So on April 4, Osborne and Plafker took off in the Cordova Airlines Widgeon on what amounted to a grand tour of the sound. While Osborne dropped off the mail, Plafker talked to survivors about the quake and jotted down information about the land deformation in his field notebook. In most cases he didn’t have time to do any actual surveying, but he didn’t need to. People who live by, and off of, the sea know their tides, and in this part of Alaska the tides had been altered by the quake. They told Plafker of the changes, and that was all Plafker needed to know, for now, about what had happened to the land.
At Tatitlek, the first stop, the village postmaster told him that the high tide was four to six feet lower than it had been before the quake, indicating that the land had risen that much. Other than that, though, Tatitlek had not been badly affected. The shaking had caused little damage—though it had made the church bell ring—and people had not been knocked off their feet, as they had elsewhere. The water had receded from the shore at one point, but unlike at Chenega, there had been no tidal wave.
The story was much the same at the next stop, nearby Ellamar. There had been no tidal wave and no one had been hurt, although there had been some damage—a chimney had collapsed and five windows were shattered. A man named Carl Aranson told Plafker that the quake was the worst he’d ever felt, that the shaking had made the furniture move around inside his house and had caused him to fall over when he ran outside.
In all, the Widgeon made seventeen stops that day. Plafker interviewed people at almost every location and took photographs everywhere. He and Osborne visited Port Nellie Juan, where the three members of the Chimovisky family had died, and other canneries at places like Port Oceanic and Port Ashton, where the winter watchmen had survived and told Plafker what they’d experienced. The Widgeon landed at Peak Island, practically in the geographic center of the sound, and at the two big islands along its southeastern edge: Hinchinbrook and Montague. When no people were around to tell him how the tides had changed, Plafker occasionally surveyed the shoreline himself. Osborne served as his rodman, or assistant, standing near the water’s edge with a stadia rod, essentially a long ruler. Plafker, on higher ground where he found evidence of the prequake tide line, sighted through a hand level—a small scope with a leveling bubble inside it—and read the markings on the rod, subtracting six feet for his height. Often he wouldn’t even need to use the leveling bubble—he could just line up the scope with the far-off horizon over the water and be assured that he was getting a level measurement.
In the afternoon they flew back to Cordova to refuel for a longer flight southeast into the Gulf of Alaska, to Kayak Island—where the Coast Guard lighthouse keeper had lost his life—and, finally, Middleton.
Middleton Island had long been home to small groups of fox farmers and, for about five years until it was deactivated in 1963, an air force radar installation. A mere four miles long and a mile wide, Middleton sits alone in the middle of the gulf, directly exposed to the Pacific, which comes rolling in on the Japanese Current. As a result, plenty of driftwood and other debris washes up on the island. Plafker remembered this from the year before—piles of graying driftwood at the back of the island’s beaches, where they had been left by high winter tides.
When Osborne eased the Widgeon down at Middleton, one look at the shoreline told Plafker all he needed to know about the earthquake’s impact. Those driftwood piles he’d remembered from the summer before were now much higher; they looked to be about eight feet above the high-tide line. The waves would never reach them again.
—
Plafker returned to Anchorage on April 6 and, after a final reconnaissance flight to Kodiak, spent his last few days interviewing survivors, including Kris Madsen, who was soon to leave Alaska for good. She told him what she had seen of the tidal wave at Chenega from her vantage point above the schoolhouse. Plafker also interviewed some of the surviving villagers, and witnesses to tidal waves elsewhere, and was developing an understanding of what had happened at the various communities around south-central Alaska. But a lot was still unknown about why events had unfolded as they did.
On April 10 the three geologists packed up their notebooks, maps and photographs and boarded a Pacific Northern Airlines flight for San Francisco. They had been on the ground in Alaska for thirteen days. Now their job was to write about what they had learned about the Good Friday earthquake.
At the Geological Survey’s offices in Menlo Park, they kept interviewing survivors and witnesses by phone. Plafker talked with Captain Stewart of the Chena and an official in Crescent City, California, among others. But mostly he and his colleagues compiled data, gave it to a team of cartographers and chart makers assembled for the project and started writing. Grantz handled much of it, but all three of them participated, working essentially nonstop for two more weeks. On April 27, just a month after the quake, the Survey published Circular 491, “A Preliminary Geologic Evaluation” of what it called “Alaska’s Good Friday Earthquake.”
The report ran to thirty-five pages, twenty of which were maps and photographs. On the title page, below their three names, were the place and date of publication: Washington, 1964. Plafker, who was proud of what they had accomplished, thought it should have been more specific: April 27, 1964, to show readers just how fast they’d done the work.
In plain, straightforward language, the opening paragraph set forth what had happened: “At 5:36 p.m. on Good Friday, March 27, 1964, a great earthquake with a Richter magnitude of 8.4 to 8.6 crippled south-central Alaska. It released twice as much energy as the 1906 earthquake that wracked San Francisco, and was felt on land over an area of almost half a million square miles.”
