Cascadia's Fault (37 page)

In other words the exact number of deaths didn't really matter. What counted, in the minds of Chairman Mao's publicity machine, was that China's ability to mobilize the masses to tackle a complex scientific challenge had paid off. A natural disaster that could have killed many more did not.

When Kelin Wang and company were allowed to see previously secret documents in 2004, a new and presumably more accurate set of numbers could be compiled for the first time. Combining “direct” and “indirect” causes—many died from fires and as many as 372 died from hypothermia, freezing to death outside just like the snakes—the total death toll for the Haicheng earthquake became 2,041 and the total number of people injured was 24,538.

To make the evacuation story look even more impressive, some news releases described the total region affected as having more than eight million people. Even if the population in the epicentral area was really closer to a million—the original figure cited by most authorities—at 2,041, the number of deaths is still quite small given the collapse of so many houses. A report by the U.S. delegation of scientists who visited the disaster zone in 1977 estimated that “casualties in excess of 100,000 would have ordinarily been anticipated.”

It's safe to say the Chinese government had a success story worthy of bragging about even without fudging the numbers. The political turmoil of the late 1970s, however, affected the publicity machine that took over in the wake of Haicheng. The context, as Kelin Wang explained it, was that “with Chairman Mao's health deteriorating, friction between the Gang of Four and other Party leaders, including Mao's would-be successor, Hua Guofeng, intensified.” Mao's wife, Jiang Qing, and her three allies in the Gang of Four were running the publicity campaign, but Hua Guofeng had his own agenda and an element of the truth may have been the first casualty.

As vice-premier, Hua was among the first to heap praise on the workers based at the Shipengyu Earthquake Observatory for their stellar efforts to warn the community about the rash of foreshocks—now known to have been true precursors of the big jolt. Followers of the Gang of Four, on the other hand, issued news releases that stressed the leadership role of provincial
Party
officials with little or no mention of Shipengyu, much less of Cao Xianqing. To make the most of this singular propaganda opportunity, it was evidently better to avoid the devilish details.

The prediction was real yet the results of the evacuation were uneven. Yingkou County's warning was spread far and wide from early that morning, thanks to the single-mindedness of Cao and his team. In Haicheng County the warnings began later in the day, many decisions to evacuate were made spur of the moment by local committees
or individuals at the work brigade or commune level, and some parts of the province—including the town of Haicheng itself—were not evacuated at all. The death toll in Haicheng County was substantially higher than in Yingkou. Thus it became a question of who got the greater credit, or who deserved the blame.

Three months after the disaster, when Vice-Premier Hua delivered a speech at the next national quake prediction conference, he told the famous story of the evacuation of delegates from the meeting hall that night in Dashiqiao just as the ground started to shake. “An officer who was directing people to exit was injured,” said Hua, “but the rest of the one thousand people were all safe.” And who made the prediction the army commanders took so seriously, the prediction that saved so many lives? Hua Guofeng said it was the Shipengyu Earthquake Observatory. The Gang of Four, had they attended the conference, would no doubt have touted Party bureaucrats.

Cao Xianqing insisted it was his Earthquake Office that provided the vital first warning. No doubt the army brass heard about it from several sources, but Cao's prediction turned out to be the most specific and timely. Perhaps because he was not a trained scientist and could not provide a detailed technical explanation for his decisions—how much was science and how much was instinct?—or perhaps because he was a lowly county official rather than a provincial bigwig, he did not get anointed as a hero of the Haicheng saga. In the feuding between Hua and the Gang of Four, Cao received no official recognition, no meritorious service awards. When China bragged about the world's first successful seismic prediction and evacuation, the story of Cao Xianqing and his Yingkou County Earthquake Office was not told to the outside world.

 

The lingering question was and still is whether the prediction had any scientific merit. When Kelin Wang and his colleagues published their findings in 2006, they found that “the most important precursor was a foreshock sequence, but other anomalies such as geodetic deformation,
changes in groundwater level, color, and chemistry, and peculiar animal behavior also played a role.” In essence, they wrote, “None of these predictions can be scientifically explained.”

