How to do seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) on site ?

SRT
Uses seismic waves to map subsurface velocity changes. The procedure involves generating a seismic wave with an explosive charge or hammer blow, and then using sensors to receive the wave as it refracts along material boundaries. SRT surveys typically generate 2D or 3D P-wave velocity profiles.
ERT
Uses electrical currents and measurements to map subsurface resistivity variations. The procedure involves transmitting a direct electrical current into the ground using a pair of electrodes, and then measuring the voltage at one or more additional pairs of electrodes.