12 days have passed since episode 55 of Kīlauea’s ongoing summit eruption, with episode 56 currently expected sometime in the first week of November. That forecast is subject to change, but is based on the volcano’s rate of movement, so far recovering 70% of the episode 55 signal while only “interrupted by several small fluctuations” which pushed the window back by a couple of days. Still, the USGS Hawaiian Volcano Observatory reminds that “given the unusual buildup to episode 55, uncertainty remains as to whether summit deformation will follow a sufficiently consistent pattern to allow for precise forecasting of the next episode.” Strong glow has been steady from the west vent and slightly less so from the north vent all week, with no precursory activity evident 3 days ahead of the forecast window except for rare spatter.
In the meantime, variable winds are bringing vog into nearby island communities, produced from the vents at an average rate of roughly 1,800 tonnes of SO2 per day between fountaining episodes. Trade winds are predicted to return on Sunday, shifting vog back towards the most frequently impacted communities. Both during and between episodes, vog and tephra remain the most common hazards for island residents, and the usual precautions and preparations apply, especially for those with respiratory sensitivities – more information at https://vog.ivhhn.org/. Earthquakes under Kīlauea summit remain low following episode 55, largely returning to recent patterns. That includes persistent south flank activity and deep quakes under Kīlauea and Maunaloa summits, as well as the hotspot feeder zone beneath Pāhala.
As usual, we summarize the monitoring signals, imagery, and reports available courtesy of the USGS Hawaiian Volcano Observatory as well as our broader community, annotating the presentation on-screen and discussing live viewer questions as we go. In this week’s special presentation, we highlight two recent USGS publications offering these new insights into Kīlauea’s dynamics:
1. New, hotter magma arrived at the summit within a few weeks of the start of the eruption, and its signal has become more dominant over time as older magma is progressively flushed out. It feeds continually from the deeper South Caldera reservoir into the shallow Halema’uma’u reservoir, which apparently only suffered “negligible effect” during the 2018 collapse.
2. “The processes that initiate, sustain, and terminate individual episodes remains uncertain.” “Whether they depend on reservoir pressure alone remains unclear. Gas observations may favor a major role for shallow H2O-rich bubble clusters” forming in the shallow conduit.
3. Episode durations and fountain heights may “be variably controlled by viscosity and/or conduit geometry changes through time,” with “no significant geochemical changes during episodes,” “including of pre-eruptive dissolved volatiles (H2O, S).”
4. Halema’uma’u still has molten material beneath its crust from the 2020-2023 era, that has mixed with fresh magma at variable rates and erupted out of the fountain. It also oozed up on the eastern crater floor during some earlier episodes.
5. The Halema’uma’u reservoir has been heating up as it “cannot keep pace with the rate of magma supply in this post-2018 caldera collapse period.”
(Lynn et al., JVGR vol. 480, Dec. 2026; Flinders et al., Science vol.394, no.6820, 8 Oct 2026)
