Scientist explores causes of Sichuan earthquake

25 September 2008

A NERC-funded scientist has returned from a field trip to China to examine the causes of the 12 May earthquake that killed more than 69,000 people.

Workers rebuilding collapsed road

Clearing up after the Sichuan earthquake

Alex Densmore, associate director of hazard research at the Institute of Hazard and Risk Research and Department of Geography at Durham University, was the first UK scientist to visit the area to explore the earthquake's causes.

He says we still don't know when or exactly where disaster will strike next in the region, but we do know which areas are at most risk. This knowledge could save lives by helping planners avoid building on dangerous ground.

"It was very noticeable that buildings 50 or even ten metres on either side of the surface rupture were often damaged but still standing," he says. "Buildings that lay directly on the rupture collapsed almost without fail. If you could prevent building directly on top of active faults, you could save a lot of lives."

He adds that authorities now have a unique opportunity to do this. Reconstruction efforts are picking up pace, and Densmore believes Chinese officials would be well-advised to consider imposing buffer zones around faults.

Given that they're also considering proposals to move all the survivors of some of the hardest-hit towns to new settlements, such buffer zones should not be prohibitively expensive.

Because of very limited historical records of previous earthquakes in the area, it's not possible to predict when the next event will happen.

Among the expedition's goals was to find out whether the earthquake activated faults that geologists had already mapped, or whether it created new ones. The answer was a bit of both, though Densmore says that the area's intensive land use and dense development complicated the process of understanding its fault lines.

Apart from the earthquake itself and its aftershocks, now dying down, the landslides it caused are still causing problems. Heavy rain is still triggering these events, blocking roads and hampering reconstruction efforts.

The landslides are also dumping tonnes of sediment in rivers, causing riverbeds to rise as much as three metres already and inundating low-lying settlements. The sediment will take decades to work its way out of Chinese rivers, and could disrupt dams and hydro power stations.

Densmore worked on the project alongside colleagues from the Chengdu University of Technology, the Seismological Bureau of Sichuan Province and Shell UK. He now plans to write up the results of the research for publication.