USGS Volcanoes: Notices released in the last day.

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 and high-resolution satellite images 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 slightly elevated, with 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 occasionally detected minor sulfur dioxide gas emissions. The frequency and magnitude of earthquakes, infrasound signals, and gas emissions all have declined over recent months.

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. 

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. Minor earthquakes were detected in the past day. Clear satellite views showed slightly elevated surface temperatures.

The current eruption began in July 2021. 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.

Unrest continues at Shishaldin Volcano, with minor seismic and infrasound activity detected. Clear webcam images showed steam emissions from the summit crater. 

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. 

Activity Update: All volcanoes in the Cascade Range of Washington and Oregon 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 and Mount St. Helens. All monitoring data remain consistent with background activity levels throughout the Cascade Range. This week, field crews conducted helicopter-supported maintenance of monitoring stations and GPS surveys at Mount Rainier, and geology field crews worked at Glacier Peak.

Overview:

Glow and flames continued from the north, south, and west vents throughout the night, with minor intermittent spatter primarily from the north vent. None of the new vents along the crater wall showed any signs of activity in the past 24 hours. The small summit deflation yesterday switched to inflation around 6 p.m. HST last night, gaining 0.5 microradians through this morning. Tremor bursts continue to be the dominant seismic signal across the summit. No anomalous seismic activity or deformation has occurred outside of the summit region.

No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone. However, tiltmeters on the East Rift Zone did minor excursions triggered by heavy rainfall over the past 24 hours. These changes are not related to magma movement.

A detailed summary of the new eruptive activity in Halema'uma'u can be found here: USGS Volcano Notice - DOI-USGS-HVO-2026-09-16T18:27:10+00:00

STATUS REPORT on changes in activity and implications for this eruption: USGS Volcano Notice - DOI-USGS-HVO-2026-09-15T03:18:09+00:00

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

Summit Observations:

Glow and flames continued all night from the north-south-west vent complex. No obvious changes in the intensity of glow from the vents could be detected. Minor intermittent spattering occurred overnight primarily from the north vent.

Strong tremor bursts continue this morning and are the dominant seismic signal across the summit. There were nine earthquakes located across the summit region but do not form clusters in time or location and are all small magnitude. 

The magnitude-4.1 earthquake that occurred last night south of Pāhala had no apparent impact on eruptive activity on Kīlauea.

The summit resumed inflating around 6 p.m. HST yesterday and continues this morning, recording an increase of about 0.5 microradians. The total inflation since the end of episode 54 is currently about 14.5 microradians, over a microradian more than was lost during episode 54 fountaining.

During inter-episode pauses, the sulfur dioxide (SO₂) emission rate from the summit typically varies between 1,000 and 5,000 tonnes per 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. No significant ground deformation was recorded in either rift zone, however, tiltmeters on the East Rift Zone did show typical, minor excursions related to heavy rainfall over the past 24 hours. These changes are not related to magma movement.

Analysis:

The main north, south, and west vents continued to glow and emit flames last night, with minor intermittent spatter from primarily the north vent. This indicates that magma remains close to the surface in these vents. Forecast windows for this episode can no longer be modeled due to the irregular changes in inflation and deflation. Current conditions remain favorable for either another fountaining episode or change in eruptive activity if inflation continues. Possibilities are outlined in the September 15 Status Report.

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.

On Thursday, September 17 at 8:36 p.m. HST, a magnitude-4.1 earthquake occurred 3 mi (5 km) south of Pāhala on the Island of Hawaiʻi at a depth of 8 mi (12 km) below sea level. The earthquake had no apparent impact on either Mauna Loa or Kīlauea volcanoes.

The USGS Hawaiian Volcano Observatory continues to monitor Hawaiian volcanoes for any changes.

