2008 Sichuan earthquake

2018-08-22 栏目:188bet客户端 作者: admin

  The 2008 Sichuan earthquake (Chinese: 汶川父亲地动; pinyin: Wènchuān dà dìzhèn; literally: "Great Wenchuan earthquake"), also known as the Great Sichuan earthquake or Wenchuan earthquake, occurred at 14:28:01 China Standard Time on May 12, 2008. Measuring at 8.0 Ms (7.9 Mw), the earthquake's epicenter was located 80 kilometres (50?mi) west-northwest of Chengdu, the provincial capital, with a focal depth of 19?km (12?mi). The earthquake ruptured the fault for over 240?km, with surface displacements of several meters. The earthquake was also felt in nearby countries and as far away as both Beijing and Shanghai—1,500?km (930?mi) and 1,700?km (1,060?mi) away—where office buildings swayed with the tremor. Strong aftershocks, some exceeding 6 Ms, continued to hit the area up to several months after the main shock, causing further casualties and damage. The earthquake also caused the largest number of geohazards ever recorded, including about 200,000 landslides and more than 800 quake lakes distributed over an area of 110,000?km2.

  Over 69,000 people lost their lives in the quake, including 68,636 in Sichuan province. 374,176 were reported injured, with 18,222 listed as missing as of July 2008. The geohazards triggered by the earthquake are thought to be responsible for at least one third of the death toll. The earthquake left about 4.8?million people homeless, though the number could be as high as 11?million. Approximately 15 million people lived in the affected area. It was the deadliest earthquake to hit China since the 1976 Tangshan earthquake, which killed at least 240,000?people, and the strongest in the country since the 1950 Chayu earthquake, which registered at 8.5 on the Richter magnitude scale. It is the 21st deadliest earthquake of all time. On November 6, 2008, the central government announced that it would spend 1?trillion RMB (about US $146.5?billion) over the next three years to rebuild areas ravaged by the earthquake, as part of the Chinese economic stimulus program.

  According to a study by the China Earthquake Administration (CEA), the earthquake occurred along the Longmenshan Fault, a thrust structure along the border of the Indo-Australian Plate and Eurasian Plate. Seismic activities concentrated on its mid-fracture (known as Yingxiu-Beichuan fracture). The rupture lasted close to 120 seconds, with the majority of energy released in the first 80 seconds. Starting from Wenchuan, the rupture propagated at an average speed of 3.1?kilometers per second 49° toward north east, rupturing a total of about 300?km. Maximum displacement amounted to 9?meters. The focus was deeper than 10?km.

  In a United States Geological Survey (USGS) study, preliminary rupture models of the earthquake indicated displacement of up to 9 meters along a fault approximately 240?km long by 20?km deep. The earthquake generated deformations of the surface greater than 3 meters and increased the stress (and probability of occurrence of future events) at the northeastern and southwestern ends of the fault. On May 20, USGS seismologist Tom Parsons warned that there is "high risk" of a major M>7 aftershock over the next weeks or months.

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