ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, July 11, 2025, 1:17 PM AKDT (Friday, July 11, 2025, 21:17 UTC)
Satellite radar data through July 10 show continued effusion of the southwest lobe with minor advancement of about 10 meters (33 feet) to the south. Rock falls from the steep flow margins continue. Elevated surface temperatures related to this activity were observed in satellite data throughout the week during periods of clear viewing conditions. Occasional small earthquakes persist.
The lava eruption that began in July 2021 is ongoing. It 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.
Great Sitkin Volcano is a basaltic andesite volcano that occupies most of the northern half of Great Sitkin Island, a member of the Andreanof Islands group in the central Aleutian Islands. It is located 26 miles (42 km) east of the community of Adak. The volcano is a composite structure consisting of an older dissected volcano and a younger parasitic cone with a ~1 mile (1.6 km)-diameter summit crater. A steep-sided lava dome, emplaced in the crater during an eruption in 1974, has been mostly buried by the ongoing eruption. The 1974 eruption produced at least one ash cloud that likely exceeded an altitude of 25,000 ft (7.6 km) above sea level. A poorly documented eruption also occurred in 1945, producing a lava dome that was partially destroyed in the 1974 eruption. Within the past 280 years a large explosive eruption produced pyroclastic flows that partially filled the Glacier Creek valley on the southwest flank.
Unrest continues at Mount Spurr. The level of activity remains slightly above background but continues to decline since the peak of unrest earlier this year. The decrease in activity suggests that the magma intrusion beneath Mount Spurr has stalled and that the likelihood of an eruption has declined.
Earthquake activity continues, with a small number of earthquakes located beneath both the summit of Mount Spurr and Crater Peak. The number of earthquakes and their magnitudes continue to show some variability from week to week but are following a decreasing trend. Ground deformation, as measured by GNSS (GPS) stations, remains paused as it has for the last two months. Volcanic gas emissions continue, as would be expected from a passively degassing body of stalled magma.
Fluctuations in unrest are common at volcanoes and eruptive activity remains possible, but unlikely. Should unrest escalate towards an eruption, we would expect to observe increases in seismic activity, gas emissions, surface deformation, and surface heating
AVO continues to closely monitor activity at Mount Spurr for signals indicating the volcano is moving closer to an eruption using local seismic, infrasound, and GNSS (GPS) stations, web cameras, airborne and satellite gas measurements, regional infrasound, lightning networks, and satellite images. Livestream camera video from station SPCL located south of Mount Spurr can be viewed at: Mount Spurr Live Stream (SPCL). A livestream of Mount Spurr, as viewed from Glen Alps in Anchorage, is available here: Mount Spurr Live Stream (ANCG).
Mount Spurr is an ice- and snow-covered stratovolcano located on the west side of Cook Inlet approximately 80 miles (129 km) west of Anchorage. The only known historical eruptions occurred in 1953 and 1992 from the Crater Peak flank vent located 2 miles (3.5 km) south of the summit of Mount Spurr. These eruptions were brief, explosive, and produced columns of ash that rose up to about 65,000 feet (20 km) above sea level and deposited minor ashfall in southcentral Alaska (up to ¼ inch or 6 mm). The last known eruption from the summit of Mount Spurr was more than 5,000 years ago. In 2004, Mount Spurr experienced an episode of increased seismicity, surface uplift, and heating that melted a large hole in the summit ice cap and generated debris flows. Primary hazards during future eruptions include far-traveled ash clouds, ash fall, pyroclastic flows, and lahars or mudflows that could inundate drainages on all sides of the volcano, especially on the south and east flanks.
Matt Haney, Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497
Pavel Izbekov, Acting Coordinating Scientist, UAF peizbekov@alaska.edu (907) 378-5460
Contact AVO: https://avo.alaska.edu/contact
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.
CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, July 11, 2025, 1:07 PM PDT (Friday, July 11, 2025, 20:07 UTC)
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, Mount Adams, and Mount Hood. All monitoring data are consistent with background activity levels in the Cascade Range.
