Lava vents are glowing through the night as Kilauea builds toward its next eruption

The north and west vents inside Kilauea’s Halemaumau crater have glowed and thrown flames through the night for days straight, the U.S. Geological Survey’s Hawaiian Volcano Observatory reported in its daily update for September 19, 2026. The volcano remains at Watch alert level with an Orange aviation color code as its summit re-pressurizes toward a fountaining episode that observatory scientists say could begin within one to two days.

Kilauea has been erupting episodically since December 23, 2024, cycling through lava-fountaining episodes that typically last less than 12 hours, separated by pauses of two weeks or more while the summit slowly reinflates. The current pause has stretched on since episode 54 ended in late August, and the observatory’s monitoring network shows the mountain is nearly back to the pressure that triggered that last outburst.

Summit tilt has recovered 15 of the 16 microradians lost in episode 54

According to the Hawaiian Volcano Observatory’s September 19 daily update, summit inflation has recovered about 15 microradians of tilt since episode 54’s lava fountaining ended on August 25, more than two microradians greater than the deflation the eruption itself caused. The system reached a peak inflation of 16 microradians last Wednesday, September 16, then deflated by roughly 2.3 microradians as the lava flows from that episode’s vents 1 through 6 stopped moving, before slow reinflation resumed the following day and clawed back most of the lost ground.

HVO’s tiltmeter data put the volcano within one to two days of returning to that same peak pressurization, the threshold that opened the vent system during episode 54. Strong tremor bursts remain the dominant seismic signal at the summit, and the observatory logged five small earthquakes scattered across the summit region in the 24 hours before the update, though none clustered tightly enough in time or location to read as a clear eruption precursor on their own.

Episode 54 sent lava 500 feet into the air for nine hours

The last confirmed eruptive episode began around 10:30 a.m. local time and ran until 7:33 p.m. on August 25, 2026, according to HVO’s status report on that episode. The north vent’s fountain reached approximately 500 feet above ground level between 12:15 and 1:00 p.m., while neither the south vent nor the newer west vent, a former collapse pit, fountained during the episode. The resulting plume climbed to roughly 17,000 feet above sea level, and most of the tephra it produced fell inside the closed section of Hawaii Volcanoes National Park, though the observatory did log a report of trace Pele’s hair reaching the Kau district further south.

That pattern of tall, short-lived fountaining separated by multi-week pauses has defined the eruption timeline since it began nearly two years ago, and it gives HVO scientists a rough but not exact template for what episode 55 might look like once the pressure threshold is crossed again.

Scientists can’t rule out a new vent opening instead of episode 55

HVO’s analysis lays out three roughly equally likely outcomes once the summit finishes repressurizing: activity could resume at the existing north-south-west vent complex, it could reactivate the vents 1 through 6 system that opened during episode 54, or the rising pressure could intrude into another weak point in the summit’s crust and open an entirely new pathway. None of those scenarios is expected to produce a strong seismic warning beforehand, which is why the observatory has held the alert level at Watch and the aviation color code at Orange even though no lava is currently reaching the surface.

The Orange code specifically flags a volcano that is “exhibiting heightened unrest with an increased potential for eruption,” the classification USGS uses when forecasting the exact timing and location of the next outburst is not possible. Outside the summit, seismicity and ground deformation remain low along both the East Rift Zone and the Southwest Rift Zone, and sulfur dioxide emissions from the East Rift Zone stay below the observatory’s detection limit, indicating the unrest is confined to the caldera rather than spreading along the volcano’s flanks.

The hazards extend beyond the lava itself

Even during the current pause, HVO’s update flags volcanic gas, primarily water vapor, carbon dioxide, and sulfur dioxide, as a continuing hazard downwind of the vents, with sulfur dioxide reacting in the atmosphere to form the volcanic smog Hawaii residents call vog. During inter-episode pauses like this one, the summit typically releases between 1,000 and 5,000 tonnes of sulfur dioxide per day. Cooling lava on the floor of Halemaumau crater and the southwest side of the larger Kaluapele caldera remains hot enough to slowly shift in the days after each episode, and the crater’s rim, closed to the public since late 2007, stays prone to cracking, slumping, and small landslides that can expose molten material underneath.

The observatory said its monitoring network has mostly recovered from a string of recent power and storm-related outages, though several summit stations remain offline while technicians restore instruments and reconnect the array. HVO is coordinating with Hawaii Volcanoes National Park and the Hawaii County Civil Defense Agency on eruptive hazards and continues issuing daily updates as the summit approaches the pressure point that has, more than fifty times now since December 2024, been followed within days by a new fountaining episode.

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

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