I could be wrong but I think the way they explore for oil is that they drill a hole, drop some dynamite in it, and study the seismic reaction?
Sounds like guesswork to me.
A seismic survey can be carried out without disturbing people or damaging the environment. It is the most important tool for finding and mapping potential oil fields. Sound waves are reflected off underground rock layers and picked up by sensitive detectors laid along the ground or towed behind a boat. Recorded on magnetic tape and analyzed by powerful computers, they reveal the underground structures which might contain oil.
In remote areas, the sound waves may be produced by dynamite, detonated several feet below the ground surface. In densely populated or environmentally sensitive areas, where explosions are not practical, vibrator trucks are used