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.”