During field activities parallel measuring lines are run across the investigation area, moving along the selected research equipment. In some cases, when the survey goes deeper than 4 meters, T&A uses boreholes for measuring or incorporates research equipment in a probe. In this phase, the investigation area will not yet face intensive surface-disturbing activities.
Performing the measurements
Objects or geological transitions in the subsurface have a direct or indirect effect on the signals sent by the measuring equipment or the natural magnetic fields. Geophysical measuring equipment registers these effects. With the collected data a 3D image of the subsurface or construction can be created.
The measurements are performed by moving the equipment over the research location by foot or by car. Sometimes electrical wires are placed on the surface. Deep-seated, small objects or thin soil layers with similar characteristics are very difficult or sometimes impossible to detect from the surface. In these cases the equipment is brought closer to the objective, for example by using a borehole.
All applied geophysical techniques are non-destructive, making the location accessible immediately aftet the survey. Sometimes a location has to be partly fenced off or mobile fences are used.
Techniques used by T&A: