When the massive Cascadia earthquake hits the Pacific Northwest, the deadliest threat to people’s lives might not be the convulsing earth, but what gets released into the air.
Multnomah County emergency staff say a 9.0 magnitude earthquake — which scientists predict could happen in the next 50 years — would likely release deadly plumes of hazardous materials from industrial facilities. Depending on the weather and time of day, these plumes could kill thousands of people, and injure thousands more.
Emergency managers delivered the dire news in a report to the Multnomah County Board of Commissioners last week, and offered few immediate solutions. They recommended county leaders partner with other county, state and federal officials to develop a more comprehensive understanding of the region’s risk to chemical exposures following a megaquake. They also recommended a public education campaign to help people living in high-risk areas become aware of the best ways to protect themselves.
The report also suggests the county consider drafting and advocating a bill for a statewide study of hazardous materials at industrial facilities.
Multnomah County Chair Jessica Vega Pederson said she would send the report to Gov. Tina Kotek along with a letter requesting “an urgent public policy response.”
“My colleagues on this board and I will not be satisfied with platitudes or promises,” she said at the board’s Oct. 12 meeting. “We will work towards solutions that these threats demand of us and ask the state to act quickly and thoughtfully to address this crisis.”
State lawmakers last year passed a bill requiring industrial facilities at a hub in Northwest Portland begin submitting seismic hazard assessments to the state. Those facilities, known collectively as the Critical Energy Infrastructure Hub, are located along a six-mile stretch of the Willamette River. About 90% of the state’s fuel supply is transported through the hub, where there are 415 active storage tanks. Of them, 91% were built before 1993 — that’s when the state started implementing basic seismic standards for chemical storage. Given their age, these fuel tanks are likely to experience at least some level of damage during a major earthquake, according to a 2022 report.
That report estimates that about 95 million to 194 million gallons of petroleum product would be released from the hub, almost half of which could flow into the Willamette River. Researchers expect significant fires will break out. Given the right conditions, those fires could spread to Forest Park, threatening more than 70,000 people.
For this month’s report, Multnomah County emergency managers assessed other high-risk industrial facilities in the county, many of which are concentrated in North Portland near the convergence of the Willamette and Columbia rivers. That area is also the most vulnerable to destruction resulting from liquefaction. That’s when earthquake shaking breaks up soil near bodies of water, creating a quicksand effect that can compromise above-ground storage tanks containing fuels and chemicals.
Multnomah County has 1,100 industrial facilities that store chemicals, known as Tier II facilities. Many of the top 70 high-risk facilities are located in areas where the soil will liquify during a major earthquake.
Portland State University Institute for Sustainable Solutions / Portland State University Institute for Sustainable Solutions
If that happens, poisonous plumes could spread through much of the county and beyond, causing injuries ranging from mild eye irritation to deadly respiratory problems. Given the right conditions — say, a near-windless summer day — up to 2,500 people could die and 17,000 people could be injured in Multnomah County, according to the report. Another 330,00 people could experience eye irritation.
County emergency management officials partnered with Portland State University researchers and other governmental agencies to come up with the predictions based on various data and studies. They identified the top 70 highest-risk industrial facilities in the county; of them, 27 are located in North Portland. Those facilities store a variety of potentially dangerous chemicals, including hydrochloric acid, sulfur dioxide, hydrogen chloride, anhydrous ammonia and diesel.
Emergency management director Chris Voss explained the storage facilities were built atop ground that will likely liquify during a major earthquake.
“We have a history here,” Voss said with a pause. “We have a history of putting hazardous chemicals on our worst soils.”
Many of those facilities chose North Portland because of its proximity to ports and river transports, Voss said. When they were built, land-use planners weren’t yet aware of the area’s considerable liquefaction risk. It wasn’t until 2010 that scientists forecasted the Pacific Northwest had a one-in-three chance of a megaquake in the next 50 years.
Another reason industrial facilities were concentrated in North Portland: The land has historically been affordable, Voss said. The area also has higher poverty rates compared to the rest of the county. According to census data, the 97203 zip code — the St. John’s neighborhood where researchers predict a significant concentration of deaths related to post-earthquake chemical release — about 22% of the population lives below the poverty line, compared to the overall county’s 12%. As such, some of the county’s most economically vulnerable population is also most threatened by post-earthquake chemical plumes.
The report focuses on four industrial facilities in North Portland, and how chemical releases from them would impact the county following a major earthquake. They predict the deadliest weather conditions could be in the summer, when winds are low, allowing the plume to remain concentrated.
Portland State University Institute for Sustainable Solutions
The report focuses on four facilities in North Portland and maps how hazardous chemicals could spread from those locations given average weather conditions in summer and winter. The report keeps the names of the facilities anonymous to “minimize the risk of this information being used to intentionally cause harm.”
Researchers in the report explain that the chemical exposures would come when roads are clogged or damaged from an earthquake, limiting first-responders’ ability to help people experiencing serious respiratory problems. Water treatment facilities could also be damaged, which would restrict people’s ability to wash their eyes and bodies immediately following a chemical exposure. And while first responders would generally advise people to shelter-in-place following a toxic airborne event, an earthquake could compromise many homes and buildings by shattering windows and crumbling walls.
