Earthquakes are caused by ground movements. The formation of earthquakes can be summarized in one sentence, that is, the ground movement is too intense, which causes the pressure accumulated underground to be released to the ground after the ground breaks, causing the ground to vibrate greatly and generating seismic waves to spread around. The main cause of earthquakes is the collision, extrusion and dislocation between crustal plates, which leads to the rupture and dislocation inside the plates, and then leads to the occurrence of earthquakes. In earthquake disasters, the earthquake source is the first place where the earthquake occurs, and the ground at the center of the earthquake source is the epicenter. The epicenter is generally the place where the earthquake is the most severe, and the damage is often greater. It can not only destroy houses and cause serious casualties, but also cause floods and fires, gas leaks, power outages and the spread of radioactive materials. More serious earthquakes can also lead to landslides, ground subsidence and tsunamis.
There are five reasons for volcanic earthquakes and tectonic earthquakes, including volcanic earthquakes, tectonic earthquakes, induced earthquakes, artificial earthquakes and subsidence earthquakes. Volcanic earthquake is the crustal vibration caused by energy impact when volcano erupts. This kind of earthquake has few times and little harm, accounting for only 7% of the total number of earthquakes. Although sometimes volcanic earthquakes are also very strong, the general impact is only within a few tens of kilometers near the volcano. Tectonic earthquake, also known as fracture earthquake, refers to the ground vibration caused by great changes in geological structure due to the fracture, dislocation or change of underground rock strata and strata.
Induced earthquake, artificial earthquake and subsidence earthquake refer to earthquakes induced by some external factors. For example, large meteorites fall from the sky, and the huge impact on the ground will cause earthquakes of different degrees; Artificial earthquake refers to the ground vibration caused by human factors. For example, some countries conduct nuclear explosion experiments in underground bases, and earthquakes are caused by explosive power, as well as earthquakes caused by human activities and industrial blasting. Collapse earthquake refers to the earthquake caused by stratum collapse. This kind of earthquake has a small influence range, a small magnitude, relatively small damage and very few occurrences, accounting for only about 3% of all earthquakes.