Relationship between plane strain rate gradient of GPS horizontal deformation and strong earthquake risk area

Rapid development of GPS observation and information processing techniques has provided a solid foundation for acquiring accurate horizontal crustal motion and related researches. In this paper, by using the horizontal deformation rate of GPS observation from 1997 to 2007, which was provided by Crustal Movement Observation Network of China, the relationship between plane strain rate gradient and strong earthquake risk area is discussed, and identifying method of mid-long term prediction of strong earthquake risk area is explored. The results show that from 2001 to 2011 most M_S≥6.8 earthquakes occurred in Chinese mainland are in the high-low transition zones of plane strain gradient and its intersection parts with the block boundary zone. GPS plane strain rate gradient can be used as a method for identifying strong earthquake risk area for mid-long term prediction by comparing the observed strain rate with the maximum shear strain rate. By using this method the judgment range of locations of strong earthquakes could be reduced. Finally, we pointed out the strong earthquake risk areas for the next 10 years or longer period.