Rupture imaging of the Wenchuan earthquake and advice for Chinese earthquake early warning system

摘要

Using the teleseismic body waves recorded by Hi-net array, the rupture image of the 2008 Wenchuan earthquake is studied by the back-projecting method. Our results show that seismic energy is mainly released in the area north to the hypocenter. Comparing with historical seismicity, aftershock rate in the source area is significantly active with a characteristic time of 11 years, indicating that seismicity in this area in the future ten years is significantly higher than background earthquake rate. A reliably and accurate EEW system is expected to play a central role in helping to mitigate seismic hazard. On the basis of experience from Japanese EEW, we recommend that China should introduce an instrumentally observable intensity scale, deploy intensity seismometers and broadcast the instrumentally observed intensity data to the public. We would point out that prediction of shaking intensity is much more important than estimating the final magnitude. It follows that seismologists should find an effective method to issue the coming S-wave shaking intensity using the P-wave data, and that the public should pay attention to the intensity index, rather than the magnitude.