Mount Rainier experienced its largest earthquake swarm on record this week, but seismic activity is now significantly dropping. Scientists with the USGS Cascades Volcano Observatory say the quakes were not expected to lead to an eruption and were likely caused by hot fluids in existing faults.

More than 300 earthquakes have erupted at Washington's Mount Rainier this week, the largest earthquake swarm at the volcano since 2009.

This is now the largest recorded earthquake swarm at Mount Rainier since seismic monitoring at the volcano began in 1982, the Cascades Volcano Observatory said. With quakes ongoing, the swarm has already surpassed a major event in 2009 “in terms of magnitude, total events, event rate, and energy release.”