Seismic Refraction

Shallow environmental and engineering studies utilise the seismic refraction method to measure the depth to a subsurface interface. Refraction surveys are widely used in foundation studies to determine depth to rockhead beneath superficial drift. The technique is also commonly used to determine the p-wave and s-wave seismic velocity of each stratum as knowledge of these parameters allow the elastic modulus to be determined which can be used in predictive geotechnical models.

To acquire seismic refraction data a series of sensitive geophone receivers are placed into the ground along the desired profile.  An energy source is then taken to 5 key positions along the profile and discharged to create a strong vibration.  The vibration from each shot is detected at the receivers and using a computer processing system that data can be combined to produce a cross-section of the strata beneath the site.