Signs of Life at Long-Quiet Volcanic Island in W. Aleutians

Friday, June 13 2014

Semisopochnoi Island in Nov. 2012. /Courtesy: Roger Clifford

A volcanic island in the western Aleutian Islands woke up this week, decades after the last time it was active.

Semisopochnoi Island is about 130 miles west of Adak. It’s home to a few peaks that have been active in the past, including Sugarloaf and Cerberus.

But the island had been quiet for more than a quarter century -- until this past Monday, when the Alaska Volcano Observatory recorded a series of small earthquakes there.

The quakes continued all week and escalated on Thursday, when the AVO recorded up to 25 small tremors around the island. The largest was around a magnitude 2.0.

That prompted the AVO to put Semisopochnoi on an advisory alert status on Friday. The advisory carries a yellow color code.

Semisopochnoi's last volcanic activity came in the form of an ash and steam plume from Sugarloaf Peak in 1987. Before then, the island had been quiet since an eruption at Cerberus Peak in the 1800s.

Semisopochnoi is the western Aleutians' biggest young volcanic island.

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