Earthquake is a natural phenomenon that the earth's crust vibrates in the process of rapidly releasing energy, and seismic waves will be generated in this process. On the earth, plates collide with each other, resulting in dislocation and rupture at the edge and inside of plates, which is the main reason for earthquakes.

The place where the earthquake started is called the source, and the ground directly above the source is called the epicenter. The strongest ground motion of a destructive earthquake is called the extreme earthquake zone, which is often the area where the epicenter is located.

Earthquakes often cause serious casualties, which can cause fires, floods, toxic gas leakage, the spread of bacteria and radioactive substances, and may also cause secondary disasters such as tsunami, landslides, collapses and ground fissures.

Damage phenomenon of earthquake:

During an earthquake, the most basic phenomenon is the continuous vibration of the ground, and its main feature is obvious shaking. People in the earthquake zone sometimes feel jumping up and down before they feel a big earthquake. Because seismic waves travel from underground to the ground, longitudinal waves arrive first. Shear waves then produce a large horizontal vibration, which is the main cause of earthquake disasters.

1960 during the Chile earthquake, the biggest shaking lasted for 3 minutes. The first disaster caused by the earthquake was the destruction of houses and structures, causing human and animal casualties. For example, in the 1976 Tangshan earthquake in China, 70% ~ 80% of buildings collapsed, causing heavy casualties.