मई 29, 2012
Geologists are once again debating whether dam construction in China has led to a proliferation of earthquakes.
A powerful earthquake struck China’s Sichuan province on the last weekend, leaving 200 people dead, over 11,000 injured and an estimated 100,000 homeless.
The magnitude-7 earthquake struck Lushan country along the same longmenshan fault line as the devastating Wenchuan earthquake in Sichuan in 2008, which killed over 90,000 people.
Local authorities issued warnings of secondary disasters, as some 4,000 aftershocks have continued to wreak havoc this week, triggering landslides in the mountainous and region. 54 dams have been damaged in the earthquake, with residents downstream of five of them evacuated, according to the South China Morning Post.
This event will add fuel to the longstanding row over the safety of large dam cascades in earthquake-prone in southwest China.
The disaster has also sparked fresh debate over whether construction of mega-dams trigger seismic events.
Fan Xiao, chief engineer at the Sichuan Bureau of Geology and Mineral Resources, told the Global Times on Sunday that authorities should realise reservoirs built on seismically active fault lines can cause movement in the earth’s crust.
“The large reservoirs built on the fault line can induce earthquakes as the huge amount of water adds huge pressure to the fracture,” Fan said.
This view has been fiercely debated among scientists both inside and outside China over the last five years, since a link was drawn between the Wenchuan earthquake in Sichuan in 2008 and the Zipingpu reservoir.
A reservoir with a capacity of over 1 billion cubic meters and a dam more than 100 metres tall would have a 30-40 % chance of inducing an earthquake, said Fan. The Pubugou reservoir, located 80 miles from Lushan county where Saturday’s quake took place, is much bigger than that at 186 metres tall with 5.39 billion cubic metres of water.
Many rivers naturally flow along fault lines and China has plans to build a series of controversial hydropower dams in the region on rivers originating on the Tibetan Plateau.