The point seemed to be that even though some things like why snakes crawled out of their dens or why some—not all—mice and rats were dazed and disoriented may not have clear scientific explanations, there was no reason to doubt that they really did happen. Wang and company confirmed that “it was the foreshocks alone that triggered the final decisions” to warn and evacuate. The good news was Haicheng proved that “at least some earthquakes do have precursors that may lead to some prediction.” To me the bottom line was this conclusion: “Although the prediction of the Haicheng earthquake was a blend of confusion, empirical analysis, intuitive judgment, and good luck, it was an attempt to predict a major earthquake that for the first time did not end up with practical failure.”

 

Seventeen months and three weeks after Haicheng, everything China thought it knew about seismic prediction came down like a house of cards. At 3:42 a.m. on July 28, 1976, lightning flashed across the sky and the earth rumbled ominously. Seconds later another major earthquake struck northern China—this time with no prediction and no evacuation. The rupture happened directly underneath the industrial city of Tangshan, roughly 90 miles (140 km) east of Beijing.

The magnitude 7.5 rupture shifted the ground about five feet (1.5 m) horizontally and three feet (1 m) vertically, destroying nearly 100 percent of the living quarters and 80 percent of the industrial buildings in the city. People were jolted from their sleep in total darkness, screaming and choking on thick dust from unreinforced brick buildings that collapsed in piles of rubble. Official reports estimated the death toll at 240,000 with 164,000 more seriously injured. That's roughly the same number who died from the Sumatra quake
and
the Indian Ocean tsunami in 2004. Critics claimed the Tangshan estimate was conservative,
however, and that the real number of people killed could have been 600,000 according to estimates made by foreign observers. Whatever the count, Tangshan was far and away the most deadly single quake in the twentieth century and one of the great tragedies of all time.

Tangshan was a major center for coal mining, iron and steel production, and the manufacture of cement. Nearly all of it was wrecked. Bridges and highways collapsed, pipelines broke, dams cracked, more than ten thousand large industrial chimneys fell, and twenty-eight trains passing through the city overturned or were derailed. The key question, though, was why nobody saw it coming. Did the lessons of Haicheng not apply here? Apparently not.

In the final two months before Tangshan, not a single foreshock was detected by a regional seismic network capable of measuring tremors as small as magnitude 1.7. Some of the other little twitches and anomalies that had preceded the Haicheng event also preceded Tangshan but apparently the signals were not strong enough to trigger a prediction or evacuation. How different could the geological structures be only three hundred miles (480 km) away from Haicheng? If Haicheng had foreshocks, why not Tangshan? Good and important questions that still need to be answered, said Kelin Wang.

Preliminary answers suggested by Wang and company could be that fault failures are unique, so different from each other that whatever anomaly or precursor helps to predict one event probably won't work for a different kind of fault in a different physical setting. And once a rupture has happened, it modifies the geological structures and rock properties enough that the precursors then change as well. The symptom that tipped us off to the
last
quake may not precede the next, even if it happens on the same fault. And then sometimes you get the symptoms but the big temblor never comes.

If that's the real lesson of Haicheng and Tangshan, why bother with prediction? When I finally got a chance to interview Kelin Wang, he still seemed hopeful about the prospects—a persistent, low-key optimist—although
he was wary of putting prediction into practice too soon. “If the Haicheng story was true,” he began, “then earthquake prediction is not impossible.” It did show us “how
early
in the stage we are still in terms of earthquake prediction. And the difference—the major difference—between these two earthquakes is the Haicheng earthquake had a foreshock sequence and the Tangshan earthquake had no foreshocks at all.” Strange as it may sound this did little to dampen enthusiasm for the dark art of prediction.

