What should you do in Puyallup during a volcanic lahar? Here’s what to expect
AI-generated summary reviewed by our newsroom.
- USGS: no-notice lahars can occur without eruption signals.
- Report: 41% of residents and 46% of homes lie in lahar zone.
- City urges immediate evacuation; sirens, bilingual alerts; drill Apr 23, 2026.
Danger from Mount Rainier isn’t always born from smoke and ash.
According to the United States Geological Survey, the last significant event to happen at Mount Rainier was a no-notice lahar: a swirling mix of mud, ash and rock that happens without an eruption.
Scientists say it could happen again.
During its March 24 meeting, the Puyallup City Council listened to a lahar report from city staff and the USGS, which details the impacts a lahar will have on Puyallup’s safety, emergency response, infrastructure, economy and more.
In a follow-up interview with The News Tribune on April 1, Kirstin Hofman, the city’s emergency manager, said the element of surprise is a hazardous reality of living in the shadow of Mount Rainier.
“The challenge with a no-notice [lahar] is that it can happen at any time,” Hofman said. “That’s another reason Mount Rainier is one of the most-watched volcanoes: the large population that lives in the potential path of a lahar.”
What is a lahar?
According to the USGS, a lahar is a collection of water, rock, dirt and ash that tumbles down a volcano’s slope and into accompanying valleys.
A moving lahar “looks like a roiling slurry of wet concrete,” the USGS website said, and grows in volume as it rushes downstream, swallowing anything it encounters, such as rocks, soil, vegetation “and even buildings and bridges.”
Lahars can happen with or without an eruption. During an eruption, lahars typically happen when snow melts and combines with ash, dirt and rocks, tumbling down the mountain’s slope, the USGS website said.
“Kind of from my understanding, and as a community member’s understanding, a [no-notice] lahar can happen on Mount Rainier because there’s a lot of unstable material, unstable rock, on the western face of Mount Rainier,” Hofman said. “So, the Sunset Amphitheater, that can become loose, turn into a mudslide, mudflow, large quantity of stuff up there. So, it can grow to the size of a lahar that can then leave Mount Rainier National Park and come down the Puyallup River Valley.”
The last lahar to happen at Mount Rainier was the Electron Mudflow, a no-notice lahar that happened 500 years ago, according to the USGS website said. It began as an avalanche of weakened rocks, flowing 60 miles downstream and coursing through the Puyallup River Valley.
Roughly 80,000 people are expected to be impacted in Mount Rainier’s lahar hazard area, the report said. Staff say the city of Puyallup has “the highest number of people and assets” in the danger zone.
The average person has a 1 in 10 chance, the report said, of seeing a lahar reach developed areas of the Puget Sound during their lifetime.
Who in Puyallup will be impacted during a lahar?
In the report, staff noted that 17,424 people live in the lahar zone, which is about 41% of Puyallup’s population. About 46% of Puyallup’s homes are also in the lahar zone.
About 14,805 workers – or 44% of Puyallup’s workforce – work within the danger zone, the report said. The city’s four largest employers are all located within the lahar zone:
- Good Samaritan Hospital: 1,696 employees
- Family Resource Care: 1,500 employees
- Miles Sand & Gravel Company: 800 Employees
- Fred Meyer Distribution Center: 500 employees
Employment sectors most prominent in the lahar zone are health care and social assistance, as well as retail trade, the report said.
What will happen during a lahar?
In the report, staff outlined the following timeline for a “worst-case scenario” lahar modeled by the USGS:
- 50 minutes after the lahar starts, it will reach the outskirts of Orting.
- It will then go downstream, arriving at the meeting point between the Puyallup and White Rivers at the three-hour mark.
- Part of the flow will move north into the White River, while the rest will travel west into the Puyallup River.
- Five hours in, the lahar will arrive “at low-elevation areas surrounding Sumner and Puyallup.”
Hofmann emphasized this does not mean residents have five hours to evacuate. It will take some time before citizens will be aware a lahar is coming.
