Maybe it would be possible to use the size of the crater to estimate it?
The crater from:
West Fertilizer Company explosion - Wikipedia, the free ...
was around 30 meters in diameter. The one from Tianjin is around 100 - 110 meters in diameter.
From what I understand the energy needed...
I converted one of the videos to stills -- it makes it "easier" to see what is going on (30 fps frame numbers superimposed):
http://imgur.com/a/ypW2D
(this is the first, smaller explosion).
The fire seems to be pulsating:
http://i.imgur.com/KxPlkj6.png
The following is an image of the aftermath of the Tianjin explosion:
http://i.imgur.com/sJShsFC.jpeg
The containers in the image seem to have been crushed/deformed - but how much energy would be needed to do this?
Closeup: http://i.imgur.com/0XBdHsw.jpg
A shot from above...