On Shaky Ground

by Nance, John J. ;

  Just prior to 4:00 A.M., while twenty-three members of a visiting French delgation slept in their Tangshan hotel rooms a hundred miles east of Beijing, the lights suddenly went on. In milliseconds some of the visitors along with hundreds of Tangshan residents awoke to an amazing display of red and white lights in the sky outside, lights flashing like an aurora borealis gone berserk, reflecting through their windows, booming away silently like sheet lighting from a violent storm—yet without a storm. One second it had been dark; now it was bright as daylight. Those who watched searched their respective minds and memories for an explanation—as did other startled people up to two hundred miles away in all directions.

  What on earth?

  As the question formed in a thousand minds, the long-dormant fault beneath Tangshan was disintegrating a last snag that had held back unmeasurable seismic strain accumulated over centuries, and hundreds of square miles of unseen rock faces rumbled past each other just a few miles below Tangshan, sending an incredibly powerful pulse of P and S waves that arrived at the surface almost simultaneously, striking the foundation of the city like a mammoth sledgehammer, propelling everything upward with accelerations exceeding one gravity, hurling thousands of people into the ceilings of the mud-brick, masonry, and tile homes, which instantly shattered, the roofs dislodging and descending on top of them, crashing back down with the other side of the very first wave. With the city simultaneously in the agonizing grip of unbelievably massive transverse wave fronts shaking the terrain like some sort of monstrous, angry dog, Tangshan simply collapsed.

  Surface faults rippled through the middle of the city like snakes as buildings disintegrated, roads and canals that crossed the faults were ripped apart laterally (some places with displacements of four feet or more), and almost all of Tangshan’s industrial facilities were reduced to rubble. The wave fronts ripped into Beijing as well, splitting a major hotel, destroying some older structures, shattering glass throughout the capital, throwing the contents of desks (including those at the Seismological Bureau) on the floors, and sending millions of residents into the streets—some of whom remained there, living outdoors for days to wait out the inevitable aftershocks.

  In what was left of Tangshan, the hotel housing the French delegation had come apart with the first shock, somehow killing only one of the group. The stunned survivors, adrift in a sea of wreckage, picked their way barefoot through the rubble, bruised and shaken—and amazed to be alive.

  The same, however, could not be said for the endless ocean of ruined masonry and embedded humanity in all directions. When the shaking had stopped, well over half a million men, women, and children—a population greater than the number of Americans who reside in Washington, D.C.—lay crushed to death or dying beneath the rubble of their buildings.

  The deeply shocked and embarrassed seismologists who scrambled to get to the bureau in Beijing within hours of the Tangshan disaster knew only that a catclysmic earthquake had occurred without the benefit of a useful prediction. They were horrified to find it was Tangshan. Amidst the despair that permeated the Seismological Bureau with each upward revision of the death toll, there was a chilling sense of failure and hopelessness in the face of nature. China had thrown societal effort and resources into preventing this sort of thing from ever happening again—and the year before all their hard work had saved millions. But this time no wells had bubbled, no earthquake swarms had provided prior warning, and no clear and certain danger had given the scientists any reason to call for an evacuation. They had not failed, but their method had—at least insofar as the seismologist in Beijing or elsewhere might have considered it consistent and reliable. Clearly, routine short-term prediction of killer earthquakes was not yet an operable reality.

  Chinese government officials, feeling acute disgrace at being unable to control their own destiny, internationally embarrassed by the utter reversal of their 1975 Haicheng prediction, which had been a triumph of Chinese scientific ability and public resolve, acted with characteristic totalitarian insularity and refused to acknowledge the details or the scope of Tangshan’s death. Officially they would admit that a great earthquake had occurred (they could hardly deny it; worldwide seismographs, the French delegation, and Western visitors to Beijing brought the news within days to the rest of the world), but there were to be no discussions of death tolls or damage, no foreign visitors, no foreign seismologists, and no admission of failure. To the rest of the world, China would simply pretend the great Tangshan disaster had never happened (in terms of social and human impact).

  Nevertheless, one of the Frenchmen who had returned home told a waiting world press that in the whole of Tangshan he had seen one solitary smokestack still standing, and that in the midst of hundreds of thousands of people, he had seen only handfuls of survivors—nothing more.

  But when so many members of the human family perish in modern times, the reality cannot be suppressed forever. Within months Western experts had arrived at a death toll of between 660,000 and 750,000. In other words, Tangshan had been the greatest killer earthquake on the planet in four hundred years.

  There was no doubt that the growing excitement over the possibility of earthquake predictive methods (which had grown substantially in the wake of the Haicheng success) had suffered a heavy blow with the Tangshan cataclysm. But by no means was it dead or dying. After all, Haicheng had proved that under certain circumstances at least some great quakes could be predicted in the short term, and outside China there had been many new and promising advances that had in no way fallen victim to Tangshan’s sudden, unheralded onset. Perhaps the most exciting of those new methods had originated with a Russian discovery which itself grew out of a major human tragedy.

