Classification according to the location of occurrence

Plate edge earthquakes (plate boundary earthquakes): Earthquakes that occur on plate boundaries, most earthquakes in the Pacific Rim seismic zone fall into this category.

Intraplate earthquakes: Earthquakes that occur inside the plates, such as those in Eurasia (including China), are mostly of this type.

The causes and patterns of intraplate earthquakes are more complex than those of plate edge earthquakes, which are influenced by the local geological environment in addition to the plate motion.

Volcanic earthquakes: They are caused by the energy impact of volcanic eruptions, resulting in the vibration of the earth's crust.

Classification according to different nature of vibration

Natural earthquakes: seismic phenomena occurring in nature.

Artificial earthquakes: ground vibrations caused by man-made factors such as blasting and nuclear testing.

Pulsations: frequent micro-movements of the earth's surface caused by atmospheric activity, wave impact, etc.

Classification by the cause of earthquake formation

Tectonic earthquakes: Earthquakes are caused by fractures in rock formations, which result in huge changes in geological structure, so they are called tectonic earthquakes or fracture earthquakes.

Volcanic earthquakes: The earth's crust vibrates as a result of the energy impact caused by volcanic eruptions. Volcanic earthquakes are sometimes quite strong. However, the area affected by such earthquakes is usually limited to a few tens of kilometers away from the volcano, and the number of occurrences is relatively small, accounting for only about 7% of the number of earthquakes and causing less damage.

Subsidence earthquakes: Earthquakes caused by the subsidence of strata. This type of earthquake occurs even less often, accounting for only about 3% of the total number of earthquakes. The magnitude is small, the impact is limited, and the damage is less.

Induced earthquakes: Earthquakes caused by some kind of external factors induced by the earth's crust in a specific area (e.g. meteorite fall, reservoir water storage, deep well injection).

Artificial earthquakes: Artificially induced ground vibrations such as underground nuclear explosions and explosive blasts are called artificial earthquakes. Artificial earthquakes are earthquakes caused by human activities. Such as vibrations caused by industrial blasting, underground nuclear explosions; high pressure water injection in deep wells and water storage in large reservoirs increase the pressure of the earth's crust and sometimes induce earthquakes.

Classification according to the depth of the earthquake source

Shallow source earthquakes: Earthquakes with a source depth of less than 70 km. Most destructive earthquakes are shallow source earthquakes.

Medium-source earthquakes: Earthquakes with a source depth of 60 to 300 km.

Deep source earthquakes: Earthquakes with a source depth of 300 km or more. So far, the deepest earthquake recorded in the world has a source depth of 786 km.

In a year, about 85% of the energy released by all earthquakes worldwide comes from shallow source earthquakes, 12% from medium source earthquakes, and 3% from deep source earthquakes.

Classification by the distance of the earthquake

Local: Earthquakes with an epicenter distance of less than 100 km.

Near-earthquake: Earthquakes with an epicenter distance of 100 to 1000 km.

Distant earthquakes: Earthquakes with epicenter distance greater than 1000 km.

Classification by magnitude

Weak earthquakes: earthquakes with a magnitude less than 3.

Induced earthquakes: earthquakes with magnitudes equal to or greater than 3 and less than or equal to 4.5.

Moderately strong earthquakes: earthquakes with a magnitude greater than 4.5 and less than 6.

Strong earthquake: An earthquake with a magnitude equal to or greater than 6, where a magnitude greater than or equal to 8 is called a giant earthquake.

Classification by the degree of damage

General destructive earthquakes: earthquakes causing several to dozens of deaths, or direct economic losses of 100 million yuan or less (including 100 million yuan).

Moderately destructive earthquakes: earthquakes causing tens to hundreds of deaths, or direct economic losses of 100 million yuan or more (excluding 100 million yuan) and less than 500 million yuan.

Severe destructive earthquakes: earthquakes of magnitude seven or higher in densely populated areas, earthquakes of magnitude six or higher in large and medium-sized cities, or earthquakes causing hundreds to thousands of deaths, or direct economic losses of more than five hundred million yuan and less than three billion yuan.

Extraordinarily destructive earthquakes: earthquakes of magnitude seven or higher in large and medium-sized cities, or earthquakes causing more than 10,000 deaths, or direct economic losses of more than three billion yuan.

Classification of tectonic earthquakes

Isolated type earthquakes: There is a prominent mainshock with few aftershocks and low intensity; the energy released by the mainshock accounts for more than 99.9% of the whole sequence; the difference between the mainshock magnitude and the maximum aftershock is 2.4 or more.

Mainshock-aftershock type earthquake: The mainshock is very prominent and the aftershocks are very abundant; the energy released by the largest earthquake accounts for more than 90% of the whole sequence; the difference between the mainshock magnitude and the largest aftershock is 0.7 to 2.4 magnitude.

Double-shock type earthquakes: More than 90% of the energy in a seismic activity sequence is mainly released by two earthquakes that occur close to each other in time, location and size.

Swarm-type earthquakes: There are more than two mainshocks of similar size and very abundant aftershocks; the main energy is released through multiple earthquakes of similar magnitude, and the energy released by the largest earthquake accounts for less than 90% of the whole sequence; the difference between the mainshock magnitude and the largest aftershock is less than 0.7 magnitude.

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