Scientists had long assumed that the tectonic plates which meet at the Cascadia subduction zone off the northwestern coast slip past each other without causing great earthquakes. Yet the same type of plate in the same type of subduction zone causes horrendous earthquakes in southern Chile and southern Japan. There, snags develop between the plates as they move past each other, the oceanic plate thrusting at a shallow angle downward beneath the continental plate, but getting stuck temporarily in the process.
The forces that drive them, however, do not stop. When two tectonic plates are coming together at a combined rate of four centimeters per year, the pressure will continue to build whether or not the leading edges are snagged, meaning that snags will eventually break. When such a “locked” section does shatter, great earthquakes of a magnitude of 8.5 to 9.5 are the result. And when the earth is lashed by seismic energy of that level, the ocean floor moves, portions of the land and the seabed are thrust upward sometimes in excess of fifteen to twenty feet, and other areas are suddenly submerged by as much as eight feet, with devastating tsunamis created just offshore by the shifting seafloor. In other words, when such gigantic quakes occur, not only are buildings and dams and highways and all the surface works of man subjected to violent shaking for minutes at a time, but coastal areas (and all things and people on them) can be hit by unbelievably powerful surges of water—sometimes in the form of breaking waves—twenty, thirty, or forty feet high.
History had only kept track of the last two hundred years in the Northwest. A great quake just three hundred years ago would be unknown, but another one might already be lurking in the unseen depths of the subduction zone beneath Puget Sound or Portland or Vancouver, building up pressure that would someday be released catastrophically. The thought of that type of destructive earthquake occurring beneath an unsuspecting populace in the Pacific Northwest was a call to action—which is why Tom Heaton journeyed to Seattle in October 1985 to speak to a three-day U.S. Geological Survey-sponsored conference of concerned civic leaders, law enforcement officials, and scientists about that very possibility.
It was a meeting Brian Atwater decided to attend.
Heaton knew that his audience would rather not believe such speculation, and that without hard proof, his carefully researched theories were just that—theories. The largest earthquake anyone had traditionally expected for the Puget Sound region was in the magnitude 7.0–7.2 range, and Seattle had already had two damaging ones in the previous forty years, one in 1949 (magnitude 7.1), and another in 1965 (magnitude 6.5). The claim that something of magnitude 8 or magnitude 9.5 (similar to the type of quake that struck Chile in 1960) could happen in the Seattle area was rather heretical—not to mention frightening. Few of the buildings, the schools, the roads, or the many defense installations in the region—let alone the people—were prepared to survive the type of massive ground motion that such quakes could produce. There were no organized earthquake preparedness projects, no upgraded building codes or emergency response plans aimed at dealing with destruction on a greater scale than even California’s San Andreas Fault could cause. And yet, if he was right, that was exactly the nature of the threat. Bad news of that magnitude is seldom accepted without skepticism.
Heaton, in other words, had an uphill battle, and he needed help from field researchers. He needed evidence—proof—before the general population or his fellow scientists would be sufficiently convinced that the Cascadia subduction zone was anything but tame and benign.1
Before moving to Seattle, Brian Atwater had heard Tom Heaton talk about this at Menlo Park, as Heaton wondered aloud why no one had found evidence of sudden rises in coastal terrain in Washington and Oregon if great quakes did occur there. Could it be that great earthquakes on the northwestern coast drop the terrain rather than raise it? Maybe there was evidence in the ground itself of the sudden dropping of entire sections of coastal land. These would be drops of two, or four, or eight feet that might have occurred over the space of only a minute as the incredible amounts of energy stored in the tortured, snagged rocks of the two plates beneath the Pacific Northwest coastline suddenly let go and readjusted themselves.
To Brian at the time the speech was only mildly memorable. He had too many other things on his mind.
Now, during the Seattle meeting, he overheard a delegate make an offhand comment which suddenly put it all in perspective—convincing him in the process that there was a role for him to play. “We can’t act,” the politician had said, “on conjecture alone.”