EARTHQUAKE DESCRIPTION

• Magnitude: 4.1
• Date and Time: September 17, 2026, at 8:36 p.m. HST  
• Location: 3 mi (5 km) S of Pāhala, Island of Hawaiʻi   
• Depth: 8 mi (12 km) below sea level 
• Aftershocks are possible in the coming days to weeks      

EARTHQUAKE INTENSITY AND AFFECTED AREA  

• Potential Damage: No damage to buildings or infrastructure expected based on earthquake intensity   
• Maximum Intensity, Modified Mercalli Scale (https://www.usgs.gov/natural-hazards/earthquake-hazards/science/modified-mercalli-intensity-scale)
  • Community-reported: IV - light shaking
  • Instrument-derived: IV - light shaking   
• Felt Reports: Over 80 within first half hour (http://earthquake.usgs.gov/dyfi/)   
• Felt Area: Island of Hawaiʻi   
• Visit NOAA’s Tsunami Warning Center website for updated information: https://www.tsunami.gov/  

EARTHQUAKE MAPS AND ADDITIONAL INFORMATION   

• USGS National Earthquake Information Center Maps and Reports for this Event: PUT NEIC EVENT PAGE LINK HERE
• USGS-HVO Interactive Earthquake Map of Hawaiʻi: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/earthquakes  

Overview:

Summit tilt and tremor began dropping slowly at about 5:00 p.m. HST coincident with the opening of vent 6. However, by 8:30 p.m. HST all of the new vents had stagnated as slow deflation of the summit continued. Glow continued from the north, south, and west vents throughout the night, but was obscured by heavy rainfall in the early morning. The small summit deflation continues but has slowed this morning. Tremor bursts began reappearing at about 9 p.m. HST last night and continue to be the dominant seismic signal. No anomalous seismic activity or deformation has occurred outside of the summit region.

No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone. However, tiltmeters on the East Rift Zone did show typical rainfall excursions early this morning. These changes are not related to magma movement.

A detailed summary of the new eruptive activity in Halema'uma'u can be found here: USGS Volcano Notice - DOI-USGS-HVO-2026-09-16T18:27:10+00:00

STATUS REPORT on changes in activity and implications for this eruption: USGS Volcano Notice - DOI-USGS-HVO-2026-09-15T03:18:09+00:00

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

Summit Observations:

Summit tilt and tremor began dropping around 5 p.m. HST yesterday just as vent 6 opened up north of the other vents.  Shortly after, eruptive activity began to diminish on the new vents and was completely stagnated at all six vents by 8:30 p.m. HST. There were short-lived, small flows from several of the vents during the night as the vents depressurized. 

Glow continued all night from the north-south-west vent complex along with flames at times. The vents were obscured by heavy rain and clouds in the early morning hours but no obvious changes in the intensity of glow from the vents could be detected. Spattering stopped at the north vent around 7 p.m. HST and about two hours later at the south and west vents.

Tremor began decreasing around 5 p.m. and by 9 p.m. HST was transitioning from continuous tremor to intermittent tremor bursts. Tremor bursts became dominant after 10 p.m. HST and strengthened until about 1:30 a.m. HST. Strong bursts continue this morning and are the dominant seismic signal across the summit. There were twelve earthquakes located across the summit region. Ten of these occurred within the last 8 hours, but do not form clusters in time or location.

The summit underwent a small deflation last night of about 2 microradians measured on the UWD tiltmeter. Slow deflation continues this morning but appears to be leveling off. The amount of deflation is similar to the deflationary "steps" recorded earlier in this repose period and in the periods leading up to episodes 51-54. The total inflation since the end of episode 54 is currently 14 microradians, over a microradian more than was lost during episode 54 fountaining.

During inter-episode pauses, the sulfur dioxide (SO₂) emission rate from the summit typically varies between 1,000 and 5,000 tonnes per day. Moderate to strong trade winds (10 miles per hour, 5 meters per second or more) are pushing the degassing plume to the southwest of Kīlauea's summit caldera this morning and are expected to continue.  Models indicate that gases as well as fine ash and Pele's hair would be transported to the south of Kaluapele if fountaining starts today with an episode 55.

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. No significant ground deformation was recorded in either rift zone, however, tiltmeters on the East Rift Zone did show typical, minor rainfall excursions early this morning. These changes are not related to magma movement.

Analysis:

The main north, south, and west vents continued to glow last night, indicating magma remains close to the surface in these vents. Current deflation is similar to the deflationary steps seen previously during the current repose period after the episode 54 fountaining. Even with the small deflation last night, pressure remains high within the system. Forecast windows for this episode can no longer be modeled due to the irregular changes in inflation and deflation. Current conditions remain favorable for either another fountaining episode or change in eruptive activity if inflation returns. Possibilities are outlined in the September 15 Status Report.

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 or satellite images 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.

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.