USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. Minor earthquakes were detected in the past day. Clouds obscured views of the volcano in both satellite and webcam 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.

Unrest continues at Shishaldin Volcano, with minor seismic activity detected when not obscured by strong wind noise. Clouds obscured satellite and webcam views of the volcano.

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 07 (0000h PDT) to September 13 (2359h PDT):

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 111 earthquakes greater than M1 were recorded, with the largest having a magnitude of M3.1.

Four 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 M2.0.

Eruption History:   

There have been 54 episodes of lava fountaining since the Halemaʻumaʻu eruption began in late December 2024 at the summit of Kīlauea. Each episode was preceded by a period of summit inflation as magma accumulated in the shallow chamber beneath Halemaʻumaʻu followed by rapid summit deflation during lava fountaining. New fountaining episodes usually occur when inflation recovers the amount lost in the previous fountaining episode indicating the system has repressurized.  This repeating pattern coupled with uniform inflation as measured on summit tiltmeters has allowed the USGS Hawaiian Volcano Observatory to track the pressurization required to initiate fountaining episodes and issue forecast windows of several days for the onset of fountaining for about 50 of the episodes. 

Description of Current Activity:   

Data from summit tiltmeters and Global Positioning Satellite (GPS) instruments indicate that the summit region is highly pressurized. This pressurization may be due to the increased height, about 500 feet (150 meters), of the north-south-west vent complex since the start of the eruption on December 23, 2024. The opening of new vents last night and this morning north of the established vent complex in Halemaʻumaʻu appears to be a response to this pressurization.  The new vents are about 150 feet (45 meters) below the level of the north vent.  The new vents opened without significant seismicity, although they are in the region where a short-lived swarm of shallow earthquakes took place from about 9:15 to 9:25 p.m. HST on the night of September 13.  

Current summit reinflation leading up to this change in activity has been very irregular since lava fountaining episode 54 on August 25 and difficult to model due to repeated deflations and periods of no inflation. On September 7, summit tiltmeters indicated that the Halemaʻumaʻu magma chamber surpassed the amount of pressurization typically observed to start a fountaining episode. Since September 7, the number of small magnitude earthquakes began to increase in the Kīlauea summit region, likely related to the general increase in pressure in the Halemaʻumaʻu magma chamber. Nearly 100 earthquakes have been located since September 7, in three general areas: about 1.5 km (0.9 miles) below Halemaʻumaʻu including the northwest side where the new vents occurred, about 3 km (1.8 miles) deep just south of Halemaʻumaʻu, and 1.5 km (0.9 miles) deep beneath Keanakākoʻi crater on the southeast side of the caldera. Most earthquakes have been smaller than magnitude-2, though the largest event was M2.6 on September 11.  

Lava has not yet erupted as high fountains, but smaller, precursory lava flows have erupted from the north vent over 104 times between September 7–12. Since then, intermittent spatter bursts on September 13–15 have built a small spatter cone around the north vent that was measured as 36-39 feet (11-12 meters) tall September 14 afternoon. Last night, September 14, cracks on and near the base of the northwest wall of Halemaʻumaʻu crater erupted lava just north of the vent complex beginning just before 9:00 p.m. HST. No fountaining was associated with the new vents, which continue to feed a small flow today in the northwest corner of the crater floor. Precursory flows have been ongoing for 8 days now, the longest period recorded during this eruption. 

No unusual activity has been detected in the Southwest or East Rift Zones of Kīlauea. All activity has been confined to the summit region of Kīlauea in Hawaiʻi Volcanoes National Park.

Interpretation:

The magma plumbing system connecting the eruptive vents in Halemaʻumaʻu to the shallow magma chamber below has been remarkably stable throughout most of this eruption. During the start of episode 30 lava fountaining on August 6, 2025, earthquakes and ground deformation in an area on the south rim of Halemaʻumaʻu crater were associated with the opening of a new fissure on the south side of the crater, which erupted briefly only during episode 30. Earthquakes occurred minutes to hours before the new fissure began erupting in this area. That vent opened about 10 minutes prior to the onset of fountaining and stopped erupting about 2 hours into the fountaining episode.  Kīlauea summit rapidly deflated during lava fountaining episode 30, and the fissure on the south side Halemaʻumaʻu did not erupt again.  