In other words, no proof, no action. Theory be damned.
Now Atwater was impressed. The evidence Heaton needed would have to come from the Pacific Northwest, and here he was in need of a new project in the same backyard. In addition, Brian knew he had just the type of background in stratigraphic geology needed to poke around in the recently deposited layers of dirt and rock, sand and silt, looking for clues to what was obviously an intriguing and increasingly urgent seismological mystery.
With a casual go-ahead from his “moneylender” (a USGS seismologist based in Denver who monitored his projects), Dr. Brian Atwater prepared to tackle the challenge.
Little Sarah Atwater died suddenly in January 1986. With the demands of Sarah’s therapy and the family’s intense concern during the previous months, leaving for even a day had been difficult. By February, however, Brian Atwater realized he no longer need be afraid to leave his family occasionally for a few days of fieldwork, and he began the first steps of his probe—a solitary scientist on a quiet, almost invisible investigation into the background of a geophysical phenomenon with the potential to affect the lives of millions.
By March, after some digging into the tidal areas of Whidbey Island north of Seattle, he was ready to look for evidence of sudden rises or subsidence along the Washington coast at the north-westernmost tip of the Olympic Peninsula: Neah Bay, along the Strait of Juan de Fuca.
The area was fascinating to Atwater, as well as varied and beautiful. Even the name of the strait had a convoluted history: Juan de Fuca, it seems, never visited the Pacific Northwest, despite his four-hundred-year-old claims to the contrary.
He was a Greek sea captain who sailed on behalf of Spain in the late sixteenth century under the name Juan de Fuca and who told what is considered a tall tale about finding a great inland sea in 1592 approximately where Puget Sound was discovered 200 years later.2 Whether or not his claim was true, no other European explorers or settlers arrived until the late 1700’s, when Spanish sailors established an outpost for a brief time at Neah Bay.
People had lived at Neah Bay before 1775, of course. The original owners and residents—the Indians of the Pacific Northwest (many of them tranquil tribes in a bountiful land)—had lived in the region for thousands of years.
But theirs was not a written history; it was verbal, and imprecise. Through the twisted sinews of that history there were some tantalizing clues about earthquakes, and one had been documented by an early white settler—an ethnologist and prolific diarist named James Swan, who had wandered from the 1849 gold rush to Puget Sound in the 1850’s (abandoning his wife and children back in New England in the process).
As well as Swan knew and respected the Northwest Indians, it was with substantial caution that he related tales of their legends and histories, lest his readers get the impression that he believed them all to be true. That care, however, gave an air of credibility to his diaries (and one book), which dealt in part with the Makah tribe—the Northwest Indian tribe that considered the Neah Bay area on the northeast side of Cape Flattery their ancestral home.
Tom Heaton and USGS geologist Parke D. Snaveley, Jr., had read Swan’s writings in an effort to uncover some documentation or hint of great earthquakes prior to 1775. What they found was a tale of an incident that resembled a tsunami in some ways, told to Swan by “an intelligent chief; the statement … repeated on different occasions by several others with [only] slight variation in detail.
“A long time ago, but not at
a very remote period, the water of the Pacific flowed through what is now the swamp and prairie between Waatch Village and Neeah Bay, making an island of Cape Flattery. The water suddenly receded leaving Neeah Bay perfectly dry. It was four days reaching its lowest ebb, and then rose again without any waves, or breakers, till it had submerged the Cape, and in fact the whole country, excepting the tops of the mountains at Clyoquot [on Vancouver Island to the north].”3
“Could this be,” wrote Heaton and Snaveley in an October 1985 professional paper, “… an account of a great tsunami? Although there are many features … that seem exaggerated, apparently Swan was convinced a remarkable sea-level disturbance had occurred.”
Now in the misty afternoon of March 24, 1986, the swamp and prairie that the long-deceased Makah chief had spoken of surrounded Brian Atwater, the steady rain still giving sound and liquid form to the low, wispy clouds that shrouded the hills and hung in the tops of the fir trees and western red cedars. With the black layer of ancient meadow now fully measured and probed—pieces of it resting in his sample bag—he could move on to another site by the stream.
