When did the Wenchuan earthquake happen?
According to the revised data of Seismological Bureau of China, the magnitude of surface wave of Wenchuan earthquake on 5. 12 was 8.0. According to the data of Japan Meteorological Agency, the seismic wave of Wenchuan earthquake on May 12 confirmed that * * * circled the earth 6 times.
The earthquake affected most parts of China and many countries and regions in Asia. The earthquake was felt in Inner Mongolia in the north of China, Shanghai in the east, Tibet in the west, Hong Kong in China and Taiwan Province Province in China in the south, and Thailand, Viet Nam, the Philippines and Japan outside China.
5. 12 Wenchuan earthquake severely damaged an area of about 500,000 square kilometers, including extremely hard-hit * *10 counties (cities), hard-hit ***4 1 county (city), and generally hard-hit * *186 counties (cities).
As of September 25th, 2008, the 512 Wenchuan earthquake * * killed 69,227 people,17,923 people were missing, 374,643 people were injured to varying degrees, and19,930,300 people lost their homes, with a total population of 46.256 million.
As of September 2008, the 512 Wenchuan earthquake caused direct economic losses of 84,565,438+400 million yuan. 5. 12 Wenchuan earthquake is the most destructive, widespread, disastrous and difficult earthquake since the founding of the People's Republic of China.
On March 2, 2009, with the approval of People's Republic of China (PRC) and the State Council, May 12 was designated as the National Disaster Prevention and Mitigation Day from 2009.
Extended data:
The strong cause of the earthquake
First, the earthquake is very big. The magnitude of the earthquake is very large. The fault is more than 300 kilometers long and 40 kilometers wide. Moreover, the average dislocation momentum of the fault is 2.5 meters and the maximum is 8.9 meters.
Second, the source is shallow. Generally speaking, the shallow focal depth means that the focal depth is only 15km, but this is not entirely the case, because the fracture surface of the earthquake extends from underground to the ground, with a length of more than 300 km and a width of 40km. The whole fault plane extends from above 30km underground to the ground, which confuses the ground. This is the second reason why this earthquake will cause such a big loss.
Third, the rupture lasts for a long time and is irregular, causing great damage to the ground.
In addition, there are two unique features of this earthquake. The asymmetry of faults leads to completely different damage of the upper wall and the lower wall.
The upper wall of this earthquake refers to the northwest of the fault zone, and the lower wall is the east. As we all know, although the source of this earthquake is very strong in Chengdu and Deyang Plain, the damage to the west is very light, which is the so-called footwall and footwall effect of the fault. We can also get such a result through calculation. Any horizontal dislocation in the upper wall is in Beichuan and Yingxiu, and so is the vertical movement.
References:
Causes, rupture process and disaster mechanism of Wenchuan earthquake, Ministry of Natural Resources of People's Republic of China (PRC).
Baidu Encyclopedia -5. 12 Wenchuan Earthquake