While considered an active volcano, Mount Rainier hasn’t erupted in at least a century, possibly much longer. The U.S Geological Survey said there was no physical evidence to confirm a reported 1894 eruption, nor eruptions earlier in the 18th and 19th centuries. The last eruption with strong geologic evidence happened about 1,000 years ago.

Officials are tracking the largest swarm of earthquakes in more than 15 years on Washington's Mount Rainier but say there is no indication that the cluster of quakes is cause for concern.