USGS Volcano Notice - DOI-USGS-HVO-2025-09-02T16:14:39+00:00

HVO/USGS Volcanic Activity Notice

Volcano: Kilauea (VNUM #332010)

Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Issued: Tuesday, September 2, 2025, 7:11 AM HST
Source: Hawaiian Volcano Observatory
Notice Number: 2025/H379
Location: N 19 deg 25 min W 155 deg 17 min
Elevation: 4091 ft (1247 m)
Area: Hawaii

Volcanic Activity Summary:

Episode 32 of the ongoing Halemaʻumaʻu eruption began at 6:35 a.m. HST on September 2. At that time, north vent dome fountains transitioned into taller lava fountains, which have since become inclined at about 45 degrees northeast, similar to but less inclined than those of episode 31. Current fountains are about 500 feet (150 meters) high and arcing an equivalent distance into Halemaʻumaʻu crater. Past episodes have produced incandescent lava fountains over 1,000 feet (300 meters) high and the eruptive plume is currently 9000 feet (2700 m) above ground level up to 20,000 feet (6,000 meters) above ground level. According to the National Weather Service, winds are blowing from the northeast direction today, which suggests that volcanic gas emissions and volcanic material will be distributed to the southwest of Halemaʻumaʻu crater. If the fountains remain inclined ash and tephra will be greatly reduced but high SO₂ gas emissions may impact communities to the south and west of Kīlaueaʻs summit.

• All eruptive activity is confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park; commercial airports in Hawaii County (KOA and ITO) will not be affected by this activity.
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: V1cam, V2cam, V3cam.
• KPcam and MKcam provide views of the plume height for aviation purposes.

Episode 32 was preceded by gas pistoning cycles beginning around 8:30 p.m. HST on September 1, then intermittent overflows from the north vent began at 12:43 a.m. HST this morn. These intermittent overflows continued until 5:31 a.m. HST, when a continuous overflow began in association with low dome fountain in the vent. This dome fountain escalated in vigor around 6:35 a.m. HST when lava fountaining became taller. Rapid deflationary tilt and stronger seismic tremor began around the same time. Inclined fountains from the north vent are estimated at 500 feet (150 meters) high and feeding multiple lava streams as of 6:50 a.m. HST. 

Most episodes of Halemaʻumaʻu lava fountaining since December 23, 2024, have continued for around a day or less and have been separated by pauses in eruptive activity lasting generally at least several days. 

• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 

No changes have been detected in the East Rift Zone or Southwest Rift Zone. 

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

Recent Observations:
[Volcanic cloud height] Current height of the convective plume is 9000 feet above ground level.
[Other volcanic cloud information] Most volcanic ash and pumice (tephra) will fall within about 1 mile (1–2 km) of the eruptive vents. Lower concentrations of finer volcanic particles, such as ash and Pele's Hair, can be transported greater distances downwind of the vent (20 miles or 30 km). Sulfur dioxide emission rate is typically 50,000 tonnes/day during eruptive episode.
[Ballistics] N/A
[Lava flow/dome] N/A
[Lava flow] Confined to Halemaʻumaʻu (within summit caldera).

Hazard Analysis:
[Ashfall] Small volcanic particles may impact downwind areas. No impact to commercial airways or airports is expected.
[Lava flow/dome] N/A
[Pyroclastic flow] N/A
[Mud flow] N/A
[Volcanic gas] Typically 50,000 tonnes/day during sustained lava fountaining episode.
[Lava flow] Confined to Halemaʻumaʻu (within summit caldera).

Remarks:

Hazard Analysis: 

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 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 hazard closer to the vent 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 and can be carried well over 10 miles (15 kilometers) from the vent. Other hot glassy volcanic fragments including Peleʻs hair, volcanic ash, pumice, scoria, and reticulite can fall on the ground within 1-2 miles (1-3 kilometers) of the eruptive vent(s) with the highest concentrations downwind of the vent(s). Pumice and other volcanic fragments have fallen on Highway 11 west of Hawaiʻi Volcanoes National Park depending on wind and eruption conditions.  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 glassy 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 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.

Contacts:

askHVO@usgs.gov

Next Notice:

HVO continues to closely monitor Kīlauea and will issue a VAN/VONA at the start of the next eruptive episode. If possible, HVO will also issue a Status Report beforehand at the onset of low-level precursory activity. Regularly scheduled daily updates for Kīlauea are posted on the HVO website at https://www.usgs.gov/volcanoes/kilauea/volcano-updates  

More Information:

• Hawaiʻi Volcanoes National Park visitor information: https://www.nps.gov/havo/index.htm
• Kīlauea activity summary also available by phone: (808) 967-8862
• Kīlauea webcam images: https://www.usgs.gov/volcanoes/kilauea/webcams
• Kīlauea photos/video: https://www.usgs.gov/volcanoes/kilauea/photo-and-video-chronology
• Kīlauea lava-flow maps: https://www.usgs.gov/volcanoes/kilauea/maps
• Kīlauea FAQs: https://www.usgs.gov/volcanoes/kilauea/faqs

Subscribe to these messages: https://volcanoes.usgs.gov/vns2/
Summary of volcanic hazards from eruptions: https://www.usgs.gov/observatories/hvo/hazards
Recent earthquakes in Hawaiʻi (map and list): https://www.usgs.gov/observatories/hvo
Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes