USGS Volcanoes: Notices released in the last day.

AVO detected seismic and pressure sensor signals associated with a large avalanche on the eastern flank of Iliamna Volcano this morning at 7:57 am AKDT (15:57 UTC). Avalanche events are somewhat common at this volcano.  Avalanches of similar seismic duration and amplitude occurred previously on May 22, 2016, June 21, 2019 and June 6, 2023.  The seismic signals from the avalanche were observed on monitoring networks throughout the Cook Inlet and as distant as the Katmai region 250 km (155 miles) away. We have not received any visual observations of the slide location or extent. The avalanche is not considered to be indicative of volcanic unrest.  

Slow eruption of lava within the summit crater continues with associated low level seismicity. Clear overnight satellite views showed elevated surface temperatures at the summit, consistent with the slowly growing lava dome.  Web camera images were cloudy over the past day.  

The current eruption began in July 2021 and, since then, lava flows have 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 earthquake activity continued over the past day. Clear web camera views from this morning showed steaming from the fumarole field on the southwest flank. Sulfur dioxide emissions were detected in satellite data.

A new temporary monitoring station was installed recently near Mount Kupreanof and is providing seismic data, infrasound data, gas measurements, and web camera images on an intermittent basis. This is by design to conserve battery power, but the frequency of data acquisition can be increased if activity warrants. The closest functioning seismometers that provide continuous data are approximately 10 miles (16 km) to the northeast of the volcano as part of the Mount Veniaminof network. Mount Kupreanof is also monitored by satellite data, remote infrasound and lightning networks, and visual observations from pilots and mariners passing by the volcano.

Unrest continues with minor seismic activity and infrasound detected during the past day. Sulfur dioxide emissions continue to be observed in satellite data and partially clear web camera views showed degassing from the summit. Satellite views were mostly cloudy.  

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 summit eruption of Kīlauea in Halemaʻumaʻu remains paused. Overnight, continuous weak to moderate glow was observed from the north vent. Glow from the south vent and recently opened crack upslope diminished significantly after 10:00 p.m. and 1:30 a.m. HST, respectively. Occasional flames and intensified glow associated with gas pistoning were observed primarily from the north vent and new crack, and less frequently from the south vent. Approximately 1.3 microradians of deflationary tilt has been recorded over the past day, with deflation continuing at this time. Current models indicate that the forecast window for episode 53 has shifted to August 10–13.

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

A summary of episode 52 is posted below.

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

Summit Observations:

Overnight, continuous weak to moderate glow and occasional small flames were observed from the north vent. Glow from the south vent and recently opened crack upslope diminished significantly after 10:00 p.m. and 1:30 a.m. HST, respectively, although both continued to intermittently produce weak glow or flames throughout the night.

At approximately 10:20 p.m. HST, continuous tremor transitioned to irregular periods of gas pistoning, with individual gas piston spikes occurring approximately 10–20 minutes apart. Webcams showed occasional flames and intensified glow coincident with gas piston spikes. Large flames were occasionally observed from the recently opened crack, most notably at 10:22 p.m. HST, near the transition to gas pistoning, and at 4:18 a.m. HST. Small flames were occasionally observed from the north vent and rarely from the south vent. No spatter was associated with gas pistoning overnight.

No earthquakes have been detected beneath Halemaʻumaʻu caldera over the past 24 hours.

Since the end of episode 52, the Uēkahuna (UWD) tiltmeter has recorded 11.0 microradians of inflationary tilt after earlier reaching a maximum of 12.3 microradians on UWD. UWD tilt has lost about 1.3 microradians since 6:00 a.m. HST yesterday and continues to record deflationary tilt at this time. Similar variations between inflationary and deflationary tilt were recorded leading up to episodes 51 and 52. The total deflationary tilt measured at UWD during episode 52 was 14.4 microradians.

The sulfur dioxide (SO₂) emission rate from the summit is likely now varying within a typical range of 1,000 to 5,000 tonnes per day. Winds are currently from the east-northeast, between 11-14 mph, with potential gusts as high as 20 mph. Degassing plumes from the new crack, north and south vents are currently being blown to the west-southwest. 

