What is Seismic survey?

Seismic refraction and reflection methods measure the transmission of sound waves through the subsurface generated using a hammer blow or explosive energy source. Individual subsurface layer depths and thickness can be calculated based on the analysis of sonic wave arrival times.
Typical applications of seismic surveying include:
*  Depth to water table,
*  Depth to bedrock,
*  Subsurface stratigraphy,
*  Locating paleochannels,
*  Identifying faults and fracture zones.