Three Alaska Peninsula volcanoes are restless

Jun 9, 2017

Bogoslof volcano has a new lava dome. Cleveland volcano continues to put up ash and extrude lava, and the alert level for Pavlof volcano was raised to "advisory."

A volcanic plume from Bogoslof on June 5, 2017
Credit US Fish & Wildlife Service, R/V Tiglax

Over the last week there has been quite a bit of volcanic activity along the Alaska Peninsula. The Bogoslof, Cleveland, and Pavlof volcanoes are all showing signs of unrest. Most recently, the Bogoslof volcano erupted briefly Wednesday around 9:30 p.m.

“Bogoslof has been continuing its eruptive activity that started in December 2016 with a series of small activities,” says Jessica Larsen, a geologist with the Alaska Volcano Observatory.  “Now we have new evidence that there’s a lava dome growing at the Bogoslof Island.”

A lava dome is a mound of lava that has been extruded from the volcano. This is characteristic of previous Bogoslof explosive periods.

“In the past it’s formed toward the end of the eruptions. We don’t know exactly if this is happening now or if the Bogoslof volcano is going to stick with the lava dome and quiet down. It could just keep continuing to have its punctuated explosions as well,” says Larsen.

The AVO’s alert level for Bogoslof remains at “watch,” and the aviation alert is at its second highest level. The Cleveland volcano is also at the “watch” alert level.

“Cleveland has been in sort of a prolonged periodic phase of eruptive activity that includes extrusion of lava in a summit crater and then periodic explosions that tend to destroy the lava and put up ash cloud,” says Larsen.

Pavlof volcano, located on the southwestern end of the Alaska Peninsula, was raised from normal alert level to “advisory” on Wednesday.  The AVO notes that there has been “an increase in low-frequency earthquake activity at Pavlof,” and such increases sometimes precede eruptions.

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This comparison of satellite radar images from May 31 and June 8, 2017 of Bogoslof volcano shows the new lava dome. According to the AVO, the dome measures about 110 m across and may be growing.
Credit Dave Schneider/ AVO/ USGS