Alaska - The Semisopochnoi joins four other volcanoes on alert.

A seismic swarm began on volcano Semisopochnoi, June 9, 2014 at 18h UTC. Its increase on June 12, around 20h UTC, motivated the AVO - Alaska Volcano Observatory, to raise alert levels: alert aviation Yellow - volcanic alert Advisory. No eruptive activity is reported at this time.

This volcano is located on the youngest volcanic island in the western Aleutians; although remote and uninhabited, the island which houses the Semisopchnoi is monitored by a network of five operational seismic stations and satellite.
 

This volcano is dominated by a caldera 8 km. in diameter, dated early Holocene, which contains a small lake, the Fenner lake, and many craters and post-caldera cones.

Its last eruption in 1987, probably located at Sugarloaf Peak, on the south coast of the island. Mount Cerberus, a set of three pointed cones occupies the southwestern part of the caldera.

 

Sources : AVO - Alaska Volcano Observatory