Alaska Volcano Observatory

Looking east over the eastern half of Fisher caldera. Shishaldin (left) and Isanotski volcanoes are in the background. The eastern caldera lake is on the left, and the far end of this lake marks the eastern caldera wall. The caldera wall is also seen as the dark ridge in the middle ground. Note the blonde phreatomagmatic surge deposits that cap all prominent ridges in the eastern portion of the caldera. The likely source of these surge deposits is the maar crater just south (right) of the eastern caldera lake. The summit of Mt. Finch, with a small crater lake, is in the foreground. Blonde areas on Mt. Finch are hydrothermally altered areas from fumarolic activity rather than surge deposits.