USGS Volcanoes: Notices released in the last day.

Minor earthquakes were detected over the past day. Satellite and webcam images obscured by clouds.

The current eruption began in July 2021 and, 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 seismicity continuing. Clouds obscured satellite images, nothing was observed.

While a new temporary monitoring station was installed in the last week near Mount Kupreanof, data are not yet available in real-time. The closest functioning seismometers 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.

Minor seismicity and infrasound were detected at the volcano over the past day. Nothing observed in satellite and webcam views of the volcano over the past day. SO2 emissions detected in TROPOMI data. The gas plume is drifiting southeast from the volcano. 

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. 

Strong northwesterly winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes have picked up loose volcanic ash erupted during the 1912 Novarupta-Katmai eruption and are carrying it to the southeast. The National Weather Service has issued a SIGMET for this low-level event and suggests that the maximum cloud height is 6,000 ft (1.8 km) above sea level.

This phenomenon is not the result of recent volcanic activity and occurs during times of high winds and dry snow-free conditions in the Katmai area and other young volcanic areas of Alaska. No eruption is in progress. All of the volcanoes of the Katmai area (Griggs, Katmai, Novarupta, Mageik, Martin, Snowy and Trident) remain at Aviation Color Code GREEN and Alert Level NORMAL. Resuspended volcanic ash should be considered hazardous and could be damaging to aircraft and health.

For more information on volcanic ash and human health, visit the following website: http://volcanoes.usgs.gov/ash/

Official warnings about these ash resuspension events are issued by the National Weather Service: https://www.weather.gov/afc/

Forecasts of airborne ash hazard to aircraft: https://www.weather.gov/aawu/. Volcanic Ash Advisories: https://www.weather.gov/vaac/

Forecasts of ashfall: http://www.weather.gov/afc

Air quality hazards and guidance from Alaska Department of Environmental Conservation, Division of Air Quality: http://dec.alaska.gov/Applications/Air/airtoolsweb/Advisories/Index

Lava continues to erupt slowly within the summit crater. Slightly elevated surface temperatures were consistently recorded throughout the week when cloud cover did not obscure the volcano. Satellite radar imagery confirmed that the lava dome is gradually expanding toward the east-southeast. Seismic activity remains low, with only occasional small volcanic earthquakes and seismic signals associated with minor rockfalls detected.

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.

Low-level seismic activity persists near Mount Kupreanof volcano, with only one earthquake exceeding magnitude 2 recorded during the past week. Persistent cloud cover obscured the volcano, and no notable activity was detected in satellite observations.

There is no real-time geophysical monitoring network at Mount Kupreanof. The closest functioning seismometer is approximately 10 miles (16 km) to the northeast of the volcano as part of the Mount Veniaminof network. However, last week field teams installed a temporary monitoring station near the volcano with seismic, infrasound, gas monitoring, and a webcam. Mount Kupreanof is also monitored by satellite data, regional infrasound and lightning networks, and visual observations from pilots and mariners passing by the volcano. 

Seismic and infrasound activity remain elevated, characterized by numerous small earthquakes, persistent tremor, and frequent infrasound signals generated by small explosions within the volcanic conduit. Although the volcano was obscured by clouds throughout the week, sulfur dioxide emissions were detected on most days.

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.

Activity Update: All volcanoes in the Cascade Range of Oregon and Washington 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: During the past week, small earthquakes were detected at Mount St. Helens and Mount Rainier. All monitoring data are consistent with background activity levels in the Cascade Range. On the evening of July 22, sensors recorded a minor debris flow in the Kautz Creek at Mount Rainier. We infer that the debris flow was likely initiated due to a passing thunderstorm and that it is unlikely that it reached the Nisqually River. Field crews conducted station maintenance at Mount Baker and Mount Rainier.

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu is paused. Degassing continues at both north and south vents, and both vents had persistent glow overnight. Summit deflation continues, having started nearly a day and a half ago. These observations have pushed back the modeled forecast time window for episode 52 fountains to between July 27 and July 31.  

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

A summary of episode 51 is posted below.

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

Summit Observations:

Degassing continues from both north and south vents, and both vents had persistent glow overnight.

Tremor remains relatively continuous with occasional tremor bursts associated with flames from the south vent. One earthquake was located beneath the summit of Kīlauea summit in the past 24 hours. 

Since episode 51 ended, inflation resumed and has recovered 11.3 microradians of tilt at the summit tiltmeter at Uēkahuna (UWD). Around midnight the night of July 23 to 24, summit tiltmeters started recording minor deflation. Over the past 24 hours, UWD has recorded a net loss of 0.9 microradians during this period. Kīlauea summit deflation totaled 14.7 microradians during episode 51.

The sulfur dioxide (SO₂) emission rate from the summit is likely now varying within a typical range of 1,000 to 5,000 tonnes per day. Degassing plumes from both vents are being blown toward the southwest 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 episode 51 along with continued glow from the vents indicates that another fountaining episode is likely. Inflation since the end of episode 51 was relatively smooth without significant deflations until very early on Tuesday, July 21, when inflation paused and was flat for over a day. Inflation resumed Wednesday July 22 in the morning, and then paused two nights ago (July 23), with minor deflation starting around midnight that night. This deflation has continued over the past day. As of this morning, inflation-based models have the forecast window for the start of episode 52 fountains to July 27 through July 31. Future periods of slow inflation or deflation may cause the forecast window to be adjusted.

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 51:

A detailed account of episode 51 is given in the HVO Status Report issued on July 15: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-16T03:55:25+00:00

• Episode 51 of the ongoing Halemaʻumaʻu eruption began around 8:30 a.m. HST on July 15 and ended abruptly at 4:46 p.m. HST on July 15, 2026.
• The maximum lava fountain height was approximately 950 feet (290 meters) above ground level from the north vent. The south vent never fountained during this episode but did emit flames and gas jets.
• 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 to the southwest of the active Halemaʻumaʻu vents. A light fall of Peleʻs hair was reported at several sites in the national park outside the closed area, including Uēkahuna overlook and Kaʻu Desert trailhead on Highway 11.

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.