USGS Volcano Notice - DOI-USGS-HVO-2025-05-26T18:32:10+00:00

Activity Summary:

Episode 23 of the ongoing Halema'uma'u eruption ended last night at 10:25 p.m. after six hours of sustained fountaining. Summit inflation has resumed, along with persistent, low level seismic tremor. Fountaining episodes have occurred approximately once per week since the beginning of the eruption. At the current rate of inflation, the next episode is anticipated to occur in a similar time frame.

Kīlauea's current eruption in Halemaʻumaʻu crater within Kaluapele (the summit caldera) began on December 23, 2024. There have now been 23 episodes separated by pauses in activity. All eruptive activity remains within Hawaiʻi Volcanoes National Park. No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone. Current hazards include volcanic gas emissions and windblown volcanic glass (Pele’s hair) and tephra that have impacted Hawaiʻi Volcanoes National Park and nearby communities.

Summit Observations:

Following an extended period of precursory low-level activity, episode 23 began yesterday at 4:15 p.m. with thin jets of lava erupting from the north vent that became sustained fountains by 4:25 p.m. Activity escalated quickly in the north vent with lava fountains reaching over 1,000 feet (300 meters) in height within 30 minutes. At 5:20 p.m., lava fountains began erupting from the south vent as well. South vent fountains grew rapidly and reached sustained heights of about 800 feet (250 meter) for much of the episode. Large lava flows erupted from both vents and covered about half of Halema'uma'u crater floor.

Seismic tremor intensified significantly at 4:36 p.m. as lava fountains became more robust in size and volume. This was accompanied by a rapid change in summmit tilt from inflation to deflation. Summit tiltmeters recorded rates of deflation over 2 microradian per hour during sustained fountaining. 

Sulfur dioxide (SO₂) emissions were estimated to be between 50,000-75,000 t/d, and based on webcam images from Mauna Loa summit, the plume reached well over 14,000 feet in height.

Fountaining began to wane when activity ceased in the north vent at 9:48 p.m. Episode 23 ended with the cessation of fountains and flows from the south vent at 10:25 p.m. The end of the eruption was coincident with a rapid change in summit tilt from deflation to inflation aling with a significant decrease in seismic tremor intensity. The Uēkahuna tiltmeter (UWD) recorded about 13 microradians of deflationary tilt during this episode. 

Summit tiltmeters recorded began recording inflation immediately following the end of episode 23. UWD has recovered 1.5 microradians of inflationary tilt overnight. Seismic tremor has returned to low levels beneath Halemaʻumaʻu crater.

The average sulfur dioxide (SO₂) emission rate during inter-episode pauses is typically around 1,200 tonnes per day (t/d).

Strands of volcanic glass known as Pele’s hair are present throughout the summit area of Hawaiʻi Volcanoes National Park and surrounding communities and can be remobilized by wind.

• Eruption resources, including the most recent map and a timeline of eruption episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Three Kīlauea summit livestream videos are available here: Kīlauea Volcano, Hawaii (West Halemaʻumaʻu crater) v1cam, Kīlauea Volcano, Hawaii (East Halemaʻumaʻu crater) v2cam, and Kīlauea volcano, Hawaii (South Halemaʻumaʻu crater) v3 cam
• Summit eruption webcams: https://www.usgs.gov/volcanoes/kilauea/summit-webcams 

The B2, KW, and F1 summit webcams are currently offline due to eruption impacts. Other HVO summit webcams are functioning and online.

Rift Zone Observations:

Rates of seismicity and ground deformation remain very low in the East Rift Zone and Southwest Rift Zone with no significant earthquake activity in the past 24 hours. Sulfur dioxide (SO₂) emissions from the East Rift Zone remain below the detection limit.

Analysis: 

The current eruption has been characterized by episodic fountaining not seen in any eruptions since the 1983-86 episodic fountains at the beginning of the Puʻuʻōʻō eruption. Fountains and lava flows have erupted from two vents within Halema'um'a'u crater that we refer to as the north vent and south vent. Each of the previous fountaining episodes lasted from a few hours to over a week and have been accompanied by strong deflation of the summit region. Pauses between the fountaining episodes have been marked by an immediate change from deflation to inflation as the magma chamber recharges and repressurizes.

Episode 23 ended on May 25. The rapid rebound of tilt from deflation to inflation, along with persistent seismic tremor, indicates that magma remains close to the surface and another fountaining episode is likely to occur in the coming weeks.

HVO continues to closely monitor Kīlauea and is in contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency about eruptive hazards.

Please see the Hawaiʻi Volcanoes National Park website for visitor information: https://www.nps.gov/havo/index.htm.

Hazards: 

This episodic eruption is occurring within a closed area of Hawaiʻi 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 forms, 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 recently updated Frequently Asked Questions document that includes information about potential health effects of Pele's hair is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs.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.