Hobbies And Interests

How Many Volcanoes Have Erupted in Alaska?

The Alaska Volcano Observatory monitors more than 130 volcanoes. Of those, about 50 have been active since records were first kept in 1760. The AVO measures seismic activity created by underground pressure and magma movement. The observatory also uses GPS and EDM (electronic distance meters) to measure changes in the size or shape of the volcano as magma moves closer to the surface and steam, in the form of various chemicals, is released. Using a correlation spectrometer, scientists can measure the most common chemical--sulfur dioxide. Satellites help monitor volcanoes for which seismic information is not yet available.
  1. Mt. Redoubt

    • Mt. Redoubt is about 100 miles from Anchorage, Alaska. On March 15, 2009, Mt. Redoubt had what is called a phreatic explosion, meaning erupting magma came into contact with water, in this case snow, causing almost instant evaporation and an explosion of steam, rock, and ash. Since March 15, Mt. Redoubt has continued to erupt and is under constant surveillance by the AVO.

    Novarupta Volcano

    • The largest eruption on Earth in the 20th Century was June 6, 1912, near the village of Kodiak. By the last day of the eruption on June 9, the ash cloud had reached Seattle, Washington, and by June 17, it had passed over Algeria. The ash and sulfur dioxide clouds were devastating to local communities and to wildlife.

    Mt. Akutan

    • Akutan is one of Alaska's most active volcanoes. Located on Akutan Island in the eastern part of the Aleutian chain, Akutan is a stratovolcano with a caldera, meaning it has steep sides formed from many layers of hardened lava. At its summit is a depression formed when an eruption collapsed the top portion of the mountain. The AVO has recorded 33 confirmed eruptions there since 1765. The last confirmed eruption was in 1992.

    Mt. Pavlof

    • Pavlof is another stratovolcano. Its name comes from the Russian for St. Peter and it has 32 confirmed eruptions to its credit. Near Cold Bay, Alaska, Pavlof is part of a stratovolcano complex that has been active since 1762. Pavlof's last reported activity was in 2007.

    Mt. Shishaldin

    • Located on Unimak Island in the Aleutian chain and rising 9,373 feet above sea level, Shishaldin is a stratovolcano fewer than 10,000 years old. Confirmed eruptions on Shishaldin began in 1775, with its last eruption recorded in 2004. It has had 24 eruptions.


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