The powerful lateral blast that swept across Spirit Lake removed giant trees, leaving splintered stumps such as this one on Harry's Ridge. The areas around the lake were stripped of soil and trees down to bedrock by a tsunami wave produced when the debris avalanche slammed into Spirit Lake. The flat brownish area on the left surface of the lake is a large raft of floating trees swept into the lake. Mount Adams is visible on the horizon beyond the eastern blast margin.

Photo by Lee Siebert, 1984 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Keywords: environmental impact

St. Helens