Fresh debris avalanches and a growing lava dome on Mount Shiveluch illustrate two of the processes that build stratovolcanoes. A stratovolcano is “built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs.” Shiveluch’s lava dome, partially obscured by a plume of gas and ash, is an example of an extremely slow lava flow.
The dome is composed of very thick lava, squeezed out of the Earth like toothpaste from a tube. As the dome rises, rocks and other debris will tumble down the sides. South of the lava dome a fresh debris flow appears dark gray, contrasting with the snow-covered slopes of the volcano. Over time, with layers of lava built on layers of debris built on layers of lava, the volcano grows.
This natural-color image was acquired by the Advanced Land Imager (ALI) aboard the Earth Observing-1 (EO-1) satellite on November 5, 2011. The western (left) side of Shiveluch is cut off because EO-1 was targeted to acquire data for Hyperion, an instrument which allows scientists to study details of the volcano, such as rock types and the composition of the volcanic plume.
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