Reflected waves from the interfaces between materials of significant different elastic properties (density and seismic velocity) are used for this type of survey. More specifically, a special acquisition and processing method called the “CDP (common-depth-point) method” is used and the final product from this survey is a section that depicts a cross-sectional image of the subsurface below the surveyed line (Fig. 1). This method was invented and has been used traditionally in exploration for natural resources (oil, coal, etc.). Since the early 1980s, it has been used mostly for shallow geotechnical engineering projects (Fig. 1). Comparing these types of reflection surveys together, they are different in dimensions surveyed and resolution achieved. Field acquisition and data processing procedures are normally much more costly than with the other types of seismic surveys.
