Kilauea’s 55th episode threw lava about 700 feet and quit after six hours

Kilauea’s 55th lava-fountain episode began before dawn on Oct. 17, 2026, threw lava about 700 feet above the north vent in Halemaumau crater, and stopped abruptly after roughly six hours. The Hawaiian Volcano Observatory recorded the fountaining from 3:19 a.m. to 9:03 a.m. Hawaii Standard Time, and the volcano has been in a pause since.

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The ending is the part that stood out to forecasters. Earlier episodes had settled into a pattern that made them predictable, and episode 55 broke it at both ends, with a record-long run of lava overflows before the fountain and a sudden stop after it. The observatory has been open about what that does to its own forecasts, and the details below come from its dated updates.

Six hours at the north vent

The observatory’s Oct. 17 daily update gives the timeline. Fountaining started at 3:19 a.m. and “ended at 9:03 a.m. HST on October 17, 2026, after about 6 hours of continuous fountaining from the north vent.” The update’s words on height were specific: “Fountains reached a maximum height of 720 feet (220 m) around 5 a.m. HST.” That is the figure behind the rounded 700 feet. The same notice says the fountain dropped back to 650 feet and then to 500 feet by 7:00 a.m., well before the end, so the peak did not last until the end.

The Oct. 20 summary repeats the 720-foot maximum, measured above ground level, and adds that the eruption cloud reached about 25,000 feet above sea level at its peak, roughly 7,500 meters. A preliminary estimate in the Oct. 17 update put the erupted volume near 9 million cubic yards, or about 7 million cubic meters.

Lava did not stay at the vent. By 8:30 a.m., the observatory reported, flows “were covering 75% of the crater floor” after flooding the western part of the crater. The south vent got the opposite treatment: a later update says it was “covered in a layer of tephra during episode 55” and showed no glow afterward.

A break in the pattern

Observatory scientists used pointed language about how the episode began. According to the Oct. 21 update, “the onset of episode 55 departed from the pattern established from previous episodes,” and the run of precursory overflows before the fountain lasted 39 days, which the report calls a record. The Oct. 23 update repeats that point and adds that tilt data recorded additional pressurization of the magma chamber, followed by a buildup that was irregular, with stretches of deflationary tilt or none at all.

The deflation at the summit was large as well. A tiltmeter at Uekahuna recorded 21 microradians of deflationary tilt during the episode. Recovery began right away: the Oct. 21 update had 9.8 microradians of inflationary tilt regained since the end, and by Oct. 24 the figure was 12.4. Tilt measures how the ground at the summit swells and sags, and the rate of that swelling is what the observatory uses to time the next fountain.

The observatory said in its Oct. 24 update that the eruption was “currently paused after episode 55 fountaining ended on October 17,” and it cautioned that “there is still uncertainty in whether inflation will remain regular and predictable.” In plain terms, the forecasting method that worked for earlier episodes now carries a stated reason for doubt, and the forecast window has moved from one update to the next: the Oct. 21 update gave Oct. 28 to Nov. 5 for episode 56, the Oct. 23 update Oct. 29 to Nov. 5, the Oct. 24 update Oct. 30 to Nov. 5, and the Oct. 26 page Oct. 31 to Nov. 6. Each is a forecast, not a schedule.

The alert level and what it means on the ground

During the episode, the observatory held Kilauea at WATCH with the aviation color code at ORANGE. As of Oct. 26, the observatory’s volcano page shows ADVISORY and YELLOW, a step down that fits a pause between fountains. The observatory’s status page carries the current level along with the most recent summit messages.

The step down is not a clearance. The Oct. 26 page puts the next fountaining, episode 56, between Oct. 31 and Nov. 6 and says uncertainty remains because episode 55 departed from earlier patterns. Summit glow, low-level tremor and gas emissions continue, which the observatory describes as typical for the pause between episodes, while rift zone seismicity and ground deformation remain low.

The hazards stay local. The Oct. 24 update says gas “emissions can remain locally hazardous in the areas immediately downwind of the vents,” with sulfur dioxide releases during pauses usually between 1,000 and 5,000 tonnes per day. Tephra fall from the episode was mostly confined to the closed area of Hawaii Volcanoes National Park southwest of the vents, and the Halemaumau crater rim has been closed to the public since late 2007. The observatory advises people to minimize exposure to the tephra fragments, which can irritate skin, eyes and airways.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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