Seismic refraction and Multichannel Analysis of Surface Waves (MASW) / Refraction Microtremor (ReMi) methods are utilized to delineate contrasts in seismic velocities within the subsurface, typically within the first few tens of meters. These methods analyze both pressure (“P”) and shear (“S”) waves, with seismic wave velocities reflecting changes in rock/soil properties such as hardness and density.
The outcome of such surveys is a 2D profile illustrating variations in velocity with depth. This approach finds application in construction and infrastructure projects requiring extensive area coverage. Key applications include determining:
- Depth to bedrock
- Depth of groundwater level
- Calculation of elastic moduli
- Identification of specific subsurface variations
The refraction method is executed swiftly and efficiently. Depth penetration is contingent on the profile’s surface length; typically, one-third of the profile length corresponds to depth penetration. For shallow targets (5m – 20m), a sledgehammer serves as the energy source, while for deeper targets (up to ~200m, subject to local conditions), a specialized truck-mounted accelerated weight hammer is employed. Alternatively, downhole seismic sources, such as explosives, may be utilized.
Under the guidance of our senior geophysicists, data processing and integration with available geotechnical data are conducted in close collaboration with the client to ensure target objectives are met.