America’s highest-risk volcanoes are right here in Washington

By Gordon Williams

The U.S. Geological Survey recently published a new ranking of the nation’s most dangerous volcanoes, and Washington State is arguably at the top.

The latest ranking updates a 2005 report, listing Kilauea in Hawaii as the most threatening volcano, followed by Washington State’s Mount St. Helens and Mount Rainier. Also in Washington are Mount Baker (14th place) and Glacier Peak (15th place). All four in-state volcanoes fall into the “high-risk” category.

Mount Hood, just across the border in Oregon, ranks sixth on the list. Washington’s fifth active volcano, Mount Adams, while down in 34th place is still considered risky.  All the state’s five active volcanoes are in the Cascade Range.

The rankings don’t try to predict when a volcano might erupt but of the potential for great damage should they erupt. Kilauea did erupt in 2018, destroying more than 700 structures and covering 14 square miles in lava on the big island of Hawaii. The eruption of Mount St. Helen in 1980 caused damage over a 250-square mile area.

Mount St. Helen blew its top at precisely 8:32 a.m. on May 18, 1980 — 39 years ago and the reason for May to be designated as Volcano Preparedness Month in Washington by the state’s Emergency Management Division.  For a list of volcano-related events, visit the Emergency Management website at https://www.mil.wa.gov/emergency-management-division.

Declaring a volcano active, does not mean it is in imminent danger of erupting but that it has erupted in the past 10,000 years. Mount St. Helen is the most active of the five Washington volcanoes, with a whole series of eruptions between 2004 and 2008 and intermittent activity since.

Visit RedCross.org for information about Volcano Preparedness

When a volcano does erupt, it can do harm in a great many ways. Shock waves from the initial blast can knock down trees and buildings. Volcanic ash and fumes from the eruption can fill the skies — making breathing difficult, if not downright hazardous. Red hot lava from the eruption can spread for miles –burying everything in its path.

Beyond all this is the risk of a lahar pouring down from the volcano’s slopes–sweeping away all in front of it. A lahar is a mudslide created by the sudden melting of the snow and ice that once covered the mountain. The eruption of Mount St. Helen created a lahar that swept the ground for miles. Lahars from other eruptions have been known to stretch out as far as 50 miles.

Mount Rainier is something of a special case among volcanoes. The state’s Emergency Management Division calls it “one of the most hazardous volcanoes in the United States.”

The report explains that Rainier “has produced at least four eruptions and numerous lahars in the past 4,000 years.”

The slopes of Rainier are steep and it is covered by more glacial ice than the rest of the Cascades combined. An eruption of Mount Rainier could trigger a lahar of unimaginable proportions. As the Emergency Management Division notes, “More than 150,000 people live on former lahars in river valleys below the volcano.”

Unlike earthquakes, which hit without warning, volcanoes usually sound some alarms before they erupt, such as increased seismic activity, and increased venting of smoke and gases. That gives you some time to prepare. But prudence suggests you plan ahead if you near an active volcano, whether there is an imminent risk of eruption or not.

The Red Cross Emergency application, available at both the Apple and Google online stores, urges a family planning session so everyone knows what to do in case of an eruption, “Discussing ahead of time helps reduce fear, particularly for younger children,” says the Red Cross app.

Keep a battery-powered or crank-up radio on hand that can receive emergency messages even if local electric service is interrupted.  As a general precaution, have a pair of goggles and a face mask for each member of your family. The Red Cross also suggests talking to your insurance agent to determine what your homeowner’s policy will cover (or not cover) in an eruption.    

If there is an eruption while indoors, close all windows, doors and dampers to keep volcano ash out. Put all machinery in a garage or barn to protect it from ash–or at least cover it with a tarp. Don’t operate machinery until all the accumulated volcanic ash has been cleaned out, get all pets inside to protect them from breathing volcanic ash.

If you are outdoors, try to get indoors as quickly as possible. While still outdoors, avoid low lying areas. Try to stay upwind of the eruption, so ash and gases aren’t blown your way. If ash is falling, cover as much skin as possible. Wear glasses but remove contact lenses.

Keep listening to a local radio or TV station for any word from the authorities managing the event. If you are told to shelter in place, stay indoors until you are told it is safe to move outside.  If you are told to evacuate, because of threatening lava flows or lahars, do so at once. Get your family to a place of safety before the eruption brings danger to your door.

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