Full-Rip 9.0: The Next Big Earthquake in the Pacific Northwest

by Sandi Doughton

  A dispatch from Dungeness Spit, a five-mile-long arm reaching into the Strait of Juan de Fuca, reported that the lighthouse “rocked to and fro most alarmingly” and was badly damaged. Vibrations were severe enough at Snoqualmie Pass to knock people off their feet. Proving that human nature hasn’t changed but newspaper writing has, one scribe described the panic: “Nimble old ladies were seen to rush out of doors and into the street looking like human comets with linen tails. One young lady who always wears a profusion of beautiful curls, which she claims were curled on nature’s tongs, was seen to rush into the street,… her head bristling with curl papers.”

  Several correspondents expressed surprise that the quake didn’t seem to have emanated from California. The Puget Sound Express blamed it on Washington’s immediate neighbor to the south: “If it was a genuine ague our mother earth had, she must have caught it in Oregon, as our Territory is comparatively free from bowel diseases.” Lacking seismometers, the citizenry could only speculate about the quake’s size and source.

  Aftershocks continued for more than a year, some so strong that merchants hammered railings onto their shelves to prevent breakage. The owner of a trading post on the Columbia said some of the shocks opened cracks in the ground up to three feet wide. “The inhabitants of the entire region were in a state of considerable fright from the numerous repetitions and the violence,” the Oregonian reported in 1873.

  The earliest earthquake catalogs for the region assumed that the epicenter must have been somewhere in the Puget Sound basin. It wasn’t until the 1950s that a Canadian geologist named W. G. Milne made the first detailed study of the quake. He looked for historical accounts and, finding many in his own British Columbia backyard, concluded the quake must have been centered there. A newspaper in Chilliwack reported a landslide that lopped one thousand feet off the summit of a local peak. Other stories described the ground oscillating like the sea. Acknowledging it was a guess, Milne pegged the quake’s magnitude at 7.5 and drew a bull’s-eye just outside the town of Hope, British Columbia, nearly 130 miles north of Seattle.

  There the quake stayed until the atomic gold rush of the early 1970s. With seven nuclear reactors on the drawing board and predictions that the region would need at least a dozen more to quench its thirst for power, what had been a seismological footnote in the region’s history was now a potential threat to multiple multimillion-dollar projects. For a few years, getting to the bottom of the 1872 quake was geology’s equivalent of the Apollo project. Consultants cranked out so many reports and proposed so many rival epicenters that Bob Royer, Seattle’s deputy mayor during part of the debate, dubbed it “the earthquake that wouldn’t stay put.”

  In order to design a nuclear power plant, utilities must identify the “maximum credible earthquake” the facility could face. If the 1872 quake was really centered in British Columbia, then it wouldn’t be much of a problem for WPPSS. All five reactors the utility consortium intended to build—two at Satsop near the Washington coast and three on the Hanford Nuclear Reservation—seemed safely removed. But what happened in 1872 was a more pressing question for Puget Sound Power & Light. The utility planned to build twin reactors on the Skagit River north of Seattle, uncomfortably close to British Columbia.

  Puget Power dispatched consultants to dig more deeply into the historic record. They visited libraries and museums across the Northwest and pored over old diaries and manuscripts. Among the new sources they uncovered were dramatic stories from east of the Cascades, where the mountains meet the Columbia Plateau and where McBride was well-known. Unfortunately, the reports weren’t timely. Most were recorded decades after the quake when newspapers finally sprang up in the area. But despite the time lag, witnesses were unanimous in recalling massive upheaval near the hamlet of Entiat.

  A man called Wapato John lived in a log house with his family. His son Peter told an interviewer that a ferocious quake struck in darkness with a booming sound like thunder. The force wrenched the cabin apart, and rocks rained down from above. The terrified family huddled in a field until dawn when they could see the extent of the devastation. A geyser spouted nearby and would continue to gush for months. One band of Indians lost its winter food cache when sulfurous water surged from the ground. But most astounding was the Columbia River. A steep hillside had collapsed, damming the territory’s mightiest waterway.

