GROUND PENETRATING RADAR
is used to map the subsoil on land, in rivers and lakes. The measuring instrument is pulled through the examination area by hand by snowmobile, car or boat
in the sediment
that in contrast of seismic surveys, georadar can be carried out in the winter time and gives just as good results as in milder seasons.
Advantage of GPR
Short description of the method
Electromagnetic waves are sent from a transmitter / receiver antenna and refracted from layer boundaries or objects in the ground. When the antenna is pulled along the ground, we get a result that gives a continuous and high-resolution profile of the subsoil. The method can therefore be compared with seismic measurements on the continental shelf.
The georadar has good depth penetration in materials with poor electrical conductivity, such as sand and gravel, peat, rock and concrete. In clay, silt and moraine clay the waves are attenuated. The georadar therefore has little depth range in fine-grained deposits.
When processing, one can remove background noise and improve the signals by "stacking" and filtering. The continuously incoming data on the recording software can help to see contrasts that represent different types of materials. The equipment is light and can be towed by car, snowmobile, in boat or by hand. Preliminary interpretations are normally performed in the field that provide the opportunity to adjust the program during the investigation.
sediment types and block content.
water bottom and sediment thickness in fresh water
of cracks and weakness zones in rock.
pavements and base layers for roads and airports.
sand, gravel and groundwater resources
cavities and reinforcement in concrete
pipes and other buried objects