BEIJING, May 13 (Xinhua) -- The Olympic venues here, including the "Bird's Nest" and "Water Cube", were not affected by the magnitude 7.8 quake in Sichuan Province on Monday, said project designers.

"The quake was reduced to magnitude 3.9 when the quake wave reached Beijing," said Tan Xiaochun, a chief designer of the National Stadium, known as the Bird's Nest, in the capital's northeastern Chaoyang District.

"This level of intensity almost posed no effects on the structure."

The National Aquatics Center, nicknamed the "Water cube," is the main venue for swimming, diving and synchronized swimming during the Olympic Games. It was also unaffected by the quake, said one of its designers.

The designer, who declined to be identified, said that the designs of the 31 Olympic venues in Beijing had undergone strict seismic appraisals before construction started.