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On Shaky Ground
America's Earthquake Alert
By John J. Nance OPEN ROAD INTEGRATED MEDIA
Copyright © 1988 John J. Nance
All rights reserved.
ISBN: 978-1-5040-2800-4
CHAPTER 1
Neah Bay, Washington — 1986
He seemed terribly out of place — barely visible in the midst of a wet, verdant meadow — crouching suspiciously at the edge of the small tidal stream which meandered with picturesque abandon toward the waters of the Pacific Ocean less than a mile to the south.
The visual richness around him was startling. The spruce-carpeted ridgeline to the east bordered the short, green valley that ran only a few feet above sea level from the Strait of Juan de Fuca on the north end to the ocean beaches on the south end, almost making an island of the highland mountain to the west. That lone mountain, covered with western red cedar and spruce and standing 1,395 feet above sea level, was the northwestern most piece of real estate in the continental United States: Cape Flattery.
From the eye of a passing eagle, watching the solitary human through the hanging mists of a Pacific Northwest late afternoon, the meadow seemed a tranquil, peaceful setting. For uncounted afternoons it must have looked the same, the majesty of nature at its finest, accompanied by the gentle sounds of softly flowing stream water in the foreground, riding lightly over the basso profundo thunder of crashing surf and boiling sea-foam in the distance, in concert with the gentle patter of raindrops falling like an afterthought through the foggy air.
The valley and the people of the Makah Indian tribe had coexisted in functional harmony for centuries, the patterns of daily human life molded to the imperatives of the seasons, blending into the backdrop of falling rains and flowing waters. But the actions of the lone figure at streamside were in contrast with those patterns — unusual, audacious, and unfamiliar. With short strokes of a camp shovel chopping into the dirt and sand of the embankment, Brian Atwater was obviously searching for something — a geological detective looking for evidence nature was suspected of hiding.
Atwater looked around at the ghostly image of the tree-covered ridge to the west, barely visible through the steady rain which had been dampening his spirits and seeping through his rain gear for much of the day.
He glanced back to the east, conscious of the rise in the landscape on that side — conscious that the area between the two sides had probably once contained the free-flowing waters of the Pacific Ocean, making Cape Flattery, to the west, a true island.
He had expected that. He had expected to find some evidence that this meadow had evolved from an ocean inlet.
But Atwater was not expecting what his shovel had just uncovered on the first series of thrusts: a black line — a flat layer — running horizontally through the sand and silt which formed the wall of the streambed.
What on earth did it mean?
There, several feet down from the top of the bank where the grasses and roots of the meadow above were anchoring a thin layer of humus — below several feet of loosely compacted gray sand with the remains of dead grass roots embedded here and there — the sand suddenly, abruptly rested on a layer of black peat.
Brian stared at the layer at first, struggling to put it into perspective.
"Okay, what do we have here?" The words were spoken to the riverbank, and to himself — a practiced, professional breakpoint between action and analysis.
He began digging into the peat then with a knife, finding the buried stems of grass like plants killed long ago interlaced in the dark material. It looked, in fact, like the remains of a brackish-water marsh, perhaps from some previous century — a marsh which had been buried so quickly and deeply by sand that its soil had been preserved.
But how could that be?
If a great ocean wave — a tsunami — had overrun the ancient meadow, could giant waves or surging salt water have washed up that much sand to cover the area completely? Or could the entire marsh have suddenly dropped below sea level?
One thing was indisputable: The layer of peat in front of him definitely existed, and that meant something catastrophic had happened in this beautiful place. But when?
He poked at the peat some more, satisfied there would be enough material to send for analysis. Once a properly equipped lab had measured the amount of radioactive decay in the carbon, he would have a reasonably close idea of how long ago the marsh had died.
Brian Atwater began digging again in earnest, spading away at an adjacent wall of the stream bank, standing on the narrow bank between water and dirt wall, exposing more of the black layer that had surprised him. His feet were protected from the water seeping around his knees by the hip waders he was wearing, while a knitted watch cap diverted much of the drizzle from his head. Even with the protection of a coarse wool sweater (a hand woven gift from his sister), the pervasive cold had distracted him.
No longer, however, was he conscious of the chill in the air. This was far too intriguing.
Atwater knew some of the theories, of course. That was why he had come to Neah Bay and Cape Flattery looking for a record of changes in the level of the land — evidence of how much it had risen or fallen relative to sea level over the centuries. He was aware of the work of a young seismologist in California, Dr. Tom Heaton, who along with several others had found some scary similarities between what was happening to the ocean floor off the coast of the Pacific Northwest, which did not seem to have a history of great, damaging earthquakes, and what was happening off the coasts of southern Japan and southern Chile, which did.
Atwater knew that Heaton had developed a substantial amount of circumstantial, scientific evidence that the Pacific Northwest should be no different from those areas of Chile and Japan that had been rocked by earthquakes so great that they were capable of killing thousands of people and producing unbelievably huge tsunamis. Such quakes were the result of incredible planetary forces shoving the ocean floor (oceanic plates) into and beneath the equally thick plates of rock which formed the major continents. It was a process called subduction in which layers of rock, each one miles thick, were being shoved in opposite directions, snagging against each other for centuries at a time, and building up incredible pressure year by year as a result.
