Shaken by tsunami alerts, will Oregon residents be stirred to action before the Cascadia Subduction Zone breaks loose — again?

Ashland resident Barbara Cervone published the following post about tsunami danger on Wednesday, Dec. 4, one day before an earthquake off Northern California caused tsunami warnings to be issued along much of the West Coast.

By Barbara Cervone

It is human nature — more or less — to pay attention to imminent risks and risks with which we have experience. On the natural disaster ledger this includes tornadoes in Kansas, hurricanes in Florida, flooding in Pennsylvania, Nor’easters in New England, and forest fires in California (or, gasp, New Jersey). This Thanksgiving, “Lake Effect” snow in five states joined the natural disaster list.

Here in the Pacific Northwest, there’s a risk no one wants to think about: “The Really Big One,” a magnitude 9 earthquake along a 700-mile stretch of coast — from Mendocino in Northern California to Vancouver Island in Canada — followed by waves reaching 100 feet high. Seismologists call it the Cascadia subduction zone, where the oceanic Juan de Fuca Plate moves to the east and slides below the much larger, mostly continental North American Plate.

“The Really Big One,” by all accounts, is unimaginable. In 2015, the FEMA director responsible for Oregon and Washington warned, “Our operating assumption is that everything west of Interstate 5 (which runs north and south roughly 50 miles east of the Pacific]) will be toast.”

A century ago, Oswald West, Oregon’s governor, had the wisdom to preserve the entire 363-mile coastline for public use. Today, the rugged land remains uniquely unspoiled, with old-growth forests, churning surf, and small seaside towns flanked by lighthouses.

On shaking ground

Our second summer in Southern Oregon, Tony and I took a three-day road trip up the coast. Escaping the wildfire smoke that had blanketed the Rogue Valley for a month — not shaking ground — was our North Star.

At Reedsport, due west of Ashland, we joined the two-lane, winding U.S. 101 that traces every bend along the Oregon coast. We soon came upon a dip in the road and a sign that would become our constant companion as we headed north: “TSUNAMI HAZARD ZONE | IN CASE OF EARTHQUAKE, GO TO HIGH GROUND OR INLAND.” A picture of a stick figure fleeing a villainous wave helped make the point. 

A quarter mile later, the road crested, inviting a new sign: “LEAVING TSUNAMI HAZARD ZONE.” The towering wave remained but the stick figure was gone. And so it went, in and out of hazard zones as the road fell and rose. 

We spent our first night in the coastal town of Yachats — pronounced Ya-hots, population 1,000, and considered the gem of the Oregon coast. Rock “haystacks” and parading waves filled our picture window at the Fireside Motel, reminding us of nature’s immensity. Instead of a Gideon Bible tucked in a drawer, though, literature about what to do when a tsunami strikes covered the desktop. The message was clear: If the earth begins to rumble, run for your life, uphill. Ten to 20 minutes separate the earthquake and the tsunami.

My iPad soon led me to Kathryn Shulz’s 2015 Pulitzer-winning article in the New Yorker, “The Really Big One”:

“Other than asteroid strikes and atomic bombs, there is no more destructive force on this planet than water. Six inches of it, flowing at a mere seven miles per hour, will knock a grown man off his feet. Two feet of it will sweep away most cars. Two cubic yards of it weighs well over a ton; if that much of it hits you at, say, 20 miles per hour, it will do as much damage to your body as a Subaru. In rough seas, a regular ocean wave can break with a force of 2,000 pounds per square foot, more than enough to snap a human neck. A rogue wave — one that is more than twice the height of those around it — can sink a 900-foot ship.

“Keep scaling up the water, and you keep scaling up the trouble — a tsunami is not like a regular wave, and it is not like a rogue wave; it is more like a rogue ocean. It forms, most often, when an earthquake shifts the seabed and displaces all of the water above it. That displaced water does not crest and fall; it simply rises, like an extremely high tide, until the entire water column is in motion, from seafloor to surface. Then it rolls inland, with 10 or 20 or 60 miles of similar waves at its back, and demolishes everything in its path.”

No exit

The next morning, Tony and I tried plotting our tsunami escape. You must understand the geology here, where the mountains touch the ocean and higher ground is largely inaccessible. We checked out the five-plus “evacuation” routes in Yachats: they ran about 150 feet uphill before they hit steep slopes, rocks, forest — and ended. 