Brian couldn’t help leaping ahead mentally to what it meant. Was this in fact the validation of Heaton’s theory? Had this meadow and the surrounding coast for many miles north and south suddenly dropped below high tide level in some prior century during a great earthquake?
The juxtaposition of serendipitous discoveries and scientific discipline has always seemed to crop up in the long history of man’s scientific breakthroughs. The thought that any scientist, no matter how obscure or remote his or her area of focus, might stumble over a major discovery—find the missing piece to a complex puzzle—or single-handedly advance science by individual effort, has spurred countless graduate students and senior scientists alike to keep on looking for answers.
He recalled the pivotal work of another USGS geologist, Dr. George Plafker, and how that one scientist had been so influential in advancing seismology and the subscience now known as plate tectonics, which embraces the growing understanding of how the plates of the earth’s crust behave when they smash into each other at subduction zones. Without plate tectonics as a working, accepted theory, Tom Heaton’s papers and suspicions about the Pacific Northwest would be groundless. The hope of forecasting great earthquakes, in fact, would be far less reasonable or possible a goal.
And what had gotten Dr. Plafker started was simple curiosity: He had been intrigued with the similarities between the great 1960 Chilean earthquake—the hundreds of miles of dropped seashore and uplifted land, the severe shaking, and the ruinous tsunamis—and what happened in Alaska in 1964.
In fact, that one seminal period—1960 through 1964—was the turning point in modern seismology in many respects. There was so much the geological and seismological community did not know at that time, and so much they have learned since; immense advancements in the science resulted directly from the intensive research and increasing governmental and public awareness spurred by the great earthquake disasters of those years. Plafker and others who had studied the Alaska quake knew that documenting and understanding the details of that event—learning the lessons of what it did to the people and the land, and what could have been done to save lives and property had there been a way to know it was coming—were a vital part of reducing earthquake hazards and lighting the way to eventual earthquake prediction.
Did the dark layer Brian Atwater had uncovered record the same sort of great earthquake as those of the early sixties? If the answer was yes, then somewhere in the next minutes or the next few thousand years the Pacific Northwest was destined to experience the sort of seismic cataclysm that had torn into the Alaskan landmass one mild March afternoon twenty-two years before.
Chapter 2
Seward, Alaska—1964
The dog looked puzzled, almost pained, as he stopped in his tracks once more, the cold salt water of Resurrection Bay dripping from his resilient fur. The young husky looked around behind him at the waterfront, across the tracks of the Alaska Railroad, searching for the source of his uneasiness, and finding nothing. His head whipped back suddenly in the direction of home, eyes looking forward at his master standing in the yard. With an almost imperceptible whine he resumed running, bounding again, toward the young man.
The high school senior—an accomplished dog musher even at the age of eighteen—waited uneasily in front of his family’s home, watching the husky galloping toward him, and groping for an explanation of what had been going on for the last hour.
He was proud of this animal, a prime sled dog, and a good pet. And, maybe a future champion in the traces. The pup had possibilities, he was certain.
Pup wasn’t the right word, of course. The young husky was into his second year and was robust—so big, in fact, that when he rode around town on his young owner’s Honda 50 (sitting on the little platform aft of the driver’s saddle), people in cars behind them would almost swear it was the dog that was driving the motorbike all by himself. The boy and his dog were rapidly becoming a vehicular legend in Seward, Alaska.
But the husky’s odd behavior this Friday afternoon was a puzzle. He never went to the beach. He never got in the water. But here it was a clear, windless, hauntingly beautiful March day with a thirty-eight-degree temperature, and the dog had already made two or three trips to the bay, coming back dripping wet each time.
The young man reached down to greet the dog, scratching him behind both ears and rubbing his neck, grabbing his muzzle in greeting.
“What on earth’s gotten into you, boy? Huh? You okay?”
