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

by Sandi Doughton

  Many scientists had staked their reputations on a quiet Cascadia. Several of the country’s most famous geologists were on contract with the nuclear industry, as was the chairman of the University of Washington (UW) Geology Department. UW geology professor Eric Cheney went up against his boss and an army of consultants when he sided with a citizens’ coalition of teachers, hippies, and farmers challenging Puget Sound Power & Light’s plan to build two reactors near the Skagit River community of Sedro-Woolley. “At every meeting there were ten of them—and infinitely more money—against one of me,” Cheney recalled.

  Like Heaton, Cheney didn’t think the plants’ seismic analyses passed the smell test. The proponents made claims based on scant evidence. He challenged them to explain how they could be so sure when seismic studies had barely scratched the region’s surface.

  Cheney eventually helped uncover a previously unknown fault running through the hills above the reactor site. It was the final straw for a project staggering under cost overruns and fierce opposition.

  The WPPSS plants at Satsop never attracted the same kind of protest as the Skagit plants. Hammered by the decline of the timber industry and far removed from the state’s urban corridor, the mill towns of southwest Washington welcomed the jobs. But a battle was brewing behind the scenes even before Heaton climbed into his rented airplane. A few clues had trickled in that the Northwest coast might be on the move, rising and tilting in perplexing ways.

  Geologists at the consulting firm WPPSS hired to analyze earthquake risks were concerned the motion might be a sign the subduction zone was locked and building toward a megaquake. They raised the issue innocently and weren’t prepared for the fallout from WPPSS and its prime contractor. “They sort of went crazy,” recalled geologist David Schwartz, one of the leaders of the consulting team.

  The contractor called a hasty meeting to lecture the upstarts on the reasons Cascadia wasn’t a threat. For Schwartz it was the beginning of a year of agony. His job was to finesse the final report in a way the client would accept while remaining true to the science. No wonder it read like a legal document to Heaton.

  “They didn’t want any changes that might upset the NRC and kill the project,” said Schwartz. At one meeting he got into a shouting match with an eminent geologist who represented WPPSS. Heaton attracted his share of flak, too. An angry Oregon official suggested the USGS find something else for the young scientist to work on.

  Heaton and Kanamori paid no attention to the politics. They were busy compiling seismic rap sheets on the world’s subduction zones to compare with Cascadia. No one had taken such a big-picture view, and what the scientists saw was disturbing. Far from being an outlier, Cascadia seemed to be in good company with some of the planet’s most notorious seismic actors.

  Size didn’t matter with the tiny oceanic plate off the coast of Mexico that triggered killer quakes. Japanese records that date back before the samurai era show quiet periods lasting two hundred years or more between quakes on the infamous Nankai subduction zone offshore from Tokyo. To Heaton, the southern coast of Chile provided the most striking parallel to Cascadia. The topography is nearly identical to the Pacific Northwest. The two subduction zones are about the same length, and neither has an obvious seafloor trench. The ocean floor off both coasts is young and warm, which makes it more likely to stick to the overriding plate.

  To their regret, South American scientists in the late 1950s had drawn the same conclusion as their Northwest counterparts, reporting that seismic risks along Chile’s southern coast were slight. A few years later, a magnitude 9.5 quake—the biggest ever recorded—struck the area and triggered a giant tsunami. More than 1,700 people died and 2 million were left homeless. The quake also set off a volcanic eruption.

  “The more we looked at the data, the more similar Cascadia looked to places that have had really large earthquakes,” Heaton said. In their final report, he and Kanamori warned there was no reason to assume the subduction zone off the Northwest coast wasn’t poised to spring with the same force that slammed Chile.

  Published in 1984, the report was more of a landmark for geologists than for the nuclear industry. To the Satsop plants, it was like a leaky faucet on the Titanic. WPPSS was already sinking. The consortium stopped construction on the twin reactors even before Heaton finished writing. His parents were among the 75,000 investors who watched WPPSS bonds evaporate from their pension funds and portfolios. The consortium scrambled for years to bring at least one of the Satsop plants online. When that effort failed, it tried to peddle the reactor parts to China, but the communists declined. Scrap dealers paid pennies on the dollar to cart off equipment worth millions.

