Dictionary:Magnetic anomaly

The difference between observed and theoretical or predicted magnetic values. A residual magnetic anomaly is what remains after removal of the longer wavelength regional; the IGRF is used widely as the regional value. The shape of a magnetic anomaly depends on (a) the geometry of a body, (b) the direction of the Earth’s magnetic field, (c) the direction and intensity of the body’s remanent magnetism, (d) the direction of the observations with respect to the Earth’s field.