USGS Volcanoes: Notices released in the last day.

Minor seismicity and small rockfalls were detected over the past day. Clouds obscured views of the active lava dome in satellite and webcam imagery.

The current eruption began in July 2021 and, 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.

Low-level unrest continues with minor earthquake activity. Sulfur dioxide gas emissions were observed in otherwise cloudy satellite imagery. 

AVO released an Information Statement yesterday (June 22, 2026) summarizing the ongoing volcanic unrest from a magmatic intrusion beneath the volcano, which is also now detected in satellite ground deformation data (satellite interferometric radar or InSAR). More details can be found in the Information Statement on the AVO website: https://avo.alaska.edu/news/view/kupreanof-information-statement-june-22-2026.

There is no real-time geophysical monitoring network at Mount Kupreanof. The closest functioning seismometers are approximately 17 miles (27 km) to the east 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. 

Minor seismic activity and infrasound signals were detected at the volcano. The typical degassing plume from the summit crater with sulfur dioxide and steam emissions was observed in partly cloudy webcam and satellite views. Weakly elevated surface temperatures were also seen within the summit crater in satellite imagery.

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. 

Overview

• Seismic activity and sulfur dioxide (SO₂) emissions from Mount Kupreanof have remained elevated since the Aviation Color Code and Volcano Alert Level change to YELLOW/ADVISORY on May 12. 
• New satellite deformation measurements have detected uplift of the ground surface in the area around the volcano occurring sometime since October 2025. 
• The seismicity, gas, and deformation signals are due to a magmatic intrusion beneath the volcano. 
• The volcano remains at YELLOW/ADVISORY, and there are no indications from available data that an eruption is imminent. 

Earthquakes

Seismic unrest that began in February 2026 beneath Mount Kupreanof (https://avo.alaska.edu/volcano/kupreanof) continues. Since the Aviation Color Code and Volcano Alert Level change to YELLOW/ADVISORY on May 12, shallow seismicity has remained elevated with more than 30 earthquakes of magnitude 1 or greater. The largest events to date occurred on June 15 and 16 and had magnitudes of 3.2 and 3.6, respectively. 

The Alaska Volcano Observatory (AVO) does not maintain a local monitoring network at Mount Kupreanof, and seismicity is therefore detected using regional stations. The closest functioning seismometer is currently located 17 miles (27 km) to the east at Mount Veniaminof. The lack of a local monitoring network and the limited number of regional stations mean that smaller events (magnitudes less than 2) are often not detected or located, and earthquake locations have relatively large uncertainties. The largest earthquakes at Mount Kupreanof may also be analyzed and reported by the Alaska Earthquake Center and the U.S. Geological Survey National Earthquake Information Center. Earthquake magnitudes and locations from these agencies may differ slightly from AVO due to differences in techniques. Mount Kupreanof is also monitored by satellite data, remote infrasound and lightning networks, and visual observations from pilots and mariners passing by the volcano. 

Gas Emissions

Since May 12, sulfur dioxide emissions have been seen in satellite data on 13 days with calculated emission rates between 100 to 800 tons per day, similar to the rate of emissions seen since April. These elevated emission rates are consistent with degassing of new, relatively shallow magma beneath the volcano.  

Deformation

Satellite interferometric radar (InSAR) ground deformation data collected in mid-June, following sufficient snow melt, compared with data from before snow cover (September 30, 2025) indicate uplift of the ground around the volcano occurred sometime in the past 8 months (https://avo.alaska.edu/image/view/197259). The source depth of this inflation signal is likely around 3.7 miles (6 km) below sea level. These results are consistent with a magmatic intrusion, in agreement with the seismic and gas data.  

Interpretations and Hazards

The earthquake types and locations, observed sulfur dioxide emissions, and new deformation signal indicate that magma has intruded to relatively shallow depths beneath Mount Kupreanof. No major changes associated with this intrusion have been observed at the steam vents in a fumarole field at about 5,000 ft elevation west of the summit. Because of the active steam venting, if eruptive activity does occur, it may be either hydrothermal (steam driven) or magmatic. Intrusions of new magma under volcanoes do not always result in volcanic eruptions. The earthquake activity, deformation, and gas emissions at Mount Kupreanof may cease with no eruption occurring. If the magma rises closer to the surface, it will likely lead to increased unrest, such as a change in the rate and style of earthquake activity, surface heating, and increased gas emissions. Therefore, it is very likely that if an eruption were to occur it would be preceded by additional signals that would allow advance warning. 

