The mountainous terrain surrounding Wenchuan county means its residents will have to rebuild on the same site, which sits on a seismic fault line, a local official said. Wenchuan, one of the most-devastated areas in the magnitude-8 earthquake two weeks ago, was marked as the epicentre before the China Earthquake Administration confirmed a week later that it was in neighbouring Yingxiu. Nearly all buildings in Wenchuan were badly damaged or flattened. Tian Wen , a chief engineer from the Sichuan Construction Bureau, said less than 10 per cent of the 20,000 square metres of buildings in downtown Wenchuan was intact. He said more than half had to be demolished and rebuilt from scratch, the Nanfang Daily reported. Unlike nearby Beichuan county, which would be completely relocated, Wenchuan would not be moved and all its reconstruction would be done on the same site. 'We have studied three options: to relocate Wenchuan, to merge it with nearby counties or to rebuild it on the same ground,' said Tian Xiaodan, deputy director of Aba Tibetan-Qiang Autonomous Prefecture, which oversees Wenchuan. 'Because Wenchuan is surrounded by mountains, it's impossible to relocate it to another flat place. And because of its big size, it's difficult to merge it with other counties. The only option we have is to rebuild it over the same site,' he was quoted by Nanfang Daily as saying. Mr Tian estimated that the reconstruction process would take three to five years. He said the quake had left 450,000 people in Aba prefecture homeless, and at least 120,000 prefabricated houses were needed to accommodate them.