  But as the Northwest’s nuclear era fizzled, the fuse was lit for an explosion in seismological research. All of a sudden, the region didn’t seem so boring anymore. “That report really got everybody’s attention,” recalled seismologist Steve Malone, who expanded earthquake monitoring at the University of Washington. News reports introduced Northwesterners to a new term—subduction—and the unwelcome news that they might not be able to thumb their noses at Californians anymore. Community leaders and government officials scratched their heads and wondered how seriously to take the prospect of megaquakes on their turf. Scientists were always changing their minds. Was this real or just a sidetrack?

  Heaton couldn’t say. His case was flimsy, and he knew it. Cascadia wasn’t convicted, merely suspect. Despite the time spent flying and driving the coast, he and Kanamori hadn’t found a scrap of evidence that the subduction zone had ever generated great earthquakes. They had no idea when—or if—earthquakes might strike. Heaton doubted that the truth about Cascadia’s nature would be resolved during his career. The mystery might be solved only if—or when—the subduction zone decided it was time.

  CHAPTER 2:

  WRITTEN IN MUD

  IT WAS BRIAN ATWATER’S THIRD DAY IN NEAH BAY, and the rain hadn’t stopped once. The tiny outpost on the Strait of Juan de Fuca is home to Washington’s Makah people, for whom blustery weather is as much a part of life as sea otters and the tides. But Atwater was a recent transplant to the Northwest. Even his fisherman’s sweater, hand knit from thick wool, couldn’t keep the March chill from seeping into his bones.

  The year was 1986. Clouds shrouded the rocky headland of Cape Flattery, the northwestern-most point of the contiguous United States. Atwater’s destination was a line of hills to the south overlooking a sweep of Pacific beach. He thought he might find evidence there to prove Tom Heaton wrong.

  But bushwhacking the highlands would be tough enough when the ground was dry. While he waited for the weather to clear, Atwater decided to poke around in the small valley that angles like an emerald boulevard between the strait and the ocean.

  According to a story told by Makah elders, seawater once surged across this boggy neck of land and turned the cape into an island. Atwater had heard the tale but wasn’t sure what to make of it. The Connecticut native had joined the tiny USGS contingent in Seattle only a year earlier. His career until then was spent mostly in California. Atwater didn’t study earthquakes, though. His specialty was mud.

  He spent those first soggy days in Neah Bay probing the lowland with a core barrel—a metal pipe with a T-bar handle on top. Over and over he plunged the barrel into the ground and cranked. The cylinders of muck he extracted were as big around as broom handles and about as interesting. Each core was a window into the marsh’s geologic history, which looked uneventful. He screwed three-foot-long extensions onto the barrel to probe deeper underground and further back in time.

  Atwater’s solo expedition was inspired by a USGS workshop he attended in Seattle six months earlier. After Heaton and Kanamori had disturbed the region’s seismic complacency, the USGS invited earthquake experts from across North America to put their heads together on the Cascadia question. Heaton traveled from California to lay out his concerns. Skeptics made their case. All that was missing were facts.

  “It really was a mat
ter of opinion at the time,” recalled John Adams, of the Geological Survey of Canada. “The evidence wasn’t very good one way or another.”

  Atwater wanted to attend the closed-door sessions where detailed discussions took place, but the organizer turned him away. What would a guy who spent his time mucking around in swamps have to contribute? So the young scientist sat with local politicians, business owners, and emergency responders in a hotel ballroom while Heaton presented an overview for the public.

  The jittery audience wanted answers, but Heaton explained that he didn’t have any. Cascadia looked like it might be dangerous, but there was no smoking gun to prove it. The only field data came from tide gauges and highway surveys, and scientists couldn’t agree if the news was good or bad.

