Mount Rainier

Mount Rainier

Did you know Mount Rainier is an active volcano?  While we can't say how many times Rainier has erupted over the course of its existence, we do expect it to erupt again someday.  The only questions is matter of when, and to what degree.

A Mount Rainier eruption will place the Puyallup valley at risk of catastrophe from a lahar, which is a volcanic mudflow that can reach 100 feet in height and travel 45 to 50 miles per hour. According to the United States Geological Survey (USGS), "Lahars look and behave like flowing concrete, and they destroy or bury most man-made structures in their paths." 

Should Mount Rainier erupt, everyone in the valley will need to avoid the oncoming lahar by evacuating to higher ground. It's for this reason that the lahar warning siren system is tested on the first Monday of each month, and it's also why we provide a map showing recommended Volcano Evacuation Routes.

Learn more about Mount Rainier and lahars, courtesy of the 

Evacuation Routes & Hazard Maps

Bridge destroyed by lahar North Fork Toutle River

Bridge destroyed by lahar in North Fork Toutle River during eruption of Mount St. Helens, May 18, 1980.  

(Credit: Waitt, Richard. Public domain.)

Open for Comment & Public Meeting


The National Park Service (NPS) has released an Environmental Assessment (EA) for the proposed Lahar Detection and Volcano Monitoring System Expansion at Mount Rainier National Park. The EA is available for review and comment through June 25, 2021. Click on the "Open for Comment" link to access the EA and appendices.

A virtual public meeting for those interested in learning more about the proposed lahar detection system and alternatives is scheduled for Wednesday, June 9 from 4:30 pm to 5:30 pm.  S
taff from Mount Rainier National Park and the U.S. Geological Survey, Cascades Volcano Observatory will discuss the project and how you can be involved in the planning process. There will be a short presentation on the monitoring system at 4:30 pm, and park staff will be available to answer questions.

Meeting Directions/Instructions:
Meeting ID: 993 3385 0415

URL/Webinar link:

New Program Connects Girl Scouts to Volcanic Neighbors

Girl ScoutsJust in time for the 41st anniversary of the 1980 eruption of Mount St. Helens, Girl Scouts of Oregon and Southwest Washington (GSOSW) announced today a brand new program, Our Volcano Neighbors, developed in partnership with the Mount St. Helens Institute (MSHI) and the United States Geological Survey (USGS). The program aims to teach girls about the cultural and geographical significance of Mount St. Helens and other volcanoes through hands-on STEM activities, career exploration and outdoor adventures.

Lahar Warning System

Upgrade & Expansion Project

Pierce County Department of Emergency Management (PCDEM) expanded the number and reach of the outdoor warning sirens in 2020. PCDEM has 42 sirens in the Puyallup River Valley and the Nisqually River Valley. The recently upgraded sirens will have more capabilities to notify people of emergencies. They include voice warnings in English and Spanish, flashing lights to reach vulnerable populations, and verbal instructions based on the emergency.

Testing happens the first Monday of each month.  The new test siren will sound similar to a Westminster chime on a clock. You can hear the tone and verbal instructions for the test by clicking here.

To learn more about the updates, visit Pierce County Department of Emergency Management.

Past Webinars

Volcano Webinar

What to Expect When You're Expecting a Volcanic Eruption: Learn about the five active volcanoes in the Washington Cascades, their hazards, and how you can be better prepared for an eruption.

To watch other recorded webinars, visit the Washington State Emergency Management Division.