Story: Magnetic field
This aeromagnetic map of the Taupō volcanic zone shows areas where the earth’s magnetic field is higher than normal (red) and lower than normal (blue). Volcanic lavas (between Taupō and Lake Rotorua) are often rich in magnetic minerals and produce an increase in the strength of the magnetic field. Geothermal areas (near the Waikato River) are associated with magnetic lows.