Hundreds of Small Earthquakes Detected at Mount Rainier

MT. RAINIER, Wash. — A swarm of small earthquakes was detected at Mount Rainier early Tuesday morning, July 8, 2025, according to the U.S. Geological Survey Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN).

The activity started just before 1:30 a.m. PDT, with hundreds of earthquakes recorded at depths between 1.2 to 3.7 miles below the summit. The largest earthquake so far has measured a magnitude of 1.7.

Despite the increased seismic activity, officials have confirmed 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 the tallest peak in the Cascade Range and classified as a ‘Very High Threat’ volcano due to various 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 occur at Mount Rainier one to two times per year, with the last significant swarm taking place in 2009, which registered over 1,000 earthquakes.