USGS Volcanoes: Notices released in the last day.

Slow lava effusion continues within the Great Sitkin summit crater. Over the past day, seismic data recorded rockfalls from the growing lava dome. Web camera and satellite views 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 persists at Shishaldin Volcano, with seismic and infrasound activity remaining elevated over the past day. Satellite and web camera views of the volcano were obscured by clouds.  

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:

Lava flowed from the north vent in Halemaʻumaʻu on Monday night, marking the start of lava fountaining episode 45 precursory activity at the summit of Kīlauea. The Kīlauea Alert Level and Aviation Color Code were raised from ADVISORY/YELLOW to WATCH/ORANGE at that time, reflecting this change in activity. Forecast models currently suggest that lava fountaining episode 45 will start sometime between today, April 22, and Sunday, April 26. 

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

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

Summit Observations:

No additional lava flows have occurred within Halemaʻumaʻu since Monday night. However, a strong burst of spatter at 11pm Tuesday night sent lava a short distance from the north vent. Glow remains consistently visible at both vents in Halemaʻumaʻu overnight, along with occasional spatter from the north vent and periods of flaming visible in the south vent—likely caused by the ignition of volcanic gases escaping the vent. 

Low-level seismic tremor continues during the ongoing eruptive pause, and 14 small-magnitude earthquakes were recorded in Kīlauea summit region in the past 24 hours. Since the end of lava fountaining episode 44 on April 9, the Uēkahuna tiltmeter (UWD) has tracked approximately 17.3 microradians of inflationary tilt, with about 0.8 microradians of inflationary tilt in the past 24 hours. This instrument recorded 17.6 microradians of deflationary tilt in total during episode 44.

During periods of low-level activity precusory to lava fountaining episodes, the sulfur dioxide (SO₂) emission rate from Halemaʻumaʻu likely varies within a typical range of 1,000 to 5,000 tonnes per day. The National Weather Service reports that winds near the eruptive vents will be light today, southerly during the day and northerly overnight and into the early morning hours.

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, glow from the Halemaʻumaʻu eruptive vents, and lava flowing from the north vent indicates that another lava fountaining episode is likely. Additional overflows from one or both of the eruptive vents are expected prior to the start of the next lava fountaining episode. This precursory activity may continue for days and could include low-level spatter and small dome fountains visible within one or both vents. Prolonged precursory activity may delay the onset of episode 45 and forecast models may be adjusted moving forward depending on how activity progresses. Forecast models based on summit inflation currently indicate that episode 45 lava fountains are likely to occur sometime between today, April 22, and Sunday, April 26, with April 22 or 23 most likely based on current data.

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 17.6 microradians of deflationary tilt 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.

The USGS Hawaiian Volcano Observatory (HVO) is detecting shallow earthquakes beneath the south rim of Halemaʻumaʻu crater, as well as localized ground deformation, in the south caldera region of Kīlauea summit. This activity highlights the dynamic and hazardous nature of the closed area in Hawaiʻi Volcanoes National Park, where changes can occur quickly and can result in rapidly escalating hazards.  

• Heed National Park Service guidance and do not enter the closed area, where potentially life-threatening hazards can occur. Be aware that significant hazards exist around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes.  
• If you are near the rim of Kīlauea caldera and feel the ground shaking, immediately move away from the edge.  

Summary 

The USGS Hawaiian Volcano Observatory has detected small earthquakes beneath the south rim of Halemaʻumaʻu crater in the south caldera region of Kīlauea summit over the past few months. Over the past day, an additional 10 earthquakes magnitude-2 and smaller in this area have been detected at depths of 0.6–1.2 miles (1–2 km) below the surface. Most of these earthquakes are too small to be felt. Deeper earthquakes have also continued to occur beneath Kīlauea summit, but these have been observed typically throughout this eruption. HVO will continue to monitor this region closely as episode 45 of the ongoing Halema’uma’u eruption approaches and unfolds. Episode 45 lava fountaining is forecast to being between today, April 21, and April 26, 2026. 

A separate and discrete swarm of 15 shallow magnitude-2 or smaller earthquakes occurred 0.6–1.2 miles (1–2 km) beneath the south rim of Halemaʻumaʻu crater in the south caldera region of Kīlauea summit during the final hours of episode 44 on April 9, 2026. Most of the earthquakes were too small to be felt; however, several earthquakes were felt by HVO staff monitoring the eruption from the rim of Halemaʻumaʻu crater. Ground deformation data show that an area of the south rim of Halemaʻumaʻu crater rose by several inches (centimeters), though the cause is uncertain. Due to a blanket of tephra that obscures visibility, HVO staff visiting the area after episode 44 did not observe any obvious ground cracks. 

• A map showing the earthquake locations and ground deformation patterns is available here: https://www.usgs.gov/media/images/april-15-2026-insar-image-kilauea-deformation-associated-episode-44-ongoing-summit  

The patterns observed at the end of episode 44 are similar to patterns observed earlier in the eruption. During the start of episode 30 lava fountaining on August 6, 2025, earthquakes and ground deformation in this area of the south rim of Halemaʻumaʻu crater were associated with the opening of a new fissure on the south side of the crater, which erupted briefly only during episode 30. Earthquakes occurred minutes to hours before the new fissure began erupting in this area.  

Additionally, this area on the south rim of Halemaʻumaʻu was affected by molten and hot tephra falling when the south vent lava fountain became suddenly inclined to the south during episode 38 on December 6, 2025, due to a change in the vent geometry. This molten material destroyed the original V3 livestreaming camera on the south rim of Halemaʻumaʻu. USGS Hawaiian Volcano Observatory monitoring cameras in this area provide situational awareness of hazards so that monitoring staff do not need to be in this hazardous area.  

• Video of original V3cam being destroyed during episode 38: https://www.usgs.gov/media/videos/december-6-2025-video-v3cam-being-destroyed-lava-fountain  

The closed area around Halemaʻumaʻu crater and Kīlauea summit caldera is an area susceptible to various volcanic hazards; changes can occur quickly and be life-threatening. Heed National Park Service guidance and do not enter the closed area.  

• Hawaiʻi Volcanoes National Park website: https://www.nps.gov/havo/index.htm 

HVO will continue to message about Kīlauea activity via official notices including Volcanic Activity Notices, Daily Updates, Status Reports, and short messages on our website and social media (@USGSVolcanoes).