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. Clouds obscured views of the volcano in satellite and webcam images most of the past day, but during brief clear periods, steam was observed rising from the summit crater.

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. 

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. Clouds obscured views of the volcano in satellite webcam images most of the past day, but during brief clear periods, steam was observed rising from the summit crater.

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. 

Activity Summary:

Lava overflowed nearly continuously from the north vent in Halemaʻumaʻu overnight, with continued pulses of dome fountaining and overflows from the south vent. Activity has decreased this morning to about one overflow per hour from the south vent and only spattering from the south vent.Kīlauea summit region showed deflation on tiltmeter UWD since about 4 p.m. yesterday. The prolonged precursory activity has extended the forecast window for the onset of episode 40 high foutaining from now to January 17. Kīlauea’s East Rift Zone and Southwest Rift Zone remain quiet.

A VAN/VONA notice will be issued at the onset of episode 40 sustained lava fountaining. Short messages tracking the evolution of the fountains and eruptive activity can be found here: HVO - Observatory Messages | U.S. Geological Survey. 

Summit Observations:

Nearly continuous overflows continued from the north vent most of yesterday and throughout most of last night. Intermittent dome fountains continued to form within the south vent over the past day and last night, feeding pulses of lava overflowing from the south vent several times an hour. Activity at the north vent decreased after 3 a.m. this morning, with lava only intermittently overflowing the vent. As of this morning, only spattering is visible within the north vent and large overflows from the south vent have slowed to about one per hour with the last overflow ending just before 9:10 a.m. HST.  Overflows from the south vent continue to feed an active lava flow that extends over 1500 feet (500 meters) across the floor of Halemaʻumaʻu crater.

Since the end of episode 39, the Uēkahuna tiltmeter (UWD) has recorded 23 microradians of re-inflation beneath Kīlauea summit; however, UWD showed nearly a microradian of deflation to 22 microradians since about 4 p.m. yesterday associated with the overflows from the north and south vents last night. 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 have dropped significantly since the end of episode 39 but probably remain in the range of 1,000 to 5,000 tonnes of sulfur dioxide (SO₂) per day, as typically observed during previous eruptive pauses.  Winds are light out of the north (less than 10 mph or 2 m/sec) and are forecast to become more southerly in the afternoon. The plume is moving to the south-southwest of Halema'uma'u. 

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.  Nearly continuous overflows of the north vent overnight coupled with overflows from both vents this morning suggested the onset of episode 40 could be close; however, slow deflation of the summit region since 4 p.m. yesterday, along with decreased activity at the vents since this morning suggest that the onset of episode 40 fountaining could be delayed as a result of the prolonged precursory eruptive activity over the past several days. Forecast models suggest the window for onset of episode 40 fountaining has been extended from 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.