# How large was the explosion at Tianjin? **URL:** \ **Category:** Factual Questions\ **Created:** [August 13, 2015, 8:40pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772 "2015-08-13T20:40:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Fiendish\_Astronaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiendish_astronaut/32/3295_2.png) [@Fiendish\_Astronaut](https://boards.straightdope.com/u/Fiendish_Astronaut)\ **Post date:** [August 13, 2015, 8:40pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/1 "2015-08-13T20:40:18Z")
I’ve heard many guestimates of the size of the recent explosion in the Chinese city of Tianjin. One commentator measured the size of the fireball and claimed it was 21 kilotons - which would make it bigger than the 16kt atomic explosion at Hiroshima. I found that difficult to believe at first because of the destructive force of that bomb and the numbers of casualties - but that was an air burst in a populated city centre with cheap buildings. Anyway, the question I have is multifold - how does one calculate the size of such an explosion? Can it be done using the size of the fireball or is it much more complex? And just how big was the Tianjin explosion? Thanks in advance! ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [August 13, 2015, 10:04pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/2 "2015-08-13T22:04:32Z")
The [USGS is reporting seismological readings](http://www.bbc.com/news/world-asia-china-33901206) of a magnitude 2 or 3 earthquake. It’s difficult to pin that down because the Chinese seismographs are considered suspect and the explosions occurred on the surface (water? boat? land?). The seismographs used to determine magnitude are outside of China. Another unidentified source was claiming/interpreting the force of the blast was equivalent to 3 to 21 tons of TNT. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [August 13, 2015, 10:08pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/3 "2015-08-13T22:08:33Z")
> [@Duckster](#): > > Another unidentified source was claiming/interpreting the force of the blast was equivalent to 3 to 21 tons of TNT. Wow. That was precise. 😃 ---
**Author:** ![snfaulkner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snfaulkner/32/433_2.png) [@snfaulkner](https://boards.straightdope.com/u/snfaulkner)\ **Post date:** [August 13, 2015, 10:36pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/4 "2015-08-13T22:36:38Z")
Precise indeed. So right now it’s any where from 3 tons, all the way up to 21 kilotons? ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [August 13, 2015, 10:50pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/5 "2015-08-13T22:50:07Z")
> [@Duckster](#): > > Another unidentified source was claiming/interpreting the force of the blast was equivalent to 3 to 21 tons of TNT. Which is almost certainly underestimating the magnitude by a very wide margin. Remember, he said “tons” not “kilotons”, which is 1,000x larger. For comparison’s sake, the [Texas City disaster,](https://en.wikipedia.org/wiki/Texas_City_disaster) which killed 581 people and leveled two square miles of the city, is estimated at nearly 3.2 kilotons equivalent. ---
**Author:** ![snfaulkner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snfaulkner/32/433_2.png) [@snfaulkner](https://boards.straightdope.com/u/snfaulkner)\ **Post date:** [August 13, 2015, 11:15pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/6 "2015-08-13T23:15:02Z")
I just went out to get a burrito since my last post on this topic and npr quoted the 21 tons number. ---
**Author:** ![standingwave](https://avatars.discourse-cdn.com/v4/letter/s/9de0a6/32.png) [@standingwave](https://boards.straightdope.com/u/standingwave)\ **Post date:** [August 13, 2015, 11:29pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/7 "2015-08-13T23:29:35Z")
> [@Duckster](#): > > The [USGS is reporting seismological readings](http://www.bbc.com/news/world-asia-china-33901206) of a magnitude 2 or 3 earthquake. It’s difficult to pin that down because the Chinese seismographs are considered suspect and the explosions occurred on the surface (water? boat? land?). The seismographs used to determine magnitude are outside of China. Another unidentified source was claiming/interpreting the force of the blast was equivalent to 3 to 21 tons of TNT. Two separate blasts, 3 _and_ 21 tons: The [China Earthquake Networks Centre said](http://www.bbc.com/news/world-asia-china-33896292) the magnitude of the first explosion was the equivalent of detonating three tons of TNT, while the second was the equivalent of 21 tonnes of the explosive. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [August 14, 2015, 12:10am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/8 "2015-08-14T00:10:06Z")
My guess is that your commentator either said 21 **tons** , not 21 _kilo_tons, and you misheard, or else he misspoke. Seems likelier than being off by a factor of 1,000. ---
**Author:** ![Morgenstern](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)\ **Post date:** [August 14, 2015, 12:11am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/9 "2015-08-14T00:11:52Z")
For comparison purposes, does anyone have a guesstimate on the stats for the Oklahoma City federal building explosion? ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [August 14, 2015, 12:52am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/10 "2015-08-14T00:52:32Z")
