Lava overflows from south vent with onset of Episode 17 Halemaʻumaʻu eruption at Kīlauea

Update: 10:30 a.m., April 9, 2025

Episode 17 of the ongoing Halemaʻumaʻu eruption ended at 9:45 a.m. HST on April 9 when low fountaining at the south vent stopped. Fountains from the south vent sustained heights of 50-200 feet (15-60 meters). Overall, episode 17 lasted 35.5 hours and consisted of sustained fountains from the south vent and minor north vent activity that stopped around 11:15 a.m. HST on April 8. The north vent pond collapsed sometime last night. 

Previous post:

Episode 17 of the ongoing Halemaʻumaʻu eruption at Kīlauea began at 10:15 p.m. on April 7, 2025 with the start of lava overflowing from the south vent.

The USGS Hawaiian Volcano Observatory reports that Episode 17 was preceded by glow from the south vent that increased at about 9:20 p.m. on April 7 indicating the gradual rise of lava in the vent prior to the start of the eruption.  

Lava continues to overflow the vent spreading across the floor of Halema’uma’u and is being fed by low spatter fountains 15-30 feet high as of 2:50 a.m. on April 8.

Each of the prior 16 episodes ultimately involved significant lava fountaining, with the fountains of episode 16 exceeding 1,000 feet in height. High lava fountains are likely to follow the current low fountaining and lava flows, the HVO reports.

UWD tilt has started slight deflation at about the same time lava began erupting. Seismic tremor initially began increasing around 10 p.m. HST on April 7 and continues to steadily increase, according to the HVO.

Emissions of SO2 gas are elevated, and during recent episodes have reached 50,000 tonnes per day or more, and similar amounts of gas are expected to accompany any high fountaining activity that may occur during episode 17. In addition, visitors to Hawaiʻi Volcanoes National Park and residents of adjacent areas may be exposed to Peleʻs hair and other small fragments of volcanic glass and tephra being carried in the plume.

Each episode of Halemaʻumaʻu lava fountaining since Dec. 23, 2024, has continued for 13 hours to 8 days, and episodes have been separated by pauses in eruptive activity lasting less than 24 hours to 12 days. 

No changes have been detected in the East Rift Zone or Southwest Rift Zone. Kīlauea Volcano Alert Level/Aviation Color Code remain at WATCH/ORANGE. All current and recent activity is within Hawaiʻi Volcanoes National Park.