Kīlauea’s 55th Lava Fountaining Episode Ends After 6 Hours

Key points

• Episode 55 started at 3:19 a.m. HST on October 17, 2026, and ended at 9:03 a.m. HST, lasting less than six hours.
• Lava fountains reached a maximum height of just over 700 feet (220 meters) by 5:00 a.m. HST, after initial heights of 100 to 150 feet.
• The event followed continuous overflows from the vents that began on October 16, less than 24 hours before the fountaining started.
• All eruptive vents and lava flows were confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park.
• This was the 55th fountaining episode in the ongoing Kīlauea summit caldera eruption, which began on December 23, 2024.

Background

The current eruption began on December 23, 2024. Prior to Episode 55, Kīlauea experienced a prolonged precursory phase that lasted 6.8 days, the longest since the eruption began, with overnight spatter bursts reaching 35-70 feet. In September 2026, six new fissure vents opened on the western wall of Halemaʻumaʻu due to high pressurization, but these did not lead to immediate fountaining. The USGS Hawaiian Volcano Observatory has noted that predicting the timing of fountaining episodes remains difficult due to irregular ground deformation and magma recharge patterns.

How outlets are covering it

The USGS Hawaiian Volcano Observatory (HVO) and Big Island Now reported that Episode 55 lasted less than six hours, ending abruptly at 9:03 a.m. HST. HVO noted that fountain heights were initially low at 100 to 150 feet before reaching a maximum of over 700 feet by 5:00 a.m. HST. Big Island Video News, citing HVO geologist Heather Winslow and data scientist Marco Bagnardi, emphasized that the magma from the new fissure vents that opened in September 2026 originated from the same shallow magma chamber that feeds typical fountaining episodes, as evidenced by similar magnesium oxide levels and low crystal content. The Honolulu Star-Advertiser reported on the end of the fountaining but did not provide specific details on the episode's duration or peak heights. All sources agree that the activity was confined to Halemaʻumaʻu crater, but HVO and Big Island Now provided more detailed timelines and peak heights than the Star-Advertiser.

Why it matters

The conclusion of Episode 55 marks a temporary pause in the ongoing Kīlauea summit eruption, which has been active since December 2024. The event highlights the unpredictable nature of the volcano's fountaining cycles, with long precursory phases and abrupt endings. The confinement of activity to Halemaʻumaʻu crater reduces immediate risks to surrounding communities, but ongoing hazards include volcanic gas emissions, tephra fall, and potential ground instability. Understanding the magma source and pressurization patterns helps scientists refine forecasts for future episodes, though the irregularity of the eruption makes precise predictions challenging.

What to watch

The USGS Hawaiian Volcano Observatory will continue to monitor Kīlauea for signs of renewed pressurization or new vent formation. Residents and visitors are advised to minimize exposure to tephra and volcanic gases, particularly in areas downwind of the vents. Lava flows on the crater floor may remain hot and slowly move in the days following the episode. The alert level for Kīlauea remains at WATCH, and scientists will continue to analyze deformation and geochemical data to assess the likelihood of future fountaining episodes.