> [@Morgenstern](#): > > For comparison purposes, does anyone have a guesstimate on the stats for the Oklahoma City federal building explosion? Wiki says the [OK City blast](https://en.wikipedia.org/wiki/Oklahoma_City_bombing#Bombing) was equal to 5,000 pounds of TNT, or 2.5 tons (not kilotons). But it should be noted that most of the fatalities were caused by the building’s collapse, not the explosion itself. ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [August 14, 2015, 2:51am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/11 "2015-08-14T02:51:45Z")
Watching videos online of the explosion, it is formidable to think that the bombs dropped on Japan were about 1000 more powerful assuming the explosion in China was about 15-20 tons. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [August 14, 2015, 3:25am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/12 "2015-08-14T03:25:42Z")
> [@snfaulkner](#): > > I just went out to get a burrito since my last post on this topic and npr quoted the 21 tons number. Pleaseclarify, that 21 tons report from npr is wrt China, not your burrito…experience. ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [August 16, 2015, 12:52am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/13 "2015-08-16T00:52:46Z")
The upper estimate of the 2013 West, Texas fertilizer explosion was 20,000 lbs of TNT (10 tons). The videos of the 2nd Tianjin explosion reminded me of the West explosion videos. Sounds like Tianjin was about twice as big then. ---
**Author:** ![Polar\_Iceman](https://avatars.discourse-cdn.com/v4/letter/p/f9ae1b/32.png) [@Polar\_Iceman](https://boards.straightdope.com/u/Polar_Iceman)\ **Post date:** [August 16, 2015, 2:44am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/14 "2015-08-16T02:44:32Z")
Has anyone yet identified the explosives involved? I am curious because my personal experience with explosives is that they require a shock to detonate; ie: they require a detonator, and they do not explode when exposed to fire. In fact in a previous career, we commonly burned C4 to heat our meals. So what was the “explosive” in China that was detonated by flame? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [August 16, 2015, 2:48am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/15 "2015-08-16T02:48:33Z")
Calcium carbide and some nitrate salts. That’ll give you some boom. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [August 16, 2015, 2:56am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/16 "2015-08-16T02:56:46Z")
I was at home in Las Vegas when this [PEPCON disaster - Wikipedia](https://en.wikipedia.org/wiki/PEPCON_disaster) happened. The reports in Wiki seem to be saying about 1.0 kilotons. From Pepcon to my house was about 18 miles. I was sitting inside eating lunch facing my rear sliding glass door. Which was on the side of my house facing away from the plant. I was astonished to see the glass suddenly flex inwards enough that I was sure it was going to shatter in on me. But it held. The noise was quite loud, but more of a lengthy boooom than the quick bang of a firecracker, gunshot or nearby artillery. I quickly climbed the roof and was amazed to see the blast cloud growing on the far side of the valley. I’d assumed it was a lot closer from the intensity of the blast. By that point in my career I’d dropped a lot of bombs and witnessed a lot of bombs and artillery from the ground. This was definitely the biggest explosion I’d ever seen or felt. ---
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [August 16, 2015, 3:07am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/17 "2015-08-16T03:07:48Z")
21 tons = 21 tons. 21 kilotons = 21,000 tons. Huge difference. ---
**Author:** ![Polar\_Iceman](https://avatars.discourse-cdn.com/v4/letter/p/f9ae1b/32.png) [@Polar\_Iceman](https://boards.straightdope.com/u/Polar_Iceman)\ **Post date:** [August 16, 2015, 3:35am UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/18 "2015-08-16T03:35:04Z")
> [@Ruken](#): > > Calcium carbide and some nitrate salts. That’ll give you some boom. Yes, but would the boom be triggered by flame?’ Again, my experience with nitrates is that they require a detonator to blast. Don’t know about calcium carbide, except if you mix it with water it makes a nice fizz. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [August 16, 2015, 6:26pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/19 "2015-08-16T18:26:37Z")
There is some speculation that the first explosion was caused by some chemical reaction that released an explosive gas, which I imagine would be more likely triggered by, say, an open flame. ---
**Author:** ![AK84](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@AK84](https://boards.straightdope.com/u/AK84)\ **Post date:** [August 16, 2015, 6:44pm UTC](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772/20 "2015-08-16T18:44:43Z")
> [@Duckster](#): > > The [USGS is reporting seismological readings](http://www.bbc.com/news/world-asia-china-33901206) of a magnitude 2 or 3 earthquake. It’s difficult to pin that down because the Chinese seismographs are considered suspect and the explosions occurred on the surface (water? boat? land?). The seismographs used to determine magnitude are outside of China. Another unidentified source was claiming/interpreting the force of the blast was equivalent to 3 to 21 tons of TNT. Considered suspect by whom? Stormfront users? [Next page](https://boards.straightdope.com/t/how-large-was-the-explosion-at-tianjin/727772.md?page=2)