizes the azide.
When acetylene detonates, you get a mixture of organic compounds. But I don't believe that there's any redox involved. You just get various hydrocarbons with single and double carbon-carbon bonds. And just to be clear, this is when there's no oxidizing agent present.
> In January 2020, a judge launched an official investigation after it was discovered that Hangar 12 was unguarded, had a hole in its southern wall and one of its doors dislodged, meaning the hazardous material was at risk of being stolen.
> In his final report following the investigation, Prosecutor General Oweidat “gave orders immediately” to ensure hangar doors and holes were repaired and security provided, a second high-ranking security official who also requested anonymity said.
> ...During the work, sparks from welding took hold and fire started to spread, the official said.
It's really mind-boggling.
https://uk.reuters.com/article/uk-lebanon-security-blast-doc...
1 - Oct 2019: financial meltdown (still ongoing, local currency has lost 80% of value vs USD since then with no end in sight. Banks aren't giving out USD deposits either, you get to take them out in local currency and lose the difference in exchange rate)
2 - Protests, riots, etc... (since the meltdown and still ongoing)
3 - Pandemic, lockdown (Mar 2020, still ongoing with rising cases/day since measures were relaxed)
4 - Huge explosion takes out half the capital and what remains of the economy (The Beirut port runs about ~70% of all the sea trade volume of Lebanon).
The whole thing is literally stranger than fiction. Someone described the latest disaster like so: "The most shocking thing about the Beirut is explosion is how none of negligence and incompetence that led there is shocking".
It’s literally firecrackers going off. It’s one of those cases where if it quacks like a duck, waddles like a duck, and swims like a duck, it’s not a camel disguised as a duck.
https://interestingengineering.com/filming-the-first-millise...
https://en.wikipedia.org/wiki/ANFO
and has a much faster speed, around 4,200 m/s and only used in mining because it is extremely cheap and relatively more secure when compared to other (more powerful) explosives.
HN can help by getting their super wealthy excessively profitable FAANG & co employers to donate money. Apple alone has $193 billion in cash on hand, more than twice as much as Lebanon's total GDP (https://www.cnbc.com/2020/04/30/apple-q2-2020-cash-hoard-her... they could rebuild Beirut three times over and still have money left. Amazon has in the range of $70 billion cash on hand.
Don't feel like you have to donate when it's corporations that hold (and hoard) all the wealth. Call them out on it if they offer a pittance.
Apple / Tim Cook has indicated they will be donating, but no mention of how much: https://twitter.com/tim_cook/status/1291746412779069440 Couldn't find anything from the other big companies.
edit: dug up the fb post a friend had about it, it appears to be an internal programme
After all, it needs to be shipped, stored and used.
If there's shipping, there will be some port city not far.
And if there is industrial use, there will be workers, and some city as well to house the workers.
See:
- Halifax explosion (how hard is it to not make explosive-carrying ships go to ports?)
- AZF explosion (how hard is it to not locate factories far away from cities?)
- Texas City Refinery explosion (how hard is it to not let refinery workers inside the refinery?)
- Tianjin explosions (how hard is it to not locate a port city near its port?)
And so forth
https://www.npr.org/2020/08/07/899776352/beiruts-explosion-l...
Port authorities impounded the Rhosus in December 2013 by judicial order 2013/1031 due to outstanding debts owed to two companies that filed claims in Beirut courts, the state security report showed.
In May 2014, the ship was deemed unseaworthy and its cargo was unloaded in October 2014 and warehoused in what was known as Hangar 12.
In February 2015, Nadim Zwain, a judge from the Summary Affairs Court, which deals with urgent issues, appointed an expert to inspect the cargo, according to the security report.
The report said the expert concluded that the material was hazardous and, through the port authorities, requested it be transferred to the army. Reuters could not independently confirm the expert’s account.
Lebanese army command rejected the request and recommended the chemicals be transferred or sold to the privately owned Lebanese Explosives Company, the state security report said.
The report did not say why the army had refused to accept the cargo. A security official told Reuters it was because they didn’t need it. The army declined to comment.
The explosives company’s management told Reuters it had not been interested in purchasing confiscated material and the firm had its own suppliers and government import licences.
From then on, customs and security officials wrote to judges roughly every six months asking for the removal of the material, according to the requests seen by Reuters.
https://uk.reuters.com/article/uk-lebanon-security-blast-doc...
It's not clear to me why, if they knew it was dangerous and had been asking for it to be removed for years, they decided to store fireworks in the same building.
This is a classic example of "normal failure" and I am sure will join other similar incidents in the literature.
Storing fireworks in the same warehouse complex was - I honestly can't think of a word that fits.
I realise this seems weird to people living in a country which has all sorts of extremely restrictive and impressive safety protocols, but in poorer countries, this kind of mistake happens __all the time__.
It just doesn't normally result in much more than a small fire.
Port authorities (who were the ones reporting the danger) were arrested.
skimmed, since I'm on the clock, but holds the key info: https://www.mtv.com.lb/en/News/Local/1088201/Lebanons-leader...
And on top of that, according to the article, the fire was started by welders who were trying to repair doors to make the ammonium nitrate secure. It's like the plot of some dumb bloke movie: so absurd it would be comic if it weren't so terrible.