Seismic Refraction (SR)

The Seismic Refraction is to provide the design consultant with sufficient information on the near-surface geologic hazards (e.g. cavities, weak zones…etc), soil profile and related dynamic parameters. Seismic refraction measurements are applicable in mapping subsurface conditions for various uses including geologic, geotechnical, hydrologic, environmental, mineral exploration, petroleum exploration, and archaeological investigations. It is used to map geologic conditions including depth to bedrock, or to water table, stratigraphy, lithology, structure, and fractures or all of these. The calculated seismic wave velocity is related to mechanical material properties. Therefore, characterization of the material (type of rock, degree of weathering, and rippability) is made on the basis of seismic velocity and other geologic information. However , this method has some limitations like deep measurements may require explosives as an energy source, requires relatively large source-receiver offsets (distances between the source and where the ground motion is recorded, the receiver), sensitive to acoustic noise and vibration, will not detect thin layers, the presence of cultural features such as building foundations, concrete retaining walls, asphalt, storm-water drainage systems, and other utilities can interfere with a seismic refraction survey.