A strong aftershock jolted Yingxiu Town in the epicenter Wenchuan County again, Xinhua reporter at Yingxiu said Thursday morning.

Rocks rolled down from the hills and some dilapidated houses, inflicted by the Monday's devastating earthquake, collapsed completely, Xinhua reporter said.

As of 1:00 p.m. Wednesday, 18 aftershocks above 5 on the Richter scale had been monitored since the devastating earthquake on Monday in southwest China's Wenchuan County, China Seismological Bureau said Wednesday.

The biggest aftershock reported so far was magnitude-6.1, which rocked southwest China's Sichuan Province at around 3:10 p.m.

(Xinhua News Agency May 15, 2008)