Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 32 & Another Inclined Fountain - September 4, 2025

Following a more typical pause of 10 days, Kīlauea’s ongoing summit eruption produced its 32nd episode on Tuesday, September 2 from about 6:30 AM to 8:00 PM, a total of 13.4 hours during which the large inclined lava fountain from the north vent peaked around 500 feet or 150 meters in height, shooting out a similar distance into the crater. Once again a larger than average amount of lava was erupted, 9 million cubic meters that emerged at a high rate and covered most of Halemaʻumaʻu crater floor, while emitting a large cloud of volcanic gas dispersing upwards and downwind. The combination of the inclined fountain and favorable winds allowed for the production of massive amounts of tephra, which looked “like swarms of dark, angry bees” according to USGS-HVO messaging. 

For the second straight episode, the new intermediate vents were actively erupting along with the south vent, peaking at 160 feet or 50 meters in height, and fed a smaller flow along the southwest side of the crater floor. The main fountain and flows from the north vent wrapped clockwise fully around the crater from the northwest to meet the south and intermediate vent flows, creating a lei of lava flows around its center.

Again, despite a lower and inclined fountain, gas emissions shot upwards through the atmosphere as well as downwind, mostly impacting the nearby and closed areas of Hawaiʻi Volcanoes National Park but also adding to the wider atmospheric load. As with every summit eruption in the last 5 years, 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/. 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, with localized adjustments increasingly evident on monitoring instruments in recent weeks, perhaps coincident with pressure changes at Kīlauea. 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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