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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 geology investigations. In this type of survey electrical resistance meters are used to detect and map subsurface archaeological features and patterning.
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 boreholes. If the electrodes are suspended in the boreholes, deeper sections can be investigated.
Vertical electrical sounding (VES) is a geophysical method for investigation of a geological medium. The method is based on the estimation of the electrical conductivity or resistivity of the medium. The estimation is performed based on the measurement of voltage of electrical field induced by the distant grounded electrodes (current electrodes).
Electrical resistivity methods can also detect objects, especially in clay-rich soil which would preclude the use of GPR. There are different equipment configurations, the dipole-dipole (fixed-offset) method is the most common which can traverse across an area, measuring resistivity variations at a set depth (typically 1-2x probe separations ...
The survey method is similar to electrical resistivity tomography (ERT), in that an electric current is transmitted into the subsurface through two electrodes, and voltage is monitored through two other electrodes. Induced polarization is a geophysical method used extensively in mineral exploration and mining operations.
Measuring electrical resistivity allows different materials and structures to be distinguished from one another and can improve knowledge of tectonic processes and geologic structures. The Earth's naturally varying electric and magnetic fields are measured over a wide range of magnetotelluric frequencies from 10,000 Hz to 0.0001 Hz (10,000 s).
There are many applications of geophysical imaging some of which include imaging the lithosphere and imaging glaciers. [5] [6] Many different techniques exist to perform geophysical imaging including seismic methods, electrical resistivity tomography, ground-penetrating radar, etc. Types of geophysical imaging: Electrical resistivity tomography
Spectral induced polarization (SIP), or complex resistivity (CR) and also complex conductivity (CC), is a geophysical survey technique and an extension of the induced polarization (IP) method, being itself an extension of measuring the Earth's resistance at a single frequency or under direct current (DC) (a technique commonly known by the name resistivity). [1]