Seismologists are closely monitoring Mount Rainier after a swarm of earthquakes struck the volcano this week. The USGS reports that hundreds of small quakes have occurred since the swarm began, making it the largest such event at the mountain since 2009.
Wes Thelen, a seismologist with the Cascades Volcano Observatory, said that the quakes began as a concentrated group of seismic events happening in quick succession.
"We had an increase in activity in seismic activity up to about 26 events an hour, which is a pretty good event rate for a quiet volcano," explained Thelen. "Since then, it's tailed off." He added that while the swarm has calmed slightly, the activity could intensify again. "We don’t necessarily have a crystal ball to understand what is happening under there."