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Hazards Associated with Pyroclastic Flows at Mount Baker

The last period of pyroclastic flow activity at Mount Baker occurred about 12,500 years ago, shortly after continental glaciers retreated from the area. They were likely generated by failure the fronts of the fronts of lava flows as the lava flows descended over the steep upper flanks of the volcano. Older pyroclastic flows are rare at Baker, but this may be because older deposits have been stripped away by glacial erosion.

When hot pyroclastic debris interacts with snow and ice, lahars are generated. Owing to the large amount of snow and ice on Mount Baker, any pyroclastic flow generated on the upper slopes of the volcano will produce lahars. Large pyroclastic-flow-induced lahars would move into the Baker-Skagit or Nooksack River systems and travel downstream, although flow down the Skagit River would occur only if there is failure of the Baker dams.