from Hacker News

Order of magnitude estimate of Beirut explosion at 3 kilotons of TNT

by sinab on 8/4/20, 7:43 PM with 247 comments

by supernova87a on 8/5/20, 6:47 AM
The amount of material must have been ridiculous to store in such a place. The blast is staggering in size, almost like the Tianjin explosion a few years ago.
Collected videos:
Angle #1 https://streamable.com/xmmoa7
Angle #2 https://streamable.com/nscx9m
Angle #3 https://streamable.com/zbjj5f
Angle #4 https://streamable.com/saoafz
Angle #5 https://streamable.com/4ga1vb
Angle #6 https://streamable.com/lmivb2
Angle #7 https://streamable.com/mcy82f
Angle #8 https://streamable.com/zg9oal
Angle #9 https://streamable.com/zykkj6
Angle #10 https://streamable.com/22e152
by sillysaurusx on 8/5/20, 4:57 AM
@quantian1 correctly determined that this was an ammonium nitrate blast by analyzing the footage:
https://twitter.com/quantian1/status/1290695231910875136
CHEMISTRY FACT: Explosives have characteristic "detonation velocities" at which shockwaves expand. Smartphone video records at 30 FPS, so the adjacent frames here suggest the front expands at ~100 m/(1/30 sec), or 3,000 m/sec. Consistent with ammonium nitrate, not black powder.
This was confirmed a few hours later:
https://twitter.com/BBCBreaking/status/1290758551737192455
Lebanese president blames 2,750 tonnes of ammonium nitrate left in warehouse unchecked for six years for devastating Beirut blast
EDIT: By the way, one of my friends was almost killed by the explosion. Thankfully they're ok. But they said:
https://twitter.com/cyrilzakka/status/1290766217989500928
This was terrifying to experience. Hospitals are being overrun with injured people. We need blood donations and disaster relief. Help however you can.
As a US citizen, is there any way I can help directly? Is there any organization that ships blood donations directly to a disaster site? I suppose that would be very difficult, so the answer is probably no; it's frustrating not being able to assist.
by kgm on 8/5/20, 2:02 AM
I am seeing other analyses that put the size of the explosion at about one tenth of this size.
The analysis in this Twitter thread correlates the observed degree of damage with the distance from the explosion. It comes up with an estimated 240 tons TNT-equivalent, though naturally this comes with a considerable margin of error.
https://twitter.com/GeorgeWHerbert/status/129071971954515968...
This Twitter thread is making the point that the explosiveness of ammonium nitrate can vary significantly depending on how it is stored. 2750 tons of AN at 20% efficiency gives 550 tons TNT.
https://twitter.com/ArmsControlWonk/status/12907955327014256...
This range is also apparently consistent with the explosion registering as a 3.5 seismic magnitude.
https://twitter.com/ArmsControlWonk/status/12907348507695267...
There are still a great many unknowns, and none of this should be mistaken for the real analysis which will come later, but these disparate sources of information all seem to agree with each other, to a first approximation.
by einarfd on 8/4/20, 9:40 PM
Al Jazeera is reporting that according to the president in Lebanon, it was almost three thousand tons of ammonium nitrate that blew up https://www.aljazeera.com/news/2020/08/huge-explosion-rocks-... .
by sio8ohPi on 8/4/20, 8:11 PM
Similar in size to the Halifax explosion, then.
https://en.wikipedia.org/wiki/Halifax_Explosion
by tzs on 8/5/20, 3:13 AM
This video [1] from The Guardian include the same video in that tweet, but also has a few other angles which gives a better appreciation of how big that thing was.
[1] https://www.youtube.com/watch?v=93tV6-0Ugwk
by lma21 on 8/5/20, 10:03 AM
I have family and friends living in Lebanon. The explosion destroyed the windows of most homes in Beirut. Apartments of my family, friends, and colleagues have been shattered. Even the ones living dozens of kilometers away from Beirut. It's horrible, what pure incompetence can do to a people already living in poverty and under the covid-stress. I hope something good comes out of this...
by bluenose69 on 8/5/20, 11:22 AM
The following is a citation for the seminal paper on this matter. G. I. Taylor was a god of fluid mechanics, and quite a lot of his work is available online for free.
