USGS Volcano Notice - DOI-USGS-CVO-2025-07-08T14:41:41+00:00

CASCADES VOLCANO OBSERVATORY INFORMATION STATEMENT
U.S. Geological Survey
Tuesday, July 8, 2025, 9:26 AM PDT (Tuesday, July 8, 2025, 16:26 UTC)

MOUNT RAINIER (VNUM #321030)
46°51'11" N 121°45'36" W, Summit Elevation 14409 ft (4392 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

On July 8, 2025, the U.S. Geological Survey Cascades Volcano Observatory (CVO) and Pacific Northwest Seismic Network (PNSN) detected a swarm of earthquakes at Mount Rainier starting at 01:29 PDT (08:29 UTC). So far, hundreds of earthquakes have been detected with event rates up to several per minute, ranging from depths of 1.2 – 3.7 miles (2-6 km) below the summit. The largest earthquake located thus far is a magnitude 1.7.  

Currently, there is no indication that the level of earthquake activity is cause for concern, and the alert level and color code for Mount Rainier remain at GREEN / NORMAL.  

Recent activity

Beginning at about 1:29 AM PDT (8:29 UTC) on July 8, a swarm of small earthquakes began near the summit of Mount Rainier.  The Pacific Northwest Seismic Network is locating earthquakes with the largest so far being a M1.7 at 04:52 PDT (11:52 UTC), ranging from depths of 1.2 – 3.7 miles (2-6 km) below the summit.  There are hundreds of small earthquakes occurring at rates of up to several per minute at times. No earthquakes have been felt at the surface.  

Instruments do not show any detectable ground deformation at the volcano, and no anomalous signals have been seen on the infrasound monitoring stations. Mount Rainier does not have a dedicated continuous volcanic gas sampling capability.  

Typically, earthquakes at this volcano are located at a rate of about 9 earthquakes per month. Swarms typically occur 1-2 times per year, but are usually much smaller in terms of number of events. The last large swarm at Mount Rainier in 2009 had a maximum magnitude of M2.3 and lasted three days. The 2009 swarm had over 1000 earthquakes, of which the PNSN officially located 120 earthquakes. Past swarms have been attributed to circulation of fluids interacting with preexisting faults. 

What we are doing 

Mount Rainier is monitored by a dense network of seismometers, infrasound sensors, GPS stations, and webcams. The U.S. Geological Survey Cascades Volcano Observatory (CVO) and Pacific Northwest Seismic Network (PNSN) will continue to monitor earthquake activity and release further updates as the situation warrants. 

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.

Additional Resources:

https://www.usgs.gov/volcanoes/mount-rainier/

https://www.usgs.gov/volcanoes/mount-rainier/science/volcanic-hazards-mount-rainier

https://pubs.usgs.gov/publication/ofr98428

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

CONTACT INFORMATION:

Michael Poland, Acting Scientist-in-Charge, Cascades Volcano Observatory, mpoland@usgs.gov

General inquiries: askCVO@usgs.gov