A Shallow Subsurface Investigation Technique for Geophysical Applications
Electromagnetic method is a rapid technique for subsurface investigation and typically one of the first tools used to delineate the subsurface extent of fluid release related to a pipeline break which reduces the ambiguity in the interpretation and yields reliable subsurface information.
Electromagnetic (EM) survey uses the response of the ground to the propagation of electromagnetic fields. EM methods are sensitive to variations in conductivity values of subsurface materials and can identify anomalous areas due to the presence of void, fluids, metals and other variations. Unlike the electrical resistivity method, no ground contact is required for EM survey. Therefore, it eliminates direct electrode coupling problems and allows a rapid data acquisition. Applications include mapping saline intrusions, locating buried tanks and drums, mapping groundwater pollution, and groundwater exploration, etc.
URBAN PLANNINGUndergrounding Utility Survey.
Water ResourceGroundwater survey.
Stability Analysis Landslide studies
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Electromagnetic geophysical approach for subsurface investigation of an urban environment
- The basic principles of the operations are based upon detecting the disturbance to earth’s magnetic field by buried magnetized materials.
- The method is entirely passive in that instrumentation does not have to generate a field itself.
- The types of materials that affect the earth magnetic field include basic igneous rock, certain forms of mineralization and a wide variety of man-made materials and fabrications such as metal pipes, reinforcement bars, electrical cables.
- surface indicators of ground instability .
- providing an evidence base that can inform the decision-making process to plan future ground investigations, maintenance, or repair works.
EM surveys use an instrument called an Electromagnetic induction meter that induces an electromagnetic signal into the ground and measures how well it is conducted by the soil.