  Trading post owner Sam Miller went to the Columbia to fetch water and was spooked to find it nearly dry. “I would have given every gray hair on my head to have been out of the country,” he told a historian. According to other accounts, Native American women who saw the same strange sight sounded the alarm. People rushed down to see for themselves just as the river broke through the dirt dam. “They saw in the distance coming for them a rush of water,” The Wenatchee World reported. “They ran for their lives and escaped.”

  The gash in the hillside remains unmistakable today. Called Ribbon Cliff for its multicolored bands of rock, it’s more than one thousand feet tall and extends for at least half a mile. Highway 97, which parallels the Columbia, sits on the toe of the slide. Remnants of the slide form small islands in the river.

  Proponents of the Skagit nuclear plants argued that the 1872 quake must have been centered very close to Entiat to wreak so much havoc there. Accordingly, they leapfrogged the epicenter over the Cascades, conveniently distant from their site. WPPSS was not pleased. A quake that had been nearly 250 miles and a mountain range away was now practically in Hanford’s backyard.

  WPPSS and its consultants countered with their own analysis. They dismissed the significance of the Ribbon Cliff landslide, pointing out that it wouldn’t take much of a shake to knock down a slope already undercut by the river. One WPPSS study—later refuted—claimed the slide predated the quake by several years.

  WPPSS also picked at discrepancies in the newspaper reports and questioned the reliability of stories told so long after the fact. “As is common with such legends, memories are distorted and individual accounts are elaborated,” the consultants cautioned. Throwing out all the stories they considered dubious, WPPSS drew its own map and lobbed the quake’s epicenter back where it started: west of the Cascades and north of the Canadian border.

  “It was like a tennis game,” recalled University of Washington geologist Eric Cheney, who represented the citizen’s coalition battling the Skagit nukes. “It would have been comical if it wasn’t so serious.”

  As the ultimate referee, the NRC decided it was time to end the game of seismic hot-potato. Even the utilities agreed. Around the same time the NRC recruited Margaret Hopper and her USGS colleagues to conduct an independent review, the utilities jointly commissioned their own “blue-ribbon panel” to settle on a final resting place for the troublesome quake. The man in charge was Howard A. Coombs, professor emeritus and former chairman of the University of Washington Geology Department.

  An influential figure, Coombs had a hand in every dam construction project across the Northwest. He served as a geological adviser to the Allied Supreme Commander after World War II, helping Japan establish a network of hydroelectric plants. When a dam on Idaho’s Teton River blew out in 1976, killing eleven people and sweeping away thousands of cattle, Coombs was one of the experts called in to investigate. He was also a paid consultant to most of the Northwest nuclear power projects.

  Coombs, Hopper, and their respective teams set off down parallel paths. Each team member independently reviewed the historic reports, gauging their credibility. The scientists ranked the force of the quake at various locations using a measurement scale much older than Richter’s. The Modified Mercalli Intensity (MMI) scale was invented in the late 1800s by Giuseppe Mercalli, an Italian scientist and priest who was also renowned for his studies of Mount Vesuvius. The scale has been tweaked multiple times and still comes in handy. The USGS “Did you feel it?” network uses an online questionnaire to quiz people about their experiences in a quake and the damage they witnessed, the same factors Mercalli focused on.


  A quake with an MMI rating of Roman numeral I is barely a tickle. A IV feels like a convoy of trucks passing by. At VII, everyone runs outside, windows break, and chimneys fall. Only a few quakes in history have attained a rating of XII, succinctly defined as “total destruction.”

  But as Coombs and his team sorted through the accounts from the 1872 quake, one of the things they found most striking was something that didn’t happen: the Omak Rock didn’t fall. Located about thirty miles from the Canadian border in Eastern Washington’s Okanagan Valley, the rock is a forty-ton chunk of granite perched atop a narrow stone base like a golf ball on a tee. The utilities hired yet another consultant to estimate how much force it would take to topple the boulder and what that suggested about the ground shaking in 1872. His conclusions later proved wildly off the mark. But at the time, Coombs and his team found it hard to believe that a powerful quake centered near Entiat, a scant fifty miles away, would have left the Omak Rock upright.

