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 USGS.
Lahar Warning System
Upgrade & Expansion Project
Join this FREE webinar to learn about the five active volcanoes in the Washington Cascades, their hazards, and how you can be better prepared for an eruption!
Thursday, May 13, 2021
1:00 p.m. to 2:30 p.m. (PST)
Unable to attend the live webinar? Fear not! A link for the presentation will be posted on the Washington State Emergency Management Preparedness webpage.
- Lahars on Mount Rainier - USGS
- Mount Rainier Hazards - USGS
- Volcanoes and Lahars - Department of Natural Resources
- Automated Lahar Detection Systems - USGS
- Are You Ready for An Eruption?
- Volcanic Hazards in Washington State
- Evacuation and Preparation
- Are You Volcano Ready?
- Pacific Northwest Seismic Network (PNSN)
- What did the previous test siren sound like?
- How Mount St, Helens Changed Our World