MT. RAINIER, Wash. — A swarm of small earthquakes was detected at Mount Rainier Tuesday morning, according to the U.S. Geological Survey Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN).
The activity began on July 8, 2025, at 1:29 a.m. PDT, with hundreds of earthquakes recorded at depths ranging from 1.2 to 3.7 miles below the summit. The largest earthquake so far has been a magnitude 1.7.
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Despite the increased seismic activity, officials have stated that there is no cause for concern at this time. The volcano’s alert level remains at “NORMAL,” and the aviation color code is “GREEN.”
“Instruments do not show any detectable ground deformation at the volcano, and no anomalous signals have been seen on the infrasound monitoring stations,” said the CVO.
Mount Rainier, located about 45 miles southeast of Tacoma, is an active stratovolcano and the tallest peak in the Cascade Range. It is considered a “Very High Threat” volcano due to its potential hazards, including volcanic mudflows known as lahars, ash fall, and pyroclastic flows.
The CVO and PNSN will continue to monitor the situation closely and provide updates as necessary.
Historically, swarms of earthquakes at Mount Rainier occur one to two times per year, with the last significant swarm occurring in 2009. Over 1,000 earthquakes were reported during the 2009 swarm.
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