Global Volcanism Program | Image GVP-06547
The easternmost of the two East Lake obsidian flows forms the sparsely vegetated area in the center of the photo near the SE shore of East Lake. This rhyolitic flow, another one to the west, and associated pumice deposits erupted from fissures parallel to the inner caldera wall.
Photo by Lee Siebert, 1997 (Smithsonian Institution).
This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.