A new method of testing of the Earth’s free oscillations on the basis of geomagnetic variation analysis

Abstract

The Earth’s free oscillations are recorded for the first time in variations of the geomagnetic field measured at the Earth’s surface. The Earth’s free oscillations in the frequency range from 0.3 to 4 mHz manifest in the spectra of geomagnetic variations in the form of clearly expressed quasi-harmonic peaks. It is shown that the spectral amplitudes of the main modes of the Earth’s free oscillations are not constant and change with a periodicity corresponding to a lunar (sideral) month. The data obtained indicate the influence of oscillations in the internal geospheres on variations in the terrestrial magnetic field. The results provide new opportunities to study the Earth’s free oscillations and to specify their multiplet components. In addition, they also have certain implications for further research into the internal structure of the Earth and geodynamic processes in internal geospheres, on the basis of magnetometric data.