USGS Volcanoes: Notices released in the last day.

Lava continues to slowly erupt within the summit crater at Great Sitkin Volcano. Minor lava dome growth to the southwest and rockfalls down the south side of the dome were observed in rare clear satellite views. Elevated surface temperatures from the warm, active lava dome were also observed when conditions allowed. Seismic activity remains low, with the detection of occasional small volcanic earthquakes and 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 continue. Seismic and infrasound activity remain elevated, with numerous small earthquakes, frequent infrasound signals, and volcanic tremor recorded throughout the week. During clear weather, steam plumes were visible in webcam images and by passing airplanes and ships, and elevated sulfur dioxide gas emissions were detected in satellite data on most days. 

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.

Low-level unrest continued at Atka volcanic complex over the last week. Moderate volcanic tremor was observed early in the week, but this activity has declined to typical levels seen at this volcano. Clear satellite views over the week showed weak-to-moderately elevated surface temperatures from the Korovin Volcano crater lake. Variable sulfur dioxide gas emissions were also detected in satellite data all week. Both the surface temperatures and gas emissions are slightly higher than are typically observed from this volcano.

The Atka volcanic complex is monitored by local seismic and infrasound sensors and webcam, satellite data, and regional lightning detection instruments.

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 Rainier, Mount St. Helens, and Mount Hood. All monitoring data are consistent with background activity levels in the Cascade Range.

On Thursday, March 26 between 2:00 p.m. and 10:00 p.m. HST, the USGS Hawaiian Volcano Observatory detected a swarm of about 28 tectonic earthquakes beneath the northeast side of Mauna Kea, in the Hāmākua region. These earthquakes mainly occurred at depths between 5–10 km (3–6 miles) below the ground surface. The largest of these events were two magnitude 3 earthquakes, and each had a couple of felt reports. During the first few hours of the swarm, the earthquake rates were lower. Following the two magnitude 3 earthquakes, which occurred about one hour apart, the seismic activity stopped for about 90 minutes before resuming. 

These tectonic events are not related to magma movement. Over the past 25 years, similar clusters of earthquakes in this region have occurred in 2002, 2004, 2006, 2008, and 2010 along with a scattering of isolated earthquakes overtime.  Maximum magnitudes have all been in the magnitude 3 range with most earthquakes less than magnitude 2.   The depth of these earthquakes put them beneath the Mauna Kea edifice and into the underlying Kohala volcano, whose rift zone extends all the way to the submarine Hilo ridge east of Mauna Kea. These earthquakes appear to be related to periodic release of stress in the elongated Kohala edifice.  Stress gradually accumulates over time and is most likely due to the weight of the island.  They do not appear to be directly related to the older submarine Laupāhoehoe slump or to flexural bending of the underlying oceanic lithosphere.

The USGS Hawaiian Volcano Observatory will continue to closely track changes in seismic activity and monitor Hawaiian volcanoes for any changes. 

• USGS-HVO Interactive Earthquake Map of Hawaiʻi: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/earthquakes   
• Short updates may be posted on the HVO webpage as necessary HVO - Observatory Messages | U.S. Geological Survey

Activity Summary:

The Halemaʻumaʻu eruption of Kīlauea is paused. The summit is currently inflating and glow was visible from the vents overnight. The forecast window is now April 5-15.

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

HVO’s monitoring network is mostly recovered from power and storm related outages.  Several summit stations, including the SDH tiltmeter, will remain offline until we are able to re-establish access across the deep tephra field south of the caldera.

A summary of episode 43 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:                                                                                                                       

Overnight, moderate to strong glow was observed at the north vent, along with rare flames. The south vent was mostly dark overnight until intermittent glow returned this morning around 4:30 a.m. HST. Currently, both vents are emitting gas plumes.

Seismic tremor was more continuous overnight and with fewer tremor bursts than the past several days. Two earthquakes were recorded at the summit during the past day.

Summit tiltmeters UWD and SMC continue to record inflation since the end of episode 43. The UWD tiltmeter has recorded an estimated 16.8 microradians of tilt since the end of episode 43. This is a gain of 1.5 microradians in the last 24 hours and a distinct increase in the inflation rate.

During eruptive 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.

Rift Zone Observations:

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

Analysis:

Rapid rebound of tilt following episode 43 fountaining, continued tremor, and visible glow from the vents suggest that another fountaining episode is likely. Summit inflation increased overnight but models continue to indicate that episode 44 fountains are likely to start between April 5 and April 15. 

Kīlauea has been erupting episodically since December 23, 2024, from two vents (north and south) in Halema‘uma‘u. Fountaining episodes, which generally last for less than 12 hours, are separated by pauses that can be longer than 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 43:

Episode 43 ended at 6:21 p.m. HST on March 10 after fountaining for just over 9 hours from both vents and sending tephra into surrounding communities. A complete summary of activity can be found here. 

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

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.

NORTHERN MARIANAS VOLCANOES
No definitive signs of unrest were detected at any 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.