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Cascade Eruptions

By Michael Stephens

Located on the northeastern rim of the seismically active Ring of Fire the West Coast of the United States serves as a hotbed for boundless volcanic activity. Many of the more sizable peaks in the Cascade Range, stretching from British Columbia in the north to California in the south, house volcanoes - considered dormant but very much alive - that have shaped our region for hundreds of thousands of years.

Most dangerous U.S. volcanoes

The United States Geological Survey rated the most dangerous volcanoes in the United States, and it comes as no surprise the peaks of the Cascades made up the majority of the spots on the list.

Four peaks in Washington, three in Oregon, two each in California and Hawaii plus one each in Wyoming and Alaska filled the first 13 spots.

Preparedness month

The USGS in May provides Washington residents an opportunity to become more familiar with volcanic risk in their communities and learn about steps they can take to reduce potential impacts.

Activity versus age

Mount St. Helens (40,000 years old) is a baby compared to the other Cascade peaks . It’s very volatile, often erupting multiple times per century compared to much less activity from its older “sisters”.

Recent eruptions in the Cascades

In the last 100 years or so, the state has seen three major eruptions with Mount Adams in 1921 and Mount St. Helens, first (and most famously) in 1980 and then again in 2004.

Mount Mazama

Oregon’s Mount Mazama erupted almost 7,700 years ago, creating the caldera that holds the striking Crater Lake. The eruption was 42 times more powerful than Mount St. Helens in 1980 and reduced a peak of over 12,000 feet to the 8,157 feet it is today.

Mount Rainier

Though its sister volcano Mount St. Helens erupted first in terms of recent history, Mount Rainier possesses a more powerful and potentially dangerous punch whenit erupts in the future.

Decade volcanoes

Sixteen volcanoes identified in the 1990s as being worthy of further study because of their history of large, destructive eruptions and proximity to populated areas.

The Decade volcano project aims to achieve a better understanding of the volcanoes and the dangers they present.

A volcano may be designated a "Decade" if it exhibits more than one volcanic hazard, shows recent goelogical activity, is located in a populated area, is politically and physically accessible for study and there is local support for the work.

Dangers of Mount Rainier

Large glacial buildup around the peak means Mount Rainier possesses the capacity upon reuption to create giant, destructive mudflows called lahars (a slurry of pyroclastic material, rocky debris and water).

When paired with large population centers in Tacoma and Seattle, hundreds of thousands of residents could be at risk in the event of a major eruption.