After the Shaking

When Cascadia hits, water and wastewater systems will be heavily impacted. For a time, faucets won’t flow, and pipes will run dry.

Hand washing, bathing, washing dishes and clothing, and obtaining fresh water for cooking, cleaning… and drinking will no longer be easy tasks. The I-5 corridor will go somewhere between one month and an entire year without water flowing from pipes. Those on the coast are expected to go between one and three years.

When the shaking stops, life in the impacted areas of the Pacific Northwest will feel as though it’s traveled back in time. Communities will be without working light switches, air conditioners, heaters, refrigerators, gas pumps, ATMs, stoves, and (gulp) electronics. Toilets won’t flush, many roads will be damaged, and bridges destroyed. Grocery store shelves will sit empty.

Even for those prepared to be self-sufficient for two weeks, the urge to evacuate the impacted area and head east to a place with running water, working electricity, and food on shelves will be undeniable. Before you decide that you’ll evacuate when the time comes, read about the potential obstacles to consider below.

Traveling by Road

Evacuating will most likely not be possible by car. Here is what the Cascadia Rising Exercise Scenario document states:

The Coast to the Valley

Most of the roads connecting coastal communities to the I-5 corridor may also suffer high damage due to extensive ground settlement. With few drivable routes from the coast to the I-5 corridor, coastal communities along U.S. 101 may be unable to self-evacuate.

The Valley to east of the Cascades

Roads connecting major urban areas in the I-5 corridor with infrastructure in eastern Oregon and eastern Washington may suffer little structural damage to the roads themselves. However, there are only a handful of eastbound routes that run through the steep, mountainous terrain of the Cascades, and many of these routes cross pre-existing landslides. The earthquake could trigger landslides that block or endanger these mountain passes.

Traveling by bike or ATV will work for some, but most who head east will do so on foot. The chart listed here on the left shows the average time it would take for an average, healthy adult to make the journey by foot (with paths in good condition). These times are taken from Google Maps.

Children, individuals with physical and mental disabilities, those injured in the earthquake, the elderly, and anyone out of shape or ill may not be able to move at those speeds listed above. DOGAMI’s Beat the Wave images in the slideshow below provide average walking speeds for impaired vs unimpaired adults, children, and the elderly, as well as walking speeds based on terrain.

The Haul

To be successful, travelers will need to somehow carry enough of the following supplies to make it to their destination.

Medical/First Aid

I don’t know about you, but walking over 100 miles isn’t something I do every week, especially up over a mountain with all the supplies listed above. If you plan to evacuate after the shaking stops, you and your loved ones might need to include a workout routine to train for “the main event”.

Where to Go?

Cities east of the Cascades will have their own infrastructure issues to deal with, as the shaking is expected to break windows, knock items off shelves, and break pipes that may take weeks to fix. The cities will struggle to provide medical care, housing, food, sanitation, and other supplies to the influx of that many people.

Volcanoes & Wildfires

Heading east through the Cascades is a problematic plan, considering that during four months (more or less) every year, they sit primed for the spread of wildfires. If you plan ahead to evacuate and then when the earthquake hits, the route is on fire, that’s a problem. In general, depending on evacuation as a plan means accepting a lot of additional risks and uncertainty. Visit Surviving Cascadia’s Summer Earthquakes page for more in-depth wildfire considerations.

As stated on Surviving Cascadia’s Worst Case Scenario page, earthquakes occasionally trigger volcanic eruptions (with the eruption occurring days to months after the earthquake). For more information on this relationship, visit the USGS PDF, Chain Reaction: Earthquakes that Trigger Other Natural Hazards or their FAQ Can earthquakes trigger volcanic eruptions?

These screen snips taken from DOGAMI’s GIS Maps show estimated Moderate Hazard Zones for volcanic eruptions in Oregon.

Three Sisters

From Three Sisters, the Moderate Hazard Zone flows along the McKenzie Hwy from the mountain to nearly reaching the Eugene-Springfield Hwy in Springfield, OR.

Mt. Jefferson

From Mt. Jefferson, the Moderate Hazard Zone flows along Hwy 22, ending about a mile east of Aumsville & roughly 7 miles east of Salem.

Mt. Hood

From Mt. Hood, the Moderate Hazard Zone flows toward Troutdale, covering the Portland-Troutdale Airport, ending 3.5 miles from the Portland International Airport, and even crossing the Columbia River into Washougal and Camas Washington.

In all three situations, evacuation routes between the Willamette Valley and Eastern Oregon are effectively cut off, especially if conditions in the mountains are prime for the spread of wildfires.

This can be further problematic when new research—some volcanos along the Cascadia arc share magma reservoirs—is taken into consideration. According to the USGS, “Volcanoes that share common magma reservoirs can sometimes trigger unrest at each other.” 

There is, on average, one Cascadia eruption every 50 years. The last one was Mt. St. Helens in 1980. If the next one were to occur as the result of the earthquake, and most communication systems were still down, alerting the public of a possible eruption would be nearly impossible. It’s possible the equipment meant to monitor the volcanoes could be damaged in the shaking, as well.

The University of Oregon and the U.S. Geological Survey, Cascades Volcano Observatory research, Time-evolving surface and subsurface signatures of Quaternary volcanism in the Cascades arc.

Math: 231 events over 11,700 years (Holocene Epoch) = 1 earthquake every 50.65 years, on average.

When to Go?

Since earthquakes don’t have a season, there is no way to know what the weather will be like when it happens. Evacuating in the winter will leave people exposed to dangerously low temps, wind, and snow. Red Cross has a good PDF and webpage on frostbite and hypothermia. Both would be good to read ahead of time if you are considering the evacuation plan. Summer heat requires additional breaks, water, and poses the additional risk of wildfires. Heat safety is another topic to research for the journey.


I don’t have any recommendations for this section, but rather just a thought to consider. If you are planning to walk 50 to 100 miles with supplies, maybe, pushing a cart of some kind, will others attempt to take the supplies from you? It will be hard to keep days worth of food and water hidden, and there will be some who are desperate.

Please take this information into consideration when you and your loved ones are creating your emergency plan. Eventually, helicopters, airplanes—and boats on the coast—will begin evacuating individuals out of the region, but that’s very unlikely to happen within the first 14 days following the earthquake and tsunami. If properly prepared, sheltering in place and waiting to be officially evacuated may be easier than going it alone. Both options, whatever you choose, will take planning.

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