USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater. Satellite data indicate gradual eastward expansion of the lava dome. Although clouds limited most satellite and web camera views last week, field teams observed steam emissions from the summit (https://avo.alaska.edu/image/view/197476).  Seismic activity remains low, with only occasional minor volcanic earthquakes and signals from small rockfalls.

The current lava eruption began in July 2021 and has filled most of the summit crater and advanced into the valleys below. There have been no explosions at Great Sitkin Volcano since an event in May 2021. The volcano is monitored using local seismic, geodetic, and infrasound sensors, satellite data, and web cameras, and regional infrasound and lightning networks.

Volcanic activity remains elevated, with frequent small earthquakes, ongoing tremor, and occasional infrasound signals from minor explosions in the conduit. Steam plumes are visible in web camera images during clear weather.  Satellite data detected sulfur dioxide gas emissions on 4 days this past week.

Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, the Alaska Volcano Observatory uses nearby geophysical networks, regional infrasound and lightning data, and satellite data to monitor the volcano. 

Mount Kupreanof continues to exhibit low-level unrest, with occasional local earthquakes and steam emissions observed in web camera images. Seismic activity remained low throughout the week, and no sulfur dioxide emissions have been detected since August 21.

A new temporary monitoring station was installed near Mount Kupreanof in July 2026 and is intermittently providing seismic data, infrasound data, gas measurements, and web camera images. Intermittent data transmission 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. 

Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal background activity levels. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon.

Past Week Observations: During the past week, small earthquakes were detected at Mount Rainier, Mount St. Helens, and Mount Hood. All monitoring data are consistent with background activity levels in the Cascade Range. Field crews conducted monitoring-station maintenance at Mount St. Helens and Newberry Volcano, did geological mapping at Glacier Peak, conducted GPS surveys at Mount St. Helens and Mount Shasta, and a geomorphic survey at Mount St. Helens.

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu is paused. Summit inflation resumed around midnight but remains very slow. Intermittent, moderate glow due to flaming was observed overnight at the north vent. Another lava fountaining episode may be likely in the coming weeks if normal tilt patterns resume, but more data are needed to model the forecast window.

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

A detailed summary of lava fountaining episode 54 on August 25, 2026 can be found below.

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

Summit Observations:

Overnight webcam views showed intermittent, moderate glow related to flaming at the Halema’uma’u north vent. Release and combustion of volcanic gas (likely hydrogen) appears to be occurring deep within the vent and is related to larger tremor bursts observed in seismic data streams. Little or no glow appears to be coming from incandescent magma, suggesting it is relatively deep and possibly crusted over between gas release tremor bursts. Both the west and south vents were dark, and the latter appears to be partially filled in by north vent spatter and tephra erupted during lava fountaining episode 54. Lava flows on the floor of Halemaʻumaʻu crater still exhibited a few scattered points of incandescence as they cool and solidify after the episode; these points may remain visible for a couple more days and nights.

Low-frequency seismic tremor bursts—typical during the early stages of pauses between eruptive episodes—began with the cessation of episode 54 and have continued through this morning. The larger bursts are related to flames and glow at the north vent and probably represent gas release deep within the vent. One shallow earthquake has been recorded beneath the summit region over the past 24 hours. 

Summit inflation resumed immediately upon the cessation of lava fountaining, and the Uēkahuna (UWD) tiltmeter recorded a peak of 1.4 microradians of inflation prior to the onset of slow deflation early Wednesday, August 26. Deflation slowed midday yesterday, and extremely slow inflation began around midnight last night. As of this update, UWD has only inflated a total of 0.2 microradians relative to the end of lava fountaining episode 54. Deflationary tilt on UWD totaled 12.7 microradians during episode 54.

During inter-episode pauses, the sulfur dioxide (SO₂) emission rate from the summit typically varies between 1,000 and 5,000 tonnes per day. Strong trade winds are pushing the degassing plume to the southwest over the Kaʻū Desert 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 abrupt switch from summit deflation to inflation at the end of episode 54 and continued glow from the eruptive vents indicate that another lava fountaining episode is likely in the coming weeks. However, the deflationary tilt that has persisted since early Wednesday, August 26 is evidence that unpredictable, stepwise reinflation will likely continue during this repose period, as it has since episode 51. The only significant glow from the north vent at this time is related to gas release and near-surface combustion, suggesting the magma column is relatively deep within the vent at this time. Inflation resumed across the summit around midnight last night, but at a rate that is much slower that is commonly observed after the end of each lava fountaining episode.

The current situation—with minimal cumulative inflation, two and a half days after the end of episode 54—is unique for this eruption. More data are needed to assess what this might mean, or to model the forecast window for the next lava fountaining episode if normal patterns of reinflation return.

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 of two or more 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 54:

A detailed account of episode 54 is given in the HVO Status Report issued on August 25: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-08-26T05:56:38+00:00

• Episode 54 of the ongoing Halemaʻumaʻu eruption began around 10:30 a.m. HST and ended at 7:33 p.m. HST on August 25, 2026, after 9 hours of continuous lava fountaining. 
• The maximum lava fountain height from the north vent was approximately 500 feet (150 meters) above ground level, reached between 12:15 p.m. and 1:00 p.m. HST. Neither the south vent nor the new west vent (formerly the collapse pit) fountained during this episode.
• The maximum plume height was approximately 17,000 feet (5,200 meters) above sea level.
• Most tephra fall was restricted to the closed area of Hawaiʻi Volcanoes National Park, southwest of the active eruptive vents in Halemaʻumaʻu. However, HVO did also receive a report of trace Pele’s hair falling in the Ka‘ū district of the Island of Hawaiʻi.

Resources:

NOTE: HVO’s monitoring network is mostly recovered from recent power- and storm-related outages. Several summit stations will remain offline as we continue working to repair instruments and re-establish connections in our monitoring network.

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.

No activity was observed in occasional clear satellite images or distal geophysical monitoring data over the past week.

Eruptive activity at Ahyi Seamount may present a hazard to mariners in the water above and near the volcano. The summit has shallowed over the course of previous eruptions to 180 feet (55 m) below sea level, but the lack of local real-time data means we are unable to forecast or warn of impending eruptions. We will continue to monitor satellite and distal hydroacoustic data for additional evidence for, or escalation of, volcanic activity.