A Foreshock is a medium-sized earthquake that comes before a major earthquake occurs.
Now, using this as a medium, the China State Seismological Bureau was able to successfully predict a major earthquake before it occurred. The successful prediction of the Haicheng Earthquake saved several thousands of lives in China on February 1975.
So how did this extraordinary event happen? What happened in February 1975 was that the China State Seismological Bureau critically studied the increase in the foreshock activities and then also vividly studied the various indications of signs of an impending earthquake like strange animal behaviors and even the ground water levels. The scientists involved in this project were extremely brilliant. They compiled all the signs together and the foreshock and instantly set to work. Having studied the crucial data before them thoroughly, scientists at the China State Seismological Bureau were able to successfully predict the Haicheng Earthquake.
Once the Haicheng earthquake was predicted by the scientists, the government instantly set to work evacuating people from the affected province. The Chinese government was able to evacuate about a million people from the affected province just a day before the Haicheng earthquake struck. This was on the 4th of February 1975. The method the Chinese used in predicting this earthquake is known as the Foreshock Prediction.
However, this Foreshock method of predicting an earthquake does not always result in a successful prediction as it has several loopholes. More often than not this method leads to false warnings. For example the Chinese government issued over thirty wrong earthquake predictions in the late 1990s using this method.
Victories have however been claimed by the Chinese government using the Foreshock Prediction to predict successfully an earthquake. For example according to the Chinese government, this same method was used in successfully predicting one other major earthquake in November 29, 1999 called the Gushan-Pianling Earthquake which occurred in about three major cities in China/
Unlike the weather, earthquakes are extremely difficult or nearly impossible to predict. Earthquake prediction at the moment seems to be beyond science. But scientists are not giving up hope yet. Scientists all over the world are still working relentlessly in the hope that someday they might be able to correctly predict earthquakes before they happen and save millions of lives.