Seismic Refraction Tomography

Seismic refraction tomography allows to reconstruct an image of the distribution in the subsoil of the speed of the seismic wave and its anomalies with high resolving power.

The seismic refraction technique uses the refraction of seismic waves by layers of rock or soil to characterize the geological conditions of the subsoil, it consists of generating a seismic wave of compression or shear (energization) and recording its arrival at the following geophones in line to known ranges. The interpretation of the recorded measurements is based on the analysis of the time it takes for the wave generated with the energizations to reach each geophone. To reconstruct the variation in the velocity of the compression waves in the subsoil, it is necessary to perform several energizations at different positions along the line.

Seismic tomography is based on the reversal of the observed and theoretical P-wave arrival times. The inversion process is an iterative process, which seeks the best fit of the observed times to a synthetic model that is updated until the final velocity model is obtained.

The calculated speed of the seismic wave is related to the mechanical properties of the material. Therefore, the main applications of this method are those related to the elastic properties of the soil: degree of weathering, depth of rocky materials, ripping capacity or ripability, and the possibility of mapping active landslide landslide planes.

It is recommended that these studies be complemented with geological data, well logs, outcropping data, or other geophysical methods to adequately interpret subsurface conditions from seismic refraction data.