By John Sexton
The May 12 earthquake left Sichuan's capital city Chengdu unscathed while Dujiangyan, less than 50 kilometers away, was badly hit and suffered terrible loss of life. Now a Chengdu geology professor, Cao Junxing, claims he can explain why the provincial capital escaped damage.
The epicenter of the May 12 quake was near the town of Yingxiu in Wenchuan, in the Longmen mountains, about 70 kilometers northwest of Chengdu.
No buildings in the Chengdu urban area collapsed or suffered serious damage on May 12, but a number of smaller cities lying further west, including the well known tourist resort of Dujiangyan and Pengzhou, suffered badly. More than 3,000 people died in Dujiangyan and nearly 1,000 in Pengzhou. Dujiangyan and Pengzhou are administered from Chengdu but lie well outside its urban area.
Professor Cao believes that the limestone and sandy strata of the Chengdu plain acted as effective shock absorbers to protect Chengdu city from the earthquake, which originated in the Yingxiu-Beichuan fault. By the time shockwaves reached the Chengdu urban area they were too weak to cause serious damage. East of Chengdu city is the Sichuan Basin, part of the Yangzi block, which, according to Professor Cao, is one of the most stable geological structures in China. He believes that Chengdu's position, and the geological structure of the surrounding area, mean that serious earthquake damage to the city is virtually impossible.
Historian Tan Lihe backed Professor Cao's view. After studying written records from the Han, Tang and Ming dynasties, Professor Tan concluded that, while Sichuan Province has been hit by many earthquakes over more than two thousand years of written history, the city of Chengdu has never suffered serious damage.
Professor Cao's paper setting out his theory will be published on July 22 in the Journal of Chengdu University of Technology.
(China.org.cn, July 19, 2008)