  In October 1948 nearly twenty thousand people had been obliterated by a catastrophic earthquake that roared in without warning along the northern rift zone of the Kopet Dagh Mountains in the extreme south-central Soviet Union city of Ashkhabad, 20 miles north of the Iranian border, and 280 miles east of the Caspian Sea. Nine months later another monstrous quake rumbled through the Garm region of rugged mountains in Soviet Tadzhikistan (700 miles east of Ashkhabad), crushing the village of Khait along with twelve thousand residents beneath a tremendous rockslide.

  Even in Joseph Stalin’s Russia that was too much. The murderous Russian dictator had never hesitated to slaughter his own citizens by the tens of thousands for the flimsiest of political reasons, but natural disasters which killed his subjects without his authorization were irritants—and economically disruptive. Accordingly, the Soviet Academy of Sciences was mobilized to find ways of preventing such disasters from striking without warning, and a large-scale study of the seismically dangerous Garm region began in earnest. The ensuing years of geologic and seismologic measurements and observations produced warehouses of information, but fifteen years passed before the Soviets had sifted a significant finding from their incredible data base. In an international geophysical symposium in Moscow during 1971—four years after the international death of the traditionalist view of the earth and the acceptance of plate tectonics—the Russians reported that before earthquakes, the seismic waves were slowing down as they traveled through the rocks.

  The ratio of the speed of P waves and S waves is always the same, or so it had been thought. That constant ratio was the very factor that enabled seismologists to read a seismic wave at any distant location on Planet Earth, and to calculate rapidly the distance of the originating earthquake by finding the difference in the arrival time of the first P wave from the later arrival of the first S wave, then applying the fixed ratio of 1.75 (P waves, in other words, travel 1.75 times faster than S waves).

  But the Russians had noticed that prior to earthquakes in the Garm region, the ratio seemed to change, and dropped as low as 1.6. The drop could go on for days or months or even years, and there seemed to be a correlation between the length of time the drop continued and the size of the earthquake that eventually followed.

  The revelation created an i
nvigorating sensation of a possible breakthrough. Was this the key? Was this the long-sought mechanism that would always work exactly the same anywhere on earth, and would permit accurate earthquake predictions?

  American seismologists, including Dr. Lynn Sykes of the Lamont-Doherty Geological Observatory in New York (who had pioneered many of the marine geological discoveries of seafloor spreading that in turn helped prove the theory of plate tectonics), returned to the United States interested but skeptical.

  Seven years before, Dr. William Brace of MIT had noticed that when rocks are squeezed under tremendous pressure in a laboratory environment, a rather strange thing happened just before they shattered: The rock would swell. Because of thousands of hairline fractures that appeared just before failure of the rock, its volume would increase slightly, and along with such swelling came a fascinating change in its ability to transmit high-frequency waves.4

  Lynn Sykes assigned one of his graduate students to a doctoral program centered on the Soviet finding, and with the results of those efforts and those of a growing number of excited seismologists in the United States, a picture began to emerge of this process, which was called dilatancy.

  The seismograms for many small earthquakes and for the 1971 San Fernando earthquake, when reexamined, all seemed to show the very same phenomenon noticed by the Soviets: For a period of time—years in the case of large quakes—the P waves slowed down, then returned to normal, followed by the quake. There was, in addition, a predictable correlation between the length of time the slowdown continued, and both the size and the timing of the eventual quake. Given Dr. Brace’s experiments, it appeared that rocks in a fault zone under increasing pressure, just before breaking and permitting the fault to move, would develop the same network of hairline fractures. Since the fractures would be voids, filled with air if with anything, compressional P waves would not be able to travel through the rock as quickly, and would slow down. That slowdown could be spotted in an instant by any seismologist reading any seismogram, and such a discovery would be a warning that the rocks were under increasing compressional strain.

  When groundwater eventually filled those cracks, the speed of the P waves would return to normal. But the presence of water would lubricate and hasten the failure of the rocks and the slippage of whatever fault was involved. Within a certain period of time, the earthquake which had been building would finally occur. That, too, could be spotted in advance by a seismologist, especially one who had noted the initial slowdown and had been watching for the P waves to return to normal in an area already suspected to be building toward a quake.

  “If all this holds up,” one eminent seismologist postulated very much off the record in 1976, “we may have found the key that will give us the ability to accurately predict earthquakes based on the slowdown of the P waves, and we may even be able to issue short-term warnings when the P wave speeds return to normal. It seems too simple, I know, but that’s where we are.”

  By the time the State Seismographical Bureau of China had issued its first warning about Haicheng, it, too, was watching the speed of P waves. (Haicheng, however, showed no evidence of the slowdown. Nor, for that matter, did Tangshan.)

  As the seismological community emerged from the crushing news of Tangshan’s death, one bright hope stayed intact, from the halls of Menlo Park to the halls of the U.S. Congress. With dilatancy possibly handing the scientists a key to short-term prediction, and with plate tectonics providing the explanation of the basic planetary engine which propelled earthquakes, there was every reason to believe that someday in the future the prediction of earthquakes could become a significant part of mitigating the hazard of earthquakes.