Along the Pacific Northwest coast, the battle line between the tectonic plates was called the Cascadia subduction zone, and Tom Heaton had a growing suspicion that it was dangerous. If he was correct, the immense pressures which would inevitably build up between any snagged crustal plates as they strained to move past each other would eventually overcome the snags and release the energy, causing great, catastrophic earthquakes in the process.
But Tom Heaton was hamstrung without hard evidence. While the last monstrous quake in southern Chile — one of the most powerful earthquakes in recorded history — had rocked the South American coast in 1960 killing fifty-seven hundred people, and southern Japan had been hit by quakes in 1944 and 1946, there was no recorded history of great earthquakes (with magnitudes above 8.0) in the Pacific Northwest from Vancouver, Canada, all the way south to the redwood forests of Northern California. If they had occurred in the Northwest, the last one must have been before white settlers arrived in the late 1700's.
Brian Atwater stopped his digging, momentarily unsure. What if this peat layer was not continuous? What if he couldn't find it elsewhere — couldn't validate what he was sure it had to represent: a suddenly deceased marsh from centuries past? That was always a possibility, but if the next few days of digging did find the same layer at different points, it would be time to head for the local post office in Neah Bay to send a postcard to Tom Heaton. He had never corresponded with Heaton before, but tempered by normal scientific caution, Brian was beginning to get excited.
It was by chance he was there to begin with. In 1985 he had moved his family to Puget Sound to be closer to medical and therapeutic help for his young daughter Sarah, a Down's syndrome child who had suffered brain damage from meningitis.
The family home had been in San Francisco, California, a forty-minute train ride from Menlo Park, the locale of the western headquarters of the U.S. Geological Survey (USGS), for which Brian Atwater had worked as a geologist since 1973.
But the San Francisco Bay area is an expensive place to live, and Sarah's disabilities were proving difficult to combat — problems which did not escape the attention of Dr. Atwater's USGS managers. They encouraged the young geologist to find a place where the best medical care would be available.
That place was Seattle, which held the teaching hospital at the University of Washington, a Down's syndrome specialty center. With great human caring and concern — and no small expense — the Geological Survey transferred Brian, his wife, Fran, and their daughters Sarah and Patricia to the Pacific Northwest in the fall of 1985, even though no one had any clear idea what projects the thirty-four-year-old geologist would work on once he settled there.
The move helped, and the professional reception was gracious: The chairman of the university's Geology Department gave Brian an office on campus almost immediately (a recognition of the value of having a USGS scientist in residence). It was a gesture that helped keep the workplace, their new home, and the hospital where little Sarah underwent frequent therapy, all within blocks of each other. And it was the best that could be made of a difficult situation.
Even before leaving San Francisco, Brian Atwater had figured he could make himself professionally useful in his new Seattle posting by mapping poorly identified areas of seismic (earthquake) risk and seismic shaking around Puget Sound, a sort of mapping that was sorely needed.
There was, however, an area of research which needed his skills even more — a project which could meld the fields of seismology and geology in search of answers to new and disturbing questions about the exposure of the Pacific Northwest to great earthquakes. It was a scientific need he knew little about — until he heard Tom Heaton address a Seattle seminar in October 1985.
Heaton, a thirty-four-year-old seismologist Ph.D. from the California Institute of Technology, had come to speak to the group because he knew the possibility of great quakes in the Pacific Northwest couldn't be ignored. If the enormous section of the ocean floor off the coasts of Washington and Oregon did produce great earthquakes, they held the frightening potential for damage and destruction and deaths to the people and structures of the Pacific Northwest on a scale never before imagined.
Shaped roughly like a huge triangle with its hypotenuse running parallel to the coastline some eighty miles offshore, that particular part of the planetary crust along the northwest coast had been named the Juan de Fuca plate and it had some unusual characteristics. As all the so-called plates which make up the earth's crust, it too was forever in motion. As seismologists like Heaton had come to understand, new lava was constantly coming up from the depths of the planet's interior at the western boundaries of the plate as it moves approximately 2 centimeters per year toward the east. At the eastern edge, however, the plate meets the rather impressive obstacle of the North American continent — the North American plate — which at the same time is moving westward at the same steady speed of at least 2 centimeters per year, driven by the same sort of mid-ocean lava flows (known as crustal spreading) more than five thousand miles away in the middle of the Atlantic Ocean. The colossal collision between the plates has been going on in very slow motion for literally tens of millions of years, but that motion — as Heaton had patiently explained to so many — is the basic engine which created most mountain ranges, volcanoes, and earthquakes on earth.
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.
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.
(Continues...)
Excerpted from On Shaky Ground by John J. Nance. Copyright © 1988 John J. Nance. Excerpted by permission of OPEN ROAD INTEGRATED MEDIA.
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