 Vibrator capability is defined by the maximum force it is capable to generate, called High Peak Force and measured in pound-force.To transmit a maximum force to the ground and prevent the shaker from bumping, part of the weight of the vibrator is applied to the shaker.The plot of Ken Follett's 1998 thriller "The Hammer of Eden" turns on the use of a stolen seismic vibrator truck by ecoterrorists.