USGS Volcanoes: Notices released in the last day.

A single, brief explosion was detected in geophysical data on October 1 at 07:27 AM AKDT (15:27 UTC). In response, AVO raised the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY. Cloudy conditions obscured the volcano at the time of the event, so it is unclear whether a volcanic ash cloud was produced. If ash was generated, it was likely minor given the very short duration of the explosion (less than one minute). Infrasound data indicate the explosion originated from the south crater of Mount Gareloi, and satellite radar data from yesterday shows a small crater‑like feature near the fumarole field on the volcano’s south flank. No additional signs of unrest have been detected since the event.

Gareloi volcano persistently emits magmatic gases from a fumarole field in the south crater and commonly exhibits low-level seismic activity. These observations suggest the presence of shallow magma and potential interaction with a hydrothermal system. The explosion on October 1 likely reflects a change to the magmatic-hydrothermal system, but it is not clear that the likelihood of a volcanic eruption has increased. AVO will continue to monitor activity to determine if the recent changes are related to influx of new magma or other changes to the magma system.

Mount Gareloi is monitored by a local seismic and infrasound network, satellite data, and regional infrasound and lightning-detection networks.

Cloudy conditions over the past week have limited most satellite and webcam observations. However, satellite data from September 28 revealed a small collapse on the south side of the lava dome and minor steaming from the summit area. Seismic activity remains low, characterized by occasional small volcanic earthquakes and signals from minor rockfalls associated with continued lava‑flow growth.

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. Small earthquakes, ongoing tremor, and occasional infrasound signals have continued over the past week. During periods of clear weather, webcam views showed steaming from the summit area, and satellite data indicated minor sulfur dioxide emissions through much of the week. Overall, the frequency and magnitude of earthquakes, infrasound signals, and gas emissions 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. 

A single, brief explosion was detected in geophysical data at 07:27 AM AKDT (15:27 UTC). In response, AVO raised the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY this morning. It is unknown whether a volcanic ash cloud was generated, as cloud cover up to about 20,000 feet above sea level is obscuring the volcano. If an ash cloud was produced, it would likely be minor given the short duration of the explosion (less than one minute). Infrasound data suggests the explosion originated from the south crater of Mount Gareloi. No further signs of unrest have been detected since the explosion this morning.

Gareloi volcano persistently emits magmatic gases from a fumarole field on the south crater and commonly exhibits low-level seismic activity. These observations suggest the presence of shallow magma and potential interaction with a hydrothermal system. This morning's explosion likely reflects a change to the magmatic-hydrothermal system, but it is not clear that the likelihood of a volcanic eruption has increased. AVO will continue to monitor activity to determine if the recent changes are related to influx of new magma or other changes to the magma system.

Mount Gareloi is monitored by a local seismic and infrasound network, satellite data, and regional infrasound and lightning-detection networks.

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

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, and minor sulfur dioxide emissions were detected in satellite data over the past day. Aside from this, no additional activity was observed in the cloudy webcam or satellite 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. 

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: Over the past week, small earthquakes were detected at Mount Hood, Mount Rainier, Mount Adams, and Mount St. Helens. At Mount Adams, the Pacific Northwest Seismic Network located 10 events ranging from M0.8 to M2.6 on September 27-28, all too small to be felt at the surface.  Seismicity over the past year continues a trend of slightly elevated earthquake activity at Mount Adams that began in fall 2024. Although this represents an increase in rate of seismicity for Mount Adams, the rate remains substantially lower than earthquake rates at its three closest volcanic neighbors: Mount St. Helens, Mount Hood, and Mount Rainier; and all monitoring data remain consistent with background activity levels throughout the Cascade Range. Field work included routine maintenance of monitoring stations at Mount Hood, and a rapid-response field-site repair to restore network connectivity to several Rainier Lahar Detection System stations.

Overview:

There have been no overflows or spatter from north or vents in the past 24 hours, although there was strong glow and flames from the vents overnight. The summit intrusion that happened the night of September 30 to October 1 did not reactive in the last 24 hours, although earthquake activity has continued underneath Halemaʻumaʻu. A summit tiltmeter near Uēkahuna also recorded modest inflation.

Episode 55 fountaining remains a possibility during the ongoing Kīlauea summit eruption. It is also possible that intrusive activity below Kīlauea summit caldera could resume and potentially lead to the eruption of lava in a new location within the caldera.

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.

STATUS REPORT published during intrusive activity: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-10-01T08:14:21+00:00

VOLCANO WATCH summarizing recent intrusive activity: https://www.usgs.gov/observatories/hvo/news/volcano-watch-intrusion-during-eruption-summit-kilauea 

STATUS REPORT on changes in activity and implications for this eruption: https://volcanoes.usgs.gov/hans-public/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:

In the past 24 hours, there have been no overflows and no spattering. Both vents had strong glow with flaming overnight. No other areas of incandescence were observed across the summit region last night. Overflows from the north and south vents stopped during the early stages of the intrusion that started underneath Kaluapele, Kīlauea summit caldera, the afternoon of September 30, but resumed later on during the intrusion. The intrusion ended on October 1 at around 4 a.m. H.S.T. South vent only had one overflow after the intrusion, ending just before 6 a.m. yesterday October 1, and north vent's last overflow was just after 6 a.m. HST yesterday morning. 