  Gauges to track tidal fluctuations and sea level had been installed up and down the West Coast beginning at the turn of the twentieth century. The data were messy, complicated by seasonal variations and storms and broken instruments. Still, scientists thought they could make out a trend. The Northwest shoreline appeared to be rising by increments so tiny they took decades to show up. Adams and others found similar creep when they compared highway leveling surveys from 1900 with measurements eighty years later. If they squinted to factor out the fuzziness, it looked like coastal mountain ranges were slowly tilting to the east.

  If the gauges and surveys were telling the truth—a big if in pre-GPS days—then the ocean floor must be shoving under the continent exactly as expected at an active subduction zone. One camp of geologists argued that the motion proved the plates were slipping smoothly and the subduction zone was toothless. Heaton and others saw the bulge as a red flag, a sign that the plates were locked and building to disaster.

  As Heaton described the ground motions for the Seattle audience, Atwater jotted notes. He might not know much about earthquakes, but he thought he knew a way to settle the debate.

  At Neah Bay the coastline seemed to be rising about a tenth of an inch a year. Geologic processes may be slow, but they grind on for eons. If the Juan de Fuca Plate was slipping harmlessly under North America with no earthquakes, Atwater reasoned, then the coast would have been rising for a very long time. A shoreline at sea level three thousand years ago would be nearly thirty feet higher today.

  “I figured that was something I ought to be able to see,” he recalled. He picked as his target a couple of ponds in the hills behind Neah Bay. He would push cores around the pond margins and pick apart the mud layers in search of saltwater plants and other signs that the ponds had been lifted up from sea level by a benign subduction zone. If he found them, the region could relax.

  It’s just as well Atwater didn’t get the chance to explain his plan to the experts assembled in Seattle. They might have fallen out of their chairs laughing. Mud was something you wiped off your boots at the door to the seismology lab. Earthquake scientists spent their time indoors, analyzing squiggles recorded on a drum as vibrations reverberated through the ground.

  The notion that it was possible to learn something about earthquakes by digging into the ground was so new it had only just been given a name: paleoseismology. One of the pioneers, Kerry Sieh, got a failing grade from his thesis committee at Stanford when he proposed to trench a section of the San Andreas Fault and look for evidence of past movement in the soil layers. Sieh would go on to validate the approach and make the case that paleoseismology was the only way to figure out what a fault had done in the distant past—and what it was likely to do in the future.

  But in the 1980s, field geology was still largely the province of hard-rock men. Many got into the business because they wanted to climb mountains and hike the high country. Their mission was to map the Earth’s ancient bones in search of mineral deposits. Mud, dirt, and anything else that stood between them and bedrock were just crud.

  But Atwater knew the crud had stories to tell. It was as an undergraduate at Stanford, where he overlapped briefly with Sieh, that he learned to read mud the way other people read novels.

  Atwater’s interest in geology was ignited by a field trip to the Grand Canyon and nurtured by the part-time job he landed at USGS headquarters in the Bay Area suburb of Menlo Park. He spent weekends sorting through hundreds of sediment cores extracted from San Francisco Bay in preparation for bridges, some of which were never built. Stored in Mason jars and brass tubes, the cores held a ten-thousand-year record of the bay’s history that no one had fully deciphered.

  To read that record, Atwater learned what the layers had to say about the bay’s ancient past. He tracked the way barren mud flats could grow into lush marshes as sediments deposited by rivers built up over time. He learned to recognize the signature of landscapes drowned thousands of years ago when sea level rose. For his doctoral research, Atwater studied the evolution of the Sacramento–San Joaquin River Delta. He immersed himself in his subject, living fifteen feet below sea level in a mouse-infested trailer.

  That background would prove ideal for stalking earthquakes in the Northwest, but it didn’t seem that way in the unrelenting rain of Neah Bay. He hadn’t found much of anything, and he was sick of being wet.

  It was a melancholy time for the young scientist. He and his wife were mourning the death of their youngest daughter, Sarah. Born with Down syndrome and a weakened immune system, she was the reason the family moved to Seattle. The University of Washington had a special program for kids like Sarah, and she did well there. But just before her second birthday she succumbed to an infection.

