Alaska Volcano Observatory

From Cameron and others, 2017: "In February and March 2014, an earthquake swarm occurred about 13 km (8 mi) southwest of Tanaga Volcano. This was the most energetic volcano-tectonic swarm at Tanaga since 2005 (McGimsey and others, 2007). The elevated seismicity continued into the summer, although at a reduced rate, and ended in late 2014. The swarm comprised 80 percent of all earthquakes located on or near Tanaga during the year. The earthquakes were all less than M2.0 and occurred at crustal depths of 5-10 km (3-6 mi). No specific cause was determined for the short-lived swarm. Despite the swarm, the Aviation Color Code and Volcano Alert Level remained at GREEN/NORMAL for all of 2014."