Newest Volcano Notice Including Kilauea

Activity Summary:

The ongoing Halemaʻumaʻu eruption is paused. Overnight webcam views showed weak and variable glow from the south vent. Summit inflation is underway and forecasting models suggest the window for lava fountaining episode 40 is between January 6 and 13. Kīlauea’s East Rift Zone and Southwest Rift Zone remain quiet.

The USGS Hawaiian Volcano Observatory regrets the outage that affected our ability to post updates to the Volcano Notification Service the past two days. Kīlauea daily updates for December 25 and 26 are available on the HVO website at the links below:

• December 25: https://www.usgs.gov/observatories/hvo/news/december-25-2025-volcano-notification-service-outage-and-kilauea-daily
• December 26: https://www.usgs.gov/observatories/hvo/news/december-26-2025-kilauea-daily-update

Summit Observations:

Overnight webcam views showed weak and variable glow from the south vent—none from the north vent—along with spots of incandescence on the Halemaʻumaʻu crater floor from episode 39 lava flows that are still in the process of cooling. Field crews reported they could hear ʻaʻā flows continuing to move in the vicinity of the south vent yesterday, but movement was difficult to detect on the webcams. Incandescent spots are expected to persist for the next few days, especially in the area around the vents.

Since the end of episode 39, the Uēkahuna tiltmeter (UWD) has recorded 9.1 microradians of re-inflation beneath Kīlauea summit.

Volcanic gas emission rates have dropped significantly since the end of episode 39 but probably remain in the range of 1,000 to 5,000 tonnes of sulfur dioxide (SO₂) per day, as typically observed during previous eruptive pauses.

Rift Zone Observations:

Rates of seismicity and ground deformation remain very low in the East Rift Zone and Southwest Rift Zone. SO₂ emissions from the East Rift Zone remain below the detection limit.

Analysis:

The rapid rebound of inflationary tilt and presence of low-level volcanic tremor after episode 39 indicate that another lava fountaining episode is likely to occur. Forecasting models suggest the window for episode 40 is between January 6 and 13; expect this window to be further refined as more data are collected in the coming days.

Kīlauea has been erupting episodically since December 23, 2024, primarily from two vents (north and south) in Halema‘uma‘u. Eruptive episodes, which can last up to 12 hours, are separated by pauses that can be as long as over two 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

Recap of Last Episode:

Episode 39 lava fountaining from the south vent stopped at approximately 2:13 a.m. HST on December 24 after 5.9 hours of sustained fountaining. The two vents within the north cone both stopped slightly earlier at 2:00 a.m. HST. Sustained fountaining began at 8:20 p.m. HST from the north and south vents after just under 2 hours of precursory overflows. Fountains rapidly grew to several hundred feet high and by 9:30 p.m. HST had reach maximum estimated heights of 1,400 feet (425 meters) for the south fountain and 900 feet for the north fountain. The main fountain from the north cone came from the "right hand" vent (as viewed from V1cam, which is pointed south), but a much smaller fountain, 100-200 feet (30–60 meters) high, began at about 8:45 p.m. HST and lasted until the north vent stopped fountaining. This "triple" fountain lasted through most of the eruption, with the south fountain highest followed by the "right hand" north vent (about 65–70% of the south fountain height) and the much smaller "left hand" north vent (about 10–20% of the south fountain height). The highest peak or instantaneous effusion rate of 960 cubic yards per second (800 cubic meters per second) occurred about 9:00 p.m. HST just before the south and north vents reached their maximum heights. Episode 39 ended with an average effusion rate of 250 cubic yards per second (190 cubic meters per second). An estimated 12 million cubic yards (9.3 million cubic meters) of lava erupted and covered about 50–60% of the floor of Halemaʻumaʻu crater. The Uēkahuna tiltmeter (UWD) recorded about 26.8 microradians of deflationary tilt during episode 39.

The following links provide more information about the current eruption that began on December 23, 2024:

• 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 that show eruptive lava fountains are available here: https://www.youtube.com/@usgs/streams
• Summit eruption webcams: https://www.usgs.gov/volcanoes/kilauea/summit-webcams
• Volcano Watch article on gas pistons: https://www.usgs.gov/observatories/hvo/news/volcano-watch-so-what-earth-or-least-kilauea-a-gas-piston

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 one major 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/

Another major hazard is fallout of Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity that can be carried well over 10 miles (15 kilometers) from the vent. Other hot glassy volcanic fragments (tephra) including volcanic ash, pumice, scoria, and reticulite can fall on the ground within 1–3 miles (1–5 kilometers) of the eruptive vent(s), with the highest concentrations immediately downwind of the vent(s). Various volcanic fragments have fallen on Highway 11 west of Hawai'i Volcanoes National Park at times, depending on wind and eruption conditions. Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once 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 wind conditions. Residents and visitors should minimize exposure to Pele's hair and other glassy volcanic fragments, which can cause skin and eye irritation and can also contaminate catchment water supplies. 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 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_v2.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.