Elevated rates of earthquakes below Kaluapele, continue following the intrusion. In the past 24 hours, there were 59 shallow earthquakes located across the summit region, primarily underneath Halemaʻumaʻu. The largest earthquake was a magnitude 3.5 earthquake at 7:55 a.m. H.S.T. this morning, October 2. Additionally, over the past 24 hours, the Uēkahuna tiltmeter (UWD) recorded approximately 4.9 microradians of inflation. A helicopter overflight yesterday morning, after the end of intrusive activity, did not find evidence of new ground cracking or eruption of lava in a new location.

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:

Monitoring data indicate that a shallow intrusion occurred the afternoon of September 30 through to the morning of October 1 underneath Halemaʻumaʻu. The intrusion did not reactive in the past 24 hours, although conditions can change rapidly, including eruption from a new vent with little or no seismicity or deformation.

In the past 24 hours, there was no spattering or overflows at north or south vents. Forecast windows for a potential episode 55 can no longer be modeled due to the irregular changes in inflation and deflation. 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:

Eruptive activity since December 2024 has been occurring within a closed area of Hawai'i Volcanoes National Park. However, this week's intrusion highlights that the location of eruptive activity could change. Intrusions can also be hazardous with potential to cause earthquakes, ground cracks, and small landslides. The primary hazards at Kilauea due to eruptive activity and/or intrusions are:

• 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/ and https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf 
• Lava flows: Hawaiian lava flows generally advance slowly downslope but destroy everything in their paths. Lava flows that erupt within Halemaʻumaʻu crater remain confined to Halemaʻumaʻu and Kaluapele. Lava flows from the eruption that started in December 2024 have been confined to Halemaʻumaʻu, an area closed to the public. Hazards associated with active or recent lava flows include hot and glassy (sharp) surfaces that can cause serious burns, abrasions, and lacerations upon contact with unprotected or exposed skin; uneven and rough terrain can lead to falls and other injuries; hot temperatures that can cause heat exhaustion or dehydration, or in heavy rain can produce steamy ground-fog that can be acidic, severely limiting visibility and sometimes causing difficulty breathing.
• Earthquakes and ground cracks: Shallow magma movement and eruptions can produce minor to severe ground fractures and subsidence features. These ground cracks can continue to widen and offset as magma migration continues, may have unstable overhanging edges, and should be avoided. Other significant hazards exist around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes.

Additionally, 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 significant activity was detected at Ofu-Olosega volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the vicinity of the volcano. 

No significant activity was detected at Taʻū volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the vicinity of the volcano. A Global Positioning System (GPS) instrument on Taʻū Island recorded no significant deformation.

The FAGA broadband seismometer located on eastern Taʻū Island was serviced on September 5 (local time), restoring data transmission; the station is now operational.

The TAU1 GPS station has experienced intermittent data outages and HVO is evaluating the quality of transmitted data.

No significant activity was detected at Tutuila volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the vicinity of the volcano.

The broadband seismic station on Tutuila (ANDI) had a data outage between September 3 and September 9 (local time); the station is now operational. 

Mauna Loa had a decrease in seismic activity compared to the previous month; a total of 53 earthquakes were detected in Mauna Loa's summit region during the September reporting period, after 87 in August. Most earthquakes occurred deep beneath the upper Southwest Rift Zone or broadly scattered around the upper flanks. No earthquakes occurred directly beneath Mokuʻāweoweo.

Data from Global Positioning System (GPS) instruments on Mauna Loa showed slight inflation across the summit region in the past month. Oscillations between contraction and inflation patterns during non-eruptive periods are normal, but inflation has been the dominant trend since the 2022 eruption, consistent with magma refilling the summit reservoir system.

Gas and temperature data from a station on Mauna Loa's Southwest Rift Zone indicate these values are at background levels, with little change relative to previous months.

HVO continues to closely monitor Mauna Loa and will issue another update in one month, or earlier, should conditions change significantly.

No significant activity was detected at Hualālai volcano during the past month. Seismic activity remained low and was representative of background activity levels at the volcano. The continuously recording Global Positioning System (GPS) instrument on Hualālai has been offline since March 15, 2026; HVO field engineers will service the station within the next few months to bring it back online.

No significant activity was detected at Haleakalā volcano during the past month. The continuously recording Global Positioning System (GPS) instrument on Haleakalā had a data outage between July 13 and September 17. No significant deformation was recorded before or after the outage. The station is owned and operated by researchers at the Pacific GPS Facility (PGF), as part of the Hawaii Institute of Geophysics and Planetology (HIGP).

No significant activity was detected at Mauna Kea volcano during the past month. Seismic activity remained low and was representative of background activity levels at the volcano. The continuously recording Global Positioning System (GPS) instrument on Mauna Kea, operated by NASA's Jet Propulsion Laboratory, recorded no significant deformation in the past month.
 

No significant activity was detected at Kamaʻehuakanaloa volcano (formerly Lōʻihi Seamount) during the past month. Seismic activity remained low and was representative of background activity levels at the volcano.

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.