Aftershocks from Sichuan earthquake pose threat of secondary disasters

Secondary disasters such as mudslides and dam-related crises may occur in the days or even months after Saturday's earthquake, threatening the safety of residents and rescuers, geologists warn.

Fan Xiao, chief engineer at the Sichuan Geology and Mineral Bureau in Chengdu, said yesterday the banks along the Qingyi River, in one of the most geologically unstable regions of the province, had taken a big hit.

Known for its high mountains and deep valleys, the area was already unstable before the earthquake, with villages and roads sitting almost in the path of potential landslides, Fan said. And shockwaves from the earthquake could profoundly increase structural instability in the region.

"Residents and rescuers must be highly alert to the dangers of mudslides, especially after rain," he said. "There will be lots of rain in the coming months."

Like all major rivers in Sichuan, the Qingyi has been heavily dammed by hydropower projects. Though none collapsed during the quake, the biggest threat to the dams' structural integrity will come during the summer flood season, Fan said.

Yang Yong , an independent geologist based in Chengdu who is familiar with hydropower projects in the region, told The Beijing News that he was worried because of the large number of dams in the quake zone.

"The closest dam was just 10 kilometres from the epicentre," he was quoted as saying. "Communications and transportation were both cut off. We don't know the situation there."