 

The Tangshan disaster gave prediction optimists a sharp reality check. So did the Parkfield experiment in California. On September 28, 2004, a magnitude 6 temblor finally rattled the farming town of Parkfield—at least twelve years after scientists predicted it would happen. To say that William Bakun and Allan Lindh of the USGS, who along with Tom McEvilly of the University of California at Berkeley had offered the forecast in 1985, were disappointed would probably be an understatement. Five moderate (magnitude 6) events with similar “characteristics” had occurred on the Parkfield segment of the San Andreas since 1857. By their calculations the seventh in what looked like a repeating series of nearly identical ruptures should have happened some time in 1988 but surely by the end of 1992 with a 95 percent probability.

Clearly the “time-predictable” part of their hypothesis was wrong. The idea that fault failures tend to repeat themselves like clockwork had been kicking around since 1910, when geologist Harry F. Reid of Johns Hopkins University suggested it ought to be possible to figure out when and where quakes would happen by keeping close tabs on the build-up of stress. Looking at how unevenly land had shifted along the San Andreas during the great San Francisco earthquake of 1906, Reid developed the elastic rebound hypothesis—a cornerstone of modern geology long before the advent of plate tectonics—which Bakun, Lindh, and McEvilly set out to test in Parkfield eight decades later.

Reid's idea was that stress built up unevenly along the fault and it
took a massive rupture—at the point where the strain was great enough to cause the rocks to fail—in order to relieve or
recover
that strain. The longer the strain built up, the bigger the shock would be. If you knew how often the fault had ruptured in the past, you could in theory estimate how long before the next one was due.

But what if the last rip did not release all of the accumulated strain? Wouldn't that alter the timeline for the next one? When Bakun and Lindh published their forecast in the August 16, 1985, edition of
Science,
they noted that the 1983 magnitude 6.5 at Coalinga, eighteen miles (30 km) off the San Andreas to the northeast of Parkfield, might have done exactly that. It had just possibly relieved enough of the “tension in the spring” of Parkfield's clock to delay the next rumble in the series. A delay of more than a dozen years, however, was way more than merely late.

Critics within the science community didn't wait until the 2004 jolt to pounce on Parkfield. Even though the expected magnitude 6 event did happen
eventually,
in more or less the same location as last time and where Bakun and his colleagues said it would be, the Parkfield prediction experiment was branded a failure shortly after the original time window closed in January 1993. A long-standing and rancorous philosophical debate intensified as some seismologists turned away from divining the future and deleted “the P-word” from their vocabularies.

By the mid-1990s Robert J. Geller at the University of Tokyo had become the most persistent and outspoken critic of everything predictive, especially Japan's massive and well-funded multiyear effort to anticipate the next big temblor near Tokyo. Geller had been scathing in his view of American efforts as well, his central thesis being that prediction studies have been going on for more than a century—and yet we seemed no nearer a solution to the problem than we were in the beginning.

Geller was fond of quoting Charles Richter, developer of the earliest and best-known earthquake magnitude scale and one of the most respected seismologists in the world, who in 1977 commented that he
had “a horror of predictions and of predictors. Journalists and the general public rush to any suggestion of earthquake prediction like hogs toward a full trough.” Vitriol and aspersions aside, Geller's central argument against prediction was and is based on the idea that “individual earthquakes are inherently unpredictable because of the chaotic, highly nonlinear nature of the source process.” Basically there are so many things going on deep underground that we can never know when a rock surface is going to fail. He dismissed the idea that “the Earth telegraphs its punches,” using auto accidents as an analogy.

The rate of car crashes may be estimated, but the time and location of an individual accident “cannot be predicted.” As for precursors, even though speeding frequently precedes accidents, only a small fraction of speeding violations are followed by serious accidents. Therefore speeding is not a reliable precursor. Similarly, he argued, there are no reliable precursors to seismic shocks. Even after a car crash has begun to happen, its final extent and severity depend on other equally unpredictable, quickly changing interactions between drivers, cars, and other objects. Put simply, car wrecks and quakes are too chaotic to foretell, according to Geller.