The young husky merely whined, wagging his tail, breaking free suddenly to bound off in another direction beneath the cobalt blue Alaskan sky, the limitless energy of a young sled dog muted somewhat by his obvious confusion.
Shadows from the ridge of mountains—glacier-capped peaks that form the western wall of the town and the western border of the wild Alaskan fjord—always began to creep over the community well in advance of darkness, like a special blue-sky twilight time reserved specifically for people lucky enough to live in deep valleys between majestic peaks. With the clocks showing nearly half past five in the afternoon, the sun was about to disappear behind Mount Marathon, all 4,603 feet of its highest pinnacle a mere 3,600 yards laterally from the almost sea-level city streets of Seward.
From the air—when viewed from the vantage point of high altitude—the tiny community was little more than the faint hint of a Crosshatch of streets, barely discernible straight lines covering a small teardrop of land attached to the upper left-hand corner, the northwest end, of the long twenty-two-mile inlet named Resurrection Bay.
From the ground it was home to a community of friends and strangers nineteen hundred strong who worked at being the rail and highway gateway to the interior of Alaska. It was a community that had just been selected as an All America City by the National Municipal League, a prideful designation which validated to Seward residents their feelings of municipal self-worth and permanancy.
But from the point of view of a geologist, it was a tenuous human development placed on a crescent-shaped fan of loose sand and gravel (known as an alluvial fan), silt and cobbles and boulders washed down from the western wall of mountains on the glacial waters of tiny Lowell Creek and deposited on the northwestern shoulder of the glacier-carved bay over the past ten thousand years (the Holocene Epoch of the Quaternary geologic Period). It was a community built on a mound of water-saturated glacial rubble—nature’s landfill—clinging like a geological afterthought to the entrance of the majestic inlet.
Even to a pragmatic mind, though, this place was evocative of poetically rich images of man and nature in slightly uneasy coexistence.
Which was, in fact, what had attracted Dan Seavey to the area.
Seavey had longed for time in the wild North, time for hunting and fishing and living beneath clean skies in a stand of timber, devoid of phones and the crush of urban life. His wife had finally given up trying to resist the dre
am. They had come to an agreement on the subject. The Seavey family, equipped with three toddlers, would move to the wilds of Alaska for two years so Dan could get it all out of his system. Then, according to the plan, the Minnesota native would take the family back to the Midwest and begin a long high school teaching career in some comfortable farming community. That, at least, was the stated intention.
The Seaveys rolled into Seward in August 1963, renting a house near Third and Adams, four blocks from the waterfront on high ground near the high school, where he had been hired sight unseen as a new faculty member. It was a small high school, with a fascinating cross section of students, many as self-sufficient as the young musher with the motorbike-riding husky.
And it was closed for this holiday, Good Friday, which gave Dan Seavey an opportunity along with another teacher to do some snowshoeing north of town, taking advantage of the snowpack in the upper valleys before the spring melt got under way in earnest.
Seavey was back now, climbing the steps of a friend’s house a half block from his own, the borrowed snowshoes in his hand, having accepted the man’s invitation to come in for a cup of coffee. The bracing, sweet, and dusky aroma of woodsmoke wafting on the crisp, still air blended with the smell of coffee as he stood in the open door, stomping the remaining snow off his boots, glancing around at the bay spread out four blocks below.
A coastal tanker Seavey recognized as the Alaska Standard was moored at the Standard Oil dock on-loading volatile aviation fuel to the whine of generators and pumps, and a switch engine could be heard rumbling and groaning dutifully around the railyards which spanned the eastern waterfront. The familiar sounds were as sharp and clear as the air—which was very still.
In fact, there was no breeze at all, and Seavey had been here long enough to know that was unusual. Normally a stiff wind would be flowing over them from the north on a clear, spring day. But today there was nothing. Not a breath, which made the thirty-eight-degree temperature seem almost warm and comfortable by contrast. Without wind, there can be no wind chill.
On Shaky Ground Page 2