If an eruption were to occur, the primary hazards would be from pyroclastic flows, lahars (volcanic debris flows), volcanic ashfall, and airborne volcanic ash. Due to its remote location, pyroclastic flows would only affect uninhabited areas but would likely generate lahars that could inundate rivers to the north and south of the volcano. The areas that could be impacted by ashfall and airborne ash are dependent on the amount of ash produced, the altitude of the ash, and the direction and speed of the wind at the time of the eruption. This could result in ashfall in nearshore waters and potentially on populations in the region. Drifting clouds of airborne ash could disrupt regional and international air traffic. 

Growth of the active lava dome to the east-southeast was observed in satellite radar imagery. Minor seismicity and small rockfalls were detected over the past day. Elevated surface temperatures and steaming were observed in satellite and webcam data. 

The current eruption began in July 2021 and, 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.

Low-level unrest continues with minor earthquake activity. No gas emissions or other signs of unrest were observed in cloudy satellite views of the volcano.

There is no real-time geophysical monitoring network at Mount Kupreanof. The closest functioning seismometers are approximately 17 miles (27 km) to the east 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. 

Minor seismic activity and infrasound signals were detected at the volcano. Sporadic partly cloudy webcam views showed a typical degassing plume from the summit crater. Sulfur dioxide gas emissions were observed in satellite data.  

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 June 15 (0000h PDT) to June 21 (2359h PDT):

Four earthquakes greater than M1 were recorded near the Lassen Volcanic Center, with the largest having a magnitude of M2.4.

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 84 earthquakes greater than M1 were recorded, with the largest having a magnitude of M3.1.

Six 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 M2.4.

One earthquake greater than M1 was recorded near the Salton Buttes, with a magnitude of M2.0.

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu remains paused. Summit inflation, strong vent glow and flaming, and degassing continues, indicating that another episode is likely. Forecast models indicate that the onset of fountaining episode 50 is likely to begin between June 25 and June 27 with June 26 most likely. 

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

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

Summit Observations:

Continuous strong glow was visible on webcams from both vents in Halemaʻumaʻu overnight. The south vent continued to produced large flames caused by the burning of gas within the top of the conduit.  Magma is close to the surface.

Pulses of seismic tremor continued (every 10-20 minutes) in the last 24 hours. One magnitude 1.0 earthquake was identified at Kīlauea volcano's summit in the past 24 hours.

Kīlauea summit deflation totaled 15.5 microradians during episode 49. Once the episode ended, inflation resumed and has since recovered 12.6 microradians of tilt at the summit tiltmeter at Uēkahuna (UWD). 

With the eruption now paused, the sulfur dioxide (SO₂) emission rate from the summit is likely now varying within a typical range of 1,000 to 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.

Analysis:

The abrupt switch from deflation to inflation at the end of episode 49 along with continued tremor and glow from the vents indicates that episode 50 fountaining is likely. Magma remains close to the surface although no spattering or overflows have been observed at this time. Forecast models suggest another fountaining episode may occur between June 25-27 with June 26 most likely.

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 that can be longer than three 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 49:

A detailed account of episode 49 is given in the HVO Status Report Issued June 14: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-06-15T03:23:25+00:00

• Episode 49 of the ongoing Halemaʻumaʻu eruption began at the summit of Kīlauea at 9:36 a.m. HST after approximately 5 hours of precursory activity. The episode ended abruptly at 5:05 p.m. HST on June 14, 2026, after 7.5 hours of continuous lava fountaining from the north vent. Lava fountains reached a maximum height of almost 700 ft (210 m) and lava flows covered 40-50% of the crater floor. The eruption is currently paused.
• Most tephra fell within the closed area of Hawaiʻi Volcanoes National Park. There were no reports of tephra fall at public viewing locations, including the Uēkahuna bluff, Keanakākoʻi overlook, and Volcano House. Similarly, there was no ash detected by field crews in nearby communities.

Resources:

NOTE: HVO’s monitoring network is mostly recovered from recent power- and storm-related outages. Several summit stations, including the SDH tiltmeter, will remain offline until we are able to re-establish access across the deep tephra field southwest of the caldera.

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.