USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater. Satellite data showed slightly elevated surface temperatures at the volcano on a few days during the week. Steaming from the summit lava flow was visible in webcam views when clear. 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 deep within the conduit. While clouds obscured most satellite and webcam views, steam plumes were visible in web camera images during clear weather. Satellite data detected minor sulfur dioxide gas emissions during the latter half of the 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. 

Seismicity at Mount Kupreanof was relatively quiet over the past week, with local earthquake activity rarely observed. Steaming continues, but sulfur dioxide emissions have become weak and rare – the last sulfur dioxide detection was on September 6. Because of the decline in unrest, the Alaska Volcano Observatory lowered the Aviation Color Code and the Volcano Alert Level at Mount Kupreanof to UNASSIGNED on September 8. 

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 Adams. All monitoring data remain consistent with background activity levels throughout the Cascade Range. Earlier this week, field crews conducted site visits and performed instrument maintenance at Mount St. Helens.

Overview:

Kīlauea volcano has been intermittently erupting lava flows from the north vent in Halemaʻumaʻu since September 7. A total of 69 overflows have occurred since then, with the most recent starting at 7:32 a.m. HST this morning. This style of activity has been typical in the hours to days before a summit lava fountaining episode. After several days of no change, slow summit reinflation returned last night and is currently slightly above the episode 54 starting level. The forecast window for the start of episode 55 fountaining is likely today, September 11, but could be pushed to tomorrow, September 12, if summit inflation rates change. 

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

PRECURSORY ALERT LEVEL NOTICE: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-09-07T20:09:10+00:00

Summit Observations:

Weak spattering from the north vent was first reported at 6:54 p.m. HST on September 6, with the first sluggish precursory overflow from the north vent starting at around 12:45 p.m. HST on September 7. Overflows from the north vent have continued intermittently since then, with a total of 69 so far lasting from a few minutes to about 2 hours long and separated by interludes of about 15 minutes to 8 hours. Overflows between September 7-9 became progressively more vigorous and were fed by a dome fountain that reached 15-30 ft (5-10 m) tall. Two main lava flows have formed during these overflows with one making it about a half mile (1 kilometer) to the southwest of the north vent, and the other making it less than half a mile (1 kilometer) to the northeast of the north vent. On September 10, overflows were generally sluggish, less frequent, shorter in duration (less than ten minutes), not fed by a dome fountain, and did not travel as far from the north vent. Overflows this morning, September 11, have been showing more vigor and lasting longer than ten minutes. Several of the overflows this morning were fed by dome fountains15-30 ft (5-10 m) tall and generated lava flows that traveled farther from the north vent than yesterday. The most recent north vent overflow began at 7:32 a.m. HST this morning and was ongoing when this notice was published. 

Webcam views at Kīlauea summit over the past day have been intermittently clear, with overnight views often obscured by weather. No overflows occurred from the south or west vents, but glow and flames were observed occasionally in all three of the eruptive vents in Halemaʻumaʻu in overnight webcam imagery. 

Tremor continues across the summit with regular intervals (about 5 minutes) of gas piston activity. When webcam views have been obscured by weather, changes in tremor were used to time the duration of recent overflows from the north vent. Over the past 24 hours, 21 small earthquakes were recorded beneath the summit region. Events occurred in two general locations: 1 mile (1.5 km) below Halemaʻumaʻu or about 2 miles (3 km) deep just south of Halemaʻumaʻu. While the largest earthquake was a magnitude-2.2, most have been smaller than magnitude-2.

Summit reinflation has been very unsteady since lava fountaining episode 54 on August 25. On September 7 around 3:00 p.m. HST, inflation at UWD reached a maximum that was higher than when episode 54 began, approximately 13.2 microradians. Following this inflationary high, UWD recorded around 1 microradian of deflation with the onset of precursory lava flows from the north vent. From then on, there was little net change until around 9 p.m. HST last night, September 10, when slow inflation returned. As of this morning, UWD is slightly above the 12.7 microradians lost 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. Trade winds are pushing the degassing plume to the southwest of Kīlauea's summit caldera this morning and northerly winds later today could blow volcanic gases as well as fine ash and Pele's hair to the south of Kaluapele if episode 55 begins.

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 lava fountaining episode 54, glow from the vents, overflows, and continued seismic tremor bursts at Kīlauea summit indicate that another lava fountaining episode is likely. The return to slow summit inflation last night, which has currently reached above the level that episode 54 started at, suggests that fountaining episode 55 could begin later today, September 11. However, any changes in ground deformation patterns, such as deflation, or no inflation, may cause the onset to be delayed.

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 notable activity was detected in distal geophysical monitoring data over the past week. However, faint discoloration of the ocean surface above Ahyi seamount was seen in high resolution satellite data from September 7.

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.

NORTHERN MARIANAS VOLCANOES
No signs of unrest were detected at any Northern Mariana Island volcanoes besides Ahyi seamount during the past week. 

Monitoring of Northern Mariana Islands Volcanoes

Northern Mariana Island volcanoes are monitored using seismo-acoustic sensors on Saipan, and by examining satellite imagery. We also use distant seismic stations in Guam and Chichijima, Japan, and hydroacoustic data from Wake Island, when available.

This level of monitoring can detect significant volcanic activity in the CNMI but cannot provide advanced warning of eruptions.

Due to a lack of geophysical monitoring on any of the volcanic islands, the following volcanoes have alert levels of UNASSIGNED: Anatahan, Sarigan, Farallon de Pajaros, Supply Reef, Maug, Asuncion, Agrigan, Pagan, Almagan, and Guguan.