USGS Volcano Notice - DOI-USGS-HVO-2026-09-23T17:16:19+00:00

Overview:

Precursory overflows from the north vent resumed overnight. Glow and flames continued from the north-south-west vent complex throughout the night, with intermittent spatter bursts from the north and south vents. There are currently no signs of activity at the recent vents 1-6. Summit tilt has been relatively flat over the past 24 hours, with slight deflation starting early this morning. Over the past 24 hours continuous tremor remains the dominant seismic signal across the summit. No anomalous seismic activity or deformation has occurred outside of the summit region. 

HVO is maintaining the Alert Level for Kīlauea at WATCH and the Aviation Color Code at ORANGE, and posted a Volcanic Activity Notice last night to highlight the resumption in precursory activity: USGS Volcano Notice - DOI-USGS-HVO-2026-09-23T08:36:47+00:00

No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone. 

STATUS REPORT on changes in activity and implications for this eruption: USGS Volcano Notice - DOI-USGS-HVO-2026-09-15T03:18:09+00:00

NOTE: Significant changes in activity between Daily Updates are posted here: https://www.usgs.gov/observatories/hvo/observatory-messages

Summit Observations:

Precursory overflows from the north vent resumed last night, September 22, beginning at 10:10 p.m. HST. Additional overflows began at 11:44 p.m. HST on September 22, and 2:46 a.m., 6:10 a.m., and 7:04 a.m. HST on September 23. Each overflow lasted about 30 minutes and produced lava flows that traveled a few hundred meters (yards) from the vent. The were all fed by vigorous fountains from the small 30-50 foot (10-15 meter)The north, south, and west vents continued to glow and emit flames. Intermittent spatter bursts were also observed from the north and south vents last night. No other areas of incandescence were observed across the summit region last night.

Strong continuous tremor is the dominant seismic signal across the summit. There were nine small earthquakes located across the summit region in the past day, but they did not form clusters in time or location. 

Summit tilt has been relatively flat over the past day, with about 0.3 microradians of deflation recorded since about 3:00 a.m. HST this morning. The current total inflation since the end of episode 54 is about 15.7 microradians, slightly less than the maximum of 16 microradians reached on September 16 and more than two microradians greater than was lost during episode 54 fountaining.

During inter-episode pauses, the sulfur dioxide (SO₂) emission rate from the summit typically varies between 1,000 and 5,000 tonnes per day.

Rift Zone Observations:

Rates of seismicity and ground deformation remain low in the East Rift Zone and Southwest Rift Zone. SO₂ emissions from the East Rift Zone remain below the detection limit. No significant ground deformation was recorded in either rift zone.

Analysis:

The north vent resumed precursory overflow activity last night. In addition, the north, south, and west vents continued to glow and emit flames, with intermittent spatter from the north and south vents last night. Strong continuous tremor dominates the seismic signal within the summit. Forecast windows for this episode can no longer be modeled due to the irregular changes in inflation and deflation. Since reaching a peak inflation of 16 microradians (UWD tilt post episode 54) on Wednesday September 16, the summit deflated about 2.3 microradians as the new lava flows from vents 1-6 ceased. Slow inflation (recorded on the UWD tiltmeter) started Thursday September 17 and had since recovered about 2.1 of the 2.3 microradians lost to the deflation event. Deflation resumed early this morning, recording a loss of 0.3 microradians after the onset of overflows. Current eruptive activity is focused on the north vent, which has produced the last 11 high fountain events (episodes 44-54). However, it is not possible to say with certainty that this activity will lead to the onset of another fountain event at this time.

Because the summit system remains active, the three most likely possibilities are that activity continues at the north-south-west vent complex, or reactivates the vent 1-6 system, or intrudes another existing weak crack system in the summit region. None of these events are likely to produce a strong seismic precursor, so the alert levels have been left at ORANGE/WATCH as the volcano continues to "exhibit heightened unrest with an increased potential for eruption". For further details about potential scenarios see the September 15 Status Report.

Kīlauea has been erupting episodically since December 23, 2024, from two vents (north and south) in Halema‘uma‘u. Lava fountaining episodes, which generally last for less than 12 hours, are separated by pauses of two or more 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

Summary of episode 54:

A detailed account of episode 54 is given in the HVO Status Report issued on August 25: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-08-26T05:56:38+00:00

• Episode 54 of the ongoing Halemaʻumaʻu eruption began around 10:30 a.m. HST and ended at 7:33 p.m. HST on August 25, 2026, after 9 hours of continuous lava fountaining. 
• The maximum lava fountain height from the north vent was approximately 500 feet (150 meters) above ground level, reached between 12:15 p.m. and 1:00 p.m. HST. Neither the south vent nor the new west vent (formerly the collapse pit) fountained during this episode.
• The maximum plume height was approximately 17,000 feet (5,200 meters) above sea level.
• Most tephra fall was restricted to the closed area of Hawaiʻi Volcanoes National Park, southwest of the active eruptive vents in Halemaʻumaʻu. However, HVO did also receive a report of trace Pele’s hair falling in the Ka‘ū district of the Island of Hawaiʻi.

Resources:

NOTE: HVO’s monitoring network is mostly recovered from recent power- and storm-related outages. Several summit stations will remain offline as we continue working to repair instruments and re-establish connections in our monitoring network.

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
• Short messages tracking the evolution of the lava fountains and eruptive activity can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages
• Three Kīlauea summit livestream cameras 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.

• Volcanic Gas: High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are continually released during an eruption. Emissions can remain locally hazardous in the areas immediately downwind of the vents, even when the vents are not actively erupting. SO₂ reacts in the atmosphere to create vog (volcanic air pollution) downwind. SO₂ and vog may cause respiratory and other problems at high concentrations. Further information on vog can be found at https://vog.ivhhn.org/
• Tephra: Small glassy volcanic fragments—volcanic ash, pumice, scoria, Pele’s hair and reticulite—are created by the lava fountains. A combination of fountaining dynamics and wind conditions determines where tephra fall may occur for any given eruption episode. Larger particles fall near the vents while light particles may be wafted greater distances. These particles may be remobilized during windy conditions following recent eruptive episodes. Residents and visitors should minimize exposure to these fragments, which can cause skin, eye, and respiratory irritation. More information and guidance on tephra fall hazards is available at https://seagrant.soest.hawaii.edu/resource-and-guidance-for-volcanic-tephra-fall/
• Lava flows: Lava on the floor of Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera, remains hot and may slowly move in the days immediately following an eruptive episode.

Other significant hazards exist around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes. Close to the eruptive vents, the tephra material on the crater rim is prone to cracking, slumping, and small landslides that sometimes expose hot and molten material within. 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.