10 ms·

A blast in Tianjin sets off an explosion online

34 points by jeo1234 11y ago

trhway 11y ago
by the way, have you seen a "21 ton TNT" crater : http://www.wsj.com/articles/tianjin-blast-destruction-from-above-1439654034 http://www.wsj.com/articles/tianjin-blast-destruction-from-a... Looking at it i'm pretty sure there should be at least 1 more trailing zero in the TNT equivalent number, and the 21 ton is just a small portion of the explosion energy, ie. it is the portion which went into the ground and formed the seismic wave.
- mapt 11y ago
  Also: Explosive energy rises much, much faster than crater diameter. http://palaeo.gly.bris.ac.uk/communication/brana/equation.html http://palaeo.gly.bris.ac.uk/communication/brana/equation.ht... says energy goes up roughly with the 3.4th power of crater diameter, in impact craters.
- tajen 11y ago
  To those who wonder, Little Boy and Fat Man, the atomic bombs, exploded each at about 18 to 21 kton TNT, which is a thousand times more. Interestingly enough, they both could have tripled their power depending on how much fissile material would react.
- jeo1234 11y ago
  Apparently the blast was so powerful it was picked up by US Geological Survey equipment which is built to detect earthquakes. http://www.theguardian.com/world/2015/aug/12/china-explosion-earthquake-recording-instruments-beijing http://www.theguardian.com/world/2015/aug/12/china-explosion...
  - nitrogen 11y ago
    Those systems (or ones like them) are also meant to detect weapons tests, so it appears they are doing their job.
- caseyf7 11y ago
  The explosion and smoke plume was picked up by Japan's new weather satellite too. http://www.citylab.com/weather/2015/08/satellites-spot-the-tianjin-explosions-foul-brown-cloud/401303/ http://www.citylab.com/weather/2015/08/satellites-spot-the-t...
  - a3n 11y ago
    The make and model of my car in my driveway was picked up by the satellite Google was buying from in 1997. I don't understand why "It was seen from space!" is at all a part of the story today.
    - ArekDymalski 11y ago
      > I don't understand why "It was seen from space!" is at all a part of the story today. Becuase most people still do not realize that the space is closer to their home, than holidays resort they have visited this summer.
- vecter 11y ago
  Thunderfoot did a video about this where, like you, he estimated the order of magnitude to be 1-2x greater than the most likely fake number reported by the Chinese government: https://www.youtube.com/watch?v=_hcwMwFbJKc https://www.youtube.com/watch?v=_hcwMwFbJKc.
  - trhway 11y ago
    interesting, he puts it between 3kt and 300 tons based on the fireball size from the video where is my first immediate estimate just based on the same video - only i used distance and blast sound wave - was 2kt. I adjusted it down (mainly by adjusting down the most speculative element - estimate of the sound wave from the video) to 500-200 tons once i saw the next day photos with the apartment buildings still standing at 300m distance. Once i saw the crater - i became pretty sure that it is more close to 500 than 200.
erikb 11y ago
Funny how a "we are dying" note reads like.
siscia 11y ago
The article make it sound like the incompetence of the Chinese officials is something particularly bad or remarkable. For my experience those level of incompetence is just what you should expect. Western world have no idea what China really means...
sohkamyung 11y ago
James Kennedy has this analysis of the explosion [ https://jameskennedymonash.wordpress.com/2015/08/17/the-chemistry-behind-the-tianjin-explosions/ https://jameskennedymonash.wordpress.com/2015/08/17/the-chem... ], including the possible chemical reactions and the amount of energy released.
- dbcooper 11y ago
  Curious that he couldn't "find" the enthalpy of reaction for the ammonium nitrate. Surely he could calculate it from the sum of the products minus the sum of the reactants.
  - TheLoneWolfling 11y ago
    Sum of products is surprisingly hard to do for something like ammonium nitrate. Among other things, there are actually multiple distinct breakdowns: NH4NO3 ----> HNO3 + NH3 5 NH4NO3 ----> 2 HNO3 + 9 H2O + 4 N2 2 NH4NO3 ----> O2 + 4 H2O + 2 N2 NH4O3 ----> N2O + 2 H2O I suspect you could do fairly well by assuming that it follows reaction 3, though. Like with assuming complete combustion.
fatman13gg 11y ago
Nice try by the author to convince people to believe whatever the social media threw at them.

