Glacier Peak labeled one of nation's most dangerous volcanoes. EVERETT, Wash. (AP) - The U.S. Geological Survey has decided to keep a closer eye on the slumbering giant in Snohomish County's wild, scenic back yard. A new study is under way for Glacier Peak, one of the most dangerous but least monitored volcanoes in the country. Scientists are working to map Glacier Peak and the valleys and peaks to the west - about 482 square miles total - using Light Detection and Ranging, or LiDAR.