by the way, have you seen a "21 ton TNT" crater :<p><a href="http://www.wsj.com/articles/tianjin-blast-destruction-from-above-1439654034" rel="nofollow">http://www.wsj.com/articles/tianjin-blast-destruction-from-a...</a><p>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.