34 points by jeo1234 11y ago

by the way, have you seen a "21 ton TNT" crater : http://www.wsj.com/articles/tianjin-blast-destruction-from-above-1439654034 http://www.wsj.com/articles/tianjin-blast-destruction-from-a... Looking at it i'm pretty sure there should be at least 1 more trailing zero in the TNT equivalent number, and the 21 ton is just a small portion of the explosion energy, ie. it is the portion which went into the ground and formed the seismic wave.

mapt 11y ago
Also: Explosive energy rises much, much faster than crater diameter. http://palaeo.gly.bris.ac.uk/communication/brana/equation.html http://palaeo.gly.bris.ac.uk/communication/brana/equation.ht... says energy goes up roughly with the 3.4th power of crater diameter, in impact craters.
tajen 11y ago
To those who wonder, Little Boy and Fat Man, the atomic bombs, exploded each at about 18 to 21 kton TNT, which is a thousand times more. Interestingly enough, they both could have tripled their power depending on how much fissile material would react.
jeo1234 11y ago
Apparently the blast was so powerful it was picked up by US Geological Survey equipment which is built to detect earthquakes. http://www.theguardian.com/world/2015/aug/12/china-explosion-earthquake-recording-instruments-beijing http://www.theguardian.com/world/2015/aug/12/china-explosion...
- nitrogen 11y ago
  Those systems (or ones like them) are also meant to detect weapons tests, so it appears they are doing their job.
caseyf7 11y ago
The explosion and smoke plume was picked up by Japan's new weather satellite too. http://www.citylab.com/weather/2015/08/satellites-spot-the-tianjin-explosions-foul-brown-cloud/401303/ http://www.citylab.com/weather/2015/08/satellites-spot-the-t...
- a3n 11y ago
  The make and model of my car in my driveway was picked up by the satellite Google was buying from in 1997. I don't understand why "It was seen from space!" is at all a part of the story today.
  - ArekDymalski 11y ago
    > I don't understand why "It was seen from space!" is at all a part of the story today. Becuase most people still do not realize that the space is closer to their home, than holidays resort they have visited this summer.
vecter 11y ago
Thunderfoot did a video about this where, like you, he estimated the order of magnitude to be 1-2x greater than the most likely fake number reported by the Chinese government: https://www.youtube.com/watch?v=_hcwMwFbJKc https://www.youtube.com/watch?v=_hcwMwFbJKc.
- trhway 11y ago
  interesting, he puts it between 3kt and 300 tons based on the fireball size from the video where is my first immediate estimate just based on the same video - only i used distance and blast sound wave - was 2kt. I adjusted it down (mainly by adjusting down the most speculative element - estimate of the sound wave from the video) to 500-200 tons once i saw the next day photos with the apartment buildings still standing at 300m distance. Once i saw the crater - i became pretty sure that it is more close to 500 than 200.

erikb 11y ago

Funny how a "we are dying" note reads like.

siscia 11y ago

The article make it sound like the incompetence of the Chinese officials is something particularly bad or remarkable. For my experience those level of incompetence is just what you should expect. Western world have no idea what China really means...

sohkamyung 11y ago

James Kennedy has this analysis of the explosion [ https://jameskennedymonash.wordpress.com/2015/08/17/the-chemistry-behind-the-tianjin-explosions/ https://jameskennedymonash.wordpress.com/2015/08/17/the-chem... ], including the possible chemical reactions and the amount of energy released.

dbcooper 11y ago
Curious that he couldn't "find" the enthalpy of reaction for the ammonium nitrate. Surely he could calculate it from the sum of the products minus the sum of the reactants.
- TheLoneWolfling 11y ago
  Sum of products is surprisingly hard to do for something like ammonium nitrate. Among other things, there are actually multiple distinct breakdowns: NH4NO3 ----> HNO3 + NH3 5 NH4NO3 ----> 2 HNO3 + 9 H2O + 4 N2 2 NH4NO3 ----> O2 + 4 H2O + 2 N2 NH4O3 ----> N2O + 2 H2O I suspect you could do fairly well by assuming that it follows reaction 3, though. Like with assuming complete combustion.

fatman13gg 11y ago

Nice try by the author to convince people to believe whatever the social media threw at them.