Mount Rainier was experiencing "the most significant seismic activity" at the volcano in more than 15 years as an "earthquake swarm" hit the site starting on Tuesday.

The earthquakes are not currently a cause for concern, and do not indicate an impending eruption, the U.S. Geological Survey ...

More than 400 earthquakes rattled Washington's Mount Rainier over just 12 hours on Tuesday, sparking fears that the ...