USGS Volcanoes: Notices released in the last day.

Slow eruption of lava within the summit crater continues with associated low level seismicity. No activity was observed in satellite images from the past day.  

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 earthquake activity continued over the past day. Web camera and satellite views of the volcano were obscured by clouds. 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 activity and infrasound detected during the past day. Sulfur dioxide emissions continue to be observed in satellite data and partially clear web camera views showed vigorous degassing from the summit. Satellite views were mostly cloudy.  

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. 

No significant activity was detected at Ofu-Olosega volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the vicinity of the volcano. 

No significant activity was detected at Taʻū volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the vicinity of the volcano. A Global Positioning System (GPS) instrument on Taʻū Island recorded no significant deformation.

The FAGA broadband seismometer located on eastern Taʻū Island is currently out of service. The TAU broadband seismometer on western Taʻū Island remains operational.

No significant activity was detected at Tutuila volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the vicinity of the volcano.

Mauna Loa had a decrease in seismic activity compared to the previous month; a total of 57 earthquakes were detected in Mauna Loa's summit region during the July reporting period, after 94 in June. Most earthquakes occurred deep beneath the upper Southwest Rift Zone or broadly scattered around the upper flanks. Very few earthquakes occurred directly beneath Mokuʻāweoweo.

Data from Global Positioning System (GPS) instruments on Mauna Loa showed slight inflation across the summit region in the past month. Most GPS stations at the summit recorded small upward vertical motions while shifting radially away from the caldera in the horizontal direction. Oscillations between contraction and inflation patterns during non-eruptive periods are normal, but inflation has been the dominant trend since the 2022 eruption, with magma refilling the summit reservoir system.

Gas and temperature data from a station on Mauna Loa's Southwest Rift Zone indicate these values are at background levels, with little change relative to previous months.

HVO continues to closely monitor Mauna Loa and will issue another update in one month, or earlier, should conditions change significantly.

No significant activity was detected at Hualālai volcano during the past month. Seismic activity remained low and was representative of background activity levels at the volcano. The continuously recording Global Positioning System (GPS) instrument on Hualālai has been offline since March 15, 2026; HVO field engineers will service the station within the next few months to bring it back online.

No significant activity was detected at Haleakalā volcano during the past month. HVO seismometers recorded one earthquake in the vicinity of the volcano. The continuously recording Global Positioning System (GPS) instrument on Haleakalā lost connection on July 13th. No significant deformation was recorded leading up to the outage. The station is owned and operated by researchers at the Pacific GPS Facility (PGF), as part of the Hawaii Institute of Geophysics and Planetology (HIGP), who will service the station within the next few months to bring it back online.

No significant activity was detected at Mauna Kea volcano during the past month. Seismic activity remained low and was representative of background activity levels at the volcano. The continuously recording Global Positioning System (GPS) instrument on Mauna Kea, operated by NASA's Jet Propulsion Laboratory, recorded no significant deformation in the past month.
 

No significant activity was detected at Kamaʻehuakanaloa volcano (formerly Lōʻihi Seamount) during the past month. Seismic activity remained low and was representative of background activity levels at the volcano.

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu is paused. Nearly continuous moderate to strong glow was observed from the north vent overnight. Intermittent, large flames produced from gas pistoning were observed overnight coming from the recently opened crack located upslope of the south vent, and once from the south vent. Summit tilt trended positively over the past day, indicating continued, steady inflation. Models indicate that the forecast window for episode 53 is likely between August 8 and August 12.

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

Moderate glow returned to the north vent overnight strengthening to strong glow early this morning.  The south vent continued to be dark except for a couple of short instances of weak glow and one period of flames. Periodic, large flames were observed from the crack system that opened up above the south vent last week.   

Large spikes punctuated the ongoing tremor signal overnight.  The spikes were irregularly spaced and associated with patterns indicative of gas pistoning in the south vent system (including the crack). They occurred 3-5 times per hour overnight and were associated with glow and frequently large flames from the crack about the south vent.   No earthquakes were detected beneath the summit region over the past day.

Since episode 52 ended, a summit tiltmeter at Uēkahuna (UWD) has recorded a total of 10.6 microradians of inflationary tilt and gained 1.3 microradians over the past day. Deflationary tilt measured at UWD totaled 14.4 microradians during episode 52. 

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. Winds are currently from the northeast, at ~16 mph, with potential gusts as high as 22 mph. Degassing plumes from the new crack and north and south vents are being blown to the southwest. 

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 52 along with glow from the vents indicates that episode 53 fountaining is likely. Inflationary tilt returned yesterday morning after just over a day of deflationary tilt trends. Current tilt-based models have a forecast window for episode 53 from August 8 through August 12. Adjustments could occur if there are changes in tilt trends.

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.

There were several clear satellite images of the ocean over Ahyi Seamount this past week, but there were no observations of underwater plumes. Distal geophysical monitoring showed no evidence of activity. 

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.

NORTHERN MARIANAS VOLCANOES
No signs of significant unrest were detected at any Northern Mariana Island volcanoes during the past week. 

Monitoring of Northern Mariana Islands Volcanoes

Northern Mariana Island volcanoes are monitored using seismo-acoustic sensors on Saipan, and by examining satellite imagery. We also use distant seismic stations in Guam and Chichijima, Japan, and hydroacoustic data from Wake Island, when available.

This level of monitoring can detect significant volcanic activity in the CNMI but cannot provide advanced warning of eruptions.

Due to a lack of geophysical monitoring on any of the volcanic islands, the following volcanoes have alert levels of UNASSIGNED: Anatahan, Sarigan, Farallon de Pajaros, Supply Reef, Maug, Asuncion, Agrigan, Pagan, Almagan, and Guguan.