ON JULY 28, 1976, the worst natural disaster of recent centuries struck the city of Tangshan, in mainland China. In minutes all but four of the city’s hundreds of multistory brick buildings were damaged, many collapsing completely on the sleeping inhabitants. Trains were derailed, highway bridges crumbled, water and electricity were cut off and 10,000 miners were trapped underground. When official casualty figures were issued three years later, 242,000 people were known to have died, with 164,000 others seriously injured.

“The seismological department had not given any warning,” admitted Chinese officials. Indeed, the massive quake at Tangshan took everyone by surprise, since a major earthquake in the area was not considered likely.

Ironically, this tragedy befell China only a year after a successful earthquake prediction there had saved thousands of lives. On that earlier occasion Chinese officials showed outdoor movies to keep the people of the Haich’ing area outside on cold February nights until the predicted earthquake arrived, right on schedule.

From Laser Beams to Catfish

Although unexpected, the Tangshan disaster was not totally unannounced. For fourteen months beforehand an observatory in the area “recorded increasingly ominous movements along the earth fault that it straddled,” according to a report in The New York Times. “Yet, for lack of other premonitory signs, no warning was issued.” By contrast, the Haich’ing earthquake was preceded by a wide variety of warning signals, including strange animal behavior, which the Chinese take seriously in forecasting earthquakes. Finally, before the Haich’ing earthquake a number of small shocks occurred in the previous December and again just days before the earthquake. It was the ominous stopping of these foreshocks that convinced officials on February 4 that a major quake was due within hours.

Sadly, many earthquakes conform to the rule that it is always easier to identify warning signs after calamity has struck. But to be practical, only those unusual quakes that give abundant and dramatic warning signs are likely to be predicted successfully. “The problem is that no two quakes are preceded by exactly the same set of warnings,” notes one writer, “and even these symptoms can be misleading.”

As a result, a dizzying variety of possible earthquake clues is being investigated here and there around the world. Here are some of them:

Animal behavior: Tales of leaping catfish before earthquakes are so common that it was once thought that “earthquakes were caused by their thrashing about in underground streams,” reports Science Digest. The Japanese have been running tests on ten Tokyo catfish and report that they “acted abnormally before 85 percent of the earthquakes large enough to be felt by humans in a seven-month experiment.” Are the fish disturbed by very low-frequency “groans” or high-frequency “shrieks” given off by tortured rocks before they break far underground? Perhaps. Other animals that are reported to act strangely before earthquakes include snakes, rats, geese, pigs, cows and dogs, all of which were observed to act up before the Haich’ing earthquake.

Terrain changes: This method of earthquake prediction seems more “scientific” than watching animals, in that it involves numerous sophisticated gadgets, such as laser beams to record changes in the level of the land, and tiltmeters to detect the slightest change in the local slope. Other devices study local magnetic and gravitational fields. If land is rising or sinking or tilting, scientists have clues as to what might be going on far beneath the surface, down where earthquakes generally occur. The fancy hardware does not automatically mean better earthquake prediction, however. For years scientists have been watching the ground rise and fall in the area of Palmdale, California. They are still not sure what it all means.

Well-water changes: When the water flow from an artesian well in central Asia slowed dramatically, Soviet scientists predicted that an earthquake was coming. Six hours later the well dried up altogether and a large quake hit. Another very popular technique is the measuring of radon gas in well water. The gas comes from radium atoms that have escaped from rocks beneath the surface. If the rocks are about to shatter from accumulated strain, they first develop tiny cracks. Water can seep into these and absorb radon.

Problems of Partial Knowledge

Despite all the promising new methods and advances, however, earthquake forecasting is still a long way from weather forecasting. “My own opinion is that it’s going to be at least 10 years before predictions can be made with sufficient reliability and consistency to be of great use to the public,” says US geologist Clarence Allen. With the stakes so high in disasters such as earthquakes, many scientists are alarmed by the responsibility placed on them and the imperfect state of their art.

Some of these scientists are afraid that someday “they will look down at a set of measurements and their experience and intuition will tell them that a major earthquake may be imminent. But they will not sound a warning that could save thousands of lives,” notes The New York Times. Why not? “They will not have enough confidence in the evidence before them to justify predicting an earthquake to a nation where a wrong prediction could bring them professional scorn, public ridicule and possibly hundreds of lawsuits.”

The earthquake predictors are in a no-win situation. If a predicted quake does not occur, the false alarm could undermine public confidence and cause a later warning to go tragically unheeded. Real-estate values could be depressed and land developers might even sue the scientists. On the other hand, if a prediction is withheld and a quake occurs, then victims and their families could sue for negligence.

The problem here goes beyond man’s imperfect knowledge of earthquakes. It is the basic problem of priorities in a greedy society that often seems willing to risk lives rather than local economies.