Aleutian volcano spews up ash cloud in two strong bursts

Aleutian volcano spews up ash cloud in two strong bursts
This Monday, Jan. 6, 2020, photo provided by Aaron Merculief shows lava flowing from a vent on the Shishaldin Volcano, as seen from Cold Bay, Alaska about 58 miles North East of Shishaldin. The volcano, in Alaska's Aleutian Island erupted at 5 a.m. Tuesday. A few hours later, another eruption pushed an ash cloud to 25,000 feet, and the National Weather Service issued a warning for passing aircraft. Seismicity significantly decreased after noon. (Aaron Merculief via AP)

A volcano in Alaska's Aleutian Islands spewed ash into flight paths, prompting a warning to pilots by the National Weather Service.

Shishaldin Volcano erupted at 5 a.m. Tuesday, the Alaska Volcano Observatory announced, and sent up an initial to 19,000 feet (5791.2 meters). Clouds initially obscured the mountain, but confirmed the ash cloud, U.S. Geological Survey geophysicist Hans Schwaiger said.

Seismicity diminished for a few hours, but it then increased again. During the increase, the spewed an ash cloud to 25,000 feet (7,620 meters), the observatory announced. The later eruption increased the volume of ash.

Wind continued to push the ash cloud northeast into the eastern Bering Sea and away from jet airliners flying between North America and Asia.

However, the National Weather Service upgraded its alert level to a warning. Trace amounts of ash were expected to fall on communities as far away as Sand Point about 140 miles (225 kilometers) east of the volcano.

Seismic activity greatly diminished after noon.

The eruptions were confirmed by lighting and , the observatory said. More explosions could occur or activity could significantly decrease with little warning, according to the observatory.

Aleutian volcano spews up ash cloud in two strong bursts
This Monday, Jan. 6, 2020, photo provided by Aaron Merculief shows lava flowing from a vent on the Shishaldin Volcano, as seen from Cold Bay, Alaska about 58 miles North East of Shishaldin. The volcano, in Alaska's Aleutian Island erupted at 5 a.m. Tuesday. A few hours later, another eruption pushed an ash cloud to 25,000 feet, and the National Weather Service issued a warning for passing aircraft. (Aaron Merculief via AP)

The observatory first detected increased seismic activity at the volcano. Elevated indicated active lava at the vent in the volcano summit, the observatory said.

Volcanic ash is angular and sharp and has been used as an industrial abrasive. The powdered rock can cause a jet engine to shut down.

The volcano is 679 miles (1,093 kilometers) southwest of Anchorage near the center of Unimak Island, the largest island in the Aleutians. False Pass, a village of 40 people, is on the island's east side. Unless winds change, the cloud would move north of False Pass and would not pose a threat, Schwaiger said.

Shishaldin also erupted Dec. 12, producing an ash cloud that reached up to 25,000 feet (7,620 kilometers), and on Friday, sending an ash cloud to about 24,000 feet, (7,315 meters).

The volcano is a symmetrical cone that is 10 miles (16 kilometers) in diameter at its base. It rises to 9,373 feet (2,857 meters) and is the highest peak in the Aleutians.

Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc. It has had at least 54 episodes of unrest, including more than 24 confirmed eruptions since 1775, according to the observatory.

Most eruptions are small. An event in 1999 spewed an ash column that reached 45,000 feet (13,716 meters).

The volcano is monitored with seismic and infrasound sensors, satellite data, a web camera and distant infrasound and lightning networks.


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Alaska volcano sends up ash cloud from Aleutian Islands

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