USGS HOME
Contact USGS

  • About
  • Observatories
  • Activity
  • Education
  • Publications

Volcanic Hazards at Glacier Peak

Glacier Peak tends to erupt explosively, and when the volcano reawakens the most serious hazards will impact population centers located relatively far away from the volcano. The mountain is within a wilderness area, and although it is isolated, areas downwind and downstream would be impacted by tephra, pyroclastic flows, and lahars. Towns of Darrington, Rockport, Concrete, Sedro Woolley, Burlington, Mount Vernon, and La Conner lie in the Sauk and Skagit river valleys, which have been inundated by lahars in the geologically recent past. Winds over Glacier Peak are usually directed to the east; therefore airborne tephra may travel over much of the United States and Canada. Towns to the east, such as Winthrop, Twisp, and the Methow River valley are most likely to receive tephra fall, but if a very large eruption occurs ash fall will be broadly regional, and international, in scope.