Emotions were mixed as Chinese and U.S. scientists mounted the stage today for "Disaster Scene Investigation: Lessons of the Wenchuan Earthquake." On 12 May 2008, a magnitude-7.9 quake leveled 5.5 million homes and killed 70,000 people in western China. The region is still struggling to recover. "It was a terrible tragedy," said Richard Stone, Science
's Asia bureau chief and organizer of the session. "But for scientists, it has turned out to be a unique laboratory for understanding killer earthquakes and how to prepare and respond to the next one." Stone joined scientists at the scene within a week of the disaster.
Luckily, the area hit by the quake was wired with one of the world's densest broadband seismometer arrays, with nearly 300 solar-powered detectors recording tremors in the ground. It delivered a flood of data to a team led by geologist Liu Qiyuan of the China Earthquake Administration in Beijing. What's more, the unstable fault line where the quake originated has now been mapped and modeled in unprecedented detail. Here at the AAAS meeting, Liu, Cui Peng of the Institute of Mountain Hazards and Environment in Chengdu, and a U.S. colleague, MIT geologist Leigh Royden, gave an overview of their analysis.
The picture that is emerging is of a highly unusual earthquake. Over
the past 10 million years, the Indian subcontinent has been pushing the
Tibetan Plateau eastward, from the Himalayan mountains toward China's
Sichuan basin. All that material is being injected horizontally, deep
beneath the surface with nowhere to go. This pent-up energy, along with
the extremely steep and unstable river valleys where millions of people
have built their homes, adds up to an inevitable disaster. "In
retrospect, we should have seen it coming," says Royden. But Cui and
Liu promised that China won't be caught off-guard again.
open is the question of whether humans had a hand in the quake. In
January, Science reported
that stresses from water piled behind the
Zipingpu Dam, 5.5 kilometers from the epicenter, may have triggered the
failure of the fault. The
scientists at today's session didn't bring up the issue, and no one in
the audience asked about it.