USGS Volcanoes: Notices released in the last day.

Strong northwesterly winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes have picked up loose volcanic ash erupted during the 1912 Novarupta-Katmai eruption and are carrying it to the southeast. The National Weather Service has issued a SIGMET (https://www.weather.gov/aawu/sigmets) for this low-level event and suggests that the maximum cloud height is 6,000 ft (1.8 km) above sea level.

This phenomenon is not the result of recent volcanic activity and occurs during times of high winds and dry snow-free conditions in the Katmai area and other young volcanic areas of Alaska. No eruption is in progress. All of the volcanoes of the Katmai area (Griggs, Katmai, Novarupta, Mageik, Martin, Snowy and Trident) remain at Aviation Color Code GREEN and Alert Level NORMAL. Resuspended volcanic ash should be considered hazardous and could be damaging to aircraft and health.

For more information on volcanic ash and human health, visit the following website: http://volcanoes.usgs.gov/ash/

Official warnings about these ash resuspension events are issued by the National Weather Service: https://www.weather.gov/afc/

Forecasts of airborne ash hazard to aircraft: https://www.weather.gov/aawu/. Volcanic Ash Advisories: https://www.weather.gov/vaac/

Forecasts of ashfall: http://www.weather.gov/afc

Air quality hazards and guidance from Alaska Department of Environmental Conservation, Division of Air Quality: http://dec.alaska.gov/Applications/Air/airtoolsweb/Advisories/Index

Lava continues to erupt slowly within the summit crater at Great Sitkin Volcano. Weakly elevated surface temperatures were observed a few times this week during breaks in the cloud cover. Otherwise, most views of the lava dome were obscured by clouds. Seismicity has been low, with occasional small earthquakes and rockfalls detected in seismic data.  Overall, the rate of lava effusion is declining gradually. 

The current lava eruption began in July 2021 and 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. 

This week, signs of volcanic unrest at Shishaldin continued to be observed. Daily web-camera images showed steaming from the summit crater. Additionally, satellite images captured a diffuse vapor plume on several occasions. There has been ongoing low-level seismic activity, with frequent small earthquakes occurring each day. Infrasound signals, likely caused by gas bubbles bursting through magma deep within the volcanic vent, were also detected throughout the week. However, satellite data revealed no signs of elevated temperatures or other changes within the summit crater, indicating that there is no lava present at or near the surface.

Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to monitor the volcano.  

Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal background activity levels. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon.

Past Week Observations: During the past week, a few small earthquakes were detected at Mount St. Helens. All monitoring data are consistent with background activity levels in the Cascade Range. A field crew performed maintenance and repair work at a site near Crater Lake.

Activity Summary:

The ongoing summit eruption at Kīlauea is paused. Moderate glow continued overnight in the vents. The onset of episode 39 is likely to occur between December 21 and 27.

Summit Observations:

Glow continued overnight from both vents.  Sustained tremor punctuated by gas pistoning at irregular intervals continues this morning.

Since the end of episode 38, Kīlauea has inflated 13.9 microradians as recorded on the UWD tiltmeter this morning with an increase of 1.9 microradians over yesterday.

Volcanic gas emissions have greatly decreased with the end of the eruption and are back in the normal range of 1200 to 1500 tonnes per day of SO₂.

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, continued tremor, and moderate glow from both vents overnight all indicate another fountaining episode is likely. The onset of episode 39 is likely to occur between December 21 and 27. The forecast interval may become tighter as more data becomes available.

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

Episode 38 fountaining from the south vent stopped at approximately 8:52 p.m. HST on December 6 after 12.1 hours of sustained fountaining. The two vents within the north cone both stopped much earlier at 11:50 a.m. HST.  Sustained fountaining began at 8:45 a.m. HST from the two vents in the north cone after about 5 hours of precursory overflows.  The south vent fountain began at 8:49 a.m. HST and within 10-20 minutes all three fountains were about 500 (150 m) high creating a rare triple fountain.  By 9:40 a.m. HST the south vent fountain grew to about twice as high as the north vent fountains. The highest peak or instantaneous effusion rate of 1,300 cubic yards per second (1,000 cubic meters per second) occurred just before 10 a.m. when the south vent exploded. The enlarged south vent produced an inclined fountain over 1,000 feet (300 meters) tall that sprayed the south wall of Halemaʻumaʻu crater. Hot pumice and molten spatter from this fountain destroyed the HVO "V3" streaming camera site. The south fountain gradually dropped in height throughout the afternoon to about 500 feet (150 meters) high along with declining effusion rates. Episode 38 ended with an average effusion rate of 250 cubic yards per second (190 cubic meters per second). An estimated 16.5 million cubic yards (12.6 million cubic meters) of lava erupted and covered about 50-60% of the floor of Halemaʻumaʻu crater. The Uēkahuna tiltmeter (UWD) recorded about 33.1 microradians of deflationary tilt during episode 38.

The following notices from December 6 provide more information about episode 38:

• Volcano Activity Notice for End of Eruption (9:08 PM HST)
• Status Report on Fountain Height and Loss of V3 camera (10:41 AM HST)
• Volcano Activity Notice for Start of Eruption (8:48 AM HST)
• Kīlauea Update for December 6 (8:25 AM HST)

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
• Two 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.