Wave-Related, Electrical, and Magnetic Effects Due to the January 15, 2022 Catastrophic Eruption of Hunga Tonga–Hunga Ha’apai Volcano

Abstract

This paper discusses the data of instrumental observations conducted at the Mikhnevo Observatory, at INTERMAGNET observatories, and at the Geophysical Monitoring Center of the Institute of Geosphere Dynamics (IGD), Russian Academy of Sciences (RAS) during the explosive eruption of Hunga Tonga-Hunga Ha’apai Volcano of January 15, 2022. It is shown that the explosion of the volcano produced a series of wave disturbances in the atmosphere, as well as electrical and magnetic variations at large epicentral distances. The atmospheric disturbances were recorded as Lamb waves emitted by a source at the center of the explosion, as well as by a virtual source situated at the antipode. The latter source was formed by convergence and summing of signals propagating on the terrestrial sphere. In addition to primary waves, the recorded phenomena also include secondary and tertiary waves due to multiple passage of the explosion-produced signal around the terrestrial sphere. We evaluated the source energy based on the characteristic frequency in the spectrum of the signal, resulting in the value ~10¹⁸ J, which corresponds to ~200 MT of TNT, when converted to an explosive source. It is shown that a volcanic explosion is accompanied by electrical and magnetic variations both at the time of the explosion and at the time when the recording site receives atmospheric wave disturbances.