The basics of refraction seismic method consider the ability of soil and rock to transmit an elastic wave. Only two fundamentals measurements are made from which all refraction seismic computations are derived. These are time and distance, that is, the time it takes an elastic wave to travel certain distance. Depending upon surface and subsurface field conditions, the required correction, interpretation and computation of field data may be complicated. This needs a high level of experience on gold prospecting and geology of gold deposits on the part of those conducting the survey and interpreting the results. It has been recognized that in good, first order seismic surveys, the computed depth to detect contacts must be within 4-6% of the actual depth.
By carefully measuring the time wave takes in travelling from the point of origin to the position of the geophones, it is possible to compute the velocities of the wave front through the surface overburden and different subsurface strata or bedrock. Through studying these travel times and the results velocities, it is possible to compute the depth to the different strata to bedrock. It is also possible to obtain considerable information as to the geological nature of the overburden and bedrock. Applications of this method can be found in searching for gold type structures, in tracing the position an extent of buried gold placer channels and in measuring the amount of overburden to be removed in stripping operations.
About the seismic equipment, a small, single trace, engineering type refraction seismographs are extremely limited in their applications and when used on this basis may give satisfactory results. Gold operations considering the serious use of the refraction seismic method must consider multiple trace equipment as they eventually end up purchasing it. The refraction seismic method is usually employed for reconnaissance type surveys where general information is desired in a hurry. It will be possible to determine the presence of rocks in a specific hill, its depth, the type of rock, the type of soil over the rock formation and its distribution. The mobility of seismic equipment enables it to be taken into areas to obtain general subsurface information where drilling equipment may not be transported easily.