Pay Attention to Our Explosive Neighbors During Volcano Month


May is Washington’s Volcano Preparedness Month, and DNR has all you need to know about how the stunning mammoths dominating much of our skyline handle the geothermal pressure bubbling below.

It will be 40 years since the deadly explosion of Mount St. Helens on May 18. The eruption produced a blast that, traveling at the speed of sound, mowed down thousands of acres of forest and showered hot ash and gases across the landscape. Fifty-seven people died, including two people who were watching the eruption some 25 miles away from the mountain.

We’re here to help you be prepared for when the next volcano blows. T

Washington is home to five major composite volcanoes or stratovolcanoes (from north to south): Mount Baker,Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams. These volcanoes and Mount Hood to the south in Oregon are part of the Cascade Range, a volcanic arc that stretches from southwestern British Columbia to northern California. If you want to check them out, take along DNR’s five-day field trip guide of the Cascade volcanoes.

Aside from the prominent peaks of our five Cascade volcanoes, Washington also has hundreds of volcanic vents scattered across the state. You can see where they are on the Washington Geological Survey’s Geologic Information Portal.

Volcanoes are also the most visual result of plate tectonics, and are one of the few places on Earth where molten rock can reach the surface.

During the past 12,000 years, these volcanoes have produced more than 200 eruptions that have generated tephra (ejected material), lava flows, and lahars (volcanic debris flows) and debris avalanches.


The primary focus of the Washington Geologic Survey is to increase public understanding of geologic hazards and help communities have the best tools to assemble disaster response plans.

Analyzing and mapping possible lahar paths is one of the primary ways we do that.

DNR Geologists have studied lahars as a part of ongoing efforts to map the geology of Washington state. These publications can be searched on the Washington Geology Library catalog.

DNR also has a centralized web catalog of tips and resources to make sure you and your loved ones are prepared for geologic hazards.

Keep your Ear to the Ground all month for information on the volcanic forces that make Washington what it is.

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