Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 34 - October 2, 2025
Episode 34 became a highlight of Kīlauea’s ongoing summit eruption with the return of double high fountains from the north and south vents, while setting the record for the highest lava fountains in over 9 months of the eruption so far. Reaching an estimated 1300 feet or 400 meters, the narrow south vent fountain shot vertically straight into the air, while the north vent fountain remained somewhat inclined to the northeast, peaking above 330 feet or 100 meters in height. Between both vents, lava was erupted at the highest rate of the eruption so far around 500 cubic yards or 400 cubic meters per second, “about twice the maximum eruptive rate measured in previous episodes” according to the USGS Hawaiian Volcano Observatory. The higher rate, combined with a similar amount of lava erupted at around 12 million cubic yards or 9 million cubic meters, meant the episode only lasted half as long as usual at just over 6 hours.
Precursory activity to episode 34 was extended over two days starting on Sunday evening, September 28, with over 110 small overflows from the north vent ahead of the start of its vigorous fountaining at 12:53 AM on October 1. The south vent began erupting about a little less than an hour later at 1:45 AM, lasting until 7:00 AM after which the north vent also shut down 3 minutes later. Lava flows fed by the fountains from both vents traveled most of the way across Halemaʻumaʻu crater floor.
With light northeast winds, the ground-level impact of volcanic gas and tephra emissions appeared limited to the southwest side of Kīlauea caldera across the Kaʻū Desert in the closed area of Hawaiʻi Volcanoes National Park. However, much of the emissions appeared to rise vertically through the relatively still air before being carried northward high in the sky across Hawaiʻi Island. 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. For now, Kīlauea’s landmark summit eruption is expected to continue after the current pause, with early monitoring signals suggesting “another fountaining episode is possible, but likely more than a week away.”
Maunaloa continues to inflate its established post-eruption pattern, with localized adjustments 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. As a bonus this week to mark its recent anniversary, we recap the chronology of the September 15-20, 2024 East Rift eruption at Nāpau.
