(BIVN) – Another episode of lava fountaining is in the forecast for the summit of Kīlauea within Hawaiʻi Volcanoes National Park.
Prior to the most recent episode, scientists with the USGS Hawaiian Volcano Observatory had abandoned attempts to try to calculate if and when another high lava fountain event would occur, due to the irregular inflation patterns and the prolonged stage of precursory lava activity.
At the end of episode 55 on October 17th, tiltmeters recorded steady re-inflation, signaling a possible return to a reliable pattern leading to another episode.
“Presuming fountaining behavior returns to the patterns established in the past, the preliminary forecast for episode 56 fountaining to occur is between October 27 and November 6, 2026,” the USGS Hawaiian Volcano Observatory reported on Tuesday.
Episode 55 lasted less than 6 hours. In that time, deflationary tilt measured at the Uēkahuna tiltmeter totaled 21 microradians. As of Tuesday morning, at total of 8.6 microradians of inflationary tilt had already been recovered.
For the USGS HVO on Tuesday morning:
Summit Observations:
Continuous glow was again observed overnight from the north and west vents in Halema’uma’u. No glow was visible from the south vent, which was covered in a layer of tephra during episode 55. In the past, summit vents have re-established themselves over the course of days to weeks following similar tephra coverage. Points of incandescence from the cooling lava flow in the crater are now mostly dark.
Low-level seismic tremor increased slightly over the past day with periodic seismic pulsing that is typical during inter-episode pauses. Eight earthquakes were recorded in the summit area in the past 24 hours.
Inflationary tilt resumed immediately upon cessation of fountains and consistent, steady tilt continues this morning. The UWD tiltmeter has recovered at total of 8.6 microradians of inflationary tilt since the end of episode 55. Deflationary tilt measured at a summit tiltmeter at Uēkahuna (UWD) totaled 21 microradians during episode 55. Post-fountaining tilt patterns have been similar to those seen after prior to episode 54.
During inter-episode pauses, the sulfur dioxide (SO2) emission rate from the summit typically varies between 1,000 to 5,000 tonnes per day. Winds are forecast from the northeast, which are pushing the gas plume to the southwest over the Kaʻū Desert this morning.
Rift Zone Observations:
Rates of seismicity and ground deformation remain low in the East Rift Zone and Southwest Rift Zone. SO2 emissions from the East Rift Zone remain below the detection limit. No significant ground deformation was recorded in either rift zone.
Analysis:
Kīlauea has been erupting episodically between December 23, 2024, and August 25, 2026, from two vents (north and south) in Halema‘uma‘u at the summit. Lava fountaining episodes generally lasted for less than 12 hours and were separated by pauses of two or more weeks. The onset of episode 55 departed from the pattern established from previous episodes, with summit tiltmeters recording inflationary tilt indicating additional pressurization of the summit magma chamber beyond levels typically seen before fountaining. The prolonged period of inflationary tilt was not steady, being marked by extended periods of irregular deflationary tilt or no tilt. The episode was also preceded by 39 days of intermittent overflows, a record for the length of precursory activity prior to fountaining. During this prolonged interval, a series of short-lived vents opened within Halemaʻumaʻu and a shallow dike was emplaced beneath Kaluapele. The initial magma chamber reinflation is currently following the normal, predictable pattern seen after most fountain episodes. Based on the amount of inflationary tilt observed at summit tiltmeters, the preliminary forecast is for episode 56 to occur between October 27 and November 6, 2026. However given the differences in the run-up to episode 55, there is uncertainty in whether future episodes will return to the regular, predictable patterns that allowed them to be forecast with reasonable precision.
HVO continues to closely monitor Kīlauea and is in contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency about eruptive hazards. Kīlauea volcano alert level and aviation color code remain at ADVISORY/YELLOW.