Overnight glow and spatter visible in the north/south/west vents indicate that the conduits remain intact and connected to the underlying chamber despite the opening of new vents nearby last night. Volcanic tremor, which has been the major seismic signal during this eruption, has also continued. While many lava fountaining episodes are preceded by lava flows or visible spatter, this period of precursory activity is now the longest since high fountains began after episode 4 from January 15–18, 2025. The rate of earthquakes has decreased slightly in the past day but the summit region of Kīlauea summit remains at a high level of pressurization despite the opening of new vents last night. The new vents are at a lower elevation than the main eruptive vent complex in Halemaʻumaʻu, which could sustain prolonged continuous eruption of lava. However, the continued high level of pressurization could also potentially result in additional changes outlined below.  

Possible Outcomes 

The impact of Kīlauea summit increased pressurization and earthquakes on the next episode of lava fountaining, if any, is unknown at this time. It is not possible to forecast an exact outcome of this activity. However, some potential scenarios are described below based on past episodic eruptions of Kīlauea (1983 Puʻuʻōʻō and the 1969 Maunaulu eruptions). These past eruptions both continued after lava fountaining episodes ended, with fissures opening nearby that erupted more continuous lava flows.   

• Eruption becomes continuous at the new vents: Lava could continue to erupt from the vents in Halemaʻumaʻu, as lava flows or spatter bursts, for an unforeseeable amount of time. The prolonged nature of low-level activity since September 7 and opening of new vents could be signs of a transition to lava erupting more continuously within Halemaʻumaʻu from existing vents. The only similar scenario is the onset of episode 48 during the Puʻuʻōʻō eruption where pressure built up to a new fountaining episode, but instead of fountaining a new fissure opened up down rift of Puʻuʻōʻō and began erupting continuously. 
• Eruption returns to fountaining: Alternatively, a fountaining episode from an existing vent in Halemaʻumaʻu could begin at any point during this period of increased pressurization.  Prior to episode 35 of the Puʻuʻōʻō eruption, a fissure erupted uprift of the vent before fountaining began and continued for 2 weeks after the end of the fountain episode. Normal fountain episodes resumed after the end of this extended excursion.  
• Formation of new vent(s) in summit region: Magma could form a new shallow pathway toward the surface, potentially resulting in other new vents erupting lava within the summit caldera.  In this scenario, we would expect earthquakes, potentially with tightly clustered locations, along with changes in the patterns of ground deformation indicative of shallow crack formation, similar to what occurred in the new vent formation during episode 30 on August 6, 2025, when a crack in the southwest wall of Halemaʻumaʻu briefly erupted.   
• Intrusion into the upper parts of the Southwest Rift Zone or East Rift Zone: Magma could migrate into the upper portion of the Southwest Rift Zone or the East Rift Zone in Hawaiʻi Volcanoes National Park. In this scenario, we would expect an extended period of increased rates of earthquakes migrating from the summit towards a rift zone, along with ground deformation indicative of summit magma chamber deflation.  

HVO Actions 

Kīlauea's summit region is monitored with a dense network of instruments recording seismic activity, ground deformation, visual and thermal imagery, and volcanic gas emissions. HVO staff closely monitor these various datasets for changes. Kīlauea Daily Updates are published each morning with a summary of the past 24 hours of activity, and we will issue additional messages as needed based on any significant changes detected. Should volcanic activity change significantly, a Volcanic Activity Notice will be issued. HVO is in frequent communication with Hawai‘i Volcanoes National Park and Hawai‘i County Civil Defense to keep them apprised of Kīlauea's activity. 

Eruption Resources  

• Recent maps and a timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information. 
• Short messages tracking earthquake activity, the evolution of lava fountains, and other activity can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages  
• Three Kīlauea summit livestream videos 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  
• Most recent Kīlauea notification: https://www.usgs.gov/volcanoes/kilauea/volcano-updates  

Continuing 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, and reticulite—are formed by lava fountains. Larger particles fall near the vents while light particles may be wafted greater distances downwind. 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 and eye irritation. More information is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf. Close to the vents, the tephra material on the crater rim is prone to cracking, slumping, and small landslides that sometimes expose hot and molten material within. 
• Lava flows: On the floor of Halemaʻumaʻu crater and the southwest side of Kaluapele—Kīlauea's summit caldera—lava flows remain 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. Visitors along the caldera rim should step away from the rim if they feel earthquake shaking and be aware of the potential for ground cracks. 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 2008. 

