Research led by the Atmospheric Physics research unit of the ELKH Institute of Earth Physics and Space Science (FI) revealed another peculiar effect of the strongly electrified plume of the Hunga Tonga-Hunga Ha’apai volcano during its outstanding eruption last January. In two time periods of duration 5-10 minutes each, the total electric charge of the Earth was increased globally by ~15% due to the transport of a large amount of electric charge from the volcanic cloud to the surface of the Earth. This happened during the most intense phase of the eruption, between 6 and 7 hours CEST (5-6 UTC) on 15 January 2022.The results were obtained in a framework of an extensive international collaboration and have been published recently in JGR Atmospheres.
The gigantic eruption of the Hunga Tonga-Hunga Ha’apai volcano last January exhibited the largest volcanic plume, most energetic explosion, and the most complex impact on the Earth’s atmosphere among the recently documented volcanic eruptions. The volcano acted as a giant charge generator, the power of which was comparable to charge separation processes taking place in thunderstorms and electrical shower clouds all over the rest of the world combined. A large amount of negative electric charge was transported from the volcanic plume to the surface of the Earth. This was detected in the atmospheric electric field simultaneously at several observatories worldwide, including the Széchenyi István Geophysical Observatory in Hungary.
The significance of the result is that it demonstrates the usability of a novel data processing method, which was applied for the first time in this investigation and allows finding a global signal hidden within a set of records of comparably large noise levels, taken using different sensors at different locations in different local environments.
The lightning activity in this eruption of the Hunga Tonga volcano has been the greatest documented activity in a single source since global lightning observations have been available. FI researchers also discussed several aspects of this lightning activity. It was demonstrated how volcanic lightning strokes excited Schumann resonances in the global-scale waveguide bounded by the surface of the Earth and the lower ionosphere. The excitation of Schumann resonances by the lightning strokes in the volcanic plume was globally dominant as it exceeded the excitation from all lightning occurring at other parts of the globe at the same time. Note that Schumann resonance is a powerful tool for studying the climate, too, as it has been demonstrated in another publication of the Atmospheric Physics research unit of FI.
FI researchers pointed out that the temporal variation in the distribution and intensity of lightning activity in the volcanic cloud is closely related to the explosions during the eruption. It has been suggested that the corresponding observations can be used to obtain further information on the dynamics of the eruption. A possible scenario for the development of the volcanic cloud has been proposed. Note that several elements of the proposed scenario have been confirmed by a study that was also published recently by American volcanologists.
Publication:
Bór, J., Bozóki, T., Sátori, G., Williams, E., Behnke, S. A., Rycroft, M. J., et al. (2023). Responses of the AC/DC global electric circuit to volcanic electrical activity in the Hunga Tonga-Hunga Ha'apai eruption on 15 January 2022. Journal of Geophysical Research: Atmospheres, 128, e2022JD038238. DOI: 10.1029/2022JD038238