Satellite data explains China earthquake

BEIJING, Oct. 15 (UPI) -- Chinese scientists say they used satellite data to detail the geological events that led to the 2008 Wenchuan Earthquake that killed nearly 90 000 people.

"One of the very fundamental issues for understanding an earthquake is to know how the rupture is distributed on the fault plane, which is directly related to the amount of ground shaking and the damage it could cause at the surface," said Jianbao Sun of China's Institute of Geology.

Sun and Peking University Professor Zhengkang Shen used radar data from European and Japanese satellites to determine the amount and scope of surface deformation produced by the earthquake.

"This is perhaps the very first time people have seen the complete deformation field produced by an earthquake on such a large scale," Sun said.

The researchers discovered the May 12, 2008, quake produced a 150-mile-long rupture along the Beichuan fault and a 45-mile-long rupture along part of the Pengguan fault.

They also determined fault junctions -- solid rock barriers that stop a quake from propagating -- failed to withstand the extraordinary energy released along the fault.

"These fault junctions are barriers, whose failures in a single event allowed the rupture to cascade through several fault segments, resulting in a major 7.9-earthquake," Shen said. "Earthquakes across fault segments like this … happen about every 4,000 years."

The study is reported in the journal Nature Geoscience.