Overview:

Cracks on and near the base of the northwest wall of Halemaʻumaʻu crater erupted lava just north of the vent complex beginning just before 9:00 p.m. HST last night. No fountaining was associated with the new vents which continue to feed a small flow this morning in the northwest corner of the crater floor. Intermittent eruptions of spatter bursts continued to build a small cone around the north vent and sporadic spatter bursts were also observed from the south vent. No precursory lava flows have erupted from the main vent complex since September 12. Summit inflation stalled last night shortly after the new vents opened. The summit region continues to be highly pressurized, but it is not possible to forecast what might happen next. Two possibilities include the new vents erupting continuously or the new vents shutting down and returning all activity to the established vents.

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

Volcano Activity Notice (VAN) for the start of precursory eruptions: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-09-07T20:09:10+00:00

Summit Observations:

Two new vents opened up on and near the base of the northwest wall of Halemaʻumaʻu crater last night, north of the established vent complex. The vents opened in the region of a small earthquake swarm on Sunday night reported in yesterday's update. No earthquakes immediately preceded the vents, which opened passively with no fountaining. The first vent began opening around 8:30 p.m. HST at the base of the crater wall. Initially it was just a small incandescent spot, but it began feeding a lava flow around 9:00 p.m. HST. The second vent opened up about 100 feet (30 meters) up the crater wall just to the south of the initial vent and immediately fed a lava flow. The second flow then stagnated, but the first flow remains active this morning. Summit inflation stalled at about the time the second vent formed last night, and tilt recorded on the UWD tiltmeter remains level this morning. Both vents are at lower elevations than the established vent complex, but on the trend of the original dike that was emplaced in December 2024.

Intermittent spatter bursts continued from the north vent yesterday after slowing yesterday morning. Around 3 p.m. HST, part of the north vent cone collapsed, and spattering picked up in frequency and intensity. The spattering, along with large flames, continued from the north vent all night and into the morning when spattering slowed again. Both the south and west vents glowed most of the night and spatter bursts were periodically observed from the south vent. 

Precursory activity has continued for about 8 days, which is now the longest period of precursory activity since high fountains began after episode 4, and has included 104 overflows. The next longest period of precursory activity was 6.2 days before episode 44. The most overflows recorded was 179 from the north and south vents combined prior to episode 36.

Tremor recorded at Kīlauea's summit has remained relatively uniform and continuous over the past 24 hours. Tremor intensity did not vary appreciably with the new eruptive activity. Over the past 24 hours, 8 small earthquakes were recorded beneath the summit region mostly on the east side of Kaluapele, the summit caldera. There were no earthquakes in the region where the new vents opened last night and the total earthquakes dropped by half from the previous 4 days.

Summit reinflation has been very unsteady since lava fountaining episode 54 on August 25. On September 7 around 3 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 on September 10, when slow inflation returned. As of this morning, UWD's inflation remains stalled since about 9 p.m. HST last night. The total inflationary tilt measured on the UWD tiltmeter remains at 15.7 microradians, well 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. Moderate to strong trade winds (10 mph, 5 meters per second or more) are pushing the degassing plume to the southwest of Kīlauea's summit caldera this morning 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 episode 55 fountaining were to begin today.

Recap of Precursory Activity Prior to Today:

Weak spattering from the north vent was first reported at 6:54 p.m. HST on September 6. Sluggish precursory overflows from the north vent started at around 12:45 p.m. HST on September 7 with no dome fountains or spattering. Overflows from the north vent continued intermittently after that, with a total of 104 between September 7 and 12. Overflows lasted from a few minutes to about 2 hours long and were 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 feet (5-10 meters) tall. Two main lava flows 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 on September 11-12 showed more vigor and lasted longer than ten minutes, with dome fountains that grew from 15-30 feet (5-10 meters) to 35-50 feet (10-15 meters) tall and generated lava flows that traveled farther from the north vent than on September 10. Overflows from September 7-12 built a small shield around the north vent which has since been capped by a spatter cone built from strombolian activity that started on September 13 and is ongoing. The spatter cone around the north vent was measured yesterday afternoon, when it was 36-39 feet (11-12 meters) tall.

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, inflation, and continued seismic tremor bursts at Kīlauea summit indicate that another lava fountaining episode could occur. Magma remains shallow in all of the vents, indicating that current conditions remain favorable for the onset of episode 55 fountaining. Additionally, the summit region has significantly exceeded the amount of deflation recorded during episode 54 and is three microradians over the level when that fountaining episode started. The summit region continues to be highly pressurized as indicated by inflation and opening of new vents, but it is not possible to forecast what might happen next. Two possibilities include the new vents erupting continuously or the new vents shutting down returning all activity to the established vents.

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.