Hawaiian Volcano Update: Slumps & Slides Post-Episode 34 of Kīlauea Summit Eruption - October 9, 2025

Over the past week, the hot remnants of Episode 34 continued to settle and slump, triggering numerous hot landslides from the mass of lava and tephra draped against and over the caldera’s southwest wall. Underground, magma is recharging in its usual pattern, causing increased ground tilt, variable glow from both main vents, and driving pistoning cycles. According to the USGS-HVO, “the variable nature of the glow correlates with rhythmic spikes in seismic tremor 10-15 minutes apart, which are indicative of gas piston activity within both vents.” Given the rate of inflation, models expect the next fountaining episode sometime from October 17 to 21.

Meanwhile, the vents continue passively venting gas, typically 1,200 to 1,500 tonnes per day in the periods between vigorous fountains. Variable winds in the past days and in the forecast may carry the sulfurous emissions into a greater number of neighborhoods than usual. As with every summit eruption in the last 5 years, vog and tephra are currently the most common hazards for island residents and visitors. The usual precautions and preparations apply, especially for those with respiratory sensitivities – more information at https://vog.ivhhn.org/.

All eruptive activity has been confined to Kīlauea’s summit caldera within Hawaiʻi Volcanoes National Park, with no increased lava threat to people. There continue to be no significant changes on either of Kīlauea’s rift zones. Maunaloa continues to inflate its established post-eruption pattern. As usual, we summarize the monitoring signals, imagery, and reports available courtesy of the USGS Hawaiian Volcano Observatory, annotating the presentation on screen as we go and discussing live viewer questions. 

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