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 abrupt switch from summit deflation to inflation at the end of episode 52 along with glow from the vents indicates that episode 53 fountaining is likely. Inflationary tilt was interrupted by deflation from August 2 to 3. A second deflationary step began at 6:00 a.m. HST Friday morning and is continuing at this time.  Deflations prior to the start of episodes 51 and 52 lasted for roughly 2-3 days. If this deflation follows this trend, it would last until Sunday or Monday with the onset of episode 53 following in 1-2 days or between Monday and Wednesday of the coming week. This fits with current tilt-based models that have the forecast window for start of episode 53 fountains between Monday August 10 and Thursday August 13. Adjustments to the forecast may be necessary if the tilt pattern changes significantly.

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

Summary of episode 52:

A detailed account of episode 52 is given in the HVO Status Report issued on July 29: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-29T13:10:51+00:00

• Episode 52 of the ongoing Halemaʻumaʻu eruption began around 7:10 p.m. HST on July 28 and ended abruptly at 2:36 a.m. HST on July 29, 2026.
• The maximum lava fountain height was approximately 500 feet (150 meters) above ground level from the north vent. The south vent never fountained during this episode but did emit flames at the end of the eruption. 
• The maximum plume height was approximately 19,000 (5,800 meters) above mean sea level. 

• Tephra fall was restricted mostly to the closed area of Hawaiʻi Volcanoes National Park to the southwest of the active Halemaʻumaʻu vents.  

   

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 southwest 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.

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu remains paused. Very slight, infrequent spatter was observed overnight within the north vent. Moderate to strong glow persisted at the north and south vents, while weak, intermittent glow was observed from the recently opened crack upslope of the south vent. Occasional small flames were detected, primarily at the south vent and less frequently at the north vent; neither flames nor spatter were associated with gas pistoning. This morning tilt meters began recording a deflationary trend, the second of this repose period. Current models indicate the forecast window for episode 53 remains between August 8 and August 12, but this window could be pushed back later if the deflation continues for an extended time period.

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

A summary of episode 52 is posted below.

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

Summit Observations:

Moderate glow returned to the north and south vents yesterday evening and intensified overnight. Weak glow was initially visible from the cracks that opened upslope of the south vent but almost completely diminished by early morning. Periodic small flames were observed primarily at the south vent. Very slight spatter and occasional flames were first observed confined within the north vent around 8:00 p.m. HST yesterday and 4:30 to 5:00 a.m. HST this morning, with the strongest spatter occurring at 4:37 a.m. HST. 

At approximately 7:00 a.m. HST yesterday, summit seismicity transitioned from irregular gas pistoning to more continuous tremor, which has persisted through this morning with recurring ragged spikes every 2–3 minutes. Three small (<M2.0) earthquakes occurred beneath eastern Halemaʻumaʻu crater at a depth of just over 4 miles (7 km). 

Since the end of episode 52, the Uēkahuna (UWD) tiltmeter has recorded 11.9 microradians of inflationary tilt after earlier reaching a maximum of 12.3 microradians on UWD. UWD tilt flattened around 4:00 a.m. HST and has lost about 0.5 microradians since 6:00 a.m. HST. Deflationary tilt is continuing at this time. The total deflationary tilt measured at UWD during episode 52 was 14.4 microradians.

The sulfur dioxide (SO₂) emission rate from the summit is likely now varying within a typical range of 1,000 to 5,000 tonnes per day. Winds are currently from the northeast, between 11-16 mph, with potential gusts as high as 25 mph. Degassing plumes from the new crack, north and south vents are currently being blown to the southwest. 

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 abrupt switch from summit deflation to inflation at the end of episode 52 along with glow from the vents indicates that episode 53 fountaining is likely. Inflationary tilt was interrupted by deflation from August 2 to 3. A second deflationary step began at 6:00 a.m. HST this morning and if it continues could extend the forecast window. Current tilt-based models have a forecast window for episode 53 fountains between August 8 and August 12. Adjustments may be necessary if the current deflationary trend continues for a prolonged time.

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

Summary of episode 52:

A detailed account of episode 52 is given in the HVO Status Report issued on July 29: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-29T13:10:51+00:00

• Episode 52 of the ongoing Halemaʻumaʻu eruption began around 7:10 p.m. HST on July 28 and ended abruptly at 2:36 a.m. HST on July 29, 2026.
• The maximum lava fountain height was approximately 500 feet (150 meters) above ground level from the north vent. The south vent never fountained during this episode but did emit flames at the end of the eruption. 
• The maximum plume height was approximately 19,000 (5,800 meters) above mean sea level. 

• Tephra fall was restricted mostly to the closed area of Hawaiʻi Volcanoes National Park to the southwest of the active Halemaʻumaʻu vents.  

   

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 southwest 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.