A magnetic anomaly is a variation in the Earth’s magnetic field resulting from the differing magnetic properties of subsurface rocks. These anomalies are used in geophysical exploration to detect buried structures, mineral deposits, and other geological features. Magnetic anomalies are crucial in the study of plate tectonics and the mapping of the ocean floor.
Source Blakely, R. J. (1995). “Potential Theory in Gravity and Magnetic Applications.” Cambridge University Press.