USGS Volcano Notice - DOI-USGS-HVO-2025-03-26T01:54:35+00:00

Activity Summary: 

Episode 15 of the ongoing Halemaʻumaʻu eruption began at 12:04 p.m. HST on March 25 with cyclic lava spatter and flows, followed by the onset of sustained high fountains from both the north and south vents at 10:20 a.m. HST March 26.  Currently fountains are in excess of 600 feet (180 meters) high.

Episode 15 fountaining was preceded by over 100 cycles of lava rise and fall, vent overflows, and spatter fountains in the north vent, a phenomenon known as 'gas pistoning', which has been observed in other eruptions at Kīlauea in recent decades. For more details about the onset of Episode 15 and the gas pistoning, see the update from earlier today: USGS Volcano Notice - DOI-USGS-HVO-2025-03-26T18:29:05+00:00

At 10:00 a.m. HST today, gas pistoning began transitioning to lava fountaining. At the time of this update, the tallest fountains from the south vent exceeded 600-700 feet (180-210 meters) high with north vent fountains generally less than half as high.

Inflationary tilt on SDH reached just over 6 microradians since the end of the last episode, recovering more than 100% of the tilt lost from episode 14. Seismic tremor began increasing and decreasing with the cyclic fountains and drainback. At the initiation of fountaining around 10:00 a.m. HST, tilt at SDH switched from inflation to deflation; at the same time, tremor increased and became sustained.

Emissions of SO₂ gas during episodes 13 and 14 have exceeded 40,000 tonnes per day and similar levels of SO₂ emission are expected to accompany the high fountains of episode 15.  Winds at the summit are forecast to be weak over the next day, which may allow the eruptive gas plume to spread around the summit region of Kīlauea.  In addition, visitors to Hawaiʻi Volcanoes National Park and residents of adjacent towns may be exposed to Pele's hair and other small fragments of volcanic glass being carried by the plume.

Each episode of Halemaʻumaʻu lava fountaining since December 23, 2024, has continued for at least 13 hours, and up 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 that can fall on the ground downwind of the eruptive vent(s). Pele's hair is strands of volcanic glass produced by lava fountaining activity. Strong winds may waft these light particles to greater distances downwind. Pele's hair can sometimes cluster and tangle together on the ground, giving it the appearance of a tumbleweed. The extent of Pele's hair is dependent on lava fountaining activity and current wind conditions. Residents and visitors should minimize exposure to these volcanic particles, which can cause skin and eye irritation. More information about how Pele's hair is formed is available here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-peles-hairs-a-beautiful-hazard-island-hawaii. 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 and the southwest side of Kaluapele, Kīlauea's summit caldera. 

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu 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, an area that has been closed to the public since late 2007.