“People will have in mind, ‘I live in Puyallup, I have a couple hours to eventually evacuate,’ but we don’t know how much time is going to pass between the lahar starting and the notification that people are in that lahar path,” Hofman told The News Tribune. “Which is why it’s so important when people are notified about that, they are evacuated immediately.”
The USGS monitors the equipment on Mount Rainier that tracks potential lahars, Hofman said. Once those systems are triggered, the USGS will ask for confirmation from their scientists before calling the Washington State Emergency Management Division, South Sound 911 and Pierce County Emergency Management.
Those partners tell the city, Hofman said, which is when the city will notify the public through its outdoor warning system and wireless emergency alerts sent straight to their phones.
“That five hours, it may take an hour of that time for USGS to notify, we just don’t know,” said Eric Johnson, spokesperson for the city of Puyallup. “The point is: don’t count on having a lot of time.”
Johnson said much of the city’s lahar preparation will apply to both an eruption and a no-notice lahar.
“Even during a no-notice, we have our sirens, we have our lahar evacuation route,” Johnson said. “So, all of those things will be working. It’s just that with the no-notice, it’s not a traditional eruption that you would see in movies or in popular culture.”
There are 42 sirens in the Puyallup River Valley and Nisqually Valley, according to Pierce County Emergency Management. Johnson said the city of Puyallup has sirens on top of city hall.
During the March 24 meeting, council member Lindsay Smolko asked Hofman how emergency management staff plan to communicate with people who don’t speak English. Hofman said the city partners with the Puyallup School District, where some schools have Spanish immersion programs. The emergency alerts will also be sent in both English and Spanish.
Council member Dennis King said the sirens on city hall will issue audible messages in English and Spanish as well.
How is the city preparing for a lahar?
Puyallup doesn’t allow certain buildings to be built in the lahar zone, the report said, unless they have a reliable alert system and an evacuation plan that allows residents to get out of the lahar range. These buildings include:
- Essential facilities such as fire and police stations, medical facilities, emergency response buildings, jails and power-generating stations.
- Hazardous facilities, which the report classifies as “structures that have toxic or explosive chemicals.”
- Covered assembly buildings that are designed to accommodate a large number of people, such as churches and schools.
The city is preparing for the 2026 Regional Lahar Evacuation Drill on April 23, which is a biannual practice that is the largest volcanic exercise in the world, according to the USGS.
During the drill, five school districts – Puyallup, Sumner-Bonney Lake, Orting, White River and Carbonado – will practice evacuating during a lahar. The drill will be from 9 a.m. to 12 p.m., and districts will take students along the evacuation routes. Districts located outside the lahar hazard zone will practice shelter-in-place procedures.
Hofman said the city will also activate three emergency operations centers for the drill.
“What is so great about the partnership with this exercise is the students and staff participate, they go and they talk to their family members or household members, or people in their community, and this can really encourage those conversations,” Hofman said. “To talk about what to do in a lahar, and really, we’re trying to build that community of resiliency. Planning for a no-notice lahar is not a one-and-done thing, it needs to be, kind of, a constant state of awareness.”
To learn more about the drill, visit laharexercise.com.
How can I prepare for a lahar?
Hofman said she wants to urge residents to practice their evacuation routes, especially because most residents will need to evacuate on foot.
“We know the roads will become very congested, very quickly, and most people will not be able to evacuate using their vehicles,” Hofman said. “So, people in the lahar zone need to be familiar with their walkout route.”
Hofman said residents can learn about evacuation routes by visiting EpicEOC.com/Pages/Lahar. The page has routes for driving and escaping on foot.
Johnson said the city is brainstorming different ways to help seniors, people with disabilities and children to escape during a lahar. In the meantime, Hofman said it is crucial for people in these groups to think of a plan in advance.
“It’s even more important for them to have a plan, to help them, love them, care for them – [talk] about what those plans are,” Hofman said.
Johnson urged residents to sign up for Puyallup Alerts. Hofman said during the March 24 council meeting that these alerts will show up on your phone in the same way an Amber Alert or Silver Alert would.
Puyallup Alerts are for other emergencies too, Johnson said, such as fires or floods. To sign up, visit alertspuyallup.org.
