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Earthquakes raise alert level at Alaska volcano

Alaska Dispatch
Aerial view of the eruption column from Mount Spurr volcano on Aug. 18, 1992. A light-tan cloud ascending from pyroclastic flows is visible at right. The 11,070 footh summit lava dome complex of Mount Spurr is visible at left.
R. McGimsey/U.S. Geological Survey photo
Mt. Redoubt's active lava dome on May 8, 2009
AVO photo
Summit of Augustine viewed from the south.
Image courtesy of AVO/USGS
Pavlof volcano and eruption plume on evening of Aug. 30, 2007. View is to the south. Plume height approximately 17-18,000 ft.
Chris Waythomas/Alaska Volcano Observatory photo
The "Snowy Hole," a fumarole on the south side of Snowy Volcano, located in the Katmai region of the Alaska Peninsula.
Cyrus Read/Alaska Volcano Observatory photo
Aerial image of Akutan Volcano. (August 5, 2011)
Burke Mees/Alaska Volcano Observatory photo
A photo of Iliamna volcano on the lower west side of Cook Inlet.
Photo courtesy AVO/USGS
Aerial view looking southwest of a portion of the 4-6 km ice-filled summit caldera of Mount Wrangell, a 14,163-foot andesite shield volcano in 1987. It is the only volcano in the Wrangell volcanic field to have had documented historical activity consisting of several minor, possibly phreatic eruptions in the early 1900's.
R. Motyka/ADGGS photo
Mount Novarupta
USGS photo
Aerial view, looking east, of Aniakchak caldera, one of the most spectacular volcanoes on the Alaska Peninsula. Formed during a catastrophic ash-flow producing eruption about 3,400 years ago, Aniakchak caldera is about 10 km (6 mi) across and averages 500 m (1,640 ft) in depth. Voluminous postcaldera eruptive activity has produced a wide variety of volcanic landforms and deposits within the caldera. The volcano is located in Aniakchak National Monument and Preserve, Alaska, which is administered by the National Park Service.
AVO photo
From the USGS caption: Mount Cleveland forms the western half of Chuginadak Island in the central Aleutian Islands. This symmetrical, 1,730-m (5,676 ft)-high stratovolcano and has been the site of numerous eruptions in the last two centuries; the most recent eruption occurred in 1994. In 1944, a U.S. Army serviceman was reportedly killed by an eruption from Mount Cleveland.
Alaska Volcano Observatory photo
Eruption of Great Sitkin Volcano, 1974.
Steve Kelly photo; courtesy Paul W. Roberts

A series of small earthquakes which began Wednesday night and continued into Thursday near a long-dormant volcanic peak in Alaska's Aleutian Islands has prompted researchers to raise the alert level for the Little Sitkin volcano. 

The nearly 4,000-foot-high Little Sitkin volcano is named for the island where it resides, located in the Rat Islands in the Aleutian chain. The volcano has shown little activity since scientists have started observing it, with only three questionable eruptive events at the volcano since that time. The most recent eruption may have come in 1900, according to the Alaska Volcano Observatory

Still, the AVO page for Little Sitkin mentions there may have been a "cataclysmic eruption" on the island sometime after the last ice age, which ended more than 11,000 years ago.

Seismic equipment located near the volcano began detecting a "swarm of high-frequency earthquakes" at about 7:15 p.m. Wednesday, the AVO reports. The earthquakes continued through the night into Thursday, prompting the alert level at the volcano being raised. The alert level is currently at yellow, which means that the "volcano is exhibiting signs of elevated unrest above known background level." Additionally, aircraft traveling in the area are advised to exercise caution.

The volcano is located in a remote part of the Aleutians, about 35 miles northwest of the World War II outpost of Amchitka and 200 miles west of Adak. 

Little Sitkin joins two other Alaska volcanoes, Iliamna and Cleveland, currently sitting at elevated alert levels.

Iliamna, 130 miles from Anchorage, Alaska's largest city, was first elevated in March of this year following a continued increase in seismic activity. 

"The current level of activity at Iliamna does not indicate an imminent or certain eruption," a status update from the AVO said Thursday. "Seismic activity, along with gas emissions, appear to be declining gradually."

Meanwhile, the oft-erupting Cleveland volcano which, like Sitkin, is located in the Aleutians, remains elevated as well. Cleveland has been upgraded a half-dozen times in since 2010 alone, and most recently erupted in June, when a pilot reported an ash cloud reaching up to 35,000 feet. Cleveland sits at a higher alert level than Iliamna or Little Sitkin, meaning the volcano still has a higher potential for eruption at any time.

For updates on these and other volcanoes across Alaska, visit the Alaska Volcano Observatory.

Contact Ben Anderson at ben(at)alaskadispatch.com