USGS Volcanoes: Notices released in the last day.

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. Clouds obscured views of the volcano in satellite and webcam images. Seismicity was mostly quiet over the past day.

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 webcams, and regional infrasound and lightning networks.

Shishaldin Volcano continues to experience unrest with numerous small earthquakes detected over the past day. Clear webcam images showed a steam plume rising from the summit crater. Overnight satellite images indicated very slightly elevated surface temperatures inside the crater as well.

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. 

Episode 40 of the ongoing Halemaʻumaʻu eruption ended abruptly at 6:04 p.m. HST on January 12 after 9.7 hours of continuous lava fountaining. Additional details on this eruptive episode will be provided in the next official report.

Short messages tracking the evolution of this episode and other eruptive activity can be found here: HVO - Observatory Messages | U.S. Geological Survey. 

• All eruptive activity was confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park
• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Three Kīlauea summit livestream videos are available here: https://www.youtube.com/@usgs/streams 
• Additional short updates shared during the episode can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages 

Activity Summary:

Episode 40 sustained lava fountaining at the summit of Kīlauea began at 8:22 a.m. HST on January 12. Sustained lava fountains erupting from the north vent are currently reaching heights of more than 660 feet (200 meters) and feeding a lava flow on the crater floor. Intermittent spatter continues from the south vent. Tephra is currently falling on the western and southern rim of Halema'uma'u crater. Volcanic gas emission rates increased significantly with the onset of sustained lava fountaining. The sulfur dioxide emission rate is typically 50,000-100,000 tonnes/day during an eruptive episode. The gas plume is currently rising straight up to heights over 13,000 feet (4,000 m) above ground level. Ground-level sensors near the eruptive vents indicate that winds are light at the summit, less than 5 mph (2 m/s), and variable in direction. This makes it difficult to predict how the eruption plume will spread during this episode, but it will probably remain closer to Halemaʻumaʻu and the summit. Kīlauea’s East Rift Zone and Southwest Rift Zone remain quiet. 

Short messages tracking the evolution of the fountains and eruptive activity can be found here: HVO - Observatory Messages | U.S. Geological Survey. 

Summit Observations:                                                                                                                        

Episode 40 sustained lava fountaining began at 8:22 a.m. HST on January 12 as indicated by strong deflation and increaseed tremor after north vent fountains increased dramatically in height and vigor at 8:13 a.m. Sustained fountaining was preceeded by several days of significant precursory activity that included cyclic spatter and dome fountains from both the north and south vents that fed large lava flows on the crater floor including a flow from the south vent that reached 3,300 feet (1,000 meters) in length.

North vent fountains are currently feeding lava flows on the floor of Halema'uma'u crater. At about 6:30 a.m. this morning, spattering in the north vent increased and began to feed an overflow from the vent. At about 7:00 a.m., the spattering transitioned to a continuous narrow and small fountain, likely caused by a restriction in the vent that resuled in a nozzle-effect that led an arcurate spatter fountain 15-30 feet (5-10 meters) high feeding a flow from the north vent. Sustained fountaining from the north vent began at 8:22 a.m. Fountain heights increased steadily and currently exceed 660 feet (200 meters) in height. Right now, the tephra fall out zone is observed to be on the western and southourn rim of Halema'uma'u crater.

Sustained lava fountains are not yet erupting from the south vent at the time of this update but intermittent lava spattering and small dome fountains continue. The south vent formed dome fountains feeding overflows from the vent at a rate of about one per hour over the past day, with about 30 overflows total feeding lava flows on the floor of Halemaʻumaʻu crater. 

UWD returned to inflation after 9 a.m. yesterday morning, with nearly a microradian of inflation since then, returning to 22.8 microradians. The Uēkahuna tiltmeter (UWD) had previously reached 23 microradians of re-inflation of Kīlauea's summit on Saturday January 10. This peak was followed by a brief deflationary period dropping to 22 microradians associated with the onset of precursory overflows from the north and south vents the night January 10.  The SMC tiltmeter mirrors the UWD tiltmeter, but SDH shows continued slight inflation, possibly influenced by the deeper south caldera magma chamber.

