Mount Rainier, the active volcano towering above southwestern Washington state, started rumbling — very lightly — on Tuesday.
A swarm of small earthquakes was detected under the mountain triggering focused monitoring from officials. But researchers have determined there is no current threat of an eruption.
The earthquake swarm started just before 1:30 a.m. local time, according to the U.S. Geological Survey's Cascades Volcano Observatory and the Pacific Northwest Seismic Network. Since the swarm began, hundreds of tiny earthquakes have occurred near the volcano's summit, with the largest's magnitude detected at 1.7.
Mount Rainier towering over Tacoma, Washington. A swarm of minor earthquakes was detected at the volcano, but monitoring officials stressed the activity was normal and was not indicative of an imminent eruption (Getty Images/iStockphoto)The earthquakes' origins have been recorded between 1.2 and 3.7 miles beneath the summit of the mountain. None have been felt on the surface, according to KPTV.
Since Mount Rainier is an active volcano officials said the seismic activity wasn't abnormal and stressed there was no cause for alarm. The volcano's alert level has remained at normal, and its color code at green, which indicates typical activity.
“Mount Rainier typically sees about nine earthquakes per month,” the agencies said in a statement after the swarms were detected. “Swarms like this happen once or twice a year, though this one is larger than usual.”
The volcano's alert level has remained at normal, and its color code at green, which indicates typical activity (Getty Images for Rock'n'Roll Mar)The last significant earthquake at Mount Rainier occurred in 2009, and rumbled on for three days. More than 1,000 seismic events were recorded with the most substantial registering a 2.3 magnitude.
Previous swarms have been attributed to fluids circulating under the mountain, and interacting with faults deep underground, and not volcanic activity.
According to the U.S. Geological Survey, the last eruptive period for Mount Rainier occurred around 1,000 years ago, but even in that incident there were no lava flows. The last major destructive eruption to hit Washington state was not at Mount Rainier, but at Mount St Helens — approximately 50 miles away, but part of the same mountain range — in 1980. That eruption killed 57 people.
The snowcapped Mount Rainier is located in Mount Rainier National Park, approximately 59 miles southeast of Seattle. The mountain is the highest peak in Washington state and on clear days is visible from Seattle.
