According to a release by the U.S. Geological Survey, National Earthquake Information Center, a magnitude 7.9 earthquake occurred 55 miles (90 km) west-northwest of Chengdu, Sichuan, China, and 960 miles (1,545 km) southwest of Beijing, China, at 2:28 p.m. local time on May 12, 2008. The organization reports that at least 8,500 people were killed and that the quake was felt in parts of Thailand and Taiwan. According to the Associated Press, official Xinhua News Agency reports that 80 percent of the buildings had collapsed in Beichuan county in Sichuan province after the quake, raising fears the overall death toll could increase sharply.

The Sichuan earthquake occurred as the result of motion on a northeast-striking reverse fault or thrust fault on the northwestern margin of the Sichuan Basin. The northwestern margin of the Sichuan Basin has previously experienced destructive earthquakes and on Aug. 25, 1933, a magnitude 7.5 earthquake killed more than 9,300 people.