Cascadia's Fault - Jerry Thompson [115]
Based on this leveling data from the Jinxian Observatory—in one case a 0.1-inch (2.7 mm) elevation change over a period of only ten days—plus the radon gas reports, a series of magnetic anomalies, and a rash of smaller tremors, Gu used an empirical formula to predict that the coming quake would be a magnitude 6 and would occur somewhere around the southern tip of the Liaodong Peninsula. Because radon gas emissions were reported as far inland as Panjin and other anomalies were indicated in Dandong and Gaixian, Gu decided to expand the potential danger zone to include the entire Liaodong Peninsula and its offshore regions. When challenged about his very short time estimate—within six months, although possibly as early as January or February— Gu dug in his heels and said it could happen “even before the end of this conference.”
When he turned out to be right—the quake struck two weeks later—Gu’s report would retroactively be proclaimed the official “short-term” prediction of the Haicheng earthquake.
At the time of the mid-January conference in Beijing, though, higher-ups were not so sure. They decided to soften Gu’s warning with a significant fudge factor. The final statement changed his prediction from a magnitude 6 within six months—possibly even two months—to a more vague magnitude 5 to 6 some time “in this year.” After the late December false alarms, the sense of urgency had started to fade. Rumors had spread that the filling of a nearby reservoir was the likely cause of the swarm of smaller tremors in December, so life in northeastern China started to return to a semblance of normalcy. The seismic threat momentarily fell off the radar for some public officials.
Oddly enough, the number of reports of bizarre animal behaviors increased during mid- to late January. In the month before the quake more than a hundred snake sightings were recorded. What did modern-day scientists think of the snake stories? Kelin Wang and his coauthors commented that “although they must represent a tiny fraction of the total snake population in southern Liaoning, such suicidal behavior is extremely difficult to explain. What the snakes and other animals sensed is not known. It could be as simple as vibrations caused by earthquake tremors that were not detected by the then very sparse seismic network.”
Along with the snakes, frogs were now coming out of their hibernation dens and freezing to death. Horses, chickens, and cows were making a racket that was duly noted by the cadre of amateur observers. Rats and mice were running around, seemingly disoriented, oblivious to cats and unafraid of people.
According to ancient Chinese lore, all of these animal anomalies were considered portents of a coming shock and people took them seriously, reporting the incidents to various observatories and government offices where men like Cao Xianqing jotted them down in logbooks. In the month before the quake he cranked out sixteen issues of his “Briefing Notes” to the county government. Cao had taken to heart a book about the Ningxia event of January 3, 1739. The book spelled out a series of circumstances and events that Cao could see unfolding before him every day of January 1975.
One significant passage apparently convinced him the time was near. “Earthquakes occur mostly in winter or spring. If well water suddenly turns muddy, there is lasting cannonlike sound from the ground, gangs of dogs bark furiously, one should be mindful of earthquakes. Excessive autumn rain will surely be followed by a winter earthquake.” Cao knew it had rained a lot in the fall of 1974. In 1975, according to the Chinese calendar, February 4 would be the last day of winter and thus Cao