Volcano Profile: Glacier Peak

Washington State Geology News

Glacier-01Location: Snohomish County, WA

Elevation: 3,213 m (10,541 ft)

Nearby towns: Darrington

GEOLOGY

Sitting relatively low on the skyline, Glacier Peak is mostly hidden from Puget Lowland residents, yet it is one of the more dangerous of the Cascade volcanoes. The volcano frequently and explosively produces dacite lava flows, tephra (ash) and far-reaching lahars (volcanic mudflows).

Geologic mapping has documented the extent of previous lahar runout in the Skagit and Stillaguamish river valleys. While Glacier Peak has shown no sign of eruption in the last few decades, lahar deposits in river valleys from past eruptions are reminders of the hazards Glacier Peak poses to nearby communities.

Lahar hazards are determined in part by figuring out where lahars traveled in the past. Evidence of massive lahars is abundant in many of the valleys that drain Glacier Peak. The above map shows the distribution of lava flows and lahars mapped at the surface. Volcanic hazard areas are shaded gray…

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