In order to truly understand the makeup of ground in an area, scientists need to perform a geophysical survey using resistivity imaging. An electrical current is shot into the ground using two electrodes. The potential that is created is measured by two other electrodes in the ground. This is calculated as an “apparent resistivity” which can be mapped to determine the likely material – such as limestone, sandstone or sand – that is at various depths in the ground. Resistivity imaging is used for a number of applications.
The use of resistivity imaging can assist in the detection of bedrock underneath the surface of the ground. This is useful for determining if an area is safe for building. Resistivity imaging can also detect fractures in the ground.
Aquatic Resistivity Imaging
Special marine resistivity imaging modules can apply the same principles used to determine rock contents to find out about elements of large bodies of water. Aquatic resistivity imaging can help to find out the largest location of shell content to help engineers design efficient water well intakes or it can be used to detect the movement of brine through a body of water.
Cave and Tunnel Detection
Along with showing the makeup of the rocks and other elements in the ground, resistivity imaging can also show the absence of objects in the ground. Gaps in the ground can be caves and tunnels – some of which may have been previously unmapped.