Glacier Peak, Washington simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.
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Glacier Peak, Washington simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.

Map showing one-year probability of accumulation of 1 centimeter (0.4 inch) or more of tephra from eruptions of volcanoes in the Cascade Range.
Map showing one-year probability of accumulation of 1 centimeter (0.4 inch) or more of tephra from eruptions of volcanoes in the Cascade Range.
Glacier Peak volcano viewed from the west, Washington.
Glacier Peak volcano viewed from the west, Washington.

The orange layer just below geologist's hiking pole is the Mazama ash (about 7700 ybp). Below that are glacial deposits. Above the Mazama is about a meter consisting mostly of fine-grained tephras from Glacier Peak, capped by soil and plants. That the tephras sit directly on top of the Mazama indicates that "Dusty" eruptions commenced about 7,000 years ago.
The orange layer just below geologist's hiking pole is the Mazama ash (about 7700 ybp). Below that are glacial deposits. Above the Mazama is about a meter consisting mostly of fine-grained tephras from Glacier Peak, capped by soil and plants. That the tephras sit directly on top of the Mazama indicates that "Dusty" eruptions commenced about 7,000 years ago.

Impressive columns like these form along the margins of ice-confined lava flows but usually are eroded off the sides due to continued glacial movement after an eruption ceases. Columns are better preserved at the ends of the flows (this photo) where they are protected somewhat from the ice.
Impressive columns like these form along the margins of ice-confined lava flows but usually are eroded off the sides due to continued glacial movement after an eruption ceases. Columns are better preserved at the ends of the flows (this photo) where they are protected somewhat from the ice.

Eruptions in the Cascade Range during the past 4000 years. USGS GIP 64
Eruptions in the Cascade Range during the past 4000 years. USGS GIP 64
Videos

Jon Major, scientist-in-charge of the USGS Cascades Volcano Observatory, provides an overview of the major volcano hazards in the Cascades, the function and responsibilities of the Cascades Volcano Observatory, and a brief synopsis of what's been going on at Mount Baker, Glacier Peak, Mount Rainier, Mount Adams, Mount St.
Jon Major, scientist-in-charge of the USGS Cascades Volcano Observatory, provides an overview of the major volcano hazards in the Cascades, the function and responsibilities of the Cascades Volcano Observatory, and a brief synopsis of what's been going on at Mount Baker, Glacier Peak, Mount Rainier, Mount Adams, Mount St.
The 1980 eruption of Mount St. Helens was monumental in so many different ways. It had a huge impact on the geography of southwestern Washington, ash affected many people, lives were lost, and lessons were learned. The eruption also led to the creation of the USGS Cascades Volcano Observatory in Vancouver, Washington.
The 1980 eruption of Mount St. Helens was monumental in so many different ways. It had a huge impact on the geography of southwestern Washington, ash affected many people, lives were lost, and lessons were learned. The eruption also led to the creation of the USGS Cascades Volcano Observatory in Vancouver, Washington.