Seismic Refraction & Reflection

Seismic reflection and refraction can identify variations in material type with depth and horizontal position. The technique images the interfaces between materials with contrasting acoustic/seismic velocities. This translates to differences in the elastic properties and/or density of the material. Mapping these contrasts across an area can identify the extent and depth to specific layers or interfaces of interest.

The most common application of seismic techniques is the determination of overburden thickness or estimating the depth to bedrock. This is due to the large contrast in seismic velocity between intact bedrock and unconsolidated superficial deposits. Based on similar principals, the seismic technique has also been employed to determine the rippability of rocks in quarries prior to blasting / excavation.

Seismic Applications

  • Stratigraphic mapping
  • Geological mapping
  • Estimation of depth to bedrock
  • Locating sinkholes & channels
  • Predict rippability of specific rock types
  • Landfill investigations
  • Estimation of depth to water table
  • Geotechnical investigations
Survey lines spanning hundreds of meters can be covered in a single day providing useful information on the underlying strata. In this example bedrock is shown in green (high velocities) and superficial deposits in red (low velocities).