Highly read on www.agu.org 15 Oct–21 Oct
A brutal secondary rupture may have been responsible for much of the devastation caused by the Wenchuan earthquake, which killed more than 69,000 people in Sichuan province, China, on 12 May 2008.
A team led by Guohong Zhang of the China Earthquake Administration in Beijing used ground-acceleration data from a national network of earthquake-monitoring stations to reconstruct the spread of the 7.9-magnitude quake. Records from 26 local stations indicate that the main slip area — a high-friction patch of fault located 25 to 50 kilometres from the epicentre — resisted the seismic stress building up around it for about 30 seconds. The slip area then failed catastrophically in a sudden 12.5-metre jolt.
Researchers have long hypothesized that an initial quake can trigger secondary ruptures. The study shows that this is a realistic scenario, the team concludes.
Geophys. Res. Lett. http://dx.doi.org/10.1029/2012GL052516 (2012)