USGS Volcanoes: Notices released in the last day.

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.

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. Cloudy conditions obscured satellite and webcam observations. 

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 is paused. Summit inflation paused around 9 p.m. H.S.T. last night, with minor deflation starting around midnight and continuing. South vent had intermittent glow last night, while north vent had strong persistent glow which weakened starting around 3 a.m. H.S.T. this morning. These observations have pushed back the modeled forecast time window for episode 52 fountains to between July 26 and July 30.  

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 .South vent had intermittent glow overnight, while north vent had strong persistent glow which weakened starting around 3 a.m. H.S.T. this morning.

Tremor last night was punctuated by more frequent drops in intensity followed by spikes in tremor typical of gas pistoning. The tremor spikes correlate with periods of brighter glow and occasionally flames from the south vent, presumably due to drainback events. One earthquake was located beneath the summit of Kīlauea summit in the past 24 hours. 

Since episode 51 ended, inflation resumed and has recovered 12.0 microradians of tilt at the summit tiltmeter at Uēkahuna (UWD). After nearly two days of steady inflation, inflation paused around 9 p.m. H.S.T. last night, with deflation starting around midnight and continuing. Despite the deflation, in the last 24 hours UWD has recorded a net gain of 0.9 microradians. 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 last night (July 23), with minor deflation starting around midnight. As of this morning, inflation-based models have pushed the forecast window for the start of episode 52 fountains a day later to July 26 through July 30. 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.

Nothing was observed in satellite data at Ahyi Seamount this week. 

Eruptive activity at Ahyi Seamount may present a hazard to mariners in the water above and near the volcano. The summit has shallowed over the course of previous eruptions to 180 feet (55 m) below sea level, but the lack of local real-time data means we are unable to forecast or warn of impending eruptions. We will continue to monitor satellite and distal hydroacoustic data for additional evidence for, or escalation of, volcanic activity.