A period of rapid, irregular, transient fluctuations of the magnetic field that are greater in magnitude, more irregular, and of higher frequency than diurnal variations. These occur most commonly during unusual sunspot activity as a result of bombardment of the Earth by high-energy particles from the sun. Magnetic storms commonly have an amplitude of 50 to 200 nanoteslas, occasionally thousands of nanoteslas, and their duration is often several days. They are usually associated with auroral displays. Magnetic prospecting has to be suspended during magnetic storms.