Imprints of Natural Phenomena and Human Activity Observed During 10 Years of ELF Magnetic Measurements at the Hylaty Geophysical Station in Poland

Current human activity produces strong electromagnetic pollution. The power spectrum in the extremely low frequency (ELF, 3-3000 Hz) range is mainly polluted by anthropogenic narrow spectral lines at 16.66, 50, and 60 Hz and their harmonics. Meanwhile, signatures connected with natural phenomena appearing in the Earth’s atmosphere, ionosphere and magnetosphere are also observed in the same frequency range