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Alaska Volcanoes: the view from above
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Alaska contains more than 130 volcanoes and volcanic fields, most of which are now inactive. Since 1760, 27 Alaskan volcanoes have had more than 230 confirmed eruptions, according to the Alaska Volcano Observatory.
This averages to nearly one eruption per year. If we add in those volcanoes and eruptions that are suspected but unconfirmed (and often, unconfirmable), then we have 54 volcanoes with about 424 possible eruptions, yielding an average of 1.7 eruptions per year.
Currently, three are defined as in the "restless" stage--hinting at possible eruptions. They include Mount Redoubt, Cleveland, and Shishaldin.
In 2006, astronauts aboard the International Space Station (ISS) photographed the Cleveland volcano, shown above, and reported the first signs of a new eruption, according to NASA's Earth Observatory:
At 3:00 p.m. Alaska Daylight Time on May 23, 2006, Flight Engineer Jeff Williams from International Space Station (ISS) Expedition 13 contacted the Alaska Volcano Observatory (AVO) to report that the Cleveland Volcano had produced a plume of ash. Shortly after the activity began, he took this photograph. This picture shows the ash plume moving west-southwest from the volcano’s summit. A bank of fog (upper right) is a common feature around the Aleutian Islands. The event proved to be short-lived; two hours later, the plume had completely detached from the volcano. The AVO reported that the ash cloud height could have been as high as 6,000 meters (20,000 feet) above sea level.
Cleveland and Shishaldin are currently at "Code Yellow", which the USGS defines as:
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level,volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
The hot spot is Mount Redoubt, currently being monitored 24/7 as it continues in a "Code Orange" state. AVO experts installed two new seismic monitors at Redoubt yesterday. They're expecting that bad weather will obscure views from webcams in the near future.
Image credit and information/ Astronaut photograph ISS013-E-24184 was acquired May 23, 2006, with a Kodak 760C digital camera using an 800 mm lens, and is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Group, Johnson Space Center. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed.
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