DEFINITION: A thumper truck (also called a "weight-drop" truck) is a vehicle equipped with a device for generating an artificial seismic source wave used in performing both reflection and refraction seismic surveys. Used by geological survey teams and prospectors seeking the location of subsurface deposits of oil, shale gas, etc. (For more, see the Wikipedia article "Seismic Source", especially the section subtitled "Thumper Truck". Now used by frackers.
' Several Lee County residents reported recently seeing "thumper" trucks in the area, so named for the sound made when they clap a steel plate against the ground, using the reverberations to pinpoint potentially gas-rich underground rock formations and faults.'
-- Billy Ball. "Before fracking begins in N.C., Texas energy company investigates shale gas deposits in Lee County." INDYweek, September 25, 2013.