GLOBAL VARIATIONS IN THE GEOMAGNETIC FIELD CAUSED BY THE EXPLOSION OF THE TONGA VOLCANO ON JANUARY 15, 2022

Abstract

The explosion of the Tonga volcano on January 15, 2022, led to significant disturbances in the Earth (lithosphere, World Ocean) — atmosphere — ionosphere — magnetosphere system. The purpose of this paper is to present the results of a study of global variations in the geomagnetic field caused by the explosion of the Tonga volcano on January 15, 2022. To analyze the variations of the X-, Y-, and Z-components of the geomagnetic field, registrations at 12 stations of the worldwide INTERMAGNET network were used. When processing the time series, the trend calculated over 60 min with a step of 1 min was first subtracted, and then a system spectral analysis was applied. An analysis of the state of space weather made it possible to choose January 13 and 17, 2022, as reference days. An analysis of time variations in the level of all components of the geomagnetic field showed the following. On the day of the volcano explosion, approximately after 04:21, there were significant variations in the level of all components, but the largest variations were observed in the level of the Y-component. The shortest time delay was 6 min. At the same time, quasi-periodic variations of the geomagnetic field with a period of 4…4.5 min and an amplitude of ~2 nT were caused by acoustic resonance in the field of a standing acoustic wave generated by the explosion of the volcano. In addition, six groups of possible disturbances stimulated by the volcano explosion were found. It is important that in each group, the time delay of disturbances increased with increasing distance between the volcano and the station. It was found that the disturbances were transported at speeds close to 4, 1.5, 1 km/s and 500, 313, and 200 m/s. Such velocities are characteristic of slow MHD waves, a blast wave, an atmospheric gravity wave, a Lamb wave, and an ionospheric tsunami wave.