The Earth's magnetic field is present but not strong enough to create powerful magnets on its surface. However, it can leave measurable traces in certain types of rock. The magnetic field is static and changes over long timescales, making the concept of "frequency" less applicable. Objects on Earth's surface can become magnetized, with steel ships built in the Northern Hemisphere magnetized oppositely to those in the Southern Hemisphere. This led to the development of degaussing techniques during World War II to protect ships from magnetic mines. The Earth's magnetic field strength is continuously monitored at various sites, which helps predict geomagnetic storms caused by solar activity. Magnetometers detect fluctuations in the geomagnetic field, with significant variations observed during storms. The discovery of magnetic striping on the seafloor provided crucial evidence for plate tectonics. Additionally, the frequency of magnetic reversals is irregular, estimated at around 100 fHz.
