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Okmok erupts near Unalaska

Submitted by Kat Bernhardt
Phone: 907-474-7853

07/14/08

Photo caption below.
Image of Okmok eruption cloud taken by LT Steve McKechnie, USCG Air Station, Kodiak, AK.
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Photo caption below.
Image courtesy of the Alaska Volcano Observatory and the University of Alaska Fairbanks Geophysical Institute.
This image shows the Okmok caldera. Seismologists have determined that Cone D is erupting. In 1997, Cone A erupted.
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Okmok Volcano in the Aleutian Islands began erupting at 11:43 a.m. Saturday, just five hours after seismologists at the Alaska Volcano Observatory began detecting earthquakes. Okmok is located on Umnak Island near Unalaska in the Aleutian Islands.

The initial ash cloud reached heights of approximately 45,000 feet. As of Monday afternoon, an ash cloud was drifting southeast of the 3,520 foot volcano at heights of 30,000 feet and posed a risk to aircraft. Two plane flights from Unalaska were cancelled due to the eruption.

A fishing vessel rescued 10 people Saturday evening, including three children, who were at Fort Glenn, a private cattle ranch south of the volcano. They were brought safely to Dutch Harbor.

"It is very rare to have things ramp up that quickly," noted Alaska Volcano Observatory coordinating scientist Steve McNutt.

Seismicity peaked at about 2 p.m. Sunday and has been gradually declining. Seismologists announced that Cone D on the east side of the caldera is erupting. Plume and thermal anomalies are present in remote sensing data. Ash samples are being sent back to laboratories for analysis.

"There was volcanic lightning observed as reported by an observer on the ground," McNutt said.

Okmok last erupted in 1997 from Cone A on the southwest side of the caldera, producing ash clouds and lava flows that traveled about five miles across the caldera floor. The volcano consists of a six-mile-wide crater about 1,600 feet deep.

An ash fall advisory for the Eastern Aleutian zone, including Nikolski and Unalaska/Dutch Harbor, remains in effect.

About AVO
The Alaska Volcano Observatory is a cooperative program of the U. S. Geological Survey, the Alaska Division of Geological and Geophysical Surveys, and the University of Alaska Fairbanks Geophysical Institute.

CONTACT: Steve McNutt, coordinating scientist, Alaska Volcano Observatory at 907-474-713. Geophysical Institute information office at 907-474-5823 or via e-mail at info@gi.alaska.edu

ON THE WEB: www.avo.alaska.edu/activity/Okmok.php