Explosions in Tianjin, China

[AcesHigh]

I hesitate to say this but it does sort of work out if the original estimate of 21 tons is used. 21 tons is only one shipping container. We have an example of a truck loaded with approx. 4800 lbs of ammonium nitrate:

https://en.wikipedia.org/wiki/Oklahoma_City_bombing

roughly 2.4 tons which "created a 30-foot (9.1 m) wide, 8-foot (2.4 m) deep crater".

And "Seismometers at Science Museum Oklahoma in Oklahoma City, 4.3 miles (6.9 km) away, and in Norman, Oklahoma, 16.1 miles (25.9 km) away, recorded the blast as measuring approximately 3.0 on the Richter scale".

Simply multiplying 2.4 tons by 10 gives us 24 tons (not quite 21 but close enough) and a 91 m. crater. Boom. Done.

I've looked at the photos and I can't deny that GZ is right at the entrance. One unfortunate truck (filled with ammonium nitrate) sitting at the entrance or at the weigh station when the fire broke out is all it took. Thoughts?

yes, but then they say they had 800 metric tons of AN(about 250 tons tnt?) and that explosion matches better the equations for crater size.

anyone wants to apply the crater size equation to 2.4 tons and 24 tons TNT?

it seems obvious to me crater size does not escalates the way you calculated. Otherwise, if a 24 tons TNT explosion would create a 100 meters wide crater, kiloton/megaton range explosions would create craters the hundred of kilometers wide.

24 megatons = 1 million times larger than 24 tons TNT.

multiply 100 meters by 1 million and you would get a 100 million meters crater... that´s 100 thousand kilometers, 1/4 of the way to the moon.

 

[rjh01]

I would have thought that to get a crater twice as wide you need four times more explosive. However if the ground is of a different type then that too would produce a crater of a different size. The reason is that the total force of an explosion would be the same no matter what the distance. However the force is spread out over a greater area that depends on the square of the distance. Ref: http://www.calculatorsoup.com/calculators/geometry-solids/sphere.php

Or https://en.wikipedia.org/wiki/Shock_factor

But I thought it was the cube of the distance, but the above says square? Please check the above.

 

[Oystein]

rjh, the "Shock factor" that you link to describes, roughly, how the amplitude of the shock wave decreases with distance. It decreases with the square of distance because it gets spread out over the surface of a sphere around the center of explosion: As the radius double, the area of the sphere where the shock wave is quadruples.

However, to create a crater, that blast energy must do work on a volume of solids - "doing work" means doing things along a distance. That gives you a third dimension and thus the cube of distance.

See it another way: A crater is approximately a cone; and all cones will have a similar slope. The volume of that cone, and thus the mass of the ejected material, increases with the cube of its radius or diameter.

So if you increase the explosive energy by a factor of 10, the diameter of the crater only increases by a bit more that a factor of 2: 10^(1/3) = 2,1544....


Anyway, that's my quick and dirty take on this. No doubt, there are some additional effects to factor in (such as: large enough charges may produce a plasma, which would have some non-linear effects)

 

[rjh01]

Oystein - thanks.

 

[Oystein]

China Holds 23 Linked to Fatal Blasts in Tianjin

HONG KONG — The Chinese authorities, facing enormous pressure to account for catastrophic chemical blasts that killed more than 100 people two weeks ago, said Thursday that they had detained or placed under investigation 23 people in connection with the disaster.

Those being investigated included the chief of the transportation department in Tianjin, the northeastern city where the blasts erupted on Aug. 12. Among those detained were employees of the company that owned the warehouse that was at the epicenter of the explosion and employees of the company that conducted the safety assessment of the warehouse.

The authorities described the detainees as directly responsible for the blasts in Tianjin, according to a report by Xinhua, a state-run news agency. The explosions killed 139 people and injured at least 700.

 

[Gawdzilla Sama]

Ah, the Gang of 23.

 

[commandlinegamer]

Reports on Twitter of an explosion at the city of Dongying, similar to that which occurred a few weeks ago at Tianjin.

 

[Skeptic Ginger]

Breaking news, you heard it on Twitter first.

Explosion at chemical plant in Dongying

The Twitter account for People's Daily reported Monday night's explosion, as did state radio. Dongying's population is about two million.

 

[MRC_Hans]

I notice that Google Earth has updated the picture of the area.

Hans

 

[Elagabalus]

Update:

http://www.bbc.com/news/world-asia-china-37927158

 

[Jrrarglblarg]

An investigation found that stocks of flammable nitrocellulose - a chemical used in nail polish - had caught fire and spread to illegal stores of the fertiliser ammonium nitrate.

By all the gods and monsters, what were those chemicals even doing on the same factory campus, much less the same facility? Of course that was illegal.

 

[catsmate]

By all the gods and monsters, what were those chemicals even doing on the same factory campus, much less the same facility? Of course that was illegal.

Ignoring safety laws is cheaper.