USGS Volcanoes: Notices released in the last day.

Earthquake activity was quiet over the past day. Clouds obscured views of the volcanoes by satellite and web camera over the past day.

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.

Slightly elevated seismic and infrasound activity continues. Minor steam and sulfur dioxide emissions were observed in satellite data over the past day. No unusual activity was observed in partly clear web camera views.

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. 

Earthquake activity was quiet over the past day. Steaming from the summit area was observed in satellite images. Clouds obscured web camera views.

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.

Slightly elevated seismic and infrasound activity continues. Sulfur dioxide emissions were observed in satellite data. Clouds obscured web camera views. 

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. 

Monitored CALIFORNIA VOLCANOES
Current Volcano Alert Level: all NORMAL
Current Aviation Color Code: all GREEN

Activity Update: All volcanoes monitored by CalVO show normal background earthquake activity and deformation. Monitored volcanoes include Mount Shasta, Medicine Lake Volcano, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.

Past Week Observations for September 21 (0000h PDT) to September 27 (2359h PDT):

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 87 earthquakes greater than M1 were recorded, with the largest having a magnitude of M2.2.

Five earthquakes greater than M1 were recorded in the Sierra Nevada Block, south of Mammoth Mountain and Long Valley, with the largest having a magnitude of M2.7.

Four earthquakes greater than M1 were recorded near the Salton Buttes, with the largest having a magnitude of M1.3.

Overview:

Episode 55 fountaining remains a possibility during the ongoing Kīlauea summit eruption. Precursory overflows from the north vent resumed on the night of September 22. Short, rapid cycles of south vent overflows and lava drainback occurred repeatedly overnight. Glow and flames were observed from the north and south vents throughout the night, with intermittent spatter bursts. Summit tilt was variable over the past 24 hours but recorded overall inflation. Continuous tremor remains the dominant seismic signal across the summit. 

No anomalous seismic activity or deformation has occurred outside of the summit region, and no significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

NOTE: A weekly VONA with accompanying VAN was issued this morning as required by ICAO (International Civil Aviation Organization) for all volcanoes in ORANGE alert status. This VONA does not represent a change in activity.

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:

Precursory overflows from the north vent resumed on September 22, beginning at 10:10 p.m. HST, after about 10 days of quiescence at the vent complex. Overflow activity from the south vent began on September 27, however, the north remained dominant until last night when short, rapid cycles of overflows and lava drainback began at 7:44 p.m. HST. The overflows have lasted about 2-5 minutes, with most pauses between each cycle lasting about 5-7 minutes.  There have now been 165 overflows since September 22, and about 80 of those occurred during these rapid cycles. The north and south vents continued to glow strongly overnight and emit flames and intermittent spatter. No other areas of incandescence were observed across the summit region last night.

Continuous tremor is the dominant seismic signal across the summit. There were 14 small and shallow earthquakes located across the summit region in the past day, but they did not form clusters in time or location. 

Summit tilt has been variable over the past day, with overall inflation of about 0.3 microradians. The current total inflation since the end of episode 54 is about 16.8 microradians, which is about 4 microradians greater than what 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. Winds are currently forecast from the east.

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.

Analysis:

The north vent resumed precursory overflow activity on September 22. Overflows from the south vent began on September 27, and there have been over 80 short cycles of south vent overflows and lava draining back into the vent since last night at 7:44 p.m. HST. The north and south vents continued to glow and emit flames and intermittent spatter overnight. Strong continuous tremor dominates the seismic signal within the summit. Forecast windows for this episode can no longer be modeled due to the irregular changes in inflation and deflation. Since reaching a peak inflation of about 17 microradians (UWD tilt post episode 54) overnight, the summit deflated slightly and is currently at 16.8 microradians. Current overflow activity is focused on the south vent since last night. The north vent has produced the last 11 high fountain events (episodes 44-54). It is not possible to say with certainty that this activity will lead to the onset of another fountain event at this time, although conditions remain favorable.

Because the summit system remains active and highly pressurized, the two most likely possibilities are that activity continues at the north-south-west vent complex, or it activates another existing weak crack system in the summit region. Neither of these events are likely to produce a strong seismic precursor, so the alert levels have been left at ORANGE/WATCH as the volcano continues to "exhibit heightened unrest with an increased potential for eruption". For further details about potential scenarios see 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.

HVO is issuing a weekly Volcano Observatory Notice for Aviation (VONA) and associated Volcano Activity Notices (VAN) which are now required to be reissued weekly for volcanoes at ORANGE. (VONA repeat interval is daily for volcanoes at RED and every two weeks for volcanoes at YELLOW).

The Halemaʻumaʻu eruption of Kīlauea volcano continues to erupt small overflows from both the north and south vents. These may either lead to episode 55 high fountains or, alternatively, to opening of a new vent. Forecast windows for episode 55 fountaining can no longer be modeled due to changes in conditions. Episode 54 fountaining ended at 7:33 p.m. HST on Tuesday, August 25, 2026. HVO continues to closely monitor ongoing activity. Please see the Daily Update for Kīlauea for more details.

• All eruptive vents and lava flows are confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park. Tephra fall from volcanic ash clouds is greatest within 3 miles (5 km) of the vents, lighter ash and Peleʻs Hair may stay suspended for large distances from the vents.
• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Three Kīlauea summit livestream videos are available here: https://www.youtube.com/@usgs/streams 
• Additional short updates shared during the episode can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages