What Is an Aftershock?

Aftershocks are small earthquakes that occur successively after the main shock. Aftershocks generally occur in the same place as the main shock that occurred inside the Earth. It is usually the case that after a main shock, a series of aftershocks follow, the intensity of which is generally less than that of the main shock. Aftershocks can last for days or even months.

Aftershocks are in

U.S. geophysicists have discovered that the main cause of "aftershocks" is "dynamics" caused by earthquakes

On September 23, 1945, after the magnitude 6.25 earthquake in Yi County, Hebei, the aftershocks lasted for half a year, and they relatively calmed down in the spring of the next year.

During the 1952 Kern County earthquake in California, the main earthquake was completely destroyed in Becksfield. Sometimes even an aftershock just over magnitude 3 can knock down some houses. Therefore, after the main shock has passed, we must also be more vigilant about aftershocks and strengthen prediction and prevention work, and we cannot take it lightly.

On May 11, 1974, a magnitude 7.1 earthquake occurred in Zhaotong, Yunnan, and two aftershocks of magnitude 5 or higher after the earthquake were predicted before the earthquake. Although the damage was caused, the casualties were small.

At 3:42 am on July 28, 1976, after the magnitude 7.8 earthquake in Tangshan, Hebei, two strong aftershocks occurred that day, with magnitudes 6.5 and 7.1. Later along the active fault zone of Ninghe, Tangshan and Shexian, around 5-6, even stronger aftershocks will continue to occur, such as a magnitude 6.9 earthquake in the northeast of Ninghe on November 15, In the spring of two years (1977), strong aftershocks were still active, and there were more small earthquakes below magnitude 5. ^[2-3]