[S-GD01] Geodesy and Global Geodetic Observing System

[SGD01-05] Spatio-temporal distribution of the atmospheric modes excited by the 2022/1/15 eruption of the Hunga-Tonga Hunga-Ha’apai volcano from GNSS-TEC observations

*Kosuke Heki^1,2, Ihsan Naufal Muafiry^3,4 (1.Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University, 2.Chinese Acad. Sci., Shanghai Astronomical Observatory, 3.Institut Teknologi Bandung, Indonesia, 4.Politeknik Sinar Mas Berau Coal, Indonesia)

Keywords:Tonga, atmospheric mode, total electron content, GNSS

Continuous Plinian eruptions often excite atmospheric free oscillations at 3.7 and 4.4 mHz, which are observed as harmonic oscillations of ionospheric total electron content (TEC) by global navigation satellite system (GNSS) receivers. Such TEC oscillations started shortly after the great eruption of the Hunga-Tonga Hunga-Ha’apai submarine volcano in 2022 Jan. 15. Here we analyze GNSS data at nearby island stations and in New Zealand, to study temporal and spatial distribution of such atmospheric modes. Strong TEC oscillations started after the onset of the eruption and have decayed in a half day. However, it became strong again around 20UT on the eruption day. This “revived” atmospheric oscillation does not occur near the volcano but showed the largest amplitude at the distance ~1,000 km from the volcano. Considering its monochronic frequency spectra and the absence of propagation, it is likely that such oscillations are not directly excited by HTHH eruption but driven by 0S29 free oscillation of the solid earth as a secondary phenomenon. Such “revived” atmospheric modes are confirmed also in New Zealand.