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Electrical resistance surveys (also called earth resistance or resistivity survey) are one of a number of methods used in archaeological geophysics, as well as in engineering geological investigations. In this type of survey electrical resistance meters are used to detect and map subsurface archaeological features and patterning.
2D resistivity inversion of ERT data Deployment of a permanent electrical resistivity tomography profile on a longitudinal section of an active landslide.. Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI) is a geophysical technique for imaging sub-surface structures from electrical resistivity measurements made at the surface, or by electrodes in one or more ...
Electrical resistance map of ancient Aphrodisias. In archaeology, geophysical survey is ground-based physical sensing techniques used for archaeological imaging or mapping. Remote sensing and marine surveys are also used in archaeology, but are generally considered separate disciplines. Other terms, such as "geophysical prospection" and ...
Magnetotellurics (MT) is an electromagnetic geophysical method for inferring the earth 's subsurface electrical conductivity from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface. Investigation depth ranges from 100 m below ground by recording higher frequencies down to 200 km or deeper with long-period ...
Ground penetrating radar is a tool used in archaeological field surveys. In archaeology, survey or field survey is a type of field research by which archaeologists (often landscape archaeologists) search for archaeological sites and collect information about the location, distribution and organization of past human cultures across a large area (e.g. typically in excess of one hectare, and ...
In 2018, the presence of a fort of at least two phases was confirmed by an electrical resistance survey, and in 2020 an assessment by Historic England using Google Maps and Lidar imagery showed that the fort was visible as crop marks, soil marks and earthworks. [3]
Exploration geophysics is also used to map the subsurface structure of a region, to elucidate the underlying structures, to recognize spatial distribution of rock units, and to detect structures such as faults, folds and intrusive rocks. This is an indirect method for assessing the likelihood of ore deposits or hydrocarbon accumulations.
The SI unit of electrical resistivity is the ohm - metre (Ω⋅m). [1][2][3] For example, if a 1 m3 solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is 1 Ω, then the resistivity of the material is 1 Ω⋅m. Electrical conductivity (or specific conductance) is the reciprocal of ...