USGS upgrades Aleutian volcano alert level: volcano stirring after 28 year slumber

March 2015 – ALEUTIAN ISLANDS – The USGS upgraded the island’s volcano alert level status to “advisory” and its aviation code to “yellow” Wednesday after an increase in seismic activity. Citing increased seismic intensity, the U.S.
Geological Survey is upgrading the volcano alert level status for Semisopochnoi, an Aleutian Island volcano, to “advisory,” the US geological agency said in a notice issued Wednesday morning. Semisopochnoi Island or Unyak Island is part of the Rat Islands group in the western Aleutian Islands of Alaska. The island is uninhabited and provides an important nesting area for maritime birds. The island is of volcanic origin, containing several volcanoes including Mount Cerberus. It has a land area of 85.558 square miles (221.59 km2), measuring 18 kilometers (11 mi) in length and 20 kilometers (12 mi) in width. Seismic activity at the Semisopochnoi volcano began in January, but “has increased in intensity over the past few days,” USGS wrote in the notice. “In addition, we have detected brief periods of seismic tremor, which can indicate movement of magma or magmatic gases.” Semisopochnoi is remote even by Alaska standards. It lies on an island of the same name some 127 miles from Adak and 1,283 miles from Anchorage. The volcano last erupted in 1987. –Alaska Dispatch News

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