Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

twitter.com

Post reply on HN
Print view View original

31–40 of 255 posts

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

#31

Post by sinab »

contravariant wrote: post #24
sinab wrote: post #9

Earlier quoted context omitted.

The underlying assumption in this analysis is that the constant is 1. Maybe I should have clarified that in the thread.. Thank you for pointing it out!

Okay looks like there is some justification for that assumption given by G.I. Taylor. By the way with your data it looks like you get a better fit if you assume your first image is not at 50ms but rather 38 ms. A line fit between t and r^(5.2) gives a slope of 1.6 10^13. This gives 4 kt if you use the lower estimate of 1 kg/m^3 for the density of air. I do worry you may have overestimated the distance slightly, as th…

Absolutely, I do think it is an overestimate. The angle of the video makes it hard to accurately estimate the size of the ball, and as you rightly pointed out an epsilon difference in size gives epsilon^5 differences in energy, so size estimates are extremely important.

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

#32

Post by aaron695 »

gamblor956 wrote: post #30
aaron695 wrote: post #4

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 pandem…

This story is on the front page of every major news site in the world right now. They're not providing an "in-depth analysis" because there aren't yet sufficient facts to analyze. Even the authorities don't yet know what actually exploded, or what caused the explosion, or the number of dead, or the number of wounded, or the number of missing. Get off your high horse.

> Get off your high horse.

President Trump(And other world leaders) commented about 3 hours ago on this issue.

So the fact it's now made a headline is I guess your horse not mine.

And authorities do know what exploded, and have made statements. The initial fire is still uncertain.

This story was also on HN earlier and Flagged, because of complicated reasons, but it still probably shouldn't have been.

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

#33

Post by GaryNumanVevo »

aaron695 wrote: post #28
einarfd wrote: post #11

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-... .

I'd like to know why it initially sounds like fireworks https://twitter.com/HeshmatAlavi/status/1290683991369097216 [camera operator probably would have died in the second blast] Is that what set it off? Or is that what ammonium nitrate sounds like burning?

AFAIK the fireworks supply fire was the primary and the ammonium nitrate was secondary

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

#35

Post by ClumsyPilot »

jungletime wrote: post #26

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.

This speculation is silly, uninformed and unhelpfull.

There was a primary fire of fireworks, you dont need to invent conspiracy. Besides one does not need a drone to start a fire in an unattended warehouse.

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

#36

Post by actuator »

hn_throwaway_99 wrote: post #23
nodesocket wrote: post #17

Earlier quoted context omitted.

It's hard to imagine, but that would mean this explosion was nearly 3.5x larger than 2015 Tianjin[1] which was 800 tonnes of ammonium nitrate (336 tons TNT equivalent). The video[2] from Tianjin looked way bigger and apocalyptic, but perhaps just because of the the fireball. [1] https://en.wikipedia.org/wiki/2015_Tianjin_explosions [2] https://www.youtube.com/watch?v=ONsmJAyFAAw

Yeah, honestly, the Beirut explosion looked bigger/scarier to me, like how they show nuclear explosions in the movies. The Tianjin explosion was an enormous fireball but didn't seem to have the same magnitude of shockwave from the videos I've seen of it.

From the videos I have seen the Tianjin fireball seemed to rage even for a longer duration. In the Beirut one maybe because of daylight, fire is not visible after the big blast. I wonder what would cause that difference, the Beirut one supposedly had more material as well.

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

#37

Post by aaomidi »

actuator wrote: post #36
hn_throwaway_99 wrote: post #23

Earlier quoted context omitted.

Yeah, honestly, the Beirut explosion looked bigger/scarier to me, like how they show nuclear explosions in the movies. The Tianjin explosion was an enormous fireball but didn't seem to have the same magnitude of shockwave from the videos I've seen of it.

From the videos I have seen the Tianjin fireball seemed to rage even for a longer duration. In the Beirut one maybe because of daylight, fire is not visible after the big blast. I wonder what would cause that difference, the Beirut one supposedly had more material as well.

Longer fire = less energy for explosion?

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

#38

Post by JorgeGT »

einarfd wrote: post #11

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-... .

Note that since ammonium nitrate has relative efectiveness (RE) factor of 0.42 [1] those ~3000 tons of AN would yield ~1.2 kt rather than 3 kt.

[1] https://www.bits.de/NRANEU/others/amd-us-archive/fm5-250%289... page 30

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

#39

Post by jcranmer »

aaron695 wrote: post #28
einarfd wrote: post #11

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-... .

I'd like to know why it initially sounds like fireworks https://twitter.com/HeshmatAlavi/status/1290683991369097216 [camera operator probably would have died in the second blast] Is that what set it off? Or is that what ammonium nitrate sounds like burning?

From what I understand, ammonium nitrate isn't particularly flammable, until it gets hot--then it gets explosive. Furthermore, ammonium nitrate conflagrations tend to give a distinctive reddish smoke cloud.

The cloud accompanying the big explosion has a very distinct red tint to it, indicating that it's a result of the ammonium nitrate going off. That before it doesn't, which suggests that the ammonium nitrate wasn't burning at the time. If you compare the Texas City disaster, it's noted that spectators were drawn towards the site by the unusual smoke clouds before the big explosion happened.

There's a lot of details that aren't clear yet, but a variety of materials being stored in a warehouse catching fire, with fireworks going off first and the ammonium nitrate going off last, is consistent with the known facts. It would, however, be exceptionally bad safety practices to store ammonium nitrate anywhere near something like fireworks. Then again, storing a large amount in a warehouse right next to downtown Beirut is itself insane, considering it has a history of being implicated in the largest explosions not involving nuclear weapons.

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

#40

Post by jcranmer »

Aerroon wrote: post #15
credit_guy wrote: post #10

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…

The ship you can see in the bottom left of the Yamato's explosion (link [2]) is a Japanese destroyer. I'm not sure which ship it is specifically, but she is likely 100-130 meters in length (those were the only ones around at the time Yamato sank). And she's closer than the actual cloud.

Another fun note about Yamato's explosion is that it appears to have been responsible for more plane losses than all of the AA fire during the battle. For a battleship with well over 100 AA guns, that's a pretty damning indictment of their quality.
Post reply on HN