If we did make it to higher ground, the prospect of surviving up to two weeks outdoors with little food or water seemed daunting. “Even under the best of circumstances, medical aid or fire and law enforcement officials may not be able to reach you for days,” the pamphlet “Living On Shaking Ground” warns.

We concluded there was no exit.

 “There aren’t many injuries in the tsunami zone,” one seismic expert with the Oregon Department of Geology and Mineral Industries said. “People just die.”

Searching for clues

What brought my thoughts back to one of the biggest hazards on our planet was an article in Monday’s Washington Post: “Tsunami researchers hunt for clues about the next big Pacific Northwest quake.” The subhead was no less catching: “A massive earthquake will one day rattle the Pacific Northwest. Minutes to hours later, a surge of seawater will swallow the land. No one knows when.”

I learned that this past summer a team of tsunami detectives, covered in waders and knee-high muck boots, trudged into soggy marshes at the mouth of Oregon’s Coquille River on the hunt for buried catastrophes.

“Finding this record intact isn’t easy,” wrote Washington Post reporter Carolyn Johnson, who had joined the team.

The paleoseismologists laced their way through waist-high marsh grasses, searching for the legendary “1700” — a 9-magnitude temblor that, according to Japanese records, “struck the Pacific Northwest, causing sudden land subsidence, drowning coastal forests, and, out in the ocean, lifting up a wave half the length of a continent. It took roughly 15 minutes for the Eastern half of that wave to strike the Northwest coast” (The New Yorker, July 13, 2015).

Searching for clues more than 300 years later, the team thrust the pointy tip of a cylindrical metal tool called “the Russian” deep into marshy sediment, twisted it like a corkscrew through layers of peat, sand and roots, and yanked up a core. They did this again and again and again.

“To a layperson, these cores would be an unintelligible tube of waterlogged sediment. But to these paleoseismologists, they were part mystery, part puzzle, part history book,” Johnson wrote.

Although the data is still sparse — digging cores is brutal work — seismologists now believe that there have been at least 19 major, megathrust earthquakes triggered at the Cascadia Subduction Zone in the past 10,000 years.

When geological time catches up to our own

None of this work can answer the question at the top of most people’s minds: When is the next big one coming? To be a seismologist in the Northwest is to be a Cassandra.

At the risk of repeating myself, the scale of risk is unfathomable. A 2022 FEMA plan warns of ground-shaking that lasts five minutes, more than 600,000 buildings toppled or damaged, 13,800 deaths and more than 100,000 injuries. The economic losses from the earthquake alone have been estimated to reach $134 billion.

“This is one time that I’m hoping all the science is wrong, and it won’t happen for another thousand years,” FEMA’s Kenneth Murphy says. Currently, scientists are predicting that there is about a 37% chance that a megathrust earthquake of 7.1+ magnitude will occur in the next 50 years.

For my part, my partner Tony and I have made seven more trips to the Oregon coast since our first in 2019. Twice we have driven the entire length. We have hiked through old-growth forests and along precipitous cliffs falling to the ocean. We’ve savored deep coves, beaches covered with driftwood, tide pools, and waves lined up as far as we could see. One day, on our hike to Cape Lookout — a 300-foot high rock jutting 2.5 miles into the Pacific and one of the best whale-watching sites on the Pacific coast — the wind was so fierce we could barely stand and dense fog cloaked the view. It was exhilarating.

Lighthouses dot the coast and we have hiked to all of them. These safety sentinels from an earlier time, we remind ourselves, would be among the first structures to go in “The Really Big One.” 

This past September, Tony and I stood transfixed at our favorite viewpoint in Yachats, watching the sun set on an uncharacteristically tranquil ocean and wondering how such a devastating disaster could lurk beyond the horizon.

But there is a fundamental story here. In a world where human-made climate disasters increasingly abound, “The Really Big One” stands apart: it is a wrinkle in geologic time. However herculean the task of redressing the practices contributing to climate change — from replacing fossil fuels with alternative energies to protecting and restoring forests — the business of altering tectonic plates is way beyond our reach. We have our hands full simply respecting our planet and each other.

Barbara Cervone moved to the Rogue Valley five years ago after 50 years in the urban Northeast. She spent her professional career championing public schools that serve all students well. A passionate writer, she has Bachelor of Arts and Doctor of Education degrees from Harvard University. Read her “Postcards from the Rogue Valley” at postcards-from-the-rogue-valley.blog. Email Cervone at [email protected]