one bag of fertiliser

Think of ONE black bin bag full of fertiliser, simply prepared and so light you can lift it up with the fingers of one hand. This is what happens when that ONE bag goes off. Fertiliser is best described as a lifting charge about 2 -4 miles a second instead of the sharp 7 miles a second plastic explosive detonation. This is the effect on a large sand filled reinforced concrete, triangle section construction. Total devestation. Now think of the amounts the terroists use in theirs. Words like a car full...a lorry full....estimated that 4 tons....and so on. Thats why when these things go off in cities whole fronts of sky scrapers fall off, people not near to the immediate scene get their lungs blasted and the blast wave which can flow around corners can get you there hiding as well. If you use a similar device/weight but use high explosive then multiply the effects above by a minimum of 100. As I mentioned somewhere else if you are not careful the nearby blast/compression wave can enter your mouth, travel to the lungs and blast out thro your chest taking all your insides with it. You see these things on the news but you fail to appreciate what these victims these poor people and kids have to deal with. Now you do. A sobering thought.