Database ID#: 176
Date: Tuesday, July 8, 2025
Location: Mount Rainier National Park
Glacier Name: None
Drainage Basin:
Event Type: Earthquake

Weather:
Varied, but mostly warm during the event.

Season: Dry

Notes:
***** FINAL UPDATE on 8/25/2025 - EVENT IS NOW OVER: *****

CASCADES VOLCANO OBSERVATORY INFORMATION STATEMENT
U.S. Geological Survey
Monday, August 25, 2025, 3:38 PM PDT (Monday, August 25, 2025, 22:38 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

Earthquake activity at Mount Rainier has returned to typical rates of seismicity, after the earthquake swarm that began on July 8, 2025. The Volcano Alert Level and Aviation Color Code for Mount Rainier remained at NORMAL/GREEN throughout the swarm, as the activity was related to the volcano's hydrothermal system. The swarm resulted in over 1,350 located earthquakes and thousands of additional earthquakes too small to locate. The average depth of the earthquakes was about 2.8 miles (4.5 km) beneath the summit of the volcano. The largest earthquake of the swarm was a magnitude 2.42 on July 11, 2025.

An earthquake swarm is a group of earthquakes that happen close together in both time and location. When the swarm began, it quickly reached a maximum rate of about 40 earthquakes per hour. Over the next several weeks, the rate of earthquakes decreased. The shift from an earthquake swarm to typical rates of activity isn’t marked by a single moment, but rather a gradual decrease interpreted through scientific review over time. After carefully reviewing the data, scientists from the U.S. Geological Survey Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN) have determined that earthquake activity has returned to typical rates for Mount Rainier, which has averaged about 10 earthquakes per month for the last several decades. The hydrothermal processes that are believed to have caused the swarm may be continuing at levels too small to generate detectable seismicity. Therefore, there is a small chance of brief increases in seismic activity under the volcano in future days to months. A volcano’s hydrothermal system is how water underground interacts with the heat of a volcano – this process creates features that can be observed at the surface like hot springs and steam vents. Earthquakes, hot springs and steam vents remind us that Mount Rainier is an active volcano.

Recent activity

Additionally, in coordination with Mount Rainier National Park, CVO scientists conducted a helicopter gas survey of Mount Rainier on August 4, 2025. The results showed that the compositions and emission rates of gases emitted from active steam vents on Mount Rainier were broadly consistent with previous measurements. Similarly, the geodetic network did not record any unusual inflation or deflation at the volcano during the earthquake swarm.


***** 2025-07-09 09:30 update: *****
From USGS/CVO:

CASCADES VOLCANO OBSERVATORY STATUS REPORT
U.S. Geological Survey
Wednesday, July 9, 2025, 9:30 AM PDT (Wednesday, July 9, 2025, 16:30 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

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.
Seismicity is continuing at low rates. As of 9 AM PDT (16:00 UTC) on July 9th, the Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN) have located 229 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 2.1 on July 8th at 2:56 PM PDT (21:56 UTC). Seismicity has decreased from 26 located events per hour at the swarm's peak on Tuesday morning to a few per hour as of Wednesday morning. The average earthquake depth is 2.5 miles (4 km) beneath the summit. There have been no changes in ground deformation or other monitoring data.
The cause of the swarm remains consist with the circulation of fluids along preexisting faults beneath the volcano. 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.


***** 2025-07-08 16:04 update: *****
Map/data of the swarm:
https://www.morageology.com/earthquake_range.php?d0=2025-07-08%2008:00:00&d1=2025-08-25%2023:59:59


***** Initial report, ongoing event: *****

From USGS/CVO:

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.


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