USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. No significant earthquake activity was detected and clouds obscured satellite and webcam images over the past day.

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.

Slightly elevated seismic activity continues. High winds obscured infrasound signals and clouds obscured satellite and webcam images. 

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:

Glow and flames continued from the north-south-west vent complex throughout the night, with minor intermittent spatter from the north vent. Slow inflation continues at the summit, gaining approximately 0.6 microradians over the past day. Over the past 24 hours strong tremor has become continuous and continues to be the dominant seismic signal across the summit. No anomalous seismic activity or deformation has occurred outside of the summit region.

The system is within 1-2 days at the current rate of inflation of reaching the maximum inflation of 16 microradians of tilt recovered since episode 54 fountaining ended. When this peak pressurization is reached, it is possible that activity will resume at the north-south-west vent complex, or reactivate the vent 1-6 system, or intrude another weak area in the summit region. None of these events are likely to produce a strong seismic precursor, so the alert levels remain at ORANGE/WATCH as the volcano continues to "exhibit heightened unrest with an increased potential for eruption".

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:

The north, south, and west vents continued to glow and sporadically emit flames, with minor intermittent spatter from the north vent last night. 

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

Summit inflation continues this morning, recording an increase of about 0.6 microradians over the past day. The total inflation since the end of episode 54 is currently about 15.6 microradians, 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, south, and west vents continued to glow and sporadically emit flames, with minor intermittent spatter from the north vent 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 has since recovered about 1.9 of the 2.3 microradians lost to the deflation event.

The system is within 1-2 days at current inflation rates of returning to the peak pressurization that resulted in the opening of vents 1-6 with no seismic precursors. If inflation rates change or deflation occurs, this could change. Because the summit system remains active, the three most likely possibilities are that activity resumes 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.