10/30/2025
Episode 35 of the ongoing Halemaʻumaʻu eruption ended on October 18 after 7.5 hours of continuous lava fountaining. Both vents continue to exhibit incandescence. Kīlauea summit inflation continues along with seismic tremor and vent glow indicating that another lava fountaining episode is probable. Models suggest a likely forecast window of November 5–10 for episode 36 with November 6-9 most probable.
Summit Observations:
The north and south vents had moderate to weak glow which diminished progressively overnight. The alternating glow pattern between vents persisted but became less distinct in the morning. The reduction in incandescent glow was accompanied by a reduction in the size of gas pistoning events observed in the seismic data.
The summit continues to inflate. The Uēkahuna tiltmeter (UWD) has recorded about 1 microradian of inflationary tilt over the past 24 hours and just under 20.5 microradians of inflationary tilt since the end of episode 35. Tremor patterns became very weak overnight and the earlier gas pistoning pattern with peaks spaced 5-10 minutes apart, could no longer be distinguished by early morning. This reduced glow and diminishing tremor bursts combined with the persistent inflation is not unexpected and suggests that the vent system is still pressurizing towards the next fountaining episode.
Plumes of gas continue from both vents this morning and sulfur dioxide (SO2) gas emissions remain at background levels, typically between 1,200 and 1,500 tonnes per day.
Episode 35 lava fountains began at approximately 8:05 p.m. HST on October 17 and ended at 3:32 a.m. HST on October 18. South vent fountains reached heights of nearly 1,500 feet (460 meters) and north vent fountains reached heights of about 1,100 feet (330 meters). These were the highest single fountain and highest pair of fountains seen during this eruption so far. Episode 35 fountains produced an estimated 13 million cubic yards (10 million cubic meters) of lava. The combined average eruption rate was over 500 cubic yards per second (400 cubic meters per second) from the dual fountains. Lava flows from the fountains covered about two thirds of the floor of Halemaʻumaʻu crater.