USGS Volcanoes: Notices released in the last day.

Slow eruption of lava within the summit crater continues. Slightly elevated surface temperatures and minor earthquakes were detected over the past day. No activity was observed in cloudy satellite and webcam images 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.

Unrest continues with minor seismic activity detected during the past day. No activity observed in partly cloudy satellite and web camera views over the past day. 

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. No activity was observed in cloudy satellite and web camera views of 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 17 (0000h PDT) to August 23 (2359h PDT):

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 78 earthquakes greater than M1 were recorded, with the largest having a magnitude of M2.3.

Three 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.

67 earthquakes greater than M1 were recorded in the Coso Volcanic Field, with the largest having a magnitude of M4.0. This week's earthquakes occurred as part of a tightly clustered swarm approximately 10 km ENE of Coso Junction, CA. Over 200 small, shallow (~2-3 km below sea level) earthquakes have been located in this area since August 20, most with magnitudes below M1.0. The largest earthquake (M4.0) occurred on Sunday, August 23, on a strike-slip regional fault. There is currently no evidence to suggest a magmatic origin to these earthquakes. CalVO scientists continue to monitor the area for further activity.
 

Overview:

Kīlauea volcano is erupting precursory overflows this morning from the north vent, following its typical pattern before lava fountaining episodes.  Summit inflation continued until about 6:00 a.m. HST when it leveled out, with deflationary tilt starting around 9 a.m. Episode 54 lava fountaining is expected to start today, if activity follows the pattern of previous episodes. 

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

A summary of episode 53 that ended August 13 is posted below.

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

Summit Observations:

Weak spattering was observed overnight from the north vent, with nearly continuous spattering occurring after midnight.  The first precursory overflow and small dome fountain occurred from 6:16 to 6:37 a.m. Several subsequent precursory overflows have occurred since that time. 

Continuous low-level seismic tremor occurred over much of the past day, switching to episodic tremor overnight. These spikes in tremor are normally associated with gas pistoning, and tremor fluctuations have occurred with the overflows this morning.  There was one earthquake recorded in the summit area in the past 24 hours. 

The Uēkahuna tiltmeter (UWD) showed continuing rapid tilt over the past day until about 6:00 a.m. HST when it flattened out.  Tilt is currently deflating.  UWD has recorded about 15.4 microradians of inflation since the end of episode 53 exceeding the 13.9 microradians of deflationary tilt measured by UWD during episode 53.

During inter-episode pauses, the sulfur dioxide (SO₂) emission rate from the summit typically varies between 1,000 to 5,000 tonnes per day. Winds are currently from the northeast blowing the gas plume to the southwest. Forecasts suggest that these conditions will hold throughout the day at both higher and lower altitudes.

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 precursory overflows and inflation well in excess of episode 53 deflation indicate that episode 54 lava fountaining onset is likely today, if the activity follows the pattern of previous episodes.

Kīlauea has been erupting episodically since December 23, 2024, from two vents (north and south) in Halema‘uma‘u. A collapse pit in the slope behind the south vent formed a new west vent during episode 53. 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 53:

A detailed account of episode 53 is given in the HVO Status Report issued on August 13: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-08-13T11:52:10+00:00

• Episode 53 of the ongoing Halemaʻumaʻu eruption began around 3:45 p.m. HST on August 12 and ended abruptly at 1:23 a.m. HST on August 13, 2026.
• The maximum lava fountain height was approximately 500 feet (150 meters) above ground level from the north vent. The south vent never fountained during this episode but did produce overflows prior to the fountaining episode. A new west vent produced precursory overflows and emitted intermittent flames through most of the eruption. 
• The maximum plume height was approximately 18,000 (5,500 meters) above mean sea level. 

• Tephra fall was restricted mostly to the closed area of Hawaiʻi Volcanoes National Park, southwest of the active Halemaʻumaʻu vents.  

   

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.

Precursory low-level activity for episode 54 of the ongoing Halemaʻumaʻu eruption at the summit of Kīlauea began around 6:16 a.m. HST on August 25 with overflows from the north vent that are continuing at this time. This activity was preceded by the onset of weak spattering from the north vent around 7:30 p.m. HST yesterday evening, August 24.  This was marked by the onset of strong, rhythmic gas pistoning spikes in tremor recorded every 5-10 minutes. Glow from the vents continued to increase until after midnight, spattering from the north vent become nearly continuous. Bright glow and flames from the west vent correlate with the tremor spikes and appear to be related to the drainback cycle of gas pistoning.  

Accordingly, HVO is raising the Alert Level for Kīlauea from ADVISORY to WATCH and the Aviation Color Code from YELLOW to ORANGE. Alert level and aviation color code definitions: https://www.usgs.gov/programs/VHP/alert-level-system. 

This low-level precursory activity can continue for hours to days before the lava fountaining episode beings. Inflationary tilt on the UWD tiltmeter continues and has exceed the deflation recorded during episode 53 by over one microradian. The forecast for episode 54 of lava fountaining to start is between August 25-26, with the onset most likely in the next 12 hours. Another VAN will be published when lava fountaining episode 54 begins.

• 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 Pele's Hair may stay suspended for large distances from the vents.
• Support science and community awareness by reporting tephra fall: https://hawaiiash.science/report_form 
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: https://youtube.com/@usgs/streams 
• KPcam and MKcam provide views of the plume height for aviation purposes
• Additional short updates as the episode progresses will be posted here: https://www.usgs.gov/observatories/hvo/observatory-messages 
• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 

Most lava fountaining episodes since December 23, 2024, have continued for a day or less.