Exploration geophysics

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**Geophysical Methods and Techniques**:
– Seismic tomography for locating earthquakes and assisting in seismology.
– Reflection seismology and seismic refraction for mapping surface structures.
– Geodesy, gravity techniques, and gravity gradiometry.
– Magnetic techniques, including aeromagnetic surveys.
– Electrical techniques, such as electrical resistivity tomography and induced polarization.
– Remote sensing for topographical mapping in civil engineering.
– Airborne electromagnetic surveys for characterizing soft sediments.
– Magnetotellurics for groundwater reservoir delineation.
– Ground penetrating radar for non-invasive utility detection and geotechnical characterization.
– Full-waveform inversion methods for imaging heterogeneous wave velocity profiles.
– BS 5930 as the UK standard for site investigations.

**Applications of Geophysical Techniques**:
– Mapping subsurface structures, recognizing rock unit distributions, and detecting faults and intrusive rocks.
– Assessing likelihood of ore deposits or hydrocarbon accumulations.
– Environmental impact monitoring, subsurface archaeological site imaging, and groundwater investigations.
– Subsurface salinity mapping and civil engineering site investigations.
– Interplanetary imaging and other applications.
– Usage in civil construction and engineering for various purposes.
– Various techniques used for environmental impact assessment.

**Mineral Exploration Techniques**:
– Magnetometric surveys for defining magnetic anomalies.
– Direct detection of ore via magnetism, such as iron ore mineralization.
– Gravity surveying for detecting dense rock bodies.
– Electromagnetic surveys for base metal sulphides and diamond exploration.
– Electric-resistance methods for detecting sulfide bodies and resistive rocks.

**Hydrocarbon Exploration Methods**:
– Seismic reflection and refraction techniques for mapping subsurface distribution of stratigraphy.
– Well logging for high-resolution information about rock and fluid properties.
– Gravity and magnetics for determining geological structures in oil and gas exploration.
– Remote sensing techniques, like hyperspectral imaging, for detecting hydrocarbon microseepages.
– Marine seismic reflection and electromagnetic seabed logging for offshore exploration.

**Specialized Applications of Geophysical Techniques**:
– Archaeological geophysical surveys using ground-penetrating radar and magnetometric surveys.
– Forensic applications for detecting grave sites, surveying shipwrecks, and battlefields.
– Unexploded Ordnance (UXO) detection using magnetic and electromagnetic surveys.
– Studies on PML-Truncated Heterogeneous Media, airborne electromagnetic and magnetic surveys, magnetometry in archaeology, and ground-penetrating radar and resistivity methods for specific applications.

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. It is most often used to detect or infer the presence and position of economically useful geological deposits, such as ore minerals; fossil fuels and other hydrocarbons; geothermal reservoirs; and groundwater reservoirs. It can also be used to detect the presence of unexploded ordnance.

Exploration geophysics can be used to directly detect the target style of mineralization by measuring its physical properties directly. For example, one may measure the density contrasts between the dense iron ore and the lighter silicate host rock, or one may measure the electrical conductivity contrast between conductive sulfide minerals and the resistive silicate host rock.

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