USGS Volcanoes: Notices released in the last day.

Lava continues to erupt in the summit crater of Great Sitkin Volcano at a low rate. A few small earthquakes were recorded over the past day. No activity was observed in clear satellite views; webcams were obscured. 

The current lava eruption began in July 2021 and since then has 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 and web cameras, and regional infrasound and lightning networks.

Unrest continues at Shishaldin. Occasional small earthquakes and infrasound signals, possibly caused by gas bubbles bursting deep within the crater, occurred over the past day. No elevated surface temperatures or other signs of activity were observed in clear overnight satellite views. 

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 lighting data, and satellite images to detect eruptions. 

Mauna Loa seismicity rates returned to long term background levels in late November similar to seismicity rates during the prior months.  A total of 147 M3+ and smaller earthquakes were detected beneath Mauna Loa's summit region in the November reporting period, while the prior month had 123 earthquakes.  Modestly higher rates of seismicity were observed from late-October to early November with 8-16 earthquakes per day in earliest November. Recent seismicity is much lower than unrest prior to the 2022 eruption and has returned to 3-6 earthquakes per day.   

Data from Global Positioning System (GPS) instruments on Mauna Loa show a slight increase in inflation beneath the summit starting in mid-November.  These rates are normal as the volcano recovers from the 2022 eruption and magma replenishes the reservoir system.  Recent data indicate that the center of deformation has shifted to the southern caldera region, indicating refilling of a south caldera magma chamber.

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; all earthquakes were of small magnitudes (<M1+). The continuously recording Global Positioning System (GPS) instrument on Hualālai recorded no significant deformation in the past month.

No significant activity was detected at Haleakalā volcano during the past month. HVO seismometers recorded no earthquakes in the vicinity of the volcano. The continuously recording Global Positioning System (GPS) instrument on Haleakalā recorded no significant deformation in the past month.

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; all earthquakes were of small magnitudes (majority of events M1+ and smaller).

No significant activity was detected at Kamaʻehuakanaloa (formerly Lōʻihi Seamount) during the past month. Seismic activity remained low, and was representative of background activity levels at the volcano; all earthquakes were of small magnitudes (below M2+).

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.

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.

Activity Summary:

Summit inflation resumed mid-day yesterday and continued until 5 a.m. HST this morning.  A slight deflation of the summit is occurring now. Overall inflation of the summit, glow from the vents, and intermittent spattering indicate that another fountaining episode is likely.  Models suggest the onset of episode 38 fountains will occur between December 6 and 9, based on ground deformation models. 

Summit Observations:

Overnight moderate glow was observed with flames from both vents. Persistent low to moderate tremor continues which were punctuated by minor seismic tremor bursts suggestive of irregular gas pistoning at depth.  Weak spattering was intermittently observed in the south vent overnight in webcams. 

As of this morning, about 12.8 microradians of inflationary tilt have been recorded by UWD since the end of episode 37, with modest inflation recorded in the past day that ended at 5:00 a.m HST.  The summit is currently deflating slightly.

Gas emissions continue from the vent area, with a white outgassing plume rising above the crater this morning.  Sulfur dioxide (SO₂) gas emissions are typically between 1,200 and 1,500 tonnes per day during eruptive pauses between lava fountaining.  

Rift Zone Observations:

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

Analysis:

The recent inflationary tilt following the end of episode 37 along with glow, intermittent spatter, and tremor indicates that another eruptive episode is likely. Repeated periods of no inflation or slight deflations over the past 4 days have slowed the repressurization of the summit. Models indicate that episode 38 fountains are likely to begin between December 6 and 9, with December 7 and 8 most likely.  The forecast may continue to change if there are more episodes of deflation or periods of slow to no inflation. 

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

Recap of previous episode:

Episode 37 fountaining from the north vent stopped at approximately 11:39 p.m. HST on November 25. The south vent was not active during episode 37. Fountains from the north vent reached maximum heights of 500-600 ft (150-180 m). Fountaining lasted for 9.2 hours at an average rate of rate of about 250 cubic yards per second (190 cubic meters per second). Episode 37 produced an estimated 8.2 million cubic yards (6.3 million cubic meters) of lava and covered about 75% of the floor of Halemaʻumaʻu crater. The Uēkahuna tiltmeter (UWD) recorded about 16.5 microradians of deflationary tilt during episode 37.

The following notices provide more information about episode 37::

• VAN VONA End of Episode 37
• VAN VONA Start of Episode 37

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
• Three Kīlauea summit livestream videos 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. High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are one major hazard of concern, as this hazard can have far-reaching effects downwind. As SO₂ is continuously released from the summit during an eruption, it will react in the atmosphere to create the visible haze known as vog (volcanic smog) downwind of Kīlauea. SO₂ and vog may cause respiratory and other problems at high concentrations. Further information on vog can be found at https://vog.ivhhn.org/

Another major hazard is fallout of Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity that can be carried well over 10 miles (15 kilometers) from the vent. Other hot glassy volcanic fragments (tephra) including volcanic ash, pumice, scoria, and reticulite can fall on the ground within 1–3 miles (1–5 kilometers) of the eruptive vent(s), with the highest concentrations immediately downwind of the vent(s). Various volcanic fragments have fallen on Highway 11 west of Hawai'i Volcanoes National Park at times, depending on wind and eruption conditions. Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once on the ground, Pele's hair can sometimes cluster and tangle together, giving it the appearance of a tumbleweed. The extent of Pele's hair deposition is dependent on lava fountaining activity and wind conditions. Residents and visitors should minimize exposure to Pele's hair and other glassy volcanic fragments, which can cause skin and eye irritation and can also contaminate catchment water supplies. More information about how Pele's hair, its hazards, and what to do is available here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-recent-lava-fountains-highlight-peles-hair-hazards. A recently updated Frequently Asked Questions document that includes information about potential health effects of Pele's hair is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf

Hawaiian lava flows generally advance slowly downslope, and during this eruption flows have been confined to Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera.

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. 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 indications that minor unrest at Ahyi seamount continued over the past week. On November 30, slightly discolored water was seen a few hundred meters east of the seamount in high-resolution satellite images. This could be related to degassing from the active vent. Single detections from Ahyi's direction at underwater pressure sensors near Wake Island, located 1,410 miles east of Ahyi, were observed on November 29 and 30. 

There are no local monitoring stations near Ahyi seamount, which limits our ability to detect and characterize volcanic unrest there. We will continue to monitor satellite and distal hydroacoustic data for additional evidence for, or escalation of, volcanic activity.

NORTHERN MARIANAS VOLCANOES
No other signs of unrest were detected at 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, all volcanoes have alert levels of UNASSIGNED. This includes Ahyi, Anatahan, Sarigan, Farallon de Pajaros, Supply Reef, Maug, Asuncion, Agrigan, Pagan, Almagan, and Guguan.