1. Key Laboratory of Geo-detection (China University of Geosciences, Beijing); Ministry of Education; Beijing 100083 China
2. China University of Geosciences; State Key Laboratory of Geological Processes and Mineral Resources; Beijing 100083 China
3. School of Geophysics and Information Technology; China University of Geosciences; Beijing 100083 China
4. Center for Earthquake Research and Information; University of Memphis; Memphis 38152 USA