  Atwater stayed close to home during those years, giving up most fieldwork in favor of office projects. Neah Bay was one of his first trips since Sarah’s death and he was eager to head home. But he hated to leave a job half done. There was one more place to look.

  A small river called the Waatch meanders through the valley where Atwater was getting doused. As long as he was there, he figured he ought to check out its banks.

  Field geology is a struggle to suss out what lays hidden below the ground without benefit of a bulldozer or X-ray vision. Atwater’s cores were helpful, but they sampled only isolated spots. Like swinging blindfolded at a piñata, it was possible to miss the good stuff. But if cores are snapshots, stream cuts are panoramas—and the water has already done the digging.

  By late afternoon the outgoing tide lowered the water level enough for Atwater to hop over the lip of the stream and drop into the channel. Feet sloshing in the water, he pulled out his World War II-vintage folding shovel and scraped away at the riverbank. A few strokes revealed a thick brown band running through the mud like a chocolate layer in the middle of a vanilla cake. Roots and other bits of vegetation identified the dark band as peat: a soil layer that had once luxuriated in the sun, thick with the same plants that cover the valley today.

  “What do we have here?” Atwater murmured to himself, smoothing the surface. Something in the past had caused the ancient marsh to abruptly drop from above sea level to underwater. After the dunking, the river and tides gradually delivered enough silt to build a new marsh atop the old one.

  Atwater thought back to the Seattle meeting. Heaton hadn’t found uplifted terraces along the coast, but he told the group that didn’t necessarily rule out subduction zone quakes. Although shorelines jerked upward in some parts of Japan, other coastal areas dropped during megathrust ruptures. Atwater also remembered hearing about coastlines in Alaska that fell below sea level in 1964.

  He wondered if what he was seeing in the banks of the Waatch River could be the missing link in the Cascadia story: proof that the Earth had been jolted in the past.

  As the light faded, he loaded his gear into the back of his government-green pickup and drove into town. At Neah Bay’s only store, Atwater bought a postcard. He jotted a few lines describing what he had uncovered and addressed the card to Heaton.

  The two researchers barely knew each other, but Atwater felt a connection. “If I wanted to share what I had just seen, who on the planet would be most interested?” Atwater recalled. “The
only person I could think of was Tom.”

  It wouldn’t be long before the entire region took note.

  On a chilly morning in November 2011, Atwater pulled his truck off a gravel road and jumped out to admire a ditch clogged with ferns and moss-covered branches. Water flowed beneath the tangle, burbling but unseen.

  “The mighty Niawiakum,” he said with a grin. “I do love this river.”

  Nearly two hundred miles south of Neah Bay, the Niawiakum had been Atwater’s next stop in the spring of 1986. Twenty-five years later snow dusted the ground as he drove the back road from South Bend, to revisit the modest waterway that yielded so many stunning insights into the Northwest’s seismic heritage.

  The Niawiakum (nee-uh-WYE-uh-kum) runs a scant five miles from its source in the Willapa Hills of Southwest Washington before merging into Willapa Bay, the shallow estuary that is the nation’s top producer of farmed oysters. By the time Atwater punched his first core there, he wasn’t working blind anymore. The mud wizard had schooled himself on great earthquakes and the strange ways they distort coastlines.

  It was hard to picture how a single type of quake could produce such a mix of effects. In Alaska, parts of Kodiak Island were shoved thirty feet skyward in the 1964 earthquake, the likes of which the United States had never seen. But near Anchorage the hamlets of Portage and Girdwood lost more than six feet of elevation in an instant. Cook Inlet flowed into houses and swamped spruce forests. Crews had to rebuild the Seward Highway to lift it back above sea level. Chile was wracked by a similar mix of ups and downs after its 1960 megathrust quake.

  SIMPLIFIED EARTHQUAKE CYCLE

  The Northwest coast bulges upward between earthquakes when the Cascadia Subduction Zone is locked. The land drops abruptly when the fault ruptures, flooding marshes and leaving clues to a history of tectonic upheaval. (image credits 2.1)