I don't have a clue. I have a POWER DVD player and use it's screenshot tool.First off why are your images scaled up and horribly compressed? I'm getting 3DPI quality on yours and 72DPI for mine.
I understand that perspective can fuck up any measurement but I dont think I really made such drastic mistake like in a screenshot you provided.
However I think it's more important to determine the effective radius of the charges.
Here:+http://www.geocities.com/idesdjurdja/as ... stance.jpg
we can see that the distance between seismic charge and the camera is no more than 100m.
This image:+http://www.geocities.com/idesdjurdja/shockwave1.jpg
shows us the creation of the planar shockwave(this is the SECOND flash not the first one mind you).
This image:+http://www.geocities.com/idesdjurdja/shockwavefinal.jpg
is taken 11 frames later and it show the shockwave reaching the camera.
Since the shockwave crossed no more than 100m in 0.44s then the speed of the shockwave is no more than 230m/s. Since the shockwave lasted about 10s the effective radius is 4600m.
Now I don't doubt the seismic charge cut cut through a multi kilometer asteroid bases on what we've seen in the film. Since it would take about 100Mt to fragment a 4.6km radius this would seem like a reasonable lower limit for the charge. The lower limit could drop if the seismic charge was closer to the camera thus diminishing the propgation speed of the shockwave.
I am sceptical however to the 12Gt figure in the ICS.