Episode 15 of Kīlauea eruption at Halemaʻumaʻu

Update: Wednesday, March 26, 2025, 7:55 p.m.

Episode 15 of the ongoing Halemaʻumaʻu eruption ended at 7:10 p.m. HST on March 26 when fountaining at the south vent stopped. North vent fountains had ceased activity earlier, around 12:00 p.m. HST. Overall, episode 15 lasted just over 31 hours with the last 9 hours consisting of high fountains predominantly from the south vent.

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Episode 15 of the ongoing Halemaʻumaʻu eruption began at 12:04 p.m. HST on March 25 with the onset of vigorous overflows from the north vent and is continuing cycles of lava rise, fountaining and vigorous overflows, and drainback events.  No high fountaining was reported in the initial reports following onset.

Episode 15 was preceded by eight cyclic, small spatter fountains in the north vent that began at approximately 9:27 a.m., 9:55 a.m., 10:11 a.m., 10:29 a.m., 10:48 a.m., 11:07 a.m., 11:27 a.m. and 11:45 a.m. on March 25 and lasted for 5-10 minutes each.  The ninth cycle lasted from 12:04-12:19 p.m. and produced vigorous overflows that extended 150 to 300 feet (50-100 meters) into Halemauʻamaʻu crater.  

Activity increased with subsequent events from at 12:25-12:39 p.m., 12:47-1:02 p.m.,1:08-1:23 p.m., 1:29-1:39 p.m., and 1:46- 1:58 p.m. These continued to increase in intensity with fountains up to 30-50 feet high (10-15 meters) from the north vent.  

Around noon on Tuesday, the south vent also became active and is feeding a lava flow out onto the crater floor.  Flows from both vents covered about 5% of the floor of Halemaʻumaʻu crater according to preliminary reports.  High fountaining was expected to follow the cyclic fountains and drainbacks as it did during episode 14.

Emissions of SO2 gas during episodes 13 and 14 have exceeded 40,000 tonnes per day and similar amounts of gas are expected to accompany fountain eruptions during episode 15, according to the Hawaiian Volcano Observatory.  

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. 

• Timeline of eruption episodes since Dec. 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 

No changes have been detected in the East Rift Zone or Southwest Rift Zone.

During this eruption flows have been confined to Halemaʻumaʻu and the southwest side of Kaluapele, Kīlauea’s summit caldera.