The circular detailed the immediate effects of the quake—the rockslides and avalanches, the cracks and mud spouts and the cracked ice and pressure ridges on frozen lakes. It inventoried the damage to the state’s roads and railroads, dock facilities and canneries and schools and other public buildings. (Damage to military infrastructure and, certainly, damage to the nuclear missiles in Anchorage were not part of the report. The Pentagon would deal with all of that on its own.)
Circular 491 described the destruction in Anchorage, Seward, Whittier, Valdez and other communities and noted the cause of it: seismic shaking, slides, tidal waves or some combination of all three. The geologists had been able to learn more about what had happened in some communities than others. They had a good understanding of the slides in Anchorage, for example: they included a fairly detailed description of the role of the slick Bootlegger Cove Clay and even a three-step, cross-sectional diagram that showed how the Turnagain Heights slide had progressed. They knew that the waterfronts of Valdez and Seward had collapsed because they were built on unconsolidated glacial sediments. They realized that Kodiak had been hit by “seismic sea waves,” as they referred to them, which had also traveled across the Pacific and to the California coast. But among other uncertainties, they were still unsure about the source of Chenega’s destruction. The village, they wrote, “was hit by a large wave of unknown origin.”
The geologists also put to rest concerns that they themselves had had when they first came to Anchorage: namely, that some rivers might have been blocked by landslides, which could have led to catastrophic flooding. They had found no evidence of this in their reconnaissance flights and fieldwork. They had discovered an odd effect of the quake on several smaller rivers, including Ship Creek in Anchorage—water flows had been sharply reduced for about a week. Perhaps fissures had formed in the riverbanks that allowed much of the water to seep into the ground, the geologists wrote, or all the shaking had made the riverbeds more porous, with the same result. All in all, though, Alaska’s rivers had made it through the earthquake in good shape.
The report also suggested a likely explanation for the phenomenon that mystified all who saw it: the dead red snappers that floated by the thousands on the water in some parts of Prince William Sound shortly after the quake. Like other bottom-feeding fish, snappers live in dee
p water—which in the case of the fjords and channels of the sound can be four hundred feet or deeper. They have an air bladder, filled with gas that dissolves out of their blood, that keeps them buoyant at depth, where the water pressure is high. But if the fish rise to the surface too quickly, the rapid decrease in pressure causes the gas in the bladders to expand very rapidly, killing them. The geologists proposed that currents created by the shaking and sliding during the earthquake stirred up the bottom waters, forcing the snappers toward the surface and their doom.
Plafker, Grantz and Kachadoorian devoted much of the report to the biggest impact of the earthquake: the rising and sinking of the land over a wide swath of south-central Alaska. Although their survey efforts had been of necessity incomplete, they calculated that at least thirty-four thousand square miles of land were affected, an area the size of Indiana, and divided the territory into three zones. One was an area of “tectonic subsidence,” which consisted of Anchorage and environs and almost all of the Kenai Peninsula—including Portage, which they’d seen from the plane on their first flight—and Kodiak Island. The land in this zone had subsided, or sunk, by more than five feet in some places. A second zone, of “tectonic uplift,” covered the southeastern half of Prince William Sound and, on the mainland, the Copper River delta southeast to Kayak Island. Here the land had risen by as much as seven and a half feet—and when more detailed surveying was undertaken in the summer, there was little doubt that areas of even greater uplift would be discovered. The third zone was described as a “tectonic hinge” between the zones of uplift and subsidence, a roughly twenty-five-mile-wide strip running southwest to northeast that included much of the northwestern part of the sound. But what was the nature of this “hinge”? Was it a flexible one, in which the strip of crust acted like a piece of rubber holding the two bigger zones together? Or was it inflexible, and the location of a sharp break between those two bigger zones, in the form of one or more faults?
The geologists were inclined to believe that the hinge was a “zone of flexure,” as they put it. For one thing, Plafker had found a location in the hinge zone where there had been no change in land level during the quake—on Perry Island, which he had visited with Osborne. If there had been a sharp break between subsidence and uplift, one wouldn’t expect to find any areas that were unchanged.
But of even greater significance was that the three men had found no sign of faulting at the surface. The lack of any evidence of a fault had intrigued Plafker during that first reconnaissance flight on the Sunday after the quake, and even after more flights over the following ten days he and the others hadn’t seen anything in the hinge zone—no obvious scarps or linear traces in the earth or snow—to suggest a fault. Of course, they had only been there for two weeks, and they might have missed it. To cover themselves, in the report they noted that “a surface break could easily have been overlooked, especially as new snow had fallen.”
Plafker remained intrigued by the absence of a visible fault. Clearly there was still much to be learned about what this earthquake did to the land. And just as clearly, he was beginning to realize that there was much to be discovered about how the quake did what it did. He was eager to get back to Alaska and learn more.
—
For all of George Plafker’s skills in the field—his ability to work in rugged backcountry Alaska, navigating rivers and hiking glaciers, setting up spike camps, living off C rations and fending off the occasional bear—the summer of 1964 was a very different experience. It was the summer he spent on a ship.
