USGS Volcanoes: Notices released in the last day.

 Lava continues to erupt slowly within the summit crater. Minor earthquakes were detected in the past day. Due to cloud cover, no activity was observed in satellite or web cam 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.

Unrest continues, with minor seismic activity detected in the past day. Cloudy weather obscured satellite views, but occasional clear webcam views show weak steaming from the summit.

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. 

Low-level earthquake activity continues. Cloudy weather obscured satellite views. Occasionally clear webcam views show no steaming from the volcano.

A new temporary monitoring station was installed recently near Mount Kupreanof and is providing seismic data, infrasound data, gas measurements, and web camera images on an intermittent basis. This is by design to conserve battery power, but the frequency of data acquisition can be increased if activity warrants. The closest functioning seismometers that provide continuous data are approximately 10 miles (16 km) to the northeast 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.

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 August 24 (0000h PDT) to August 30 (2359h PDT):

One earthquake greater than M1 was recorded within the Clear Lake Volcanic Field, with a magnitude of M2.2.

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 59 earthquakes greater than M1 were recorded, with the largest having a magnitude of M2.4.

Sixteen 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 M2.9.

39 earthquakes greater than M1 were recorded in the Coso Volcanic Field, with the largest having a magnitude of M2.7. The swarm of earthquakes that began in the Coso Volcanic Field on August 20 continued this week, but at a reduced rate. There is currently no evidence to suggest a magmatic origin to these earthquakes, and CalVO scientists continue to monitor the area for further activity.

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu is paused. A few very brief instances of glow were observed overnight at the north vent. Summit reinflation has been very irregular since lava fountaining episode 54 on August 25, and it slowed again over the past day. Another fountain episode may occur in the coming weeks if normal patterns of reinflation resume. Due to continuing irregular behavior, more data are needed to model the forecast window for the next episode.

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

Summit Observations:

Overnight webcam views showed several brief instances of glow at the Halema’uma’u north vent mostly between 10:00 p.m. and 1:00 a.m. HST.. Release and combustion of volcanic gas (likely hydrogen) appears to be occurring deep within the vent, in association with larger tremor bursts observed in seismic data streams. Little or no glow appears to be derived from incandescent magma, suggesting it is relatively deep and possibly crusted over between gas release bursts.

Low-frequency seismic tremor bursts—which began after the conclusion of lava fountaining episode 54—continued over the past day with more regularity and slightly increased strength. As discussed above, the larger bursts are related to flames at the north vent, probably representing gas release deep within the vent. No shallow earthquakes have been recorded beneath the summit region over the past 24 hours.

Summit reinflation has been very unsteady since lava fountaining episode 54 on August 25, and it began slowing again around 2:00 a.m. HST yesterday. The summit then deflated slightly between about 7:00 a.m. and 12:00 p.m. HST, but tilt has been mostly flat since then. As of this update, the Uēkahuna (UWD) tiltmeter has measured a total of 3.5 microradians of inflation relative to the end of lava fountaining episode 54; this value is very low for being almost a week removed from the episode. Deflationary tilt on UWD totaled 12.7 microradians 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. Strong trade winds are pushing the degassing plume to the southwest over the Kaʻū Desert this morning.

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 and continued seismic tremor bursts from the Halema’uma’u eruptive vents indicate that another lava fountaining episode may occur in the coming weeks. Reinflation has been slow and irregular, having been interrupted by multiple deflations of varying magnitude and duration. Coupled with minimal vent glow, these observations suggest that magma is relatively deep in the vent conduits at this time. HVO will provide a forecast for the next lava fountaining episode once the reinflation pattern stabilizes and there is enough tilt data to model the activity.

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.

Yellowstone Caldera activity remains at background levels, with 61 located earthquakes in August (largest = M2.0). Deformation measurements indicate no significant uplift of the north caldera rim since January 2026 and only minor uplift of the caldera since the beginning of the year.

Recent Work and News

August field work included studies of hydrothermal explosion craters and glacial geology, as well as continued upgrades to the Yellowstone Seismic Network.  In September, YVO hopes to bring a new seismic and infrasound station fully online in Upper Geyser Basin.  The station is designed to record hydrothermal activity in the region, especially in the vicinity of Geyser Hill.

Black Diamond Pool, in Biscuit Basin, had a few small eruptions in early to mid August.  Monitoring data suggest there was also one large eruption that probably threw water and mud tens of feet (many meters) into the air, but it occurred at about 10 PM on August 13, and no visual observations from nearby cameras were possible.  Water temperature data indicate no clear eruptions and only two overflow events on August 22 at Echinus Geyser, in Norris Geyser Basin, and nearby Steamboat Geyser had only minor eruptive activity during the month.  Giant Geyser, in Upper Geyser Basin, erupted on August 17 and 30—its second and third eruptions of the year.

Seismicity

During August 2026, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, located 61 earthquakes in the Yellowstone National Park region. The largest event of the month was a micro earthquake of magnitude 2.0 located about 22 miles east-northeast of Canyon Village in Yellowstone National Park on August 5 at 4:05 p.m. MDT.

There were no swarms identified during August.

Earthquake activity in Yellowstone is at background levels.

Ground Deformation

Data from continuous GPS stations indicate that the uplift that started in July 2025 on the north caldera rim ceased by mid-January 2026 and has not resumed.  Subtle uplift of the caldera itself amounted to about 1 cm or less (a fraction of an inch) over the course of the past few months, possibly due to seasonal variations associated with groundwater conditions.

An example of GPS data can be found at http://www.unavco.org/instrumentation/networks/status/pbo/data/NRWY (click on Static Plots / Cleaned)