Cause of earthquake: In process of crustal movement, when the rock stratum is squeezed or stretched, when the squeezing pressure or stretching force exceeds the bearing capacity of the rock stratum, the rock stratum will break, thus releasing the energy gathered in the rock stratum and forming the ground earthquake ground, which is called earthquake for short.

The extent to which earthquakes change the natural environment and damage buildings can be divided into several categories: non-inductive earthquakes, minor earthquakes, felt earthquakes, destructive earthquakes, destructive earthquakes and destructive earthquakes.

Extended data:

earthquake magnitude

Magnitude is divided according to the energy released by the earthquake. The magnitude scale was first put forward by Kurt, an American seismologist, when he was studying the local earthquake in California in 1935. It stipulated that the common logarithm of the maximum horizontal amplitude recorded by the "standard seismograph" at the epicentral distance 100km was the magnitude of the earthquake.

Later, it was developed into records of telemetering stations and non-standard seismographs, which can also be used to determine the magnitude after conversion. Magnitude can be divided into different categories, such as surface wave magnitude (MS), body wave magnitude (Mb) and near earthquake magnitude (ML), and can also be converted among them.

According to Li Xite's calculation method, the largest earthquake known in 2000 did not exceed 8.9; The smallest earthquake measured by high-magnification microseismic instrument is -3. According to the magnitude, it can be divided into microseisms, microseisms, weak earthquakes (or small earthquakes), strong earthquakes (or moderate earthquakes) and large earthquakes.

Baidu encyclopedia-earthquake