1975 Haicheng earthquake
|UTC time||1975-02-04 11:36:06|
|Local date||February 4, 1975|
|Local time||19:36 CST|
|Magnitude||7.5 Ms; 6.2 mb|
|Areas affected||Northeast China|
The 1975 Haicheng earthquake hit Haicheng, Liaoning in China at 19:36 CST on February 4. This earthquake had an Ms magnitude of 7.5,which is associated with total destruction of infrastructure and property. Haicheng had approximately 1 million residents at the time of the earthquake, which is known for being one of the few earthquakes to be successfully predicted throughout history.
Early in the morning of February 4, 1975, Chinese officials ordered that the city of Haicheng be evacuated, believing there to be a large chance of an earthquake occurring. The prediction was allegedly based on reports of changes in groundwater and soil elevations over the past several months as well as widespread accounts of unusual animal behavior. A low-level alert was triggered by regional increases in seismicity (later recognized as foreshocks). Both authorities and citizens were finally placed on high alert and an evacuation order was issued due to an increase in foreshocks. Though this particular prediction of the earthquake was initially believed to be just the latest in a recent string of false alarms that had occurred in the preceding months, including one case of an earthquake swarm being caused by the filling of a reservoir, the evacuation of Haicheng proceeded anyway and eventually paid off.
The evacuation, despite successfully removing most of Haicheng's population, did not prevent deaths in its entirety. When the main quake struck at 7:36 pm, 2,041 people died, over 27,000 were injured and thousands of buildings collapsed. However, the death toll was much lower than the estimate of over 150,000 dead which is believed to have resulted if the evacuation had not taken place. This was the only successful evacuation of a potentially affected population before a devastating earthquake in history.
Another sign of the earthquake coming was the unusual animal behaviour. In December 1974, rats and snakes appeared "frozen" on the roads. Starting in February 1975 reports of this type increased greatly. Cows and horses looked restless and agitated. Rats appeared "drunk", chickens refused to enter their coops and geese frequently took to flight.
In recent years, the success of the earthquake's prediction has come under scrutiny. Seismologists have agreed that the Haicheng earthquake can't be looked to as any sort of "prototype" for predicting future earthquakes, as the foreshocks that played a huge role in leading to prediction of this earthquake are not a regular, reliable occurrence before all earthquakes. However, Qi-Fu Chen, a research professor at Beijing's China Earthquake Administration, explained that this earthquake at least "showed the importance of public education," prompting a further discussion about the necessity of making the public aware of the dangers, preparations, and warning signs related to earthquakes.
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