Kilauea is refilling for episode 56, and the observatory has given it a window of October 30 to November 5

Kilauea’s summit is refilling, and the Hawaiian Volcano Observatory has placed the next lava-fountaining burst, episode 56, inside a window running from Oct. 30 to Nov. 5, 2026. The observatory set out that window in its Saturday, Oct. 24, daily update, and it is a forecast built on how quickly the ground beneath Halemaʻumaʻu crater is swelling, not a scheduled event. Episode 55, the burst before it, stopped abruptly at 9:03 a.m. Hawaii time on Oct. 17.

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The measuring stick is a summit tiltmeter called UWD, stationed at Uēkahuna. Episode 55 drew the summit down by 21 microradians of deflationary tilt, and since the fountain shut off the instrument has been logging that tilt coming back as magma refills the chamber below. A microradian is a one-millionth-of-a-radian change in slope, far too small to see and legible only to instruments, which is why the observatory reports the recovery in running totals rather than anything a visitor could notice.

Four updates in five days, and a start date that keeps sliding later

The window did not arrive fully formed. In its Oct. 20 update the observatory gave a preliminary range of Oct. 27 to Nov. 6, with 8.6 microradians recovered. The Oct. 21 update trimmed it to Oct. 28 through Nov. 5 at 9.8 microradians. By the Oct. 23 update the range was Oct. 29 through Nov. 5 at 11.6, and the Oct. 24 update reached Oct. 30 through Nov. 5 at 12.4 microradians. The far end of the range has barely moved, while the near end has slipped a day with each report.

The observatory treats that drift as ordinary. Its Oct. 24 update says inflation is steady but slowing gradually, which HVO describes as normal early in a pause between episodes, and it says the post-fountaining tilt pattern resembles the one that preceded episode 54. The Oct. 21 update also noted that the tilt had leveled out that morning, a detail the observatory reported without comment on what it meant for timing.

Put against the 21 microradians that episode 55 removed, the 12.4 recovered by Oct. 24 amounts to roughly 59 percent, a ratio worked out from the observatory’s own totals.

Episode 55’s 39-day run-up and why the forecast comes with a caveat

Episode 55 began at 3:19 a.m. HST on Oct. 17 and ended at 9:03 a.m., nearly six hours later. The observatory describes the eruption in Halemaʻumaʻu as episodic since Dec. 23, 2024, with fountaining that usually lasts under 12 hours and pauses of two weeks or more. According to the observatory’s Oct. 17 update, the fountain peaked at 720 feet (220 meters) at the north vent between 4:50 and 5:10 a.m., fell to about 500 feet by 7 a.m. and to about 300 feet by 8 a.m. Effusion peaked near 1,000 cubic yards per second around 5 a.m., the episode averaged about 380 cubic yards per second, and a preliminary estimate put the erupted lava at roughly 9 million cubic yards. The plume reached about 25,000 feet above sea level.

What makes the next forecast unusual is how episode 55 was approached. It was preceded by 39 days of intermittent overflows, which the observatory calls a record for precursory activity before fountaining, and during that stretch short-lived vents opened within Halemaʻumaʻu and a shallow dike was emplaced beneath Kaluapele, the summit caldera. Inflation before the episode was irregular, with periods of deflationary tilt or none at all.

The Oct. 17 update said the irregular deformation prevented forecast modeling for the next episode. Three days later it offered one, and it attached a warning in plain terms: there is uncertainty in whether future episodes return to the regular, predictable patterns. The Oct. 24 update repeats that the forecast assumes magma chamber inflation has returned to the established pattern, and that there is still uncertainty in whether inflation stays regular and predictable.

Gas, glow and a closed crater rim between bursts

Between episodes the summit is far from silent. The Oct. 24 update reports continuous, low-level seismic tremor, two earthquakes in the summit area over the previous 24 hours, strong continuous glow overnight at the west vent, and weak to moderate glow at the north vent, whose pond had mostly crusted over again. The south vent showed no glow because tephra from episode 55 covered it. Seismicity and deformation in the East and Southwest Rift Zones remained low.

Sulfur dioxide drops sharply once the fountain stops. The observatory says summit emissions of around 100,000 tonnes per day during fountaining fall to a typical 1,000 to 5,000 tonnes per day in the pauses, and on Oct. 24 light northeast winds were forecast to carry the plume southwest over the Kaʻū Desert. East Rift Zone emissions were below the detection limit.

The hazards the observatory lists have not changed with the pause: volcanic gas that can stay locally hazardous downwind, glassy tephra that irritates skin, eyes and airways and can be stirred up again by wind, and ground cracks with unstable overhangs. Lava from the eruption has stayed within Halemaʻumaʻu, though the observatory cautions that intrusions could move activity outside the crater. Tephra from episode 55 fell mostly inside the closed area of Hawaii Volcanoes National Park southwest of the vents, and the crater rim has been closed to the public since late 2007.

For anyone tracking the volcano, the observatory’s newest-notice page for Kilauea carries the current alert level, which stood at ADVISORY with aviation color code YELLOW on Oct. 24. Because the Oct. 30 to Nov. 5 range is a forecast, the next daily updates are where it is likely to shift again, as each new tilt total either confirms the pace or stretches it.

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

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