USGS Volcano Notice - DOI-USGS-HVO-2026-04-09T16:54:43+00:00

Activity Summary:

Over the past day, the Halemaʻumaʻu south vent has overflowed at least 20 times, with slightly increased vigor starting yesterday afternoon. These lava flows have been associated with gas piston tremor cycles in the vent, with limited spattering and low dome fountaining. There was a single overflow from the north vent early this morning, along with intermittent spattering. Gradual summit inflation and low-level seismic tremor have persisted through the past 24 hours. Overflows and spattering may continue until lava fountaining episode 44 begins, but periods of deflation and reduced vent activity may still occur and delay the onset of 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 next several days, when the NWS has forecast possible southerly winds.

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

Summit Observations:

The south vent in Halemaʻumaʻu crater has overflowed at least 20 times since yesterday morning's update; rainy, foggy conditions occluded webcam views for a multi-hour period midday yesterday, preventing an accurate count. Lava flow vigor increased slightly starting yesterday afternoon, with activity still confined to the southwestern portion of the crater floor. These overflows have been associated with gas piston tremor cycles in the south vent, with limited spattering and low dome fountaining. A single overflow from the north vent started around 2:25 a.m. HST this morning and lasted 10–20 minutes, though intermittent spattering has continued in the vent since then.

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 On Tuesday, April 7, and continues at this time. UWD has now recorded about 25.4 microradians of inflationary tilt since the end of episode 43. After initially being affected by heavy rainfall on Tuesday, SMC tiltmeter began tracking the inflation yesterday morning.

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 variable directions between the south and west over the past 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.

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, periods of deflation and reduced vent activity may still occur and delay the onset of the episode. 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.