Will humans ever be able to predict earthquakes?
There is now a better understanding of how the Chinese achieved one of the most mysterious triumphs in disaster foretellingcolumns Updated: May 18, 2015 10:10 IST
During his charmed visit to China, Prime Minister Narendra Modi should have taken President Xi Jinping aside and whispered into his ear, “Did you guys really predict the massive Haicheng earthquake in 1975?” And comrade Xi would have certainly told him, aloud, the official position China has maintained for four decades — that China had ‘successfully predicted’ the Haicheng earthquake.
These are the facts, they are not disputed: On February 4, 1975, a massive earthquake struck Haicheng, a city in northeastern China that had a population of over a million. Weeks before the event, lasting until the very moment the quake struck, the Chinese government had set in motion a series of evacuation plans. A government official named Cao Xianqing had stated that the quake will strike by 8pm on February 4. Cao said that if the quake struck at 7pm its magnitude would be seven on the Richter scale, and if it struck at 8pm the magnitude would be eight. The quake struck at 7:36 pm, and its magnitude was 7.3.
Four decades later, as the prediction of earthquakes is still beyond the grasp of science and remains the prized goal of seismology, there is a better understanding of how the Chinese might have achieved one of the most mysterious triumphs in disaster foretelling.
All causes of naturally occurring earthquakes are not known, but the most common cause is believed to be events deep in the Earth’s fractured crust, which is made up of rock plates that slither over the planet’s mantle. There are no clear signals that can help scientists predict the time and location of an earthquake.
If you wish to annoy a scientist in the field you may ask if animals can sense an impending quake. People love ascribing special powers to animals and some scientists have wasted much time and money trying to find proof.
After a major earthquake, people usually claim that they witnessed strange occurrences before the event, most of them concerning animal behaviour. Scientists do take note of such reports, as they have for decades. Some are even attempting to use bats and migratory birds and burrowing animals to predict quakes. But the history of this type of research is not rich.
In her book, Predicting the Unpredictable: The Tumultuous Science of Earthquake Prediction, seismologist Susan Hough says that in the past researchers have tried to find a correlation between lost pet advertisements in newspapers and earthquakes assuming that a pet that is disturbed by an impending seismic event is most likely to run away. They didn’t find any correlation, but found one between lost pets and storms. The animals did not sense the approaching storms though; they were running away during them.
Hough mentions a seismologist who, in the 1970s, tried to find a correlation between cockroach activity and impending quakes, but failed; and Swedish researchers who fixed sensors on the backs of cows. “When a magnitude 4.7 quake struck just a few miles from the herd, the animals not only failed to show any unusual behaviour prior to the quake, they also failed to react to the quake,” she writes, and quotes a disenchanted researcher as saying, “One can probably say that as a species, cows are not the world’s most earthquake-sensitive animals.”
But then, in the days preceding the Haicheng earthquake, there were reported sightings of an inordinate number of snakes and frogs even though it was a bitter winter and the creatures should have been hibernating underground.
It is not difficult to assume that animals that live in the ground might be able to sense the portents of a massive quake. Hough grants that but as a scientist she emphasises that no study has been able to prove the ability. What is often proved is that people are unreliable when they recount extraordinary sightings, and that they often succumb to the infectious mass hysteria of a fable.
But the fact remains that Cao did predict the Haicheng earthquake almost to the hour, he even predicted the magnitude. As a result, it is believed that just about 2,000 people died, among them babies who, according to Hough, “were brought safely to shelters only to die from suffocation, the result of desperate attempts by caregivers to keep them warm”.
A lot of facts have emerged over the years that illuminate what had been a mystery with a paranormal quality to it. Hough points out that unlike many major quakes, the Haicheng quake was preceded by a series of seismic activity in the region for at least weeks, and the Chinese government had made several predictions. Only Haicheng came true.
On February 4, 1975, as the day progressed, and the foreshocks escalated, Cao intensified the evacuations. He seemed to know in his heart what he had publicly stated – that the earthquake would strike before 8 pm, and that its magnitude would be dependent on the time it struck.
“In interviews following the earthquake,” Hough states, “he explained that he was motivated by something he had read in a book, Serendipitous Historical Records of Yingchuan. According to this book, heavy autumn rains would ‘surely be followed’ by a winter earthquake.”
There had been, indeed, heavy autumn rains. And, Cao’s understanding was that the Chinese winter officially ended at 8 pm on February 4. That was why he was so sure the quake will strike before 8 pm. But, Hough points out, “Mr Cao’s calculations were off by an hour: winter officially ended at 6:59 pm that night. The earthquake was actually a half-hour late.”
Hough says that what helped the Chinese predict the quake were a bit of data and dumb luck. “There are times when one is right for the wrong reasons. Then there are times when one is right for spectacularly wrong reasons.”
Manu Joseph is a journalist and the author of the novel, The Illicit Happiness of Other People
The views expressed are personal. The writer tweets at @manujosephsan.
First Published: May 17, 2015 21:50 IST