Seismic Refraction

The seismic refraction method is based on the measurement of the travel time of seismic waves refracted at the interfaces between subsurface layers of different velocity. Seismic energy is provided by a source ('shot') located on the surface. Energy radiates out from the shot point, either travelling directly through the upper layer (direct arrivals), or travelling down to and then laterally along higher velocity layers (refracted arrivals) before returning to the surface. This energy is detected on surface using a linear array of geophones. Observation of the travel-times of the refracted signals provides information on the depth profile of the refractor.

Seismic Refraction surveys are commonly carried out to determine depth to bedrock and other features.  ClearView Geophysics uses hammer sources or its specially designed Seis-Gun.  The gun uses in-house powder packed 12-gauge shells.  A hole is augered into the ground to a safe depth for each shot.