Eruption chronology of the December 2021 to January 2022 Hunga Tonga-Hunga Ha’apai eruption sequence

The 15 January 2022 eruption of Hunga Tonga-Hunga Ha’apai, and the preceding eruptions
on 19 December 2021 and 13 January 2022, were remarkable, partly because the eruptions
generated extensive umbrella clouds, regions where the volcanic clouds spread laterally. Here
we use satellite remote sensing to evaluate the umbrella cloud tops’ heights, longevities,
water contents, and volumetric flow rates. We identified two umbrella clouds at distinct
elevations on 15 January 2022. Specifically, after 05:30 UTC, the strong westward propagation
of an upper umbrella cloud at 31 km ± 3 km enabled the visibility of the lower umbrella
cloud at 17 km ± 2 km. The satellite-derived volumetric flow rate for 15 January 2022 was
~5.0 Å~ 1011m3 s−1, nearly two orders of magnitude higher than the volumetric flow rates
estimated for the 19 December 2021 and 13 January 2022 eruptions. Finally, we found that
the umbrellas on all three dates were ice-rich.