The free fall of an array of heavy chains (360 kg/sq m) generates extensive pressure in the depth of the ground. These pressures have been measured and compared to the threshold pressures that trigger anti-personnel landmines. When dropped from moderate heights (1 m), chains can generate enough pressure to set off active landmines buried 20 cm, provided that the area of their pressure plates is larger than a few square centimeters.
Baras, Christian; Gautier, Bernard; Goepfert, Robert; Hancy, Jean-Pierre; and Joeckle, Rene
"Forces Generated by the Free Fall of DEMICHAIN,"
Journal of Conventional Weapons Destruction: Vol. 19
, Article 17.
Available at: http://commons.lib.jmu.edu/cisr-journal/vol19/iss1/17