Studying tree rings helped scientists pinpoint when Mount Rainier last sent a lahar down its steep slopes, which could help planners anticipate future mudflows.

Something stirred beneath Mount Rainier this summer, sending over 1,000 earthquakes through the ground in weeks—the largest swarm ever recorded at this towering volcano. Seismometers glowed with ...

Mount Rainier has rattled through thousands of tiny earthquakes this year, a reminder that America’s most lethal volcano is very much alive beneath its ice. Those quakes, and a burst of viral alarmism ...

Researchers detected the largest Mount Rainier earthquake swarm on record. Over 400 small quakes have been located as of Friday and many more have been detected. The temblors have shown no evidence ...

An outpouring of magma isn’t the biggest risk to people downhill from Mount Rainier. The active volcano’s greatest danger comes from lahars — amalgams of mud, rock and water that are as dense as wet ...