  Hopper was less impressed with the rock. Mercalli’s scale doesn’t mention boulders, so she focused on the effects people reported across the region. “The kind of proof you want is a good report from a reliable person who says, ‘The furniture was knocked over, things fell off shelves, windows broke,’ ” Hopper said. “That’s the kind of thing I can work with.”

  And that’s exactly what the outlaw John McBride seemed to offer.

  From the moment researchers came across it in the archives of a long-defunct newspaper, there was no doubt McBride’s description was vivid and compelling. But was it reliable? “When you’re working with historical data, you take what you get,” Hopper said. Every other account from Central Washington—the tales of Ribbon Cliff and the day the Columbia ran dry, the yarns about geysers, and even the destruction of Wapato John’s cabin—were committed to paper years later. But McBride was chatting with a big-city journalist almost before the dust had settled.

  In his interview with the Portland Press Herald, McBride didn’t explain why he had traveled to Oregon’s biggest settlement a couple of weeks after the quake. But the experience was fresh in his mind. When the shaking started, he told the reporter, he and Ingram were asleep at their ranch on the Wenatchee River, just a few miles from its confluence with the Columbia. The commotion was so loud they thought the stove had tipped over. “They immediately sprang from their couch, and were about donning their clothes, when they were thrown to the floor in a rather sudden manner.” the article said. McBride had weathered two quakes in California, and he quickly realized what was happening. He and Ingram jumped on their horses in the moonlight and headed for the trading post, “the ground undulating in a disorderly manner as they rode along.”

  The trading post owners were in a tizzy, McBride told the reporter. When the quake shook them from their beds, they figured the store was being attacked by Indians. Armed with shotguns and pistols, they found a mess instead of would-be thieves. Flour sacks were strewn on the floor. The roof of the cabin was knocked askew and the kitchen had ripped away from the main building.

  “The effect outside, Mr. McBride says, was terrible,” the article continued. The peaks of several hills were “hurled over and broken” and trees crushed to bits. “Great masses of earth, as if from a tremendous landslide, rushed down the mountainside, mixed with stone and wood, and the gulches lost their identity by being filled with debris.” Some of the shocks were preceded by explosions like “the discharge of several pieces of artillery simultaneously.” Panicked tribal members gathered at the trading post, adding to the chaos. “The entire country was still alarmed and unsettled when (Mr. McBride) left there, fifteen days ago,” the report concluded.

  McBride’s flamboyant narrative implied that the quake’s fury was focused east of the Cascades, which wasn’t good news for WPPSS. But it wasn’t hard to find evidence that impugned the witness’s credibility. There were ledgers from the trading post where McBride and Ingram were frequent purchasers of whiskey. Records also revealed the pair had originally owned the store but were forced to sell as a result of their legal entanglements. When the quake struck, McBride was out on bail, awaiting the trial that would send him to Walla Walla.

  Coombs was inclined to trust the Omak Rock more than this ne’er-do-well. “Some of his observations are open to question,” the blue-ribbon report noted. In the end Coombs split the difference. His blue-ribbon panel put the quake’s epicenter east of the Cascades, which pleased the Skagit proponents, and close to the Canadian border, which pleased WPPSS. “He found a place to park it where it wouldn’t be a problem, and everyone was happy,” Cheney said.

  But if the utilities expected that to be the final word, they should have known better.

  Hopper and her colleagues gave McBride’s account more weight. “It was reasonable enough,” she said. “I didn’t see why he would have lied about it.” Nor did she see any reason to downplay stories from multiple sources about the Ribbon Cliff landslide. The USGS team ranked the ground shaking around Wenatchee and Entiat at level VIII—higher than either WPPSS or the blue-ribbon panel had. That difference, along with a few others, was enough to land the epicenter just north of Entiat, near the south end of Lake Chelan.

