Underground investigations using non invasive methods for natural or artificial structures (such as excavations, tunnels, utilities) are based on the physical property contrast between the target and the surrounding rocks. This property is represented by mass density, magnetic susceptibility, resistivity, velocity of the elastic waves, radioactivity, all these being bases of geophysical methods. The values of these parameters are sometimes directly related rock types and can be used to select the method or technique of geophysical investigation. This relation is determinant in data interpretation .
There is no perfect geophysical method and also there is no general available algorithm to perform an investigation. Using several methods or combining techniques always will increase the precision of the results. Also the experience of the interpreter can be a determinant factor, because the combination of some natural and artificial factors usually creates complex situations.
Geomathics One applies a large variety of geophysical techniques to produce relevant images of the underground geological and non-geological structures, reflecting relationships between the objects-target and surrounding medium. These images are very useful to project and develop an investment, in any construction or exploitation activity.