USGS Volcanoes: Notices released in the last day.

Weak earthquake activity, related to growth of the lava dome, was observed over the past day. Clouds obscured satellite and webcam images.

The current eruption began in July 2021. Since then, lava flows have filled most of the summit crater and advanced into valleys below. There have been no explosions at Great Sitkin Volcano since an event in May 2021. The volcano is monitored using local seismic and infrasound sensors, satellite data, webcams, and regional infrasound and lightning networks.

Wind obscured most seismic and infrasound signals over the past day, though seismic tremor could still be observed. Clouds blocked satellite and webcam views. 

Local seismic and infrasound sensors, web cameras, and a geodetic network are used to monitor Shishaldin Volcano. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lightning data, and satellite images to detect eruptions. 

Overview:

Episode 55 remains a possibility during the ongoing Kīlauea summit eruption. Precursory overflows from the north vent resumed on the night of September 22 and continue this morning. The south vent also produced a few very small overflows overnight. Glow and flames were observed from the north-south-west vent complex throughout the night, with intermittent spatter bursts from all three vents. There are currently no signs of reactivation of the recent vents 1-6. The summit tilt has remained relatively flat over the past 24 hours, and continuous tremor remains the dominant seismic signal across the summit. 

No anomalous seismic activity or deformation has occurred outside of the summit region, and no significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.  

Poor weather has greatly reduced visibility on streaming cams and webcams available to the public. Monitoring will continue using a variety of geophysical tools.

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 on Tuesday night, September 22, beginning at 10:10 p.m. HST. Since then, there have been 53 overflows, most of them from the north vent, although several small overflows occurred from the south vent overnight. Most of the overflows have lasted about 5-35 minutes and produced lava flows that traveled a few hundred meters (yards) from the vent. Many of the overflows were fed by vigorous fountains that rise 15-30 feet (5-10 meters) above the small 30-50 foot (10-15 meter) cone that has built up at the north vent. The north, south, and west vents continued to glow strongly overnight, and emit flames and intermittent spatter. No other areas of incandescence were observed across the summit region last night.

Continuous tremor became punctuated with tremor spikes starting just after midnight. The tremor spikes appear to be correlated with strong spatter bursts from the west vent. There were 15 small and shallow earthquakes located across the summit region in the past day. Seven of these clustered around the "outlet" area at the south end of Kaluapele, the summit caldera.

Summit tilt has remained relatively flat over the past day, with slight overall deflation of about 0.4 microradians beginning around midnight. The current total inflation since the end of episode 54 is about 16.4 microradians, which is about 4 microradians greater than what 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. Lower level winds are currently forecast from the northeast while higher level winds become more easterly.

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 on Tuesday night, September 22. In addition, the south vent produced several small overflows overnight. The north, south, and west vents continued to glow, and emit flames and intermittent spatter overnight. 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 16.8 microradians (UWD tilt post episode 54) yesterday, Saturday, September 27, the summit deflated slightly about 0.4 microradians. 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, although conditions remain favorable.

Because the summit system remains active and highly pressurized, the two most likely possibilities are that activity continues at the north-south-west vent complex, or it activates another existing weak crack system in the summit region. Neither 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.