USGS Volcano Notice - DOI-USGS-HVO-2025-04-01T04:28:31+00:00

Activity Summary: 

Episode 16 of the ongoing Halemaʻumaʻu eruption began at 10:57 p.m. HST on March 31 with the start of lava overflowing from the north vent.

Episode 16 was preceded by weak spattering in the north vent that began at approximately 5:20 p.m. HST on March 31, 2025. Since 6:00 p.m. HST, spattering became continuous and increased to low fountaining (15-30 feet or 5-10 meters high). Lava level gradually rose in the vent and is now overflowing out of the north vent cone onto the floor of Halemaʻumaʻu. Each of the prior 15 episodes ultimately involved significant lava fountaining, with the fountains of episode 15 exceeding 1,000 feet (305 meters) in height. High lava fountains are likely to follow the current dome fountaining and lava flows within 24 hours or less.

Inflationary tilt on the UWD tiltmeter reached around 8 microradians since the end of the last episode, recovering about 90% of the tilt lost from episode 15. UWD tilt has flattened, but has not started deflating, at this time. Seismic tremor initially began increasing around noon HST on March 31, 2025, followed by a sharper increase around 4:30 p.m. HST the same afternoon. Tremor continues to steadily increase. Infrasound signals also strengthened beginning just before 6 p.m. HST when spattering became continuous and visible in north vent.

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 16. Currently, winds at the summit are forecast to be weak, which may allow the plume of gas to spread around the summit region of Kīlauea. 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, as they were during episode 15.

Each episode of Halemaʻumaʻu lava fountaining since December 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 December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Two Kīlauea summit livestream videos are available here: Kīlauea Volcano, Hawaii (West Halemaʻumaʻu crater) v1cam and Kīlauea Volcano, Hawaii (East Halemaʻumaʻu crater)v2cam

No changes have been detected in the East Rift Zone or Southwest Rift Zone. HVO continues to closely monitor Kīlauea and will issue an eruption update tomorrow morning unless there are significant changes before then. 

Kīlauea Volcano Alert Level/Aviation Color Code remain at WATCH/ORANGE. All current and recent activity is within Hawaiʻi Volcanoes National Park.

Hazards: 

This episodic eruption is occurring within a closed area of Hawai'i Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are the primary hazard of concern, as this hazard can have far-reaching effects downwind. As SO₂ is continuously released from the summit during an eruption, it will react in the atmosphere to create the visible haze known as vog (volcanic smog) downwind of Kīlauea. SO₂ and vog may cause respiratory and other problems at high concentrations. Further information on vog can be found at https://vog.ivhhn.org/

Additional hazards include Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity. Volcanic fragments can fall on the ground within a few hundred yards (meters) of the eruptive vent(s), or downwind of the vent(s). Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once they are on the ground, Pele's hair can sometimes cluster and tangle together, giving it the appearance of a tumbleweed. The extent of Pele's hair deposition is dependent on lava fountaining activity and current wind conditions. Residents and visitors should minimize exposure to Pele's hair and other volcanic fragments, which can cause skin and eye irritation. More information about how Pele's hair, its hazards, and what to do is available here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-recent-lava-fountains-highlight-peles-hair-hazards. A Frequently Asked Questions document developed for the 2022 Mauna Loa eruption includes information about potential health effects of Pele's hair and is available here: https://vog.ivhhn.org/sites/default/files/FAQ_on_air_quality_and_health_during_Mauna_Loa_eruption_v1.6.pdf

Hawaiian lava flows generally advance slowly downslope, and during this eruption flows have been confined to Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera. 

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. This underscores the extremely hazardous nature of Kīlauea's caldera rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since late 2007.

For discussion of Kīlauea hazards, please see: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/hazards.