GLACIER PEAK | Lahar Map | USGS fact sheet
Snohomish County's Glacier Peak is the most remote of the five active volcanoes in Washington State, and more than a dozen glaciers descend it's flanks, prompting it's name.
Glacier Peak is not prominently visible from any major population center, and so it's attractions, as well as it's hazards, tend to be overlooked. Yet since the most recent ice age, this volcano has produced some of the largest and most explosive eruptions in the United States. Since the most recent ice age, it has erupted multiple times during at least six separate episodes. Glacier Peak and Mount St. Helens are the only volcanos in Washington State that have generated very large explosive eruptions in the past 15,000 years. During some of these eruptions, Glacier Peak erupted massive volumes of volcanic ash that was carried eastward by winds. Lahars (volcanic mudflows) rushed down the same river valleys that now sustain farmlands and communities.
MOUNT BAKER | Lahar Map | USGS fact sheet
Dominating Whatcom County’s skyline, Mount Baker is the playground of outdoor enthusiasts. Mount Baker is also an active volcano. The most recent eruption of Mount Baker was about 6700 years ago but explosions, collapse and lahars and a reheating in 1975 reminded local people of the volcano’s potential. On cold, clear days, you can see steam plumes rising from its crater. Mount Baker will erupt again, disrupting the landscape and the lives of people downstream and downwind.
During an eruption at Mount Baker, you can expect:
There will be warning. Future eruptions will be preceded by days or more of increased earthquakes and, possibly, by measurable swelling of the volcano and the increased emission of volcanic gases. USGS-CVO monitors the volcano for signs of unrest and provides public notifications.
- Lahars (volcanic mudflows caused by melting of snow and ice) that flow for tens of miles down valleys.
- Ash fall, even during small eruptions, that disrupt air and ground transportation and dust our forests, farms, and towns with gritty rock fragments.
While an eruption or lahar might not happen in our lifetime, being prepared is our best defense. A little time and effort spent in preparation now could keep you, your family, and your community safe when Glacier Peak next erupts.
Ice-clad beauties cause hazards during eruptions
Get to know the hazards.
Lahars (volcanic mudflows) can flow for tens of miles down valleys. Ash fall, even during small eruptions, can disrupt air and ground transportation and dust towns with gritty rock.
During an eruption, expect the following:
Mount Baker—lahars and some ash fall
Glacier Peak—lahars and substantial ash fall
There will be warning. Future eruptions will be preceded by increased earthquakes, and possibly by measurable swelling of the volcano and the increased emission of volcanic gases.
Is your community eruption ready?
A few moments spent in preparation now can keep you and your family safe during the next eruption.
Mount Baker dominates the skyline of northwestern Washington and southwestern British Columbia. Glacier Peak is more hidden from view. Both volcanoes have erupted in recent centuries, and will erupt again, disrupting the landscape and the lives of people downstream and downwind.
Glacier Peak has produced some of the largest and most explosive eruptions in the state. A massive eruption 13,000 years ago was ten-times larger than the 1980 eruption of Mount St. Helens. Ash from this eruption has been found in the peat bogs of Ireland. Photo by J. Scurlock
The most recent activity of Mount Baker occurred in 1847 when a lahar flowed into the Baker River Valley. A reheating in 1975 reminded local people of the volcano’s potential. On cold clear days that follow damp weather, condensation of water vapor causes a vigorous steam plume. Photo by D. Tucker
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