17 articles
Aeromagnetic survey
An aeromagnetic survey is a geophysical method in which a low-flying aircraft with a magnetometer records magnetic anomalies from rocks below, used for geological mapping and mineral exploration.
Anisotropy of magnetic susceptibility
Anisotropy of magnetic susceptibility (AMS) is the dependence of a rock's magnetic susceptibility on field direction, defined by three principal susceptibilities forming an ellipsoid that records mineral fabric.
Bouguer anomaly
The Bouguer anomaly is a gravity anomaly corrected for elevation and the surrounding terrain, so remaining values reflect density variations used in mineral exploration and crustal studies.
Downward continuation
Downward continuation is a geophysical processing technique that projects potential field data, such as gravity or magnetic anomalies, to a level closer to its sources, enhancing shallow features.
Earth tide
The Earth tide, or solid Earth tide, is the elastic deformation of the solid Earth, up to about 10 cm, caused by the gravity of the Moon and Sun.
Euler deconvolution
Euler deconvolution is a semi-automatic method for interpreting magnetic and gravity survey data, estimating the location and depth of field sources by solving Euler's homogeneity equation over moving data windows.
Fluxgate magnetometer
A fluxgate magnetometer is a vector instrument measuring DC and low-frequency magnetic fields via a saturating ferromagnetic core, invented in 1936 and used from space missions to submarine detection.
Geopotential model
A geopotential model is a mathematical representation of Earth's gravitational potential, delivered as spherical harmonic coefficients from which geoid undulations, gravity anomalies, and satellite orbits are computed.
Gravimetry
Gravimetry is the measurement of gravitational acceleration and its variations in space and time, using instruments on the ground, ships, aircraft, or satellites to infer Earth's mass distribution.
Gravity gradiometer
A gravity gradiometer is an instrument that measures the rate at which gravity changes from one point to a nearby point, used in resource exploration and passive navigation.
Gravity gradiometry
Gravity gradiometry is a geophysical surveying method that measures how gravitational acceleration changes from point to point, revealing subsurface density structure from aircraft or satellites.
Gravity inversion
Gravity inversion is the geophysical process of estimating a subsurface density model from measured gravity anomalies. It is non-unique and unstable, so regularization and constraints are needed.
Magnetic anomaly detection
Magnetic anomaly detection (MAD) analyzes measured local magnetic fields to detect weak magnetic sources such as buried ferromagnetic material, applied in mineral exploration, unexploded ordnance clearance, archaeology, and military submarine detection.
Magnetic survey
A magnetic survey is a geophysical method that maps spatial variations in Earth's magnetic field to image subsurface geology, mineral deposits, and buried structures, measured in nanotesla.
Optically pumped magnetometer
An optically pumped magnetometer (OPM) is a magnetic field sensor that reads the Larmor precession of laser-pumped alkali vapor atoms, reaching femtotesla sensitivity comparable to SQUIDs.
Upward continuation
Upward continuation is a potential-field technique that recalculates gravity or magnetic data at a higher elevation, acting as a low-pass filter that suppresses shallow-source noise.
Vertical derivative (potential-field method)
In use since 1936, the vertical derivative is a transformation of gravity and magnetic data that narrows anomalies, helping interpreters locate the rock bodies that cause them.