Kīlauea’s north vent produced 29 intermittent lava overflows after activity began on September 7, 2026, and the U.S. Geological Survey said on September 9 that a new episode of lava fountaining was likely within a September 9–10 forecast window. The count covered roughly two days of activity in Halemaʻumaʻu, where a glow was visible overnight between overflows when rain, steam and cloud did not obscure the webcams.
The Hawaiian Volcano Observatory kept Kīlauea at WATCH and its aviation color code at ORANGE in that daily update. Those labels describe an active eruptive situation, but they do not mean a fountain had already begun: the agency was reporting precursory overflows while watching for a transition to episode 55.
The north vent produced 29 short-lived overflows
The 29 events did not form a single continuous lava flow. The observatory recorded individual overflows lasting from 15 minutes to about two hours, separated by pauses ranging from roughly 15 minutes to eight hours. The first began at about 12:45 p.m. Hawaii time on September 7 after weak spattering had been observed the previous evening.
In its September 9 daily update, HVO said the most recent north-vent overflow had started at 7:27 that morning. The agency described the activity as becoming more vigorous, with a dome fountain reaching about 15 to 30 feet high during the overflow sequence.
Two lava flows formed during those episodes. One reached about a half-mile southwest of the north vent; the other traveled less than a half-mile northeast. Those measurements apply to flows inside the summit crater area, not to an advancing flow outside the national-park closure.
Tremor and ground tilt gave scientists a way to read hidden activity
Weather complicated the visual record. Heavy rain, cloud and steam associated with Hurricane Lowell had often blocked the summit cameras, so HVO used changes in tremor to time many of the overflows. Tremor is a continuous vibration signal that can accompany moving magma and gas; it offered an independent observation when a camera could not see into the vent.
The daily report also noted regular gas-piston activity at about five-minute intervals and two small earthquakes beneath the summit region during the preceding 24 hours. HVO’s observatory messages are the agency’s channel for significant changes between its daily updates, while its summit webcams show why cloud cover can limit a visual read of an active crater.
Ground deformation supplied another clue. HVO reported that the summit had reinflated irregularly after the prior fountaining episode on August 25, then showed little change during the 24 hours before the September 9 update. The agency treated that combination of glow, overflows and tremor as evidence that another fountain could occur, not as proof that it was inevitable at a fixed hour.
That distinction is central to HVO’s language. A forecast window expresses the observatory’s assessment of changing conditions, while an alert level communicates the broader state of unrest. Neither turns an observation at one vent into a prediction of a particular eruption time, height or impact outside the closed summit area.
The forecast concerned episode 55, not a new volcano-wide eruption
Kīlauea had been erupting episodically from north and south vents in Halemaʻumaʻu since December 23, 2024, according to HVO. The observatory describes lava-fountaining episodes that usually last less than 12 hours and are separated by pauses of two weeks or more. Episode 55 was the next possible fountain in that sequence.
HVO said a return to inflation or a change from intermittent overflow to sustained fountaining could precede episode 55. It also noted that a stalled tilt signal or a longer deflation could delay the event for days. The USGS eruption-information page maintains the timeline and maps for the ongoing summit eruption, and the agency’s lava-flow maps show the geography of the summit activity.
No significant activity had been observed along Kīlauea’s East Rift Zone or Southwest Rift Zone in the cited update. Keeping the report tied to Halemaʻumaʻu matters: a dramatic count at the summit does not establish that every part of the volcano is experiencing the same behavior.
The active crater remained inside a closed area
The USGS said the episodic eruption was occurring within a closed area of Hawaiʻi Volcanoes National Park. Volcanic gases, including sulfur dioxide, can remain hazardous downwind even during a pause, and fountain activity can create tephra such as ash, pumice and Pele’s hair. The agency’s hazard guidance explains why the crater rim has its own risks, including cracking, rockfalls and unstable ground.
That setting supplies the proper scale for the September 9 account: 29 overflows in about two days, a monitoring-based forecast for a new fountain, and a confined summit hazard zone. The report was a snapshot of a closely watched episodic eruption, not a declaration that an eruption had newly spread across Hawaiʻi.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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