USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. Seismic activity continues at a very low level. Satellite and webcam images were cloudy. 

The current lava eruption began in July 2021 and, since then, has 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.

Unrest continues at Shishaldin Volcano. Seismic activity remains elevated, with numerous small earthquakes and periods of volcanic tremor being observed. Weakly elevated surface temperatures were observed at the summit in satellite imagery, and a weak gas plume was seen in 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. 

A small explosion occurred yesterday evening at Semisopochnoi volcano and was detected by seismic and infrasound sensors on Semisopochnoi Island. Weather conditions have been cloudy, and no eruption cloud or deposits were detected in satellite or webcam data. No subsequent infrasound has been detected, and seismicity has returned to background levels. This unheralded event posed little hazard, as it was localized to Mount Young, which last erupted in 2023. The north cone of Mount Young—the likely source of the explosion—hosts a crater lake and has vigorous fumaroles that produce a small gas plume. The alert level at the volcano was not changed following this event and remains at GREEN and NORMAL.

Semisopochnoi volcano is monitored by local seismic and infrasound sensors, web cameras, regional infrasound and lightning networks, and satellite data.

Activity Summary:

The Halemaʻumaʻu eruption of Kīlauea is paused. Episode 42 ended February 15 at 11:38 p.m. HST. Preliminary models suggest the likely forecast window for the onset of episode 43 lava fountaining is March 6-16.

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

A recap of episode 42 can be found in this Status Report.

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

Summit Observations:

Weak intermittent glow from both vents was visible through the night, although glow was stronger and more frequent from the south vent. At the time of this report, both vents are quiet and emitting robust degassing plumes. Seismic tremor continues during the current pause and is punctuated by bursts every 5-10 minutes. At least some of the bursts were correlated with brighter periods of glow from the south vent and flames from the north vent. There were 3 shallow earthquakes located across the summit region during the past day.

Another period of weak deflation began yesterday afternoon and continues this morning. The UWD tiltmeter has recorded a total recovery of nearly 13.4 microradians of inflationary tilt since the end of episode 42, with a loss of about 0.6 microradians over the past 24 hours.

Plume geometry and weather prevented measurements of sulfur dioxide (SO₂) emission rate during episode 42's fountaining, but the emissions were likely in the range of 100,000 t/d, similar to during previous episodes. During pauses, like the current conditions, the SO₂ emission rate from the summit has varied within a typical range of 1,000 to 5,000 tonnes of SO₂ per day. This morning, webcams show little to no wind with the plume rising vertically from the summit vents.
 

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 initial rapid rebound of tilt and glow from both vents indicate that another fountaining episode is likely. The inflationary trend over the past several days has been interrupted by significant periods of no inflation or slight deflation recorded across all four summit tiltmeters that may impact the onset of episode 43 fountaining. Periods of weak deflation or no inflation have not been common in the early stages of repose between fountaining episodes. These changes in tilt rate are not predictable and create uncertainty in modeling the onset of episode 43 fountaining. Another deflationary event took place in the past 24 hours moving the forecast window back by a day. Preliminary models suggest the forecast window for the start of episode 43 fountaining is likely between March 6 and March 16.  Additional data are needed to more accurately determine the forecast window.

Kīlauea has been erupting episodically since December 23, 2024, primarily from two vents (north and south) in Halema‘uma‘u. Eruptive episodes, which generally last for less than 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 episode 41:

A recap of episode 42 can be found in this Status Report.

Resources:

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 fountains and eruptive activity can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages 
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: https://www.youtube.com/@usgs/streams
• Note: The V3 camera is experiencing data issues and we have ordered a new camera to replace it following episode 42.
• 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 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.

No signs of volcanic unrest have been observed at Ahyi seamount since January 9, 2026, when satellite views last saw a plume of discolored water near the seamount. Distant underwater pressure sensors near Wake Island (1,410 miles east of Ahyi) have also not detected any activity from the direction of Ahyi seamount for several weeks.

Due to the apparent absence of activity, and the lack of local monitoring stations near Ahyi Seamount, the Aviation Color Code and Volcano Alert Level are being lowered to UNASSIGNED.