Seismic Refraction
The refraction seismic method is used to measure the depths and velocities of subsurface layers. It is particularly useful for mapping the depth and topography of the bedrock surface. It can also be used to find the elastic properties of these layers, which are useful for engineering purposes. Using the velocity of the bedrock, the rippability of the bedrock can be determined along with an estimate of the size of machine required.
When seismic waves are created on the ground surface they penetrate the subsurface until they encounter layers with different velocities and/or densities. In the case of refraction seismic, the subsurface layers must have successively increasing layer velocities with depth. At the layer boundaries, part of the incident wave is refracted along the surface of the layer boundary.