Taylor, Geoffrey. “The Formation of a Blast Wave by a Very Intense Explosion. - II. The Atomic Explosion of 1945.” Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences 201, no. 1065 (March 22, 1950): 175. https://doi.org/10.1098/rspa.1950.0050
by KMag on 8/5/20, 3:24 AM
Note that the distinctive orange color is probably a large volume of nitrogen dioxide at pretty high concentration. If it was an ammonium nitrate explosion, the orange cloud supports the idea it was accidental. The explosion would have been easier to set off and more powerful had there been a fuel (or more fuel) mixed with the ammonium nitrate.
by Leherenn on 8/4/20, 10:10 PM
A comparable explosion happened in Toulouse, France, in 2001, estimated at 20-40 tons of TNT.
It was also some nitrate storage that blew up. Similar end result, pretty much everything window in the city was blown away, and most of the injuries were caused by broken glass.
by emeraldd on 8/5/20, 1:04 AM
When they started talking about ammonium nitrate, my first thought was of this:
https://en.wikipedia.org/wiki/West_Fertilizer_Company_explos...
and the possibility of a shipment of fertilizer somehow getting caught in a fire ...
by animal_spirits on 8/4/20, 8:02 PM
I am awestruck. What an awful event. I will be keeping up to date with this and looking for ways I can help... All I know to do right now is pray for those that have suffered from this. My breath has been taken away...
by credit_guy on 8/4/20, 9:30 PM
Wikipedia's page of the largest non-nuclear explosions [1] was already updated and states "It generated a shock-waves equivalent to 13 tonnes TNT". Not sure who made this estimation and how, but various photos on that page can give you an idea what a large explosion looks like. For example take a look at the Yamato explosion [2]. Yamato was a 70000 ton Japanese battleship; the large explosion was due to its magazines being hit by bombs (this happened quite frequently when battleships were hit as they were fundamentally stacks and stacks of gun ammunition surrounded by a hull); it's likely that Yamato was carrying a few thousand tons of explosives, so that's how you get a few kt TNT non-nuclear explosion. Now in that photo you can see for reference another ship in the lower left. It looks quite puny. So, it appears to me the Yamato mushroom cloud was much, much bigger than today's mushroom cloud in Beirut.
Edit: The wikipedia page was updated and now states 1kt TNT.
[1] https://en.wikipedia.org/wiki/Largest_artificial_non-nuclear...
[2] https://en.wikipedia.org/wiki/Largest_artificial_non-nuclear...
by jonplackett on 8/5/20, 7:25 AM
This is insane, this is tactical nuclear weapon size explosion right? I think they start at under 1kt up to about 10kt
(not saying it is one, just for comparison of how insanely massive this explosion is)
by ashtonkem on 8/5/20, 7:42 AM
This seems unlikely.
Officially, they had 2750 tones of ammonium nitrate on that dock. Even if it were properly mixed with fuel oil to make ANFO, that would give you 2200 tones of tnt equivalent. It is quite unlikely that it was mixed to the perfect proportions, so we’d expect actual yield to be below theoretical max
So unless if something else was involved (or the official amount of ammonium nitrate was wrong) I would expect the final blast to be under 2kt.
by contravariant on 8/4/20, 9:17 PM
Unless I'm missing something they forgot to account for the fact that dimensional analysis will only give you a result up to a constant.
This should be somewhat obvious as otherwise you'd get a different result with different units (and no SI units won't save you here, those just work for several common equations in physics not ones you came up with yourself).
by guerrilla on 8/5/20, 2:22 AM
> The cause of the explosion was not immediately clear. Officials linked the explosion to some 2,700 tonnes of confiscated ammonium nitrate that were being stored in a warehouse at the port for six years.
https://www.aljazeera.com/news/2020/08/huge-explosion-rocks-...
by aunetx on 8/5/20, 8:03 AM
This reminds me a lot about AZF, a chemical explosion that happened in Toulouse, France back in 2001 [1]... And it was hundred of tons of ammonium nitrate here too.
