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There are many methods and types of instruments used in geophysical surveys. Technologies used for geophysical surveys include: [1] Seismic methods, such as reflection seismology, seismic refraction, and seismic tomography. This type of survey is carried out to discover the detailed structure of the rock formations beneath the surface of the Earth.
Induced polarization is a geophysical method used extensively in mineral exploration and mining operations. Resistivity and IP methods are often applied on the ground surface using multiple four-electrode sites. In an IP survey (and when making resistivity measurements), capacitive properties of the subsurface materials are determined as well.
Exploration geophysics is an applied branch of geophysics and economic geology, which uses physical methods at the surface of the Earth, such as seismic, gravitational, magnetic, electrical and electromagnetic, to measure the physical properties of the subsurface, along with the anomalies in those properties.
Well logging, also known as borehole logging is the practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole.The log may be based either on visual inspection of samples brought to the surface (geological logs) or on physical measurements made by instruments lowered into the hole (geophysical logs).
TEM / TDEM methods are generally able to determine subsurface electrical properties, but are also sensitive to subsurface magnetic properties in applications like UXO detection and characterization. TEM/TDEM surveys are a very common surface EM technique for mineral exploration, groundwater exploration, and for environmental mapping, used ...
Figure 4. Dipole–dipole electrode array profiling. Figures 1–4 show the possible configuration of the measurement setup. The electrodes A and B are current electrodes which are connected to a current source; N and M are potential electrodes which are used for the voltage measurements. As source, the direct current or low frequency ...
Long recording times are needed to ascertain usable reading due to the fluctuations and the low signal strength. Generally, the signal is weak between 1 and 5 kHz, which is a crucial range in detecting the top 100 m of geology. The magnetotelluric method is also used in marine environments for hydrocarbon exploration and lithospheric studies. [49]
Geophysics is applied to societal needs, such as mineral resources, mitigation of natural hazards and environmental protection. [4] In exploration geophysics, geophysical survey data are used to analyze potential petroleum reservoirs and mineral deposits, locate groundwater, find archaeological relics, determine the thickness of glaciers and ...