Volcano

Activity at Cleveland Volcano, Aleutian Islands, Alaska

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 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.

Cleveland Volcano, situated on the western half of Chuginadak Island, is one of the most active of the volcanoes in the Aleutian Islands, which extend west-southwest from the Alaska mainland. It is a stratovolcano, composed of alternating layers of hardened lava, compacted volcanic ash, and volcanic rocks. At a summit elevation of 1,730 meters, this volcano is the highest in the Islands of the Four Mountains group. Carlisle Island to the north-northwest, another stratovolcano, is also part of this group. Magma that feeds eruptions of ash and lava from the Cleveland Volcano is generated by the northwestward movement of the Pacific Plate beneath the North American Plate. As one tectonic plate moves beneath another—a process called subduction—melting of materials above and within the lower plate produces magma that can eventually move to the surface and erupt through a vent (such as a volcano). Cleveland Volcano claimed the only known eruption-related fatality in the Aleutian Islands, in 1944.