Mount Rainier has been experiencing a seismic swarm that began on 1:29 AM PDT (8:29 UTC) on July 8th. Since the start of the swarm, earthquake event rates have been gradually decreasing from a peak of 30 events per hour on the morning of July 8th to only a few events per hour as of today at 1:00 PM PDT (20:00 UTC). The largest magnitude event was a 2.4 that occurred on July 11th at 12:23 PM PDT (19:23 UTC). Since the start of the swarm, 423 events that are mainly spread between 1.5-4 miles (2-6 km) beneath the summit have been located by the Cascades Volcano Observatory and the Pacific Northwest Seismic Network.
For more information on this swarm, see: https://www.usgs.gov/observatories/cvo/news/monitoring-stations-detect-small-magnitude-earthquakes-mount-rainier
The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington Pacific Northwest Seismic Network continue to monitor Washington and Oregon volcanoes closely and will issue additional notifications as warranted.
Website Resources
For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information
Michael Poland, Acting Scientist-in-Charge, Cascades Volcano Observatory, mpoland@usgs.gov
General inquiries: askCVO@usgs.gov
Media inquiries: volcanomedia@usgs.gov
CASCADES VOLCANO OBSERVATORY STATUS REPORT
U.S. Geological Survey
Friday, July 11, 2025, 9:12 AM PDT (Friday, July 11, 2025, 16:12 UTC)
This is an update on the ongoing seismic swarm at Mount Rainier that began at 1:29 AM PDT (8:29 UTC) on July 8th.
Swarm event rates continue to decrease. As of 9 AM PDT (16:00 UTC) on July 11th, the Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN) have located 391 events since the start of the swarm, although many more have occurred but cannot be located. The largest event of the swarm so far was a magnitude 2.3 on July 8th at 2:56 PM PDT (21:56 UTC). Seismicity has decreased from 30 located events per hour at the swarm's peak on Tuesday morning to a few events per hour as of Friday morning. The earthquakes are mainly spread between 1.5-4 miles (2-6 km) beneath the summit. There have been no changes in ground deformation or other monitoring data.
This swarm surpassed the 2009 swarm in terms of total events, event rate, and energy release. The cause of the swarm remains consistent with the circulation of fluids along preexisting faults beneath the volcano, which is considered background activity at Mount Rainier. There is currently no indication that the swarm is associated with magmatic unrest.
PNSN and CVO will continue to monitor activity, locate earthquakes, and provide additional information as needed.
For more information, see: https://www.usgs.gov/observatories/cvo/news/monitoring-stations-detect-small-magnitude-earthquakes-mount-rainier
About Mount Rainier
Mount Rainier is an active, ice-clad stratovolcano geographically located within the Mount Rainier National Park. Mount Rainier is located about 45 miles (73 km) southeast of Tacoma and 60 miles (97 km) south-southeast of Seattle in Washington State. It is the tallest peak in the Cascade Range and is covered by the greatest concentration of glaciers in the contiguous United States.
Hazards and Normal Background Activity
The most hazardous phenomena from Mount Rainier are volcanic mudflows called lahars, many of which reached as far as the now densely inhabited Puget Sound lowland. Other hazards include ash fall, pyroclastic flows, and short lava flows, however these stay well within the present limits of the National Park. Mount Rainier is considered a Very High Threat volcano according to the USGS National Volcano Warning System (NVEWS) based on many factors including the types of hazards and distance to people, property and infrastructure. The volcano has a widely distributed network of monitoring devices. Normal background levels of activity at Mount Rainier include steam and gas emissions, and low levels of seismicity.
Holocene Volcanic Activity (activity in the last 15,000 years)
Nearly all of Mount Rainier’s far-traveled lahars formed during times of eruptions, but one contains a large volume of altered rock that avalanched from Sunset Amphitheater on Mount Rainier’s upper west flank about 500 years ago with no known triggering eruption. A lahar with no known trigger is known locally as a “no-notice lahar.” Future eruptions are likely to produce lahars that could descend river valleys on any side of the volcano, but a “no-notice lahar” is also possible from the upper west flank of the volcano and could feed into the Puyallup and the Nisqually River systems. No physical evidence exists to confirm a reported but disputed eruption in 1894, nor eruptions earlier in the 18th and 19th centuries. The most recent eruption with strong geologic evidence was about 1,000 years ago.
The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington Pacific Northwest Seismic Network continue to monitor Washington and Oregon volcanoes closely and will issue additional notifications as warranted.
