The cause of Sichuan earthquake

The reason for the Sichuan earthquake is that the Indian Ocean plate and the Eurasian plate are squeezed, and the Indian Ocean plate is constantly diving into the Eurasian plate, which makes the Qinghai-Tibet Plateau uplift. Therefore, when the compressive stress of the plates reaches the maximum, an earthquake occurs in the weak fault zone in Sichuan, so the geographical location of Sichuan causes the high incidence of earthquakes.

Sichuan has a complex terrain, spanning many geomorphic units such as Qinghai-Tibet Plateau, Hengduan Mountains, Yunnan-Guizhou Plateau, Qinba Mountain Area and Sichuan Basin. The terrain is high in the west and low in the east, and it slopes from northwest to southeast. The highest point is Gongga Mountain, the main peak of the western snow mountain, with an altitude of 7556 meters. It is adjacent to Longmen Mountain in Daliangshan, Sichuan Basin and its marginal mountains in the east, and western Sichuan alpine plateau and southwest Sichuan in the west.

The climate of Sichuan

East Sichuan, that is, Sichuan Basin and its surrounding mountainous areas, belongs to the humid climate zone in the middle subtropical zone and has maritime climate characteristics. This area is warm and humid all the year round, with an annual average temperature of 16 ~ 18℃, a daily temperature of ≥ 10℃ lasting for 240 ~ 280 days, a cumulative temperature of 4,000 ~ 6,000℃, a small daily temperature difference, a large annual temperature difference, warm in winter and hot in summer, and a frost-free period of 230 ~ 340. There are more clouds and less sunny days in the basin. The sunshine time in 20 13 years is short, only 1000 ~ 1400 hours, which is 600 ~ 800 hours less than that in the lower reaches of the Yangtze River basin at the same latitude.

The altitude difference of the alpine plateau in northwest Sichuan is great, and the climate change is obvious in three dimensions. Subtropical zone, warm temperate zone, middle temperate zone, cold temperate zone, sub-frigid zone, frigid zone and permafrost zone appear in turn from valley to ridge. Generally speaking, the climate is dominated by cold temperate zone, with dry and warm valleys, wet and cold mountains, cool Leng Xia in winter and insufficient water and heat. The annual average temperature is 4 ~ 12℃, the annual precipitation is 500 ~ 900 mm, the weather is clear and the annual sunshine 1600 ~ 2600 hours.

Reference to the above content: Baidu Encyclopedia-Sichuan