  And that recognition in itself combined with political happenstance and a disturbing phenomenon called the Palmdale Bulge to create a critical mass on Capitol Hill.

  Palmdale, in the Mojave Desert north of Los Angeles, sits astride the San Andreas Fault not far to the southeast of Fort Tejon—an area of the fault which had been locked tightly since 1857. Suddenly, in 1975, however, USGS scientists discovered that Palmdale was rising. When elevation survey data from 1959 were compared with those of 1975, it appeared that the entire Palmdale area—at least thirty-two thousand square miles of desert—had risen as much as eighteen inches. In view of its location on a locked portion of the largest exposed active fault in the country, even a first-year geology student could find reason to believe that the Palmdale Bulge (as it was quickly dubbed) and the “big one” (the great earthquake that lay in Southern California’s future) were related. The bulge just had to be a precursor of the impending earthquake, but how could it be used to determine a specific date or a reasonably precise time period in which the inevitable tectonic snap would occur? From F.E.M.A. in Washington to the California Seismic Safety Commission (which had just been established in 1975), concern began to grow over what to do, and when to do it.

  By the first months of 1977 with a new president, Jimmy Carter, in the White House, a bill to establish a national earthquake hazards reduction program, which had been batted down for five years in a row in Congress, finally attained administration support. In the previous session of 1976 the Senate had passed the bill only to have it defeated by the House, largely because the Ford administration believed there were already enough federal agencies with authority to handle disaster preparedness.

  But the problem was not disaster preparedness, or preparing to react after a disaster had occurred. The problem was learning how to prepare before a disaster, and government on all levels was unfamiliar and uncomfortable with such an approach.

  The problem was finding ways to fund basic research, and to foster basic education of the citizenry that earthquake hazards could be minimized if older, highly vulnerable buildings were torn down or reinforced, new building codes were encouraged in all seismic areas, and people were taught what to do ahead of time to prepare their homes and themselves for surviving the aftermath of a major quake—whether in New York City or Los Angeles. In addition, there was a crying need for better coordination of disaster response agencies, especially in areas that didn’t realize they could be sitting on a seismic bomb.

  The bill had grown out of the ideas and efforts of the 1970 Steinbrugge task force and the upset over the pitifully inadequate state of preparation exposed by the 1971 San Fernando quake. But its greatest contribution would be to focus the nation’s attention on the fact that by no stretch of the imagination were earthquakes simply a “West Coast problem” or an “Alaska problem.” Fully thirty-nine states were high-risk zones, and most of the rest would bear the economic brunt for a disaster anywhere else.5

  The Palmdale Bulge provided the final shove over the top. Answers were needed to questions of what the bulge meant, and such answers would cost money in the form of research and coordination of projects to figure out ways of predicting earthquakes. With the success of Haicheng (and despite the disaster of Tangshan), the excitement over the dilatancy theory, and the growing confidence of the seismological community that it was in full cry on the trail of ways to predict the place, size, and time of damaging earthquakes, prediction became the goal. That coupled with worry over the Palmdale Bulge and the last-minute support of the outgoing Ford administration (along with the support of the incoming Carter administration) to get it past both houses of Congress and onto the President’s desk—at the same time Kerry Sieh was finalizing his doctoral thesis, which would provide a significant leap forward in both prediction and the new infant science of paleoseismology.

  The Earthquake Hazards Reduction Act of 1977 would not be the final solution, but it would be the start of a consensus that might one day lead to a full national resolve. At long, long last the United States was going to pull its head at least partway out of the sand and face the fact that Americans did not have to wait helplessly to be victims of seismic disasters.

  Chapter 17

  Pasadena, California—November 29, 1978

  Karen McNally was practically yelling at her
car radio as she pressed the accelerator toward the floor, the vehicle’s speedometer already reporting illicit velocities to an inattentive driver.

  “Where is it? Where?”

  Some announcer in some station somewhere in the Los Angeles area had read the item—obviously a fast-breaking five-bell story off the news wires—but he hadn’t said enough.

  As she wove between several cars, trying to make headway through the usual L.A. freeway traffic toward Caltech in Pasadena where she could get answers, the possibility that this was the very thing she had been waiting for and working for during the past nine months filled her with a sense of frustration.

  “There has been,” the announcer had said, “a major earthquake in Mexico.”

  “Oh, damn!” had been Karen’s first response. The squashed accelerator had come a few seconds later.

  I’ll bet this is our quake! The words echoed in her head as she changed lanes once again, downtown Pasadena sliding by her now, the off ramp leading to Caltech just two miles ahead.

  The image of her colleagues from both the United States and Mexico tending the array of seismographs placed around the southern coastline of Mexico in the state of Oaxaca, 290 miles south of Mexico City—the thought that the very earthquake they were trying to capture might have occurred on the very day she had returned to the United States to finish a technical paper (which had gone begging for weeks)—was very upsetting. But it was an upset filled with excitement that the earthquake prediction might have come true on schedule, and perhaps—just perhaps—right in the middle of their seismograph network.