USGS Volcanoes: Notices released in the last day.

Lava continues to slowly erupt within the summit crater at Great Sitkin Volcano. Satellite radar data from February 17 showed continued slow growth of the lava dome near the vent regions. Elevated surface temperatures consistent with erupting lava at the summit were observed in satellite imagery when weather conditions were clear.  Seismic activity remains low, with occasional small volcanic earthquakes detected as well as seismic signals from small rockfalls within the crater.

The current lava eruption began in July 2021 and has filled most of the summit crater and advanced into the 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. 

Signs of volcanic unrest at Shishaldin Volcano continued this week. Low-level seismic activity, including frequent small volcanic earthquakes and volcanic tremor, was detected throughout the week. Infrasound signals were mostly obscured by high winds. Minor steaming was consistently observed in webcam views throughout the week and sulfur dioxide emissions were seen in satellite data on Friday morning.  

Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, the Alaska Volcano Observatory uses nearby geophysical networks, regional infrasound and lightning data, and satellite data 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, small earthquakes were detected at Mount St. Helens, Mount Rainier, and Mount Hood. All monitoring data are consistent with background activity levels in the Cascade Range.

Activity Summary:

The Halemaʻumaʻu eruption of Kīlauea is paused. Episode 42 ended February 15 at 11:38 p.m. HST. Tilt at summit instruments have resumed inflation over the past 24 hours. Preliminary models suggest the likely forecast window for the onset of episode 43 lava fountaining is March 5-15.

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

A recap of episode 42 can be found in this Status Report.

Significant changes in activity between Daily Updates are posted here: https://www.usgs.gov/observatories/hvo/observatory-messages

Summit Observations:

Weak glow from both vents was visible through the night. At the time of this report, both vents are quiet and emitting robust degassing plumes. Seismic tremor continues during the current pause. There were no earthquakes located across the summit region during the past day.

The UWD tiltmeter has recorded a total recovery of nearly 11.3 microradians of inflationary tilt since the end of episode 42, with 2.7 microradians of that over the past 24 hours.

Plume geometry and weather prevented measurements of sulfur dioxide (SO₂) emission rate during episode 42's fountaining, but the emissions were likely in the range of 100,000 t/d, similar to during previous episodes. During pauses, like the current conditions, the SO₂ emission rate from the summit has varied within a typical range of 1,000 to 5,000 tonnes of SO₂ per day. This morning, webcams show that the plume from the summit vents is being carried to the southwest.
 

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 tilt and glow from both vents indicate that another fountaining episode is likely. Preliminary models suggest the forecast window for the start of episode 43 is likely between March 5 and March 15.  Additional data are needed to narrow the forecast window.

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 episode 41:

A recap of episode 42 can be found in this Status Report.

Resources:

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 fountains and eruptive activity can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages 
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: https://www.youtube.com/@usgs/streams
• Note: The V3 camera is experiencing data issues and we have ordered a new camera to replace it following episode 42.
• 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 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.

No signs of significant unrest were observed in satellite data or geophysical data. The last visible plume of discolored seawater was observed on January 9.

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 definitive signs of unrest were detected at any other 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.