How well do you know USGS volcano observatories? Part 1: Cascades
Mount St. Helens in December 2004, a few months after the start of the volcano's most recent eruption, as seen from the Johnston Ridge Observatory in Mount St. Helens National Volcanic Monument in Washington. Inset: The USGS Cascades Volcano Observatory in Vancouver, WA, monitors volcanoes in Washington, Oregon, and Idaho. USGS photos.