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

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

#201

Post by Denvercoder9 »

rmm wrote: post #73
WalterBright wrote: post #52

Earlier quoted context omitted.

My fluid mechanics prof told the class that a scientist in the 1940's published the yield of the Hiroshima bomb. Since this was top secret, he got investigated. But he showed how the yield could be calculated from the film of the explosion - how fast the blast radius expanded. So I imagine the yield of the Beirut explosion could be calculated the same way from the video.

Paper in question. http://sites.science.oregonstate.edu/~restrepo/MTH481/Classn... From videos: R=450m t=1.5s rho=1.2kg/m3 E=9.84E12 kg.m2/s2 or 9.84E19 erg Equiv TNT = 2.5kTonnes -TNT Equiv AN = 5400 Tonnes So double what current media is saying. edit:formatting.

You have to be careful about your errors though with this method, because you get higher-order powers. If the radius estimation was wrong by only 10%, your final answer will be wrong by almost 50%.

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

#202

Post by Donthatme »

throwaway_pdp09 wrote: post #113
sillysaurusx wrote: post #76

@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…

(utter newbie here): "Explosives have characteristic "detonation velocities" at which shockwaves expand" but the detonation velocity isn't that; from https://en.wikipedia.org/wiki/Detonation_velocity "Explosive velocity, also known as detonation velocity or velocity of detonation (VoD), is the velocity at which the shock wave front travels through a detonated explosive." I assume that for an infintely sharp explosion…

Looking into blast waves might be of interest. The jargon of the difference between a shock wave and a blast wave somewhat depends on the sub field of interest.

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

#203

Post by taneq »

peteretep wrote: post #99
sillysaurusx wrote: post #76

@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…

> help directly You could do much worse than donating to the Red Cross and selecting “Disaster Relief”, and if you want to take an action, call your representatives and let them know how important you’d find a robust USAID response. Neither are sexy options, but both will have an effect https://www.redcross.org/donate/D072002.html

It's a different branch of the Red Cross, but I gave them some money back when the Philippines was hit by an earthquake and a cyclone in quick succession. I swear they spent more on sending me big glossy fundraising brochures every few months for the next decade than I'd donated in the first place. I later read that the Philippines only got a small percentage of their donations for that campaign.

Never again.

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

#204

Post by privateuser1981 »

AnimalMuppet wrote: post #13
privateuser1981 wrote: post #7

At max 0.2K TNT

What is your evidence or logic for claiming so? Just a bare claim is not very convincing.

This was the aftermath of 15 kilotons: https://upload.wikimedia.org/wikipedia/commons/a/a0/Hiroshim...

Despite 2750T of ammonium nitrate the yield of explosion was around 0.2-0.3KT TNT

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

#205

Post by coldcode »

emeraldd wrote: post #34

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 ...

When I first saw the initial video, I immediately assumed a nitrate explosion. A bomb that large would be too hard to place or even deliver (if a plane), and fireworks would not explode with a such a perfect shockwave. The red color of the original smoke is rather telling as well and that it occurred in a dockyard.

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

#206

Post by caf »

madaxe_again wrote: post #156
sillysaurusx wrote: post #76

@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…

There’s an even easier giveaway - the bloody great cloud of NO2 that immediately appears. I think anyone who’s ever seen a fertiliser dump go up will have immediately recognised this explosion - reminded me of my childhood, when we’d regularly go and explode things with the stuff.

Known in liquid fuelled rocketry as a BFRC.

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

#207

Post by mattkrause »

moksly wrote: post #108
colordrops wrote: post #96

Earlier quoted context omitted.

Trump is saying that military intelligence indicates that it's a bomb: https://m.youtube.com/watch?v=tPvH-CqH7Q8 Edit: why am I being downvoted. I am not agreeing with him or saying he is right. Just stating what was said. It seems noteworthy that the president of the US commented on it regardless of accuracy or trustworthiness.

Why is Trump used as a source on HN? I don’t think I’ve ever seen that man say something that was useful or true. I’m not American, mind you, so I’m certainly biased because he’s mainly in our media when he does something stupid, but everything I have ever heard him say about Europe has been so far from the truth that it’s hard to take his word on anything.

You are mixing up two related issues.

Trump may be a terrible source for actual facts. You would be nuts to use his statements as advice for running your own dockyard, for example.

Nevertheless, what he thinks about this is relevant because it will shape how the US reacts.

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

#208

Post by luxuryballs »

p1necone wrote: post #110
colordrops wrote: post #96

Earlier quoted context omitted.

Trump is saying that military intelligence indicates that it's a bomb: https://m.youtube.com/watch?v=tPvH-CqH7Q8 Edit: why am I being downvoted. I am not agreeing with him or saying he is right. Just stating what was said. It seems noteworthy that the president of the US commented on it regardless of accuracy or trustworthiness.

Trump is not a reliable source for anything. He lies/misleads more than he tells the truth whenever he's talking about something verifiable as far as I can tell.

"We have a very good relationship with the people of Lebanon and we will be there to help. It looks like a terrible attack," Trump told reporters at the White House.

"I've met with some of our great generals and they just seem to feel that this was not some kind of manufacturing explosion type of an event ... They seem to think it was an attack. It was a bomb of some kind."

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

#209

Post by p1necone »

rendall wrote: post #183
speedgoose wrote: post #140

Earlier quoted context omitted.

Unverified and likely false information (fake news) is downvoted. If you question the accuracy of the information it's better, still not good, but you didn't before your edit.

It is literally true that Trump said it was a military attack, as OP stated. This is verifiable. That Trump's statement is false and dangerously irresponsible is not OP's fault.

Generally other people's misinformation should not be shared without some kind of disclaimer that it isn't true

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

#210

Post by caf »

lm28469 wrote: post #178
kgm wrote: post #44

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 mak…

> I am seeing other analyses that put the size of the explosion at about one tenth of this size. Random twitter users are guesstimating from smartphones videos and have 0 knowledge of the actual location, so yeah, it's just guesstimates. I'm still wondering why people do that, it's kind of a weird flex and bring literally nothing of value to the table besides trying to sound like a smartass.

Some of those are involved in the OSINT community where they do this as their day job, because analysing random strange explosions can sometimes tell you things about military weapons development programs that aren't otherwise advertised.
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