USGS Volcano Notice - DOI-USGS-HVO-2025-06-21T19:16:22+00:00

Activity Summary:

Episode 26 of the ongoing Halema'uma'u eruption ended yesterday morning, June 20, at 10:25 a.m. HST after about 8 hours of sustained fountaining. The end of the episode was coincident with a change from deflationary to inflationary tilt at the summit and a decrease in seismic tremor intensity. This morning, summit inflation continues, along with persistent, low level seismic tremor, suggesting another episode is possible. However, more time and data are needed before a forecast window can be made for episode 27. 

Fountaining episodes have occurred approximately once per week since the start of the eruption on December 23, 2024. 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 ongoing volcanic gas emissions and windblown volcanic glass (Pele’s hair) and tephra deposited during past episodes in the Kīlauea summit region of Hawaiʻi Volcanoes National Park and nearby communities.

Summit Observations:

Episode 26 was preceded by about 2 hours of precursory low-level activity including small, sporadic spattering and lava overflows from the north vent that began at approximately 11:26 p.m. HST on June 19 and continued to increase in intensity until 1:40 a.m. on June 20 when sustained fountaining began. Fountains from the north vent were as high as 800 feet (250 meters) and feeding a lava flow at 1:55 a.m. The vigor of activity continued to increase and at approximately 3:26 a.m., lava fountains from the north vent reached heights of well over 1,000 feet (305 meters). By about 2:00 a.m., fountaining began at the south vent. Lava fountains continued to erupt from both vents, feeding large lava flows that covered parts of Halema'uma'u crater floor. Eruption vigor at the north vent began to decrease first. The north vent stopped erupting at approximately 10:07 a.m. on June 20. The south vent stopped erupting at approximately 10:25 a.m. on June 20 marking the end of the episode. Lava flows from this episode that covered the floor of Halemaʻumaʻu crater within the southern part of Kaluapele (Kīlauea caldera) may continue to exhibit slow movement or incandescence as they cool and solidify over the coming days. 

The eruptive plume from episode 26 reached at least 20,000 feet (6,000 meters) above ground level by 3:00 a.m. HST on June 20. Sulfur dioxide (SO2) emissions could not be directly measured; however, typical values observed for past episodes are between 50,000-75,000 tonnes per day (t/d). The average SO2 emission rate during inter-episode pauses, such as the current pause, is typically around 1,200 t/d.

Episode 26 was accompanied by more than 18 microradians of deflationary tilt at the tiltmeter near Uēkahuna (UWD), which was 4 microradians more deflation than the amount seen during episode 25. The end of the episode was coincident with a change from deflationary tilt to inflationary tilt at the summit and a decrease in seismic tremor intensity. UWD has recovered over 3 microradians of inflationary tilt in the 22 hours since the end of episode 26. Seismic tremor has returned to slightly elevated levels beneath Halemaʻumaʻu crater.

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: 

Additional time is needed to accumulate tiltmeter data before a forecast window can be made for episode 26. However, given that the deflationary tilt during the past several episodes was similar, we expect a roughly similar pause duration following episode 25. The pause between the past several recent episodes ranged from 6 to 10 days.  

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. Lava fountaining episodes have occurred approximately once per week since the start of the eruption. 

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.