On Tuesday (July 8), in the early morning hours, a series of small earthquakes were detected beneath Mount Rainier in Washington state, prompting scientists to enhance monitoring efforts. However, officials emphasized that there are currently no signs of an imminent volcanic eruption.
According to data from the United States Geological Survey’s Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN), the small earthquakes began at 1:29 AM Pacific Daylight Time. Following this, hundreds of small earthquakes occurred near the summit of Mount Rainier, with the largest registering a magnitude of 1.7.
These earthquakes occurred at depths ranging from 1.2 to 3.7 miles (approximately 2.9 to 6.9 kilometers) beneath the summit of Mount Rainier, with some earthquakes occurring multiple times per minute. Currently, there have been no reports of ground shaking.
Despite the frequent activity at Mount Rainier, scientists have noted that such occurrences are not uncommon for the volcano and have emphasized that there are no signs of escalating volcanic activity. The volcano’s alert level remains “normal,” and the color code remains “green,” indicating typical background activity.
“Mount Rainier typically experiences about 9 earthquakes per month,” stated the CVO and PNSN in a joint update. “Earthquake swarms like this occur one to two times per year, but this event is larger in scale compared to usual.”
The last significant earthquake swarm at Mount Rainier took place in 2009, lasting for three days and recording over 1,000 earthquakes. One of the earthquakes during that event reached a magnitude of 2.3. Past swarms have been attributed to the interaction of underground fluids and faults, rather than indicative of imminent volcanic eruption.
Instruments have not shown any signs of ground deformation or abnormal gas emissions, and sensors have not detected any unusual sounds.
Mount Rainier is a towering ice-covered stratovolcano located approximately 60 miles southeast of Seattle, considered one of the most potentially hazardous volcanoes in the United States.