​We cannot predict exactly when and where an earthquake will occur, but there is an example in history when timely evacuation saved thousands of people. An earthquake measuring 7.3 on the Richter scale occurred in a Chinese city with a population of one million 48 years ago. What happened next? Why was this a mega exception?

The prestigious United States Geological Survey (USGS) makes it clear that we CANNOT predict earthquakes, and that no earthquake has yet been accurately identified (location, time, magnitude), except for the very special case of China.

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On February 4, 1975, an earthquake measuring 7.3 on the Richter scale occurred in the city of Haicheng in northeastern China (Liaoning Province). 2,000 people died and 27,000 were injured, but official estimates suggest that the number of dead and wounded could have been 150,000 if the city had not been evacuated. The USGS writes about the China 75 case here.

The earthquake struck at 7:36 p.m., and early that morning, authorities decided to evacuate the city because they believed there was a high chance of a major earthquake.

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What made Chinese officials decide on the need to evacuate? A few weeks before the earthquake, both specialists and ordinary people without technical training observed various strange things.

The soil has risen in some areas, there have been changes in the water table, and there have been many reports of strange animal behavior.

In December 1974, people in the area noticed that rats and snakes appeared to be “frozen” on the roads, and in late January and early February there were reports of cows and horses being very agitated and chickens refusing to come inside. chicken coops and geese that kept trying to fly away.

However, the prediction was based on the high level of seismicity recorded in the area during those weeks: there were many small earthquakes that appeared to precede a larger earthquake in a short period of time (a few days or weeks).

Why was the Haichen earthquake an exception? Because many of the earthquakes that caused many casualties were not preceded by smaller earthquakes or strange animal behavior detected more than a month before the big event.

China was not very transparent about the decisions made at the time, and evacuations were not completed in all areas. But this was an absolutely unusual case.

The February 1975 earthquake also caused minor damage to Seoul (South Korea) and was felt in Kyushu (Japan) and Primorsky Krai (USSR).

After this episode, a lot of optimism appeared in the world of seismologists: here!, they say, forecasts can be made successfully and lives can be saved. The disappointment came a year later when an earthquake also in China, in Tangshan, killed more than 250,000 people and became one of the worst in human history.

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