To put it simply, the main causes of earthquakes are: the mutual extrusion of various large plates of the earth. In addition, they are caused by volcanic eruptions.
Earthquakes are divided into two types: natural earthquakes and artificial earthquakes. Categories. Natural earthquakes are mainly tectonic earthquakes. They are caused by the rupture and dislocation of rocks deep underground, which sharply release the energy accumulated over a long period of time and spread in all directions in the form of seismic waves, causing shaking and ground shaking on the ground. Tectonic earthquakes account for more than 90% of the total number of earthquakes. Followed by earthquakes caused by volcanic eruptions, called volcanic earthquakes, accounting for about 7% of the total number of earthquakes. In addition, earthquakes may also occur under certain special circumstances, such as cave collapse (collapse earthquakes), large meteorites impacting the ground (meteorite impact earthquakes), etc.
Artificial earthquakes are earthquakes caused by human activities. For example, vibrations caused by industrial blasting and underground nuclear explosions; high-pressure water injection in deep wells and water storage in large reservoirs increase the pressure on the earth's crust and sometimes induce earthquakes.
The place where seismic waves originate is called the earthquake source. The vertical projection of the earthquake source on the ground is called the epicenter. The depth from the epicenter to the source is called the focal depth. Usually, earthquakes with a focal depth less than 70 kilometers are called shallow earthquakes, earthquakes with a depth of 70-300 kilometers are called intermediate earthquakes, and earthquakes with a depth greater than 300 kilometers are called deep earthquakes. Destructive earthquakes are generally shallow earthquakes. For example, the focal depth of the 1976 Tangshan earthquake was 12 kilometers.
Thermal convection of mantle material. It is driven by energy generated by the decay of radioactive elements within the Earth. It is the external manifestation of the release of energy within the earth. Internal energy release mainly takes the following forms: earthquakes, volcanoes, plate movements, and geological structures. Earthquakes are one of them.
[1] There is a seismic source inside the earth, which releases energy (seismic waves) outward, causing vibrations within a certain range.
[2] Other geological disasters or natural disasters can also indirectly induce earthquakes.
Thermal convection of mantle material. It is driven by energy generated by the decay of radioactive elements within the Earth. It is the external manifestation of the release of energy within the earth. Internal energy release mainly takes the following forms: earthquakes, volcanoes, plate movements, and geological structures. Earthquakes are one of them.
Surface processes such as precipitation, wind, ocean currents, and rivers are all driven by the earth’s external energy, the sun.
Causes of earthquake disasters and prevention and control measures
What are the causes of earthquakes?
Earthquakes can be divided into natural earthquakes and artificial earthquakes (such as nuclear explosions). Earthquakes are generally called natural earthquakes and can be divided into (1) tectonic earthquakes (2) volcanic earthquakes (3) impact earthquakes (for example, meteorite impact) according to the causes of their occurrence. Among them, the main ones are crustal changes caused by plate movements (tectonic earthquakes).
Because there is a stress in the earth that pushes the rock formations, when the stress is greater than the strength that the rock formations can withstand, the rock formations will dislocation, and this dislocation will suddenly release huge energy and cause Elastic waves are produced, which we call seismic waves. When they reach the surface, they cause the earth to vibrate, which is an earthquake.