An earthquake is a natural phenomenon in which the rapid release of energy from the earth's crust causes vibrations during which seismic waves are generated. The main cause of earthquakes is the mutual crushing and collision of plates on the Earth, which causes misalignments and ruptures along the edges and inside the plates.

The location where an earthquake begins is called the source, and the ground directly above the source is called the epicenter. The most intense ground vibrations of a destructive earthquake are called the extreme zone, which is often the area where the epicenter is located. Earthquakes often cause serious casualties and can cause fires and floods, toxic gas leaks, the spread of bacteria and radioactive materials, and can also cause secondary disasters such as tsunamis, landslides, collapses, and ground cracks.

According to statistics, about more than 5 million earthquakes occur on Earth each year, that is, tens of thousands of earthquakes occur every day. The vast majority of them are too small or too far away for people to feel. There are about a dozen or two dozen transitory earthquakes that can really cause serious harm to humans; there are about one or two earthquakes that can cause particularly serious disasters. Earthquakes that are not felt by people must be recorded by seismographs, and different types of seismographs can record earthquakes of different intensities and distances. There are thousands of seismic instruments operating around the world to monitor the movement of earthquakes day and night.

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