Where do earthquakes usually occur?

Earthquakes can happen anywhere. If you are in an earthquake zone, there will usually be an earthquake, and it is a big earthquake.

Earthquakes usually occur in mountainous areas and rivers, but major earthquakes mostly occur in plain areas. If there is an earthquake in Changsha and Beijing, it may be around 5-7. The Tangshan earthquake, which happened in Tangshan, near Beijing, was 7.8, and Beijing was also affected.

Some earthquakes are caused by the dislocation and rupture of rock strata deep underground, which are called tectonic earthquakes. It has the highest frequency and the most destructive power, accounting for more than 90% of the global earthquakes.

In contrast, the most frequent places are in mountains and rivers, followed by sea areas. Because the sea area is larger than the land, the earthquake covers the largest area, but there are also underwater mountains and rivers. If all the mountains and rivers are counted, it should be the most, but the places with many earthquakes are not necessarily large in magnitude. Theoretically, in areas where small earthquakes often occur, because the energy of crustal movement is often released, large earthquakes may not occur, and many of them are mild or no induced earthquakes. However, it does not rule out that there is undiscovered energy accumulation in the other direction, and the population is relatively sparse, so earthquakes in these areas will not have a great impact, and the areas where earthquakes occur are relatively small and generally will not be reported. Earthquakes are most likely to occur in seismically active seismic zones, whether in mountainous areas or plains. In some areas, earthquakes can occur for a long time, but due to the accumulation of rock energy in the deep underground, earthquakes have occurred. It will be a big earthquake, which is often located in the plain area on the earthquake zone and also in the area where people's cities are concentrated, so it has a great impact and gives people a deep impression. For example, the Tangshan earthquake is always mentioned when people mention earthquakes.

Generally speaking, the magnitude of an earthquake should be between 5 and 7. If there are earthquakes in Changsha and Beijing, Beijing will also be affected by the Tangshan earthquake, which is very close to Beijing.

Earthquakes are mainly distributed in Pacific Rim, Albis-Himalayan Belt, Mid-Atlantic Ridge and Indian Ridge. Generally speaking, earthquakes mainly occur in tectonic active zones such as ridges and rifts, trenches, transform fault and ancient plate margins within the mainland.

China is located between the Pacific Rim seismic belt and the Eurasian seismic belt, squeezed by the Pacific plate, the Indian plate and the Philippine Sea plate, and the seismic fault zone is very developed. Since the 20th century, there have been nearly 800 earthquakes of magnitude 6 or above in China, which are distributed in all provinces, autonomous regions and municipalities except Guizhou and Zhejiang provinces and Hong Kong Special Administrative Region.

China is a country with severe earthquake disasters because of its high frequency, high intensity, shallow focal point and wide distribution. Since 1900, the number of earthquake deaths in China has reached 550,000, accounting for 53% of the global earthquake deaths; Since 1949, there have been more than 100 destructive earthquakes in 22 provinces (autonomous regions and municipalities directly under the central government) in China, including 14 provinces in the eastern region, which caused more than 270,000 deaths, accounting for 54% of all kinds of disaster deaths in China. The earthquake affected an area of more than 300,000 square kilometers and 7 million houses collapsed. The severity of natural disasters such as earthquakes is one of the basic national conditions in China.

The seismic activity in China is mainly distributed in 23 seismic zones in five regions. These five areas are: ① Taiwan Province Province and its adjacent waters; (2) Southwest China, mainly Tibet, western Sichuan and central and western Yunnan; (3) Northwest China, mainly distributed in Hexi Corridor of Gansu, Qinghai and Ningxia and the foothills of Tianshan Mountain; ④ North China, mainly located on both sides of Taihang Mountain, Wei Fen Valley, Yinshan-Yanshan area, Luzhong and Bohai Bay; ⑤ Southeast coastal areas such as Guangdong and Fujian. Taiwan Province province in China is located in the Pacific Rim seismic belt, Tibet, Xinjiang, Yunnan, Sichuan and Qinghai provinces are located in the Himalayan-Mediterranean seismic belt, and other provinces are located in related seismic belts. The distribution of China's seismic zones is an important basis for formulating key earthquake monitoring and defense areas in China.

Distribution of earthquakes in China (Figure)

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