Earthquake at 7.8 Eastern Sichuan, China

United States Geological Service Information centre Timed at 2.28 AM EDT
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.

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.

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.

Deaths reported

The Daily Telegraph report the official Xinhua News Agency who report the Sichuan provincial government as saying 7,651 people died across the province, but the situation in at least two counties remain unclear.

In Beichuan county, just east of the epicenter, up to 5,000 people were killed and 80 per cent of buildings collapsed, Xinhua said. Another 10,000 people were injured.