May 12, 2008 Earthquake: Sichuan Province, China

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 in Hong Kong. Also felt in parts of Bangladesh, Taiwan, Thailand and Vietnam. Seiches were observed at Kotalipara, Bangladesh.

The May 12, 2008, M 7.9 Sichuan earthquake occurred as the result of shallow oblique reverse faulting on the northwestern margin of the Sichuan Basin. Focal mechanism solutions indicate that rupture occurred on either a steeply dipping reverse fault or a shallowly dipping thrust fault. The epicenter, focal-mechanism, and finite-fault modeling of globally recorded seismic data for this earthquake are consistent with it resulting from the result of movement on the Longmenshan fault or a tectonically related structure, striking towards the southwest and dipping shallowly beneath the range front. 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 at a velocity of about 50 mm/yr. 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.

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Reverse-faulting events of the size of the May 12, 2008, earthquake are typically about 145x40 km (length x width), while strike-slip events of this magnitude are typically about 210x25 km in size. Modeling of this earthquake implies dimensions of about 250x30 km, involving complex faulting surrounding the hypocenter and further slip propagating to the northeast.

The northwestern margin of the Sichuan Basin has previously experienced destructive earthquakes. The M 7.5 earthquake of August 25, 1933, resulted in more than 9,300 fatalities.

Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)

2008, May 12, 06:28:00 UTC (2:28 PM local time). An earthquake occurred 90 km WNW of Chengdu, Sichuan, China and 1545 km SW of Beijing, China.

Felt Report

At least 69,185 people killed, 374,171 injured and 18,467 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 47,000 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 IX was assigned in the Wenchuan area. Seiches were observed at Kotalipara, Bangladesh.

Tectonic Summary

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.

(above ref #1053)

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 (ref #10015)

Direct economic losses for the May 12 Sichuan earthquake centered in Wenchuan County hit 845.1 billion yuan (about 121 billion U.S. dollars)[…]The southwestern province of Sichuan suffered the worst, accounting for 91.3 percent of the total direct economic losses, according to Shi Peijun with the Wenchuan earthquake expert panel. Its neighboring provinces Gansu and Shaanxi accounted for 5.8 and 2.9 percent of the total losses, respectively. (ref #4018)

87,476 killed, 45,976,596 affected, $85,000 billion damage (ref #1250)

12 May 2008 (03:16:40, UTC), the Sichuan (China) earthquake of Mw7.9 took place at 19 km depth on the Longmenshan fault in the Sichuan Province of southwestern China, which killed 87,587 people. This earthquake caused a total monetary loss of 146 billion US dollars. The maximum intensity for this earthquake was found to be X on the MMI scale. (ref #13294)

2008 May 12 06:28:00.47 UTC, 30.98 N 103.396 E, magnitude 7.91 Mw (ref #10476, v9.1)

$121.6 billion economic loss (ref #13727)