U.S. Geological Survey scientists monitoring Kīlauea report that the volcano remains paused following its October 17 eruption episode, with the next fountaining phase anticipated during the first week of November as steady summit inflation continues under Advisory alert levels.
The Halemaʻumaʻu summit eruption of Kīlauea sits in a quiet phase following episode 55 fountaining on October 17. Hawaiian Volcano Observatory scientists tracking the deformation patterns initially adjusted the forecast window for episode 56 to early November, pointing to steady post-fountaining recovery across the summit.
Summit Tilt and the Shift in Forecast Timelines
Predicting the exact moment of Kīlauea’s next outburst relies heavily on ground deformation data. Instruments known as tiltmeters measure minute shifts in the slope of the volcano’s summit. According to Hawaiian Volcano Observatory research geophysicist Ingrid Johanson, when lava drains from the chamber during a fountain, the ground above sinks inward, and as deeper magma recharges the reservoir, the surface bulges and tilts outward.
On June 1, 2026, Kīlauea volcano on the Island of Hawaiʻi made history.Its ongoing summit eruption in Hawaiʻi Volcanoes National Park has now produced 48 fountaining episodes—surpassing the previous record set by Puʻuʻōʻō eruption in the 1980s (47 fountaining episodes).With… pic.twitter.com/BxOZcmj79H
Since episode 5 in January 2025, Johanson wrote that the tilt lost during fountaining has roughly mirrored the tilt regained during the subsequent pause. However, unusual behavior preceded the 55th episode. Summit tiltmeters recorded positive tilt beyond levels typically observed before fountaining, suggesting heightened pressurization of the magma chamber. Instead of climbing steadily, the tilt remained negative or stable for extended periods.
That erratic buildup altered forecasting models. Following a brief negative trend on October 26, summit inflation resumed, pushing the projected window for episode 56 fountaining to November 2–9, 2026, though the U.S. Geological Survey initially shifted the prediction to November 1–7. HVO has used that link to publish forecast windows since episode 5 in January 2025, though it had to stop for several weeks in September 2026.
Anatomy of Episode 55 and the September Intrusion
The current episodic eruption began on December 23, 2024, originating from two primary vents inside Halemaʻumaʻu crater. Most cycles feature spatter and overflows, followed by short-lived fountaining and a multi-week pause. Episode 55 broke records for precursory activity, arriving after 39 days of intermittent lava overflows—the longest run-up recorded in the ongoing eruption. The eruption started at about 2:20 a.m.
The fountaining event itself was brief and explosive. It began at 3:19 a.m. local time on October 17 and ended abruptly at 9:03 a.m. According to Hawaiian Volcano Observatory reports, lava from the north vent reached a maximum height of approximately 720 feet, generating a plume that reached approximately 25,000 feet above mean sea level. While the north vent exhibited weaker incandescence and the west vent showed strong glowing intermittently, the south vent remained dark after being buried beneath tephra during episode 55. Rising from the northern vent, lava jetted to a peak elevation of roughly 720 feet (220 meters) above the ground. Neither the southern nor the western vent produced any fountaining throughout this period, though both had generated lava overflows beforehand. The maximum plume height was approximately 25,000 (7,500 meters) above mean sea level.
Weeks before that activity, scientists with the U.S. Geological Survey’s Hawaiian Volcano Observatory noted that a caldera intrusion from September 30 to October 1 had people wondering what would come next, following a pattern where Kīlauea has experienced many summit and rift zone intrusions over recent years. Geologists note that such magmatic intrusions and shifting vents reflect the normal, highly dynamic behavior of Kīlauea following the 2018 lower East Rift Zone eruption and summit collapse. On the night of September 30, a shallow intrusion of magma formed beneath the caldera. A first seismic swarm comprised over 30 recorded earthquakes, while a second swarm produced more than 50 events tracked by HVO.
Hawaiian Volcano Observatory Monitoring and Safety Hazards
The Hawaiian Volcano Observatory maintains Kīlauea’s volcano alert level at ADVISORY and its aviation color code at YELLOW. While East and Southwest Rift Zone monitoring shows low seismicity and minimal ground deformation, summit hazards remain a constant concern within the closed areas of Hawaiʻi Volcanoes National Park. Ever since fountaining stopped on October 17th, roughly 13.4 microradians of tilt have bounced back, following an initial span of fountaining that produced 21 microradians of swift downward tilt.
Tephra fallout from episode 55 was restricted mostly to the restricted park zones southwest of the vents. Beyond ash and pumice, the volcano continuously releases high levels of volcanic gas, including sulfur dioxide emission rates that typically range from 1,000 to 5,000 tonnes per day during inter-episode pauses. Furthermore, instability along the Halemaʻumaʻu crater wall and thermal cracking on the rim pose severe risks of rockfalls and small landslides.