Website Resources
For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information
Michael Poland, Acting Scientist-in-Charge, Cascades Volcano Observatory, mpoland@usgs.gov
General inquiries: askCVO@usgs.gov
Media inquiries: volcanomedia@usgs.gov
HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Friday, July 11, 2025, 9:13 AM HST (Friday, July 11, 2025, 19:13 UTC)
Activity Summary:
Episode 28 of the ongoing Halemaʻumaʻu eruption ended just before 1:30 p.m. HST on July 9, 2025. Summit inflation resumed immediately and continues today. Low-level degassing and seismic tremor also persist.
No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.
Current hazards include volcanic gas emissions, along with windblown volcanic glass (Pele’s hair) and tephra deposited during earlier eruptive episodes.
Summit Observations:
Episode 28’s activity, with maximum fountain heights near 1,200 feet (365 meters), was focused at the north eruptive vent. Deposits from the episode completely covered the south vent and have also nearly connected the growing eruptive cone with the top of the surrounding cliff in some places. Slumping of the eruptive cone around the vent area was very apparent in webcams last night, as it exposed significant incandescent material. Such slumping may continue over the next hours to days.
Lava flows on the floor of Halemaʻumaʻu within the southern part of Kaluapele (Kīlauea caldera) are cooling and showed only minor incandescence in webcams overnight. One small oozeout lava flow was noted as persisting through to this morning.
At present, tremor and degassing persist at lower but still elevated levels. Typical sulfur dioxide (SO2) emission rates associated with pause periods are 1,200 to 1,500 t/d
Fountaining associated with Episode 28 resulted in 15 microradians of deflation. At the time of this update, UWD had re-inflated by just over 5 microradians.
Strands of volcanic glass known as Pele’s hair are present throughout the summit area of Hawaiʻi Volcanoes National Park and surrounding communities and can be remobilized by wind even after fountaining has ceased. Trade winds are forecast for today and would likely blow both volcanic gases and erupted particles (tephra, ash, and Pele’s hair) to the west and southwest of Kīlauea summit.
Rift Zone Observations:
Rates of seismicity and ground deformation remain very low in the East Rift Zone and Southwest Rift Zone, with no significant earthquake activity in the past 24 hours. Sulfur dioxide (SO2) emissions from the East Rift Zone remain below the detection limit.
Analysis:
Summit inflation resumed at the end of Episode 28, and low-level degassing and seismic tremor persist, all of which suggest that another episode of fountaining is likely. Additional time is needed to accumulate tiltmeter data before a specific forecast window can be made for Episode 29. However, early data projections indicate that a new episode may take place toward the middle or end of next week.
The current eruption has been characterized by episodic lava fountaining not seen in any eruptions since the 1983–86 episodic fountains at the beginning of the Puʻuʻōʻō eruption. Lava fountains and flows have erupted from two vents within Halema'um'a'u crater that we refer to as the north vent and south vent. Each of the previous fountaining episodes lasted from a few hours to over a week and was accompanied by strong deflation of the summit region. Pauses between the fountaining episodes have been marked by an immediate switch from deflation to inflation as the magma chamber recharges and repressurizes. Fountaining episodes have occurred approximately once per week since the start of the current eruption on December 23, 2024.
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.
General Updates:
Tilt azimuths for SDH and UWD tiltmeter plots, as displayed on USGS websites, have been updated to optimize showing maximum magnitudes of deformation consistent with the current activity at the summit of Kilauea.
Hazards:
This episodic eruption is occurring within a closed area of Hawaiʻi Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)—are the primary 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/
Additional hazards include Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity. Volcanic fragments can fall on the ground within a few hundred yards (meters) of the eruptive vent(s), or downwind of the vent(s). Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once they are 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 current wind conditions. Residents and visitors should minimize exposure to Pele's hair and other volcanic fragments, which can cause skin and eye irritation. More information about how Pele's hair forms, 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.
More Information:
The Hawaiian Volcano Observatory is one of five volcano observatories within the U.S. Geological Survey and is responsible for monitoring volcanoes and earthquakes in Hawaiʻi and American Samoa.
Subscribe to these messages: https://volcanoes.usgs.gov/vns2/
Summary of volcanic hazards from eruptions: https://www.usgs.gov/observatories/hvo/hazards
Recent earthquakes in Hawaiʻi (map and list): https://www.usgs.gov/observatories/hvo
Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes