Global Volcanism Program | Image GVP-05384
Lava flows cover large parts of the Okmok caldera floor on NE Umnak Island, some of which erupted during historical time. The small lakes within the caldera are remnants of a larger lake that filled the caldera to depths of more than 200 m before overtopping the rim and eroding a 180-m-deep notch through the northern caldera wall.
Photo by Chris Nye, 1980 (Alaska Division of Geological & Geophysical Surveys, Alaska Volcano Observatory).
This image is made available as a Public Domain Work, but proper attribution is appreciated.