More than 400 earthquakes detected beneath Mount Rainier
Jul 8, 2025, 11:52 AM | Updated: 11:53 am
Mount Rainier can be seen from Eatonville near Mount Rainier National Park. (Photo: Thomas O'Neill, Getty Images)
(Photo: Thomas O'Neill, Getty Images)
Scientists with the U.S. Geological Survey (USGS) and the University of Washington (UW) recorded more than 400 minor tremors beneath Mount Rainier.
The series of small earthquakes began early Tuesday morning, at approximately 1:29 a.m., lasting until midday. Researchers told KIRO 7 that the ongoing swarm is larger than the typical one or two smaller swarms that occur at the volcano each year.
A map of the swarm of small earthquakes and tremors underneath Mount Rainier. (Photo courtesy of the U.S. Geological Survey and the University of Washington)
The largest earthquake measured at a magnitude of 1.7. Despite the large number of tremors, there have been no signs of ground deformation, according to USGS.
“Earthquake swarms like this have been attributed to circulation of hydrothermal fluids that are interacting with preexisting faults at shallow levels below the summit of the volcano,” USGS said in an official statement.
The last time Mount Rainier experienced a swarm of this size was in 2009, according to KIRO 7, when hundreds of earthquakes occurred over a three-day period. The largest in that span reached a magnitude of 2.3.
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