Katmai National Park, Alaska. The largest volcanic eruption
of the 20th century occurred in 1912. It covered a huge area with volcanic ash,
and filled the valley in the foreground with thick pyroclastic-flow deposits. Once known
as the "Valley of Ten Thousand Smokes", the thick pyroclastic deposits have now
cooled and only a few fumaroles remain. This 1962 air photo shows Trident Volcano erupting
in the background.
Photo by Dave Bogert, National Park Service
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