Magnitude 7.9 - EASTERN SICHUAN, CHINA
2008 May 12 06:28:01 UTC
- This event has been reviewed by a seismologist.
|Depth||19 km (11.8 miles) set by location program|
|Region||EASTERN SICHUAN, CHINA|
|Distances||80 km (50 miles) WNW of Chengdu, Sichuan, China|
145 km (90 miles) WSW of Mianyang, Sichuan, China
350 km (215 miles) WNW of Chongqing, Chongqing, China
1545 km (960 miles) SW of BEIJING, Beijing, China
|Location Uncertainty||horizontal +/- 5 km (3.1 miles); depth fixed by location program|
|Parameters||NST=357, Nph=357, Dmin=592.1 km, Rmss=1.38 sec, Gp= 14°,|
M-type=centroid moment magnitude (Mw), Version=R
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The following is a release by the United States Geological Survey, National Earthquake Information Center: An earthquake occurred 90 km (55 miles) WNW of Chengdu, Sichuan, China and 1545 km (960 miles) SW of BEIJING, Beijing, China at 12:28 AM MDT, May 12, 2008 (2:28 PM local time in China). The magnitude and location may be revised when additional data and further analysis results are available.
At least 69,195 people killed, 374,177 injured and 18,392 missing and presumed dead in the Chengdu-Lixian-Guangyuan area. More than 45.5 million people in 10 provinces and regions were affected. At least 15 million people were evacuated from their homes and more than 5 million were left homeless. An estimated 5.36 million buildings collapsed and more than 21 million buildings were damaged in Sichuan and in parts of Chongqing, Gansu, Hubei, Shaanxi and Yunnan. The total economic loss was estimated at 86 billion US dollars. Beichuan, Dujiangyan, Wuolong and Yingxiu were almost completely destroyed. Landslides and rockfalls damaged or destroyed several mountain roads and railways and buried buildings in the Beichuan-Wenchuan area, cutting off access to the region for several days. At least 700 people were buried by a landslide at Qingchuan. Landslides also dammed several rivers, creating 34 barrier lakes which threatened about 700,000 people downstream. A train was buried by a landslide near Longnan, Gansu. At least 2,473 dams sustained some damage and more than 53,000 km of roads and 48,000 km of tap water pipelines were damaged. About 1.5 km of surface faulting was observed near Qingchuan, surface cracks and fractures occurred on three mountains in the area, and subsidence and street cracks were observed in the city itself. Maximum intensity XI was assigned in the Wenchuan area. Felt (VIII) at Deyang and Mianyang; (VII) at Chengdu; (VI) at Luzhou and Xi'an; (V) at Chongqing, Guozhen, Lanzhou, Leshan, Wu'an, Xichang and Ya'an. Felt in much of central, eastern and southern China, including Beijing, Guangzhou, Hefei, Nanjing, Shanghai, Tianjin, Wuhan and Hong Kong. Also felt in parts of Bangladesh, Taiwan, Thailand and Vietnam. Seiches were observed at Kotalipara, Bangladesh.
The Sichuan earthquake of May 12, 2008, occurred as the result of motion on a northeast striking reverse fault or thrust fault on the northwestern margin of the Sichuan Basin. The earthquake's epicenter and focal-mechanism are consistent with it having occurred as the result of movement on the Longmenshan fault or a tectonically related fault. The earthquake reflects tectonic stresses resulting from the convergence of crustal material slowly moving from the high Tibetan Plateau, to the west, against strong crust underlying the Sichuan Basin and southeastern China.
On a continental scale, the seismicity of central and eastern Asia is a result of northward convergence of the India plate against the Eurasia plate with a velocity of about 50 mm/y. The convergence of the two plates is broadly accommodated by the uplift of the Asian highlands and by the motion of crustal material to the east away from the uplifted Tibetan Plateau.
The northwestern margin of the Sichuan Basin has previously experienced destructive earthquakes. The magnitude 7.5 earthquake of August 25, 1933, killed more than 9,300 people.
Scientific & Technical Information
- Preliminary Earthquake Report
- U.S. Geological Survey, National Earthquake Information Center:
World Data Center for Seismology, Denver