method of investigating subterranean structure, particularly as related to exploration for petroleum, natural gas, and mineral deposits (mineral deposit). The technique is based on determinations of the time interval that elapses between the initiation of a seismic wave at a selected shop point and the arrival of reflected or refracted impulses at one or more seismic detectors. Though dynamite exploded (explosion seismology) underground is most commonly used to initiate the seismic waves, an electric vibrator or falling weight (thumper) may also be employed at sites where an underground explosion might cause damage—e.g., where caverns are present. Upon arrival at the detectors, the amplitude and timing of waves are recorded to give a seismogram (record of ground vibrations).

Interpretation of the depths and media reached by seismic waves thus depends on the distance between shot points and receiving points and the densities of the strata. The results of a seismic survey may be presented in the form of a cross-sectional drawing of the subsurface structures as if cut by a plane through the shot point, the detector, and the centre of the Earth. Such drawings are called seismic profiles.