[1] https://en.wikipedia.org/wiki/Toulouse_chemical_factory_expl...
by worldpeacenow on 8/5/20, 1:43 PM
Ammonium nitrate is 1.35 less potent than TNT. So this was just over 2,000 tons of TNT blast. The first nuclear bomb ever dropped was 15,000 tons of TNT of force. So this was 13.3% of the force of what Hiroshima experienced. About 70,000 people died from Hiroshima. So 13.3% of Hiroshima force is still devastating. It's probably not going to be nearly as bad as 13.3% of 70,000 deaths because Hiroshima was more densely packed and there wasn't the electromagnetic pulse wave that vaporizes people and long lingering radiation associated with a nuclear bomb. ... Still what happened in Beirut is immensely devastating.
by sytelus on 8/5/20, 4:54 AM
Just in case people are wondering reason this explosion: there was 2,750 tonnes of ammonium nitrate stored without safety measures in a warehouse that went off.
by totalZero on 8/6/20, 9:27 AM
I wonder if the shape of the storage receptacle and the geometry of surrounding buildings could have resulted in an elliptical fireball shape. If so, that could be one drawback of this method. Depending on viewing angle, you could overestimate or underestimate the R figure versus a same-energy spherical fireball.
by RantyDave on 8/6/20, 2:39 AM
No. Because that would imply that ammonium nitrate has a higher specific energy than TNT. Which it doesn't.
https://en.wikipedia.org/wiki/Energy_density_Extended_Refere...
by agumonkey on 8/5/20, 9:20 AM
What are the pollution consequences of this (if any) ?
by golemiprague on 8/5/20, 3:11 AM
what was the white ball during the explosion? it looks like some liquid spraying up in the shape of a ball, was it sea water? other liquid? or was it just looking to me like a liquid but actually was gas of something?
by SDJ100 on 8/5/20, 9:18 AM
According to my estimate the Beirut explosion was about one quarter the explosive force of the Hiroshima bomb. Does anyone concur with this?
by SDJ100 on 8/5/20, 9:20 AM
I estimate the Beirut explosion was one quarter the explosive force of the Hiroshima bomb. Does anyone concur?
by privateuser1981 on 8/4/20, 9:19 PM
At max 0.2K TNT
by shadowprofile77 on 8/5/20, 1:57 AM
Nitpicking here maybe but this does not look like a 3 kiloton blast to me. Neither the size of the core explosion or the apparent shock wave damage correspond to that magnitude from a surface blast. Guessing here but I'd say closer to 2 kilotons at most.
Amazingly, the massive, hollow grain silo right next to the detonation itself remained standing afterwards.
by jungletime on 8/4/20, 10:54 PM
Lebanon has its share of enemies, internal and external. All it would take is a mavic inspire drone to fly over and drop the initial explosive.
Trump said "it looks like a terrible attack" at his news conference. Which is probably what his intelligence officers/advisors speculated when they briefed him.
by aaron695 on 8/4/20, 8:51 PM
The media doesn't seem to understand how big this is yet in short and long term damage and loss of life. I guess that doesn't matter? They are more for political bickering now?
Running theory Ammonium Nitrate stored at port for many years -
https://mobile.twitter.com/HachemYassin/status/1290702640930...
[Edit] Skipping the loss of grain and produce in port and the actual port in a country on the brink during a pandemic this isn't just 50 dead short term https://mobile.twitter.com/asharfouch/status/129071410457584...
by aaron695 on 8/5/20, 1:48 AM
I should just pre-flag this comment, so feel free.
But Hezbollah use Ammonium Nitrate and could use the other small explosives stored near by.
I think under current rules being actioned if there was intel people were stealing from the factory it would be considered a legitimate target.
The question would be, would the analysis of intel be good enough to know exactly what was stored there and if it is clearly not an appropriate target. And I think their analysis would suck.
If you want a source, the President of the United States said it was an attack. So we either believe official statements or we should learn to think for ourselves.
Equally arson or a fire due to lack of security and maintenance due to coronavirus stress.