USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. Small earthquakes and rockfall events were detected but the volcano was seismically quiet over the past day. Elevated surface temperatures were observed in satellite data. Clouds obscured the volcano in web camera images over the past day.

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.

Low-level unrest continues at the Atka volcanic complex characterized by weak seismic tremor. Elevated surface temperatures from the Korovin crater lake were observed in satellite data over the past day.

The Atka volcanic complex includes several vents, including Korovin Volcano, Mount Kliuchef and Sarichef Volcano. Korovin has been the site of most historical eruptions that typically produce minor amounts of ash and occasional but small lava flows. The Atka volcanic complex is monitored by local seismic and infrasound sensors and webcam, satellite data, and regional lightning detection instruments.

Unrest continues at Shishaldin Volcano. Seismic and infrasound activity remains elevated over the past day. A plume of sulfur dioxide gas was observed in satellite data from yesterday afternoon. Satellite and web camera views of the volcano were obscured by clouds over the past day. 

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. 

Volcano Observatory Notices for Aviation (VONA) and associated Volcano Activity Notices (VAN) are now required to be repeated every day for volcanoes at RED, every week for volcanoes at ORANGE, and every two weeks for volcanoes at YELLOW.

The Halemaʻumaʻu eruption of Kīlauea volcano remains paused, and the current forecast for lava fountaining episode 44 is now through April 15. Lava fountaining episode 43 ended at 6:21 p.m. HST on March 10, 2026.

• All eruptive vents and lava flows are confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park. Tephra fall from volcanic ash clouds is greatest within 3 mi (5 km) of the vents; lighter ash and Peleʻs Hair may remain suspended for greater distances from the vents.
• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Three Kīlauea summit livestream videos are available here: https://www.youtube.com/@usgs/streams 
• Additional short updates shared during episodes can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages 

Activity Summary:

Kīlauea summit inflation returned yesterday afternoon, then south vent overflows and associated spattering resumed early this morning. Overflows and spattering may continue until lava fountaining episode 44 begins, but further periods of deflation and reduced vent activity may still occur before the next episode. The current forecast window for episode 44 is between now and April 15.

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

NOTES:

The National Weather Service (NWS) issued a Special Weather Statement yesterday about the potential for tephra fall from episode 44 in downwind communities, especially if the episode occurs in the latter half of this week, when the NWS has forecast possible south to southeasterly winds.

Access to the Hawaiian Volcano Observatory webpage may be affected by maintenance to U.S. Geological Survey websites starting at 2:00 p.m. HST today, with the work expected to last until around 10:00 p.m. HST. During this time, any necessary updates on volcanic activity will still be published via Volcano Notification Service emails, and the three Kīlauea summit livestream cameras will remain available.

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

Summit Observations:

Heavy rain and resulting steam occluded webcam views of Halemaʻumaʻu crater for much of last night, but evidence of a fresh lava flow from the south vent became visible at 3:20 a.m. HST, and another brief overflow occurred around 6:30 a.m. HST; these were the first overflows since Monday morning, April 6. Intermittent spattering and gas jetting has also been observed at the south vent this morning, and there has been continued strong glow from the north vent.

Seismic tremor is continuous with frequent small, poorly defined bursts possibly related to the rise and fall of magma within the vents. 

Following a two-day period of summit deflation starting Sunday, April 5, inflation returned to UWD tiltmeter yesterday afternoon and continues at this time. UWD has now recorded about 25.2 microradians of inflationary tilt since the end of episode 43. SMC tiltmeter has not recorded the inflation as clearly, but its data trend has likely been affected by heavy rainfall around the instrument over the past 24 hours.

During eruptive pauses like the one at present, the sulfur dioxide (SO₂) emission rate from the summit has varied within a typical range of 1,000 to 5,000 tonnes of SO₂ per day. Winds have been gusty out of the south and southwest since midday yesterday.

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.

Analysis:

Rapid rebound of tilt following episode 43 lava fountaining, continued tremor, visible glow, and precursory overflows from the eruptive vents suggest that another lava fountaining episode is likely soon. Continued overflows and associated spattering may be observed as the onset of episode 44 lava fountaining approaches; however, further periods of deflation and reduced vent activity remain possible before the episode begins. Models based on summit inflation indicate that episode 44 lava fountains are likely to occur between now and April 15.

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 that can be longer than three 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 43:

Episode 43 ended at 6:21 p.m. HST on March 10 after lava fountaining continued for just over 9 hours from both vents, sending tephra into surrounding communities. UWD tiltmeter recorded 33.9 microradians of deflationary tilt during the episode. A complete summary of activity can be found here. 

Resources:

NOTE: HVO’s monitoring network is mostly recovered from power and storm related outages. Several summit stations, including the SDH tiltmeter, will remain offline until we are able to re-establish access across the deep tephra field south of the caldera.

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.