USGS Volcanoes: Notices released in the last day.

Slow eruption of lava within the summit crater continues. Minor earthquakes were detected over the past day, likely associated with rockfall on the growing dome. 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.

Low-level earthquake activity continued over the past day. No activity was observed in cloudy satellite and webcam images. Sulfur dioxide emissions were detected in satellite data.

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.

Unrest continues with minor seismic and infrasound activity detected during the past day. Sulfur dioxide emissions were observed in satellite data. Steaming at the summit crater was observed in webcam and satellite views, and a steam plume was reported by numerous passing aircraft 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. 

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 03 (0000h PDT) to August 09 (2359h PDT):

One earthquake greater than M1 was recorded within the Clear Lake Volcanic Field, with a magnitude of M1.3.

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 69 earthquakes greater than M1 were recorded, with the largest having a magnitude of M2.7.

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 M1.5.

Five earthquakes greater than M1 were recorded in the Coso Volcanic Field, with the largest having a magnitude of M1.6.

One earthquake greater than M1 was recorded near the Salton Buttes, with a magnitude of M2.1.


 

HAWAIIAN VOLCANO OBSERVATORY INFORMATION STATEMENT

On Tuesday, August 11, 5:48 p.m. HST, a magnitude-5.2 earthquake occurred beneath Kamaʻehuakanaloa volcano 26 mi (42 km) east-southeast offshore of Nāʻālehu on the Island of Hawaiʻi at a depth of 7 mi (11 km) below sea level.  

The magnitude-5.2 earthquake is part of an ongoing sequence of earthquakes associated with unrest of Kamaʻehuakanaloa (formerly Lōʻihi) Seamount that started on Sunday, August 9. These earthquakes have no apparent impact on either Mauna Loa or Kīlauea volcanoes. 

The USGS Hawaiian Volcano Observatory continues to monitor Hawaiian volcanoes for any changes. 

EARTHQUAKE DESCRIPTION 

• Magnitude: 5.2 
• Date and Time: August 11, 2026, at 5:48 p.m. HST 
• Location: 26 mi (42 km) ESE of Nāʻālehu 
• Depth: 7 mi (11 km) below sea level 
• Aftershocks are possible in the coming days to weeks 

EARTHQUAKE INTENSITY AND AFFECTED AREA 

• Potential Damage: No damage to buildings or infrastructure expected based on earthquake intensity 
• Maximum Intensity, Modified Mercalli Scale (https://www.usgs.gov/natural-hazards/earthquake-hazards/science/modified-mercalli-intensity-scale)  
• Community-reported: IV - light shaking 
• Instrument-derived: IV - light shaking 
• Felt Reports: More than 48 within the first hour (http://earthquake.usgs.gov/dyfi/) 
• Felt Area: Mostly across the southern and eastern parts of the Island of Hawaiʻi 
• Visit NOAA’s Tsunami Warning Center website for updated information: https://www.tsunami.gov/ 

EARTHQUAKE MAPS AND ADDITIONAL INFORMATION 

• USGS National Earthquake Information Center Maps and Reports for this Event: https://earthquake.usgs.gov/earthquakes/eventpage/hv75018296 
• USGS-HVO Interactive Earthquake Map of Hawaiʻi: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/earthquakes 

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu remains paused. Continuous weak to moderate glow and intermittent small flames were observed from the north vent overnight while the south vent remained dark. After recording 2.5 microradians of deflationary tilt since early Friday morning, the Uēkahuna (UWD) tiltmeter leveled out around midnight last night. Current inflation models indicate that the forecast window for episode 53 has shifted to August 13–17.

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

A summary of episode 52 is posted below.

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

Summit Observations:

Overnight, continuous weak to moderate glow and frequent flames were observed from the north vent, while the south vent remained dark. Rare, weak glow was visible from the new fissure, along with persistent spots of incandescence near its northern end.

Continuous tremor remained the dominant seismic signal over the past day, with a few small gas piston-related spikes between approximately 2:00 and 4:30 p.m. HST yesterday. One very small (less than M1.0) earthquake was detected near the center of Halemaʻumaʻu crater over the past 24 hours. Summit seismometers detected a series of offshore earthquakes around 3:30 a.m. HST near Kamaʻehuakanaloa, all smaller than M3.2. 

The Uēkahuna (UWD) tiltmeter recorded variable tilt over the past day, with little net change overall. Steady, slow deflation ended around noon yesterday and was followed by periods of slight inflation and deflation that are continuing this morning. Cumulative inflationary tilt since the end of episode 52 was 10.0 microradians as of 6:30 a.m. HST this morning. A total 14.4 microradians of deflationary tilt was recorded during episode 52.

Summit sulfur dioxide (SO₂) emission rates are likely varying within the typical range of 1,000–5,000 tonnes per day. Winds are currently from the east at 8–14 mph, with gusts potentially reaching 18 mph. Degassing plumes from the north vent and new fissure, with minor contributions from the south vent, are being carried west-southwest. A weather system that is approaching the islands from the southeast may impact tephra dispersal with wind and rain if it overlaps with episode 53 fountains.

Rift Zone Observations:

Rates of seismicity and ground deformation remain low in the East Rift Zone. SO₂ emissions from the East Rift Zone remain below the detection limit.

Seismicity has returned to normal in the Southwest Rift Zone after a swarm of 18 small earthquakes were recorded yesterday morning between 4:00 - 6:20 a.m. HST.

Analysis:

The abrupt switch from summit deflation to inflation at the end of episode 52, along with continued glow from the vents, indicates that episode 53 fountaining is likely. Inflationary tilt since the end of episode 52 was interrupted by deflation from August 2 to 3. A second deflationary step began at 6:00 a.m. HST Friday and continued through late Monday. Deflations preceding episodes 51 and 52 lasted roughly 2–3 days. The current tilt pattern has followed a similar progression, although at a slightly slower rate. Deflation stopped around noon yesterday and and UWD tilt is currently alternating between weak inflation and weak deflation. The combination of prior deflations and tilt-based models have been used to forecast the onset of episode 53 fountaining between Thursday, August 13 and Monday, August 17. The forecast window may be adjusted if summit tilt patterns change significantly.

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 52:

A detailed account of episode 52 is given in the HVO Status Report issued on July 29: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-29T13:10:51+00:00

• Episode 52 of the ongoing Halemaʻumaʻu eruption began around 7:10 p.m. HST on July 28 and ended abruptly at 2:36 a.m. HST on July 29, 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 emit flames at the end of the eruption. 
• The maximum plume height was approximately 19,000 (5,800 meters) above mean sea level. 

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