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 camera 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. Minor steaming at the summit crater was observed in one clear webcam image 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. 

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu remains paused. Continuous weak glow and intermittent small flames were observed from only the north vent overnight. The south vent and new fissure remained dark. Approximately 2.5 microradians of deflationary tilt has been recorded since early Friday morning, 0.4 microradians in the past day. Current inflation models indicate that the forecast window for episode 53 has shifted to Wednesday-Saturday, August 12–15.

Earthquake activity has increased in the lower Southwest Rift Zone, including a swarm of 18 earthquakes recorded over the past 24 hours.

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

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 vent activity remained subdued, with persistent weak glow from the north vent and no glow from the south vent. Small spots of incandescence persisted near the northern end of the new crack, while intermittent small flames were observed from the north vent. No spatter was detected. Satellite measurements indicate that the crack, which first opened on July 30, has since enlarged and is currently approximately 65.6 feet (20 m) long from north–south by 32.8 feet (10 m) wide, east–west.

Intermittent, irregular gas pistoning continued over the past day, with larger tremor spikes generally spaced 30 minutes to 2 hours apart. Beginning around 7:00 p.m. HST yesterday, continuous tremor became the dominant seismic signal, although occasional gas piston spikes have continued through this morning. No earthquakes were detected beneath the summit region of Kīlauea over the past 24 hours, but a swarm of small

The Uēkahuna (UWD) tiltmeter continues to record gradual deflation, interrupted by brief periods of slight inflation lasting approximately 1–3 hours. Over the past day, UWD recorded a net loss of 0.4 microradians as of 7:00 a.m. HST. Cumulative inflation since the end of episode 52 is now 9.8 microradians, down from a maximum of 12.3 microradians reached Friday morning, for a total of approximately 2.5 microradians of deflation since then. Brief spikes in summit tilt signals at approximately 2:48 and 2:59 a.m. HST were likely associated with seismic waves from a distant M7.4 earthquake in Colombia at 2:34 a.m. HST.

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 around 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.

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 increased in the Southwest Rift Zone (SWRZ) with a localized swarm of 18 located earthquakes occurring between 4:00 and 6:20 a.m. HST. The earthquakes clustered in a relatively small area spanning approximately 3 square miles (8 square km) of the lower SWRZ past the Koʻae fault zone.  Quakes ranged from very shallow to depths of about 3.7 miles (6 km). The largest earthquake in the swarm was a magnitude of 2.3.

Analysis:

The abrupt switch from summit deflation to inflation at the end of episode 52 along with 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 morning and is continuing at this time. Deflations preceding the start of episodes 51 and 52 lasted for roughly 2-3 days. If the current trend follows a similar pattern, deflation may continue through today, before inflation resumes for another 1-2 days ahead of episode 53. This is consistent with current tilt-based models, which forecast the onset of episode 53 fountaining between August 12 and 15. 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.