Volcanic gas emission rates increased significantly with the onset of sustained lava fountaining. The sulfur dioxide emission rate is typically 50,000-100,000 tonnes/day during an eruptive episode. The gas plume is currently rising straight up to heights over 13,000 feet (4,000 m) above ground level.

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 rapid rebound of inflationary tilt and presence of low-level volcanic tremor after episode 39 indicate that another lava fountaining episode is likely to occur. Continued overflows from both the north and south vents, as well as a return to summit region inflation over the past 24 hours suggest the onset of episode 40 could be close. Forecast models suggest the window for onset of episode 40 fountaining is now through January 17. Precursory activity could continue through then, with low dome fountains and spattering with the north and south vents feeding lava flows onto Halemaʻumaʻu crater floor. 

Kīlauea has been erupting episodically since December 23, 2024, primarily from two vents (north and south) in Halema‘uma‘u. Eruptive episodes, which generally last for less than 12 hours, are separated by pauses that can be as long as over two 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

Recap of Last Episode:

Episode 39 lava fountaining from the south vent stopped at approximately 2:13 a.m. HST on December 24 after 5.9 hours of sustained fountaining. The two vents within the north cone both stopped slightly earlier at 2:00 a.m. HST. Sustained fountaining began at 8:20 p.m. HST from the north and south vents after just under 2 hours of precursory overflows. Fountains rapidly grew to several hundred feet high and by 9:30 p.m. HST had reach maximum estimated heights of 1,400 feet (425 meters) for the south fountain and 900 feet for the north fountain. The main fountain from the north cone came from the "right hand" vent (as viewed from V1cam, which is pointed south), but a much smaller fountain, 100-200 feet (30–60 meters) high, began at about 8:45 p.m. HST and lasted until the north vent stopped fountaining. This "triple" fountain lasted through most of the eruption, with the south fountain highest followed by the "right hand" north vent (about 65–70% of the south fountain height) and the much smaller "left hand" north vent (about 10–20% of the south fountain height). The highest peak or instantaneous effusion rate of 960 cubic yards per second (800 cubic meters per second) occurred about 9:00 p.m. HST just before the south and north vents reached their maximum heights. Episode 39 ended with an average effusion rate of 250 cubic yards per second (190 cubic meters per second). An estimated 12 million cubic yards (9.3 million cubic meters) of lava erupted and covered about 50–60% of the floor of Halemaʻumaʻu crater. The Uēkahuna tiltmeter (UWD) recorded about 26.8 microradians of deflationary tilt during episode 39.

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. 

• 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 polution) 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, and reticulite—are created by the lava fountains. 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 and eye irritation. More information is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf. Close to the vents, the tephra material on the crater rim is prone to cracking, slumping, and small landslides that sometimes expose hot and molten material within. 
• Lava flows: on the floor of Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera, remain hot and may slowly move in the days immediately following an eruptive episode. 

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes. 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.

Episode 40 of lava fountaining in Halemaʻumaʻu began at the summit of Kīlauea began at 8:22 a.m. HST on January 12. 

Ground-level sensors near the eruptive vents indicate that winds are light at the summit, less than 5 mph (2 m/s), and variable in direction. This makes it difficult to predict how the eruption plume will spread during this episode, but it will probably remain closer to Halemaʻumaʻu and the summit. 

• All eruptive activity is confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: https://youtube.com/@usgs/streams 
• KPcam and MKcam provide views of the plume height for aviation purposes
• Additional short updates as the episode progresses will be posted here: https://www.usgs.gov/observatories/hvo/observatory-messages 
• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 

Most lava fountaining episodes since December 23, 2024, have continued for a day or less.