An earthquake swarm characterized by hundreds of small tremors has been detected around Mount Rainier, Washington, beginning early on July 8, 2025. The swarm started at approximately 1:30 AM local time, with the largest recorded quake reaching a magnitude of 1.6 at 4:52 AM PDT. These small earthquakes are occurring at depths ranging from 1 to 4 miles (2-6 km) below the volcano’s summit and are too minor to be felt by residents or cause any damage.
The Pacific Northwest Seismic Network (PNSN) is actively monitoring this activity, identifying the location and depth of each earthquake, though some of the smaller events may be too insignificant for precise location. Currently, the alert level for Mount Rainier is designated GREEN, indicating normal conditions with no immediate concerns associated with the swarm.
Historically, Mount Rainier experiences some form of earthquake swarm about once or twice a year; however, the size of this swarm stands out as it contains a particularly high number of events, significantly more than the typical rate of around nine earthquakes per month at the volcano. Past swarms have been linked to fluid movements interacting with existing geological faults.
For reference, a previous large swarm in 2009 had a peak magnitude of 2.3 and lasted three days, generating over 1,000 recorded earthquakes, with 120 officially located by the PNSN.
Residents and interested parties can stay informed about the ongoing seismic activity and receive alerts by signing up for USGS volcano notifications. The continued monitoring of these small earthquakes is crucial not only for understanding volcanic behavior but also for ensuring public safety. There are no immediate risks from this swarm, offering a reassuring perspective on Mount Rainier’s activity level.