USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. The volcano was seismically quiet over the past day with very few observed events. Satellite and web camera images were obscured by clouds 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. Satellite observations were obscured by clouds 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 mostly 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. 

Overview:

The Halemaʻumaʻu eruption of Kīlauea is paused. The south vent has continued to glow over the past day, and incandescence remains visible on the crater floor as lava flows from episode 44 continue to cool and solidify. Lava fountaining episode 44 ended at 7:41 p.m. HST on April 9.

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

NOTES: 

At the time episode 44 ended, Kīlauea's Volcano Alert Level was dropped to ADVISORY and its Aviation Color Code was dropped to YELLOW. This is a new procedure that has been adopted due to the lower ground and aviation hazards during eruptive pauses, between episodes.

• An Information Statement on the new Volcano Alert Level and Aviation Color Code procedures can be found here: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-04-03T03:32:24+00:00
• A Volcano Watch article on the new Volcano Alert Level and Aviation Color Code procedures can be found here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-adapting-evolving-eruption-revising-kilaueas-alert-level-and

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

Summit Observations:

Thick steaming was observed yesterday in Halemaʻumaʻu as heavy rains poured onto still-hot lava flows from episode 44, which stopped lava fountaining at 7:41 p.m. HST on April 9. Overnight, glow was visible from the south vent; both vents are now quiet and emitting plumes of gas. Lava flows on the crater floor have remained partially incandescent, and spatter emplaced near the north vent has continued to slowly creep downslope into the crater. Incandescence on the crater floor and slumping around the vent will likely continue for several more days.

Seismic tremor continues during the current pause, with bursts every 1–10 minutes likely associated with gas pistoning cycles in the eruptive vents.

Since the end of lava fountaining episode 44 on April 9, the Uēkahuna tiltmeter (UWD) has tracked approximately 4.5 microradians of inflationary tilt. This instrument recorded 17.6 microradians of deflation in total during the episode.

With the eruption now paused, the sulfur dioxide (SO₂) emission rate from Halemaʻumaʻu is likely now varying within a typical range of 1,000 to 5,000 tonnes per day. Winds near the eruptive vents were gusty out of the southwest yesterday, but they transitioned to more variable directions early this morning.

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:

The rapid return of inflationary tilt and strong glow from both Halemaʻumaʻu eruptive vents indicates that another lava fountaining episode is likely. At this time, there is not enough information to develop a detailed forecast window for the next episode.

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 44:

Episode 44 ended at 7:41 p.m. HST on April 9 after 8.5 hours of continuous lava fountaining from the north vent, sending tephra to the north into public areas of Hawai'i Volcanoes National Park and into surrounding communities. UWD tiltmeter recorded approximately 17.6 microradians of deflation during the episode.

A full summary of episode 44 can be found in a Status Report here: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-04-10T06:25:16+00:00

Resources:

NOTE: HVO’s monitoring network is mostly recovered from recent 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.