The David A. Johnston Cascades Volcano Observatory is a volcano observatory in the US that monitors volcanoes in the northern Cascade Range. It was established in the summer of 1980, after the eruption of Mount St. Helens. The observatory is named for United States Geological Survey volcanologist David A. Johnston, who was killed by the 1980 eruption of Mount St. Helens. The observatory's current territory covers Oregon, Washington, and Idaho.
