Earthquake is a huge natural disaster that instantly destroys human civilization. Its occurrence is independent of human will. At present, the level of earthquake prediction can not accurately tell the time, place and magnitude of the earthquake. However, after decades of exploration, we have a way to reduce the losses caused by earthquakes, which is "earthquake prevention and disaster reduction". In order to improve the people's awareness of earthquake prevention and disaster reduction, master the skills of self-help and mutual rescue, and reduce the loss of earthquake disasters, we should strengthen the publicity of earthquake prevention and disaster reduction knowledge among the people. The common sense about earthquake disaster reduction is as follows: the causes and classification of earthquakes: the continuous movement and change of the deep materials in the earth have contributed to the continuous movement and change of the surface, especially the crust, thus gradually accumulating huge energy in the long geological years. In some fragile areas of the earth's crust, when it can't bear great stress, or the rock stratum suddenly breaks, or the original fault moves, this is an earthquake. Earthquakes can be divided into natural earthquakes, induced earthquakes and artificial earthquakes according to their causes, among which natural earthquakes mainly include tectonic earthquakes, volcanic earthquakes and collapse earthquakes. Tectonic earthquake: an earthquake caused by dislocation and rupture of rock strata deep underground. This kind of earthquake has the highest frequency, accounting for more than 90% of the global earthquakes, and is also the most destructive. Volcanic earthquake: An earthquake caused by volcanism, such as magmatism and gas explosion. Volcanic earthquakes generally affect a small area and occur less frequently, accounting for about 7% of global earthquakes. Collapse earthquake: an earthquake caused by stratum collapse. For example, when underground caves or mined-out areas can't support the pressure at the top, they will collapse and cause vibration. Such earthquakes are relatively few, accounting for less than 3% of the global earthquakes, and the losses caused are relatively small. Earthquakes are a frequent natural phenomenon. There are about 5 million earthquakes in the world every year, of which more than 50,000 can be felt, more than 1,000 can cause damage, and more than a dozen earthquakes of magnitude 7 or above can cause great disasters. Several concepts of earthquake: source, epicenter, epicentral distance and focal depth. The place where the earth directly breaks is called the source. The ground opposite the source is called the epicenter. The distance from the epicenter to the observation point is called epicentral distance. The distance from the source to the epicenter is called the focal depth. According to the different focal depths, earthquakes can be divided into shallow earthquakes, moderate earthquakes and deep earthquakes. The focal depth of shallow earthquakes is less than 60 kilometers; The focal depth is 60-300 kilometers, which is a moderate earthquake; Earthquakes with a focal depth greater than 300 kilometers are deep earthquakes. Seismic wave: when an earthquake occurs, it stimulates elastic waves that spread around, which is called seismic wave. Seismic waves are divided into longitudinal waves and shear waves. P-wave: When propagating outward, the vibration direction of particles is consistent with the wave propagation direction, and rocks are alternately pushed (pressed) or pulled (expanded). Shear wave: When propagating outward, the particle vibration direction is perpendicular to the wave propagation direction, which makes the rock shear in the direction perpendicular to Apollo propagation. Compared with shear waves, longitudinal waves travel faster, generally five or six kilometers per second in the earth's crust, with small intensity and fast attenuation; The latter propagates slowly, generally three or four kilometers per second in the earth's crust, with high intensity and slow attenuation. Therefore, in an earthquake, longitudinal waves always arrive first and shear waves arrive later. The vibration of shear wave is stronger than that of longitudinal wave. Magnitude and intensity: Magnitude is a measure of the magnitude of an earthquake, which is divided according to the amount of energy released during the earthquake. The stronger the earthquake, the greater the magnitude. Intensity refers to the degree of damage to buildings such as ground and houses caused by earthquakes. An earthquake has only one magnitude, and the intensity of the same earthquake is different in different areas. Near the epicenter, the damage is great and the intensity is high; It is far away from the earthquake, with less damage and lower intensity. Intensity is not only related to magnitude and epicentral distance, but also related to focal depth, geological structure, groundwater distribution and soil conditions, building structure and seismic performance. Earthquakes can be divided into the following categories according to magnitude: earthquakes felt by people near the epicenter. Microseismic magnitude1microseismic magnitude ≤