DISASTERS

Alaska's busy volcano: Seawater, magma figure in eruptions

  • In this May 10, 1994, aerial photo provided by Alaska Volcano Observatory/U.S. Geological Survey shows the Bogoslof Island looking south. Trace amounts of ash and the smell of sulfur reached an Alaska city 61 miles away after the latest eruption of Bogoslof Volcano in the Aleutian Islands. Bogoslof Volcano erupted late Monday night, Jan. 30, 2017, and its ash cloud reached 25,000 feet high. The Alaska Volcano Observatory says Bogoslof was quieting down Tuesday. (T. Keith/Alaska Volcano Observatory/U.S. Geological Survey via AP)

    In this May 10, 1994, aerial photo provided by Alaska Volcano Observatory/U.S. Geological Survey shows the Bogoslof Island looking south. Trace amounts of ash and the smell of sulfur reached an Alaska city 61 miles away after the latest eruption of Bogoslof Volcano in the Aleutian Islands. Bogoslof Volcano erupted late Monday night, Jan. 30, 2017, and its ash cloud reached 25,000 feet high. The Alaska Volcano Observatory says Bogoslof was quieting down Tuesday. (T. Keith/Alaska Volcano Observatory/U.S. Geological Survey via AP)  (The Associated Press)

  • An 1895 photo shows the Bogoslof Island seen from the northwest in Alaska. Bogoslof Island or Agasagook Island is the summit of a submarine stratovolcano located along the southern edge of the Bering Sea, 35 miles (56 km) northwest of Unalaska Island of the Aleutian Island chain. Bogoslof Volcano erupted late Monday night, Jan. 30, 2017, and its ash cloud reached 25,000 feet high. The Alaska Volcano Observatory says Bogoslof was quieting down Tuesday. (USGS Denver Library Photographic Collection via AP)

    An 1895 photo shows the Bogoslof Island seen from the northwest in Alaska. Bogoslof Island or Agasagook Island is the summit of a submarine stratovolcano located along the southern edge of the Bering Sea, 35 miles (56 km) northwest of Unalaska Island of the Aleutian Island chain. Bogoslof Volcano erupted late Monday night, Jan. 30, 2017, and its ash cloud reached 25,000 feet high. The Alaska Volcano Observatory says Bogoslof was quieting down Tuesday. (USGS Denver Library Photographic Collection via AP)  (The Associated Press)

An underwater volcano in Alaska's Aleutian Islands has erupted more than two dozen times since mid-December and may keep going for months.

Geologists at the Alaska Volcano Center continue to monitor Bogoslof (BOH-gohs-lawf) Volcano because its ash clouds threaten aircraft.

Most of the 6,000-foot volcano is underwater. The summit forms tiny Bogoslof Island 850 miles southwest of Anchorage.

U.S. Geological Survey research geophysicist Chris Waythomas says at least two factors are at play in the eruptions.

Dissolved gases under high pressure in magma explode when they approach the Earth's surface. Magma also explodes when it comes in direct contact with seawater.

Waythomas says eruptions could end when the system runs out of magma or if the volcano extrudes a dome above sea level, lessening the interaction of magma and seawater.