Not a ship, precisely—a flat-bottomed motor barge, of the kind that prowls the Alaskan coastline, delivering goods to isolated shoreline communities. This one was about eighty feet long, with a wheelhouse and bunkhouse on the deck and a mast and boom for loading supplies. The crew consisted of a captain and a seaman who doubled as a cook, and there were berths for four researchers and assistants. It was owned by the Geological Survey—they had picked it up on the cheap after its goods-hauling days were over—and had spent most of its summers taking scientists around the fjords and bays of southeastern Alaska. It had been laid up in Seattle for the winter, and was rushed back up to Alaska for earthquake research.
Its name was a familiar one to Plafker: the Don J. Miller.
Starting in the early days after the quake, the Geological Survey had been working to set up an ambitious research program for the summer, with scientists recruited from throughout the agency. George Gates, a former head of the Alaska branch, had been chosen to coordinate the field program. Two geologists were assigned to study the Anchorage slides in detail; two more worked in Seward and Valdez; and two worked with the Alaska Railroad. But there were many others, among them engineering geologists, soil geologists, marine geologists, hydrologists, experts at making gravity measurements and researchers who had made careers of studying landslides. What was lacking were many scientists who had studied earthquakes—it was still a fledgling field of research at the Survey.
The plan was to produce a series of in-depth professional papers on all aspects of the quake that would document and analyze what had occurred and, more important, help scientists and engineers prepare for future ones, in Alaska and elsewhere. Eventually more than fifty researchers would be involved in the publication of the various papers. There might be some doubt as to whether the Good Friday earthquake was the most powerful of all time, but there was no doubt that it would be the most studied of all time.
Grantz had wanted to stay involved, but his wife had health problems that forced him to remain in California that summer. Kachadoorian did return to Alaska to focus on the damage to and reconstruction of the state’s roads. And Plafker had signed up to continue studying the uplift and subsidence, focusing on Prince William Sound and part of the Gulf of Alaska. So on May 18, after a little more than a month back home with Ruth and the children—and having spent much of that time at the Survey offices in Menlo Park—Plafker boarded a flight to Seattle. The next day it was on to Juneau and then Cordova. After a couple of days of interviews and reconnaissance—including another flight in the Widgeon with Jim Osborne—Plafker met up with the crew of the Don J. Miller and his fellow researchers and headed out into the sound. Their destination that first day was Knight Island, near Chenega.
Plafker had come to understand that for the purposes of his research he had been fortunate in where this earthquake had occurred. Here was a huge area of land that had been deformed by the quake, and it was relatively easy to study. Some of it was mountainous terrain that was difficult to reach, but much of it was on and around large bodies of water with plenty of shoreline where changes in elevation could be measured. With its many bays, fjords, channels and islands, Prince William Sound alone had close to four thousand miles of coastline. The Don J. Miller, Plafker realized, would make most of it easy to reach. And measuring the changes in elevation along it would be made easy by something else: the barnacle line.
Plafker had first learned of the barnacle line during his two weeks in Alaska immediately following the quake and had talked to marine biologists then to better understand how barnacles fit into the environment of the Alaskan coast. The idea of using barnacles to measure uplift and subsidence was not new—it had been employed in a previous Alaska earthquake, near Yakutat Bay, southeast of Cordova, in 1912—but it’s fair to say Plafker and his colleagues perfected the technique and used it to a far greater extent than previously. They made hundreds of elevation measurements, the bulk of them using the barnacle line.
The concept was relatively simple. Because northern acorn barnacles establish themselves at a certain spot on rocks and pilings—at or close to mean high water—they could be used as a reference point to measure both uplift and subsidence. In an area where the land had risen up, the prequake barnacle line would now be higher than it was before, and out of the water. After a few weeks the barnacles would have died, but their white-colored plates remained, firmly cemented to the rock or wood. For areas where the land had sunk
, the barnacle line would now be underwater most or all of the time. Either way, to determine the amount of elevation change, in most cases all that was needed was to know the stage of the tide—which the US Coast and Geodetic Survey had been busy recalculating all over Alaska after the earthquake—and then measure from the waterline to the top of the barnacle line.
Say the land had risen up. And say the measurement was being done at a time of day when the tide was two feet below mean high water. The amount of uplift would be equal to the measurement from the waterline to the barnacle line, minus two feet. A similar measurement could be made to determine subsidence, although in that case the measurement would be made from the waterline into the water to the barnacle line.
In practice things could be a little more complicated. The Geodetic Survey’s tide heights and times were precisely determined at relatively few stations, so tides elsewhere had to be interpolated. And depending on local conditions, barnacles might establish themselves a little lower relative to mean high water than elsewhere. But Plafker learned to adjust and adapt as necessary, and even if the measurements had a margin of error it was small enough that the overall trends in uplift and subsidence were still obvious.
Later in the summer the work became easier, and Plafker found that often he didn’t need to worry about the tides at all. Late summer was when juvenile barnacles, which had hatched after the quake and developed, settled down for good—at the new, postquake mean high-water line. Then Plafker would have two barnacle lines—before and after—and determining the elevation change was simply a matter of measuring the distance between them.
The Great Quake: How the Biggest Earthquake in North America Changed Our Understanding of the Planet Page 20
