World

Alaska Aleutian Islands volcano erupts again, spews ash that could threaten aircraft

AP

A volcano in Alaska’s Aleutian Islands has sent up another ash cloud that could threaten aircraft, the Alaska Volcano Observatory announced.

Shishaldin Volcano erupted at 5 a.m. Tuesday, said Hans Schwaiger, a geophysicist with the U.S. Geological Survey, one of the agencies that make up the observatory.

Elevated surface temperatures indicated active lava at the vent in the volcano summit, the observatory said.

The observatory first detected increased seismic activity at the volcano. When clouds parted, a satellite recorded images of an ash cloud to 23,000 feet (7,010 meters) and a plume that led back to the vent, Schwaiger said, meaning the eruption had continued after 5 a.m.

Wind blew the ash cloud northeast into the Bering Sea and north of the route used by jets flying between North America and Asia. The National Weather Service issued an ash cloud warning for aircraft to 23,000 feet (7,315 meters).

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 km) 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 km), and last Friday, sending an ash cloud to about 24,000 feet, (7,315 meters).

The volcano is a symmetrical cone that is 10 miles (16 km) 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, with 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).

More explosions could occur with little warning, according to the observatory. The volcano is monitored with seismic and infrasound sensors, satellite data, a web camera and and distant infrasound and lightning networks.