The many interconnected geological techniques we use to gather valuable information

In situations when the geological structure or depth to bedrock is variable or poorly defined, geophysics can provide valuable information to support other investigation techniques. Natural voids, sedimentary structures or fractures and faults can cause significant problems if they remain undetected.

Electromagnetic mapping, electromagnetic profiling, electrical resistivity imaging, electrical resistivity sounding, seismic refraction and seismic reflection are all commonly employed in assessing near-surface geology. Stratigraphy, depth to bedrock, presence of voids and hydrogeological assessments are all common applications of geophysical techniques.

Locating and characterising mineral deposits

Geophysical surveys can play a vital role in the mapping of high-quality gravel deposits, including providing information to support viability assessment, such as the lateral extent and thickness of mineral and the thickness of overburden.

Thickness of superficial deposits and depth to bedrock

Geophysical surveying across a site can highlight variations in sediment thickness and bedrock depth. It is especially useful for mapping geological layers between boreholes.
Fault mapping

Faults manifest as vertical and horizontal discontinuities in geological strata. Where detectable variations in electrical and physical properties exist between faulted units, techniques such as seismics, electrical resistivity tomography and conductivity can be used to detect the presence of faults and fracture zones.

Depth to groundwater table

Electrical and electromagnetic methods can be used to indicate the presence of groundwater within the shallow strata. Repeat measurements can show daily or seasonal changes. Saline intrusion can also be detected and mapped.

Mapping the extent of contamination

Mapping variations in the electrical conductivity of the subsurface across a site can highlight anomalously conductive targets such as metallic tanks, pipework and any ground contamination. Although pure water is generally not a good conductor of electricity, groundwater – especially contaminated groundwater – contains dissolved compounds and ions that can greatly enhance its ability to conduct electricity.

Locating buried drums and tanks

Encountering unknown buried objects can significantly increase the cost of developing a site. Geophysics can be used to search for buried features and to reduce the risk of finding unforeseen features during development. Drums and underground storage tanks present as highly conducting discrete features in the ground because of their metallic construction. Their location and depth can generally be detected by time domain EM (TDEM) and ground-penetrating radar (GPR) methods. Plastic tanks and other associated infrastructure can also generally be detected by GPR techniques.

Other geophysical survey applications

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