  As the 1970s drew to a close, the nuclear plant files were bulging with geologic reports and maps suggesting at least four possible locations for the 1872 quake. In 1979 a University of Washington seismologist weighed in with a different interpretation that put the magnitude at 7.4 and the epicenter in the North Cascades, back in Skagit’s court.

  It didn’t really matter. Public opposition in Skagit County was boiling over, and the project’s budget was out of control. As the Skagit plants foundered, WPPSS was nearing its own precipice. The NRC approved the seismic analysis for the Columbia Generating Station, the only WPPSS plant to go into operation. The study concluded that the biggest historic quake in Hanford’s vicinity was not 1872, but a magnitude 5.8 that struck near the Oregon border in 1936.

  By 1980 McBride and his quake were fading back into obscurity. Two decades would pass before another USGS researcher decided to whack the tennis ball again. Bill Bakun, who worked in the agency’s Menlo Park office, was armed with the latest science, including a method he developed to statistically weigh and cross-reference eyewitness accounts of historic quakes and factor in data about the way seismic waves reverberate in different areas.

  Colleagues warned him off 1872. One described it as a can of worms that Bakun didn’t want to get tangled up in. That only intrigued him more. A Seattle native, Bakun was keen to work in the Northwest. “For me, it was like going home,” he recalled. With the nuclear controversy defused, there was none of the hyperventilating that surrounded the early studies. “No one really cared anymore, so we could look into these things without anybody getting upset.”

  Sorting through the old records again with Hopper, Bakun agreed that McBride made a credible witness. “It’s really important, because if you believe his account, there was a lot of strong shaking there.” But equally important was Bakun’s new approach, which is now used around the world. It did away with the old method of mapping out intensity levels, then drawing concentric circles. Instead, computers crunch the data and come up with a more accurate estimate of where a quake was centered and how big it was. The approach also helped solve the mystery of whether the 1872 quake originated deep underground or on a shallow fault.

  The picture Bakun and his colleagues assembled was unambiguous in concluding that the quake struck on a shallow fault near the southern end of Lake Chelan, just north of Entiat. He pegged the magnitude at 6.8, though with enough uncertainty that it could have fallen anywhere between 6.5 and 7.

  Bakun’s study may or may not be the final word. The Entiat area continues to rumble, with hundreds of small quakes in recent years. Most are tiny, but a few are as big as magnitude 4. It’s enough to make the utilities that operate several Columbia River dams nervous. They’re reevaluating seismic risk and contemplating ways to shore up the structures if
necessary.

  Depending on which magnitude estimate you believe, 1872 was the biggest or second-biggest quake in Washington’s written history. The fact that it struck Central Washington makes sense in light of the tectonic squeezing that continues to crumple the area like a throw rug. “It’s all riddled by faults,” Bakun said. “It wouldn’t surprise me to have a magnitude 6.8 quake anywhere in that region, including near Hanford.”

  During the nuclear rush, geologists scoured the surrounding hills for signs that the 1872 quake broke the surface. They found nothing. But the newest lidar surveys show a suspicious scarp not far from Entiat that Brian Sherrod and his team can’t wait to dig into. If McBride were around, he’d no doubt be happy to wet their whistles while they work—for a price.

  The Northwest’s first seismometer was installed in Victoria, British Columbia, in 1899, nearly thirty years after McBride’s earthshaking experience. The second was set up in 1909 by the Jesuits at Gonzaga University in Spokane. The Catholic order, which has always emphasized the teaching of science, began installing the newly developed instruments at missions and universities around the world in the late 1800s. The Jesuit Seismological Service was once the world’s most extensive. Most of the stations were closed in the 1960s, when an explosion of seismic monitoring rendered them superfluous. By 2012 the Pacific Northwest was wired with more than four hundred seismometers that capture every twitch and automatically spit out epicenter information within seconds.

  But pinning a size on an earthquake remains such a convoluted process that seismologists break out in a sweat trying to explain it to a layperson. The Pacific Northwest Seismic Network, based at the University of Washington, uses three scales, each measuring different properties. One yardstick works only for tiny shakes. Another